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https://science.feedback.org/review/pyramid-shaped-peaks-antarctica-naturally-carved-by-glaciers-not-constructed-by-ancient-civilization/

Inaccurate

Facebook, YouTube, TikTok, X/Twitter, 2024-03-20

Ancient civilizations once inhabited Antarctica, as shown by the pyramids there, but the continent’s position and climate rapidly changed due to ‘tectonics and pole shift’.

Factually inaccurate: There is no evidence of ancient civilizations or pyramids in Antarctica. The pyramid-shaped landform shown in recent social media videos is called a ‘horn’ or ‘pyramidal peak’ and forms naturally as glaciers carve (i.e., erode) different rock faces. There is also no evidence for a rapid shift in the climate or position of Antarctica on Earth; studies show that Antarctica slowly drifted over millions of years through tectonic plate movements.

The rocky pyramid-shaped feature in Antarctica is a natural landform called a ‘horn’ or ‘pyramidal peak’. These peaks form when three or four intersecting glaciers carve out mountain faces in different directions, thus making a horn or pyramidal shape. They are common in Antarctica and found in many other places on Earth. Scientific evidence shows that Antarctica slowly drifted to its current position over millions of years through tectonic plate movement; not a sudden shift of the poles or crust.

Thawing ice in Antarctica is revealing pyramids and other remnants of an ancient civilization. Antarctica quickly moved across Earth into its current position through plate tectonics and pole shift, causing Antarctica’s surface to flash-freeze.

1- Hess (2016) McKnight’s Physical Geography: A Landscape Appreciation. 2 – Sugden et al. (2017) The million-year evolution of the glacial trimline in the southernmost Ellsworth Mountains, Antarctica. Earth and Planetary Science Letters. 3 – Palin and Santosh (2021) Plate tectonics: What, where, why, and when?. Gondwana Research. 4 – Zahirovic et al. (2015) Tectonic speed limits from plate kinematic reconstructions. Earth and Planetary Science Letters. 5 – Kulakov et al. (2021) Jurassic fast polar shift rejected by a new high-quality paleomagnetic pole from southwest Greenland. Gondwana Research. 6 – Moulin et al. (2011) An attempt to constrain the age, duration, and eruptive history of the Karoo flood basalt: Naude’s Nek section (South Africa). Journal of Geophysical Research: Solid Earth. 7 – Svensen (2018) Gondwana Large Igneous Provinces: plate reconstructions, volcanic basins and sill volumes. Geological Society, London, Special Publications.

On 20 March 2024, a video on YouTube claimed that ‘Antarctica has pyramids from an ancient civilization’, and that ‘the continent’s surface flash-froze as it rapidly shifted on Earth‘. This video has gathered over 3.4 million views, and in recent months it has been clipped and shared on TikTok, Facebook, and X/Twitter. A quick search on TikTok turns up many of these clips and dozens of similar videos speculating about these alleged ‘pyramids’ and the history of Antarctica. Keys to Antarctica’s geologic past do peek from the ice and lay buried below – but regarding social media claims, what does the scientific evidence show? Pyramid-shaped landform in Antarctica is called a ‘horn’ and is formed through glacial erosion; similar peaks are found around the world A pyramid-shaped mountain (Figure 1) in Antarctica has sparked speculation among social media users who are sharing claims that it is not natural, but rather a pyramid built by an ancient civilization. Although the mountain does have some visual similarities to a pyramid – e.g., having a peak and four sides – there are several clues and lines of evidence indicating that this is a natural mountain peak, as we will detail below. Figure 1 – Unnamed horn located in Antarctica at 79°58’38″S 81°57’44″W (view here). Source: Google Earth screenshot Although this mountain is particularly pyramidal, the shape itself is not rare. Peaks with similar shapes exist around the world and geologists have studied these to understand the natural processes that form them – a field of study called geomorphology. Geologists refer to these types of peaks as ‘horns’ – examples include the famous ‘Matterhorn’ in Switzerland, and the lesser known ‘Alpamayo’ mountain in Peru (Figure 2). Figure 2 – Examples of glacially carved horns: Alpamayo mountain, Peru (left) and the Matterhorn mountain, Switzerland (right). Source: Pexels and Frank R/Wikimedia.org As described in the United States Geological Survey Glossary of Glacier Terminology, horns are “a pointed, mountain peak, typically pyramidal in shape, bounded by the walls of three or more cirques . . . when a peak has four symmetrical faces, it is called a Matterhorn”. Cirques are hollow areas carved into mountains as glaciers move downward and erode (i.e., remove) underlying rock[1]. The intersection of multiple cirques leaves behind a peak (i.e., horn) connected to 3 or 4 ridges – marking the outer boundaries of where the glaciers eroded, as shown in Figure 3 below. Figure 3 – Diagram showing horns, their ridges (i.e., arete), and cirques (i.e., hollowed out areas carved by glaciers). Vertical lines along the faces of the horns represent steep areas resulting from glacial erosion. Source: Illustrated Glossary of Alpine Glacial Landforms: Karen A. Lemke, University of Wisconsin-Stevens Point There is clear evidence of past glacial erosion in this region of Antarctica[2]; however, in some areas, snow and ice cover many of the lower landscape features that make this more apparent. Note that the examples in Figure 2, which are not covered by ice sheets, show less of a pyramidal shape near the base of these mountains. However, the pyramidal peak (Figure 1) shown in social media videos is largely covered in snow and ice, covering many of the landscape features near its base that would likely make it easier to identify as a glacial horn. For this reason, sometimes other observations and information must be gathered from the surroundings to characterize geologic features. This is something that we discussed in a similar past Science Feedback review, linked here. So what do the surroundings tell us? The horn-formation process we described above occurs in cold, glaciated environments, such that of the Ellsworth Mountains of Antarctica where the pyramidal horn is located. Thus, its location matches the environment where this type of peak forms. In fact, this process of glacial erosion is common in Antarctica as evidenced by the number of horns and pyramidal peaks nearby (Figures 4-6). Many pyramidal peaks are documented in a report titled “Geographic Names of the Antarctic” including Abbott Peak, Achilles Mountain, and several others. Figure 4 – A semi-pyramid shaped mountain peak located 9.5 kilometers east-southeast of the mountain shown in Figure 1. Note that with increased snow coverage, this mountain could also appear somewhat pyramid-shaped given the four evenly spaced ridges meeting at a point. Source: Google Earth screenshot Figure 5 – Another pyramidal mountain peak located roughly 230 kilometers north-northwest of the mountain shown in Figure 1. Note that it has a similar pyramid shape, but the snow cover and surrounding ridges in this area makes it clear that this is a mountain that is connected to other peaks and ridges (i.e., not an isolated feature). Source: Google Earth screenshot Figure 6 – Photo of a pyramidal peak near the Princess Elisabeth Station (polar research station). Note the concave eroded faces of the horn, curved ridges, and uniformity of the rock (i.e., no cut blocks, as seen in pyramids), showing evidence of its natural origin and glacial erosion features labeled in Figure 3. Source: International Polar Foundation – René Robert Overall, the peak’s physical characteristics, surrounding glacial environment, and proximity to a number of other pyramidal peaks with similar patterns of glacial erosion, is strong evidence that the pyramidal feature shown in viral social media videos is a natural mountain peak – called a pyramidal peak or horn – formed over time through glacial erosion. Additionally, there is no record of an ancient civilization or any constructed pyramids in Antarctica, which has been surveyed since the early 1900s. Antarctica slowly moved to its current position over millions of years; no evidence of rapid shift A number of viral clips on social media feature Billy Carson speculating about Antarctica’s past. In these videos, Carson claims that ‘Antarctica quickly shifted into its current position on Earth through tectonics and sudden crustal pole shift’. Carson suggests that these two concepts somehow work together; however, they are actually incompatible and only one of them – plate tectonics – is supported by scientific evidence and widely accepted by geology experts[3], as detailed below. As described in Palin and Santosh (2021), “the theory of plate tectonics is widely accepted by scientists and provides a robust framework with which to describe and predict the behavior of Earth’s rigid outer shell – the lithosphere – in space and time”[3]. This well-accepted theory explains that Earth’s outer shell is broken up into different tectonic plates, like a giant jigsaw puzzle (Figure 7), which move around very slowly – i.e., a few centimeters per year[4], or as the USGS explains, roughly at the same rate that your fingernails grow. Figure 7 – Earth’s tectonics plates and continents that overlie them. Source: United States Geological Survey (USGS) Over millions of years, they can carry their overlying continents to different positions on Earth’s surface, and thus sometimes to different climates. Together, these concepts describe the widely accepted theories of plate tectonics and continental drift. In conjunction with past climate variations, these concepts help explain why icy regions (e.g., Antarctica) show geologic evidence of different conditions in their past (e.g., being in warmer climates). Contrary to the universally accepted theories above, some have speculated a ‘cataclysmic pole shift’, caused these climate changes due to rapid shifts in Earth’s crust and poles. However, this does not match the scientific evidence. For example, researchers have studied past shifts in Earth’s poles spanning 160 million years and they explain that the evidence does not support the ‘rapid’ or ‘massive’ polar shift being claimed[5]. Scientific evidence also does not support a rapid shift in Antarctica’s position – a claim suggested in social media videos. Instead, evidence shows that Antarctica began slowly moving to its current position roughly 182 million years ago[6,7]. At that time it was part of a larger supercontinent called Gondwana (Figure 8) – which also included land that we now call South America, Africa, Madagascar, India, Western Australia, and Arabia[7]. To emphasize how slow this transition was, it’s worth noting that East Antarctica and Australia only split from each other around 85 million years ago[7] – 97 million years after Antarctica began separating from Gondwana. Figure 8 – Evolution of Earth’s continents from 250 million years ago to present day. Note that Antarctica was closer to the equator prior to the breakup of Gondwana (or ‘Gondwanaland’) roughly 182 million years ago[6,7], after which it slowly drifted to the south pole over millions of years. Source: USGS Conclusion: There is no evidence of an ancient civilization, nor any pyramids in Antarctica, contrary to claims from viral videos on social media. There are, however, several pyramid or semi-pyramid shaped mountains called ‘horns’ or ‘pyramidal peaks’, which form through glacial erosion. These peaks are well-documented in Antarctica and many other glaciated areas around the world, such as Switzerland and Peru. Contrary to other claims made in these videos, Antarctica did not experience a sudden change in climate due to a sudden shift in the poles or Antarctica’s position on Earth. Scientific evidence shows that Antarctica slowly drifted to its current position over millions of years through tectonic plate movement.

https://science.feedback.org/review/sea-levels-have-risen-for-over-100-years-despite-misleading-photos-social-media/

Inaccurate

Facebook, 2024-06-06

Sea-level rise is not occurring or showing any impacts, based on photographic evidence.

Inaccurate: Scientific evidence unambiguously shows rising sea levels based on measurements of global mean sea level and tidal gauge data, even the ones collected near the locations from social media posts claiming that ‘sea level is not rising’. Misleading: It is misleading to show ‘before and after’ photos from select locations without proper context (e.g., tidal conditions) or an appropriate scale (i.e., one in which the sea level rise that has been reported at these locations could be reasonably seen).

Scientists have shown that global mean sea level has risen since the year 1880 by analyzing sea-level data from tidal gauges and satellites. Relative sea level rise – which is measured at a local or regional scale – can vary due to Earth’s shape and ocean dynamics. However, the data collected from the locations shown in ‘before and after’ posts on social media also show evidence of sea level rise. Certain locations around the world are more strongly impacted by the effects of rising sea levels.

There is no evidence of sea-level rise in before and after photos (i.e., from the past and present) from some locations. Therefore, sea-level rise is not occurring or causing negative impacts.

1 – Church et al. (2011) Sea-level rise from the late 19th to the early 21st Century. Surveys in Geophysics. 2 – Rovere et al. (2016) Eustatic and Relative Sea Level Changes. Current Climate Change Reports. 3 – Slangen et al. (2016) Anthropogenic forcing dominates global mean sea-level rise since 1970. Nature Climate Change. 4 – Horton et al. (2018) Mapping Sea-Level Change in Time, Space, and Probability. Annual Review: of Environment and Resources. 5 – IPCC (2019) Special Report on the Ocean and Cryosphere in a Changing Climate.

Several social media posts have gone viral after sharing ‘before and after’ photos from the past and present to claim that sea-level rise has not occurred. For example, a number of these posts show photos of Sugarloaf Mountain in Brazil, labeled with the years 1880, 1910, and 2020 and captions claiming that sea level is not rising. One such post on Facebook, linked here, has been shared thousands of times. Below we will investigate these claims using scientific evidence, and explore how scientists measure sea-level rise. Scientists determine sea-level rise by collecting and analyzing data, not by comparing a few photos Before investigating the evidence, we will first explain why these viral posts are highly flawed in their ‘method’ of assessing sea-level rise. These posts claim that sea level has not risen based on photos taken at certain locations in different years; examples of which are shown in Figure 1. Figure 1 – Examples of locations shown in social media posts claiming that ‘sea levels have not risen’. The two top left photos are of Fort Denison in Sydney Harbour; the two bottom left photos are of the Statue of Liberty in New York City; and the two photos on the right half of the figure are of Sugarloaf Mountain in Brazil. Source: social media screen captures However, using these photos for comparison is flawed because they are missing critical details and context. There are a number of variables that affect sea level; one of the most important in this case is tidal conditions. Even if two photos are taken at the exact same location on the same day, the sea level at that location will be different at low and high tide (i.e., at different times of the day). As explained by the National Oceanic and Atmospheric Administration (NOAA), tides are changes in sea level that are caused by the gravitational pull on our oceans by the Earth, Moon, and Sun. These forces cause the oceans to bulge outward, roughly in line with the moon, and dip inward at a right angle to this line (Figure 2). Figure 2 – Diagram showing tidal bulge as a result of net gravitational pull on Earth’s oceans. Note that these bulges are exaggerated for visualization purposes, and that as a coastline passes through a bulge, its respective landmass (e.g., continent) has a much higher elevation than the rise in sea-level – and thus does not become fully submerged by the rising oceans. But instead, it experiences a high tide. Adapted from the following source: NASA/Vi Nguyen Because Earth rotates over a 24 hour period, sea-levels change throughout the day as both landmasses and oceans collectively move through these bulge and dip zones. This causes alternating high and low tides every 6 hours. The difference in sea level at low and high tide depends on the position of the Moon. For example, NOAA explains that “the greatest difference in height occurs around new and full moons, 6.27 ft. (1.91 m) and 7.18 ft. (2.19 m) respectively”. An example of sea-level fluctuations over days to weeks with different tides is shown in Figure 3 below. For a more in-depth explanation and visualization of how tides work, see the link here. Figure 3 – Sea-level fluctuations in Santa Barbara, California, over days to weeks. Days are shown on the x-axis and average/mean sea-level height (MSL) in feet is shown on the y-axis. The moon phases are shown above the graph, with the corresponding differences in high and low tide elevations shown directly below them. Note that the largest differences occur during a new moon and a full moon. Source: NOAA Because of the processes described above, it is flawed to compare sea level in two different photos without knowing the date and time, and thus the tidal conditions when they were taken. Hypothetically, an older photo could be taken at a high tide and a newer photo taken at a low tide, disguising the sea-level change occurring between those years. However, even with more context for the photos, there is still another major flaw with this method; they collected no actual measurements, and there is no appropriate scale in the photos. For example, in one of the claim-making posts they show photos of the ocean below a landmark called Sugarloaf Mountain, with a peak of 396 meters (1,299 feet) located in Rio de Janeiro. However, there is no scientific consensus that this landmark, or the others shown in these posts, should show visual changes due to sea level rise that occurred between the photo dates. Over the alleged time period shown in the photos of 1880-2020, global mean sea level (GMSL) has risen roughly 21–24 centimeters (8-9 inches), according to NOAA (Figure 4). However, based on Google Earth measurements, the photo was taken at a distance that shows nearly a 2 kilometer stretch of land – a scale that does not match the magnitude of sea-level rise in this period. Figure 4 – Global average absolute sea-level change (in inches) from 1880-2021, based on tidal gauge measurements (orange line) and recent satellite measurements (blue line). Note that ‘absolute’ sea-level change is used to represent the ocean’s surface, without regard to changes in nearby land elevation. Figure source: United States Environmental Protection Agency (EPA) with data from NOAA and CSIRO (2017)[1] It is also misleading to cherry pick a few locations (e.g., near Sugarloaf Mountain) to show the ‘impacts’ of sea-level rise, because sea-level rise and its effects vary by region. This is part of the reason scientists create flood vulnerability and exposure maps, like the one linked here. One reason for this variability is that steep areas are less susceptible to inundation (i.e., flooding from rising water) than low-lying areas. This occurs because water needs to rise higher to submerge high-elevation areas than does for areas of lower elevation. This is apparent on flatter beaches, for example, because at high tide the ocean moves much further inland than it does on steeper beaches. When scientists study sea-level rise, they do not rely on ‘before and after’ photographs from one location. Instead, they collect data from around the world and use it to observe trends. In doing so, they can measure sea-level rise more accurately, and avoid the uncertainty that comes with comparing photographs without adequate information and scale. So what does the evidence show when scientists properly collect and analyze sea-level data? Data from around the world shows that global mean sea-level has risen over the last century; some areas have risen more than others The social media posts actually make two claims – the explicit claim that sea level is not rising and the implied claim that it is not problematic, otherwise we should see visual evidence of impacts in photos of these locations. The reason these types of posts can convince viewers is that they simplify a complex topic. The underlying assumption in these posts, for example, is that ‘if sea level has risen, these locations – and by extension, all coastal areas – on Earth should show evidence of it in before and after photographs’. However, this disregards an important scientific observation: sea level does not rise at the same rate everywhere on Earth[2] – it is uneven and varies by location, as we will explain below. To evaluate how sea levels change over time, scientists evaluate trends in data from tide gauges and satellites. As shown in Figure 4 from the previous section, these data clearly show that global mean sea level has risen since 1880 – the earliest alleged date of the photos recently shared in these posts. If global mean sea level (i.e., overall sea level) has risen, and sea level does not rise at the same rate everywhere on Earth – what happens at a local or regional level? What changes should we see? That depends on the location. At a local level, some places are more vulnerable to the effects of sea-level rise than others. As we briefly explained earlier, one reason for this is that the terrain (e.g., flatness or steepness) of different areas can affect how ocean water moves inland during tidal changes. For this reason, a photo taken at low tide might show land exposed that would later be submerged in a photo taken at high tide. An example of this is shown in Figure 5 below. Note the difference in land exposure between the photos, which could be misleading without context about the tidal conditions when they were captured. Figure 5 – Photographs taken at high tide (left) and low tide (right) at the Bay of Fundy in Canada. Note that the land exposure changes between high tide and low tide. Source: NOAA SciJinks At a broader/regional scale, there are other physical processes that affect sea-level rise. As we mentioned, sea-level rise is not even – it does not rise in the intuitive way that water does in something like a bathtub. This is because at a planetary scale, there are many other factors at play. As explained by NASA, “The globally averaged trend toward rising sea levels masks deeper complexities. Regional effects cause sea levels to increase on some parts of the planet, decrease on others, and even to remain relatively flat in a few places.” They explain that two of the factors influencing uneven sea-level rise at a regional level are ocean dynamics (i.e., redistribution of water mass by currents, wind, etc.) and varying gravitational strength. They explain that “because the distribution of Earth’s mass is uneven, Earth’s gravity is also uneven. Therefore, the ocean’s surface isn’t actually a perfect sphere or ellipsoid; it is a bumpy surface” (Figure 6). Figure 6 – Visualization of Earth’s gravitational field showing regions with red showing areas where gravity is stronger, blue where gravity is weaker, and a spectrum between. Source: NASA with data from University of Texas Center for Space ResearchDespite local and regional variability, several individual locations – such as those shown in the social media post photos – do in fact show sea-level rise based on tidal gauge data. For example, one of the locations discussed earlier – Sugarloaf Mountain (Figure 1) – that was shared in the posts has nearby sea-level measurements from 1963-2016, which show that sea level rose 12.6 centimeters (4.5 inches) in that period. Another location shown in these posts is Sydney Harbour (Figure 1). Science Feedback has already addressed claims regarding sea-level rise at this location in a previous review, linked here. The results of that review are well-summarized in a quote provided to Science Feedback by Dr. Thomas Frederikse, Postdoctoral researcher at the Jet Propulsion Laboratory/California Institute of Technology: “At Fort Denison, which is the building in the picture [Figure 1], we have two long tide gauge records. One that covered 1886-1993, and one that started in 1915 and is still measuring today. I’ve plotted both individual records and the average of them. Both the records clearly show that sea level is rising in Sydney, and that the rate of the rise is increasing.” A third location from these social media posts is the Statue of Liberty in New York City (Figure 1). As with the other examples, this location also shows a clear rise in sea level; from 1856-2023 the sea level in this area rose by roughly 49.1 centimeters (19.33 inches) (Figure 7). Figure 7 – Relative sea level trend based on data from 1856-2023 at The Battery in New York (close to the Statue of Liberty). Source: NOAA In summary, all three locations above – which are commonly used in social media posts to claim sea levels have not risen – show clear evidence of sea-level rise. In addition, previous Science Feedback reviews have also found evidence that global mean sea level rise is speeding up. As explained in a review from 2021 linked here: while land mass movements and ocean circulation patterns influence sea levels, human-induced climate change is accelerating the rate of sea level rise[3]. This point is also summarized in a 2018 paper by Horton et al.: “a large portion of the twentieth-century rise, including most GMSL rise over the past quarter of the twentieth century, is tied to anthropogenic warming”[4]. The Intergovernmental Panel on Climate Change (IPCC) – the world’s leading authority on climate science – explains that “as a consequence of natural and anthropogenic changes in the climate system, sea level changes are occurring on temporal and spatial scales that threaten coastal communities, cities, and low-lying islands”[5].They also explain that “coastal ecosystems are already impacted by the combination of SLR [sea-level rise], other climate-related ocean changes, and adverse effects from human activities on ocean and land”[5]. Conclusion: Scientists have shown that global mean sea level has risen since the year 1880 by analyzing data from tidal gauges and satellites. Relative sea level rise – that which is measured at a local or regional scale – can vary due to Earth’s shape and ocean dynamics. However, contrary to claims from social media users, even the locations from photos on their posts show rising sea levels based on tidal gauge measurements. Social media posts comparing ‘before and after’ photos of cherry-picked locations to ‘assess’ sea-level rise are flawed because they are missing important details about tidal conditions, scale, and context about how sea levels are measured and vary across Earth. Additionally, implying that there are no impacts is inaccurate because evidence shows that rising sea levels have already caused negative impacts (e.g., to coastal ecosystems).

https://science.feedback.org/review/colorful-auroras-seen-may-2024-caused-by-mass-ejections-from-sun-not-haarp-experiments/

Incorrect

Facebook, YouTube, TikTok, X/Twitter, 2024-05-11

May 2024 auroras were caused by experiments from High-frequency Active Auroral Research Program (HAARP) experiments

The origin of auroras in Earth’s atmosphere is well-studied and occur as solar winds and ejections of magnetized plasma from the Sun approach Earth and interact with our planet’s magnetic field. HAARP is incapable of producing the auroras that were observed because their power output is orders of magnitude less than would be necessary to do so.

The High-frequency Active Auroral Research Program (HAARP) is a research facility that uses a high-power, high-frequency transmitter to study the physical properties and behavior of the highest point of the atmosphere, the ionosphere. Radio transmissions from HAARP only cause small effects in the ionosphere that last for a brief span of a few seconds. HAARP is incapable of causing the magnitude of aurora effects witnessed in May 2024; evidence shows these effects were caused by mass ejections of magnetized plasma from the Sun.

The vivid lights seen around the world on May 10 2024 were artificial aurora effects caused by High-frequency Active Auroral Research Program (HAARP) experiments, not by a geomagnetic storm.

1 – McCoy et al. (2018) Haarp, a Powerful Active Ionospheric Laboratory Open for International Research. 42nd COSPAR Scientific Assembly. 14-22 July 2018, Pasadena, California, USA 2 – Todd Pedersen (2015) HAARP, the most powerful ionosphere heater on Earth. Physics Today. 3– Inan et al. (2004) Multi‐hop whistler‐mode ELF/VLF signals and triggered emissions excited by the HAARP HF heater. Geophysical Research Letters. 4 – Piddyachiy et al. (2011) DEMETER observations of the ionospheric trough over HAARP in relation to HF heating experiments. Journal of Geophysical Research: Space Physics.

On 10 May 2024, solar eruptions caused a several-day geomagnetic storm on Earth, causing a vivid display of colors, called auroras, which were witnessed in skies around the globe. This natural event coincided with experiments by the High-frequency Active Auroral Research Program (HAARP), which triggered dozens of social media users to claim that these experiments were responsible for the widely-seen aurora effects. As of the publication date for this article, one YouTube video gathered over 270K views after discussing some of the claims people are making about HAARP’s connection to the recent auroras. We will investigate the main claims below and explore the scientific evidence for the cause of the recent auroras. Colorful auroras appeared across the globe in May 2024 due to asolar storm that scientists warned about Although the recent auroras were exceptionally wide-spread and a surprise to most who saw them, their presence was not a mystery to scientists. Scientists have long known that certain types of solar activity lead to aurora effects in Earth’s atmosphere. The most well-known example of this phenomenon is the aurora borealis (i.e., the northern lights), which have been documented for centuries – long before the establishment of HAARP in 1990. Auroras are caused by the interactions between solar winds and Earth’s magnetic field (i.e., magnetosphere) which protects our planet, as shown in Figure 1 below. These solar winds contain a plasma of electrically charged particles which interact with Earth’s magnetic field, accelerating electrons along its magnetic field lines (blue lines in Figure 1) which then bombard and energize molecules in Earth’s atmosphere causing them to glow and form auroras. Figure 1 – Simplified illustration (not to scale) showing solar wind (orange arrows) interacting with Earth’s magnetic field (blue) which causes the aurora borealis in a region called the ‘auroral oval (green). Source: Tromsø Geophysical Observatory (TGO) The northern lights are a more regular occurrence in the auroral oval due to the interactions described above and geometry shown in Figure 2 below; however, the Sun occasionally has increased activity (e.g., solar storms) which leads to greater visibility of auroras from other places on Earth, as witnessed on 10-11 May 2024. Figure 2 – Location of the auroral oval (green) where the northern lights are commonly seen. This region can vary with changes in solar winds, which accelerate electrons along the magnetic field lines (thin lines shown above) and down to Earth’s atmosphere where they excite molecules which glow and form auroras. Source: NOAA On 9 May 2024, the National Oceanic And Atmospheric Administration (NOAA) issued a Severe (G4) Geomagnetic Storm Watch due to a series of solar flares and coronal mass ejections (CMEs) that began the day prior. One of the solar flares from sunspot ‘AR3664’ was observed by NOAA’s GOES-16 satellite on 9 May 2024, as shown around the four second mark in the video linked here, and shown in the ‘after’ photo of Figure 3 below as a bright flash of light on the lower right. Figure 3 – Solar flare from sunspot ‘AR3664’ observed by NOAA’s GOES-16 satellite on 9 May 2024. Images screen-captured from NOAA’s GOES-16 video footage, with the before photo (left) captured seconds before the after photo (right). Source: NOAA’s Space Weather Prediction Center (SWPC) NOAA later shared an X/Twitter post explaining that the geomagnetic storms reached level G5 – the highest in the scale from 1-5 – which last occurred in 2003. This solar storm originated from a cluster of sunspots that is roughly 17 times the diameter of Earth, which spewed magnetized plasma that hurtled towards Earth at ~1,800 kilometers/second. Once reaching Earth’s magnetic field, this resulted in an aurora that could be seen from areas on Earth where it is normally not possible. Based on this evidence, we can confidently conclude that a solar storm was responsible for the auroras witnessed around the world on 10-11 May 2024. However, as we noted earlier, dozens of social media posts claimed that HAARP experiments were the cause of these auroras. Examples of these posts can be found in the following links: X/Twitter post, TikTok video 1, TikTok video 2, Facebook post. Below we will explore what HAARP is and the experiments they were conducting. No evidence that the HAARP experiments were related to the auroras observed in May 2024 A press release from HAARP was posted on 13 May 2024, explaining that “the HAARP scientific experiments were in no way linked to the solar storm or high auroral activity seen around the globe”. But what is HAARP and what experiments did they recently conduct? HAARP is a research facility operated by the University of Alaska Fairbanks[1]. It transmits high-frequency radio signals into the highest point of the atmosphere, the ionosphere, using 360 radio transmitters and 180 antennas. The facility covers about 14 hectares (0.14 kilometers squared) near the town of Gakona, Alaska, which is about 250 kilometers northeast of Anchorage, Alaska’s largest city. The radio signals are partially absorbed between 100 kilometers and 350 kilometers in altitude, accelerating electrons in the ionosphere and briefly “heating” it up[2]. By analyzing how radio waves interact with electrons in the ionosphere[3,4], researchers at HAARP are able to study phenomena, such as the effects of the aurora borealis (i.e., northern lights) on radio systems and aircraft communications at high altitudes. The experiments that HAARP conducted between 8-10 May 2024 “supported research proposals from the University of Alaska Fairbanks to study mechanisms for the detection of orbiting space debris”. They explain that these experiments were conducted to help improve collision detection for satellites, and were scheduled roughly a month and a half ahead of the geomagnetic storm. As they HAARP explains in their press release, “the timing was purely coincidental; geomagnetic storms are unpredictable, with lead times before a solar event is detected from Earth measured in minutes, not months”. Beyond the fact that the HAARP experiments were unrelated to the observed auroras in May 2024, the HAARP instruments are also incapable of producing those effects. The maximum radiative power of HAARP’s antennas is 3.6 megawatts[2], whereas a strong geomagnetic storm – such as that observed on 10-11 May 2024 – inputs upwards of 100 gigawatts of power into Earth’s magnetosphere and ionosphere (i.e., the study area of HAARP experiments). This means that the power received from the geomagnetic storm was 10,000 times greater than HAARP’s maximum power output. In a similar explanation from HAARP, they note: “interestingly, coronal mass ejections, like the one associated with the recent geomagnetic storm, typically release more than 10^24 Joules of energy. By comparison, the high- frequency (HF) transmitter at HAARP is only a ~3 megawatt (MW) transmitter; it would take HAARP over 10 billion years to produce enough energy to affect this naturally occurring phenomenon”. Science Feedback has covered the limitations of HAARP’s capabilities in previous claim reviews – an example is linked here. Conclusion: In summary, there is conclusive evidence that the aurora observed around the globe on 10-11 May 2024 was caused by a solar storm that began erupting from the Sun on 8 May 2024. The claims attributing the auroras to HAARP experiments that coincided with this event are simply incorrect. As explained above, not only is HAARP incapable of producing the observed auroras from its limited power output, but the experiments – which were scheduled over a month in advance – were conducted to study space debris, unrelated to auroral effects.

https://science.feedback.org/review/no-evidence-significant-influence-volcanoes-solar-variability-on-recent-climate-change-contrary-judith-curry-claims-prageru-video/

Misleading

PragerU, Judith Curry, 2024-04-15

Climate scientists disagree about how much warming is associated with our emissions and whether this warming is larger than natural climate variability from the sun and volcanic eruptions

Misleading: Climate scientists have studied natural climate variability and the contribution of human CO2 emissions to recent climate changes. The resulting evidence unequivocally shows that anthropogenic CO2 emissions are the most significant driver of recent climate change, while natural variability has made a minimal contribution. Unsupported: There is no evidence to support that solar variability or volcanic activity have had a significant impact on recently rising global temperatures at multidecadal to century timescales. In fact, solar intensity is currently declining while global temperatures are rising.

Scientific evidence shows that modern global warming is primarily driven by increasing CO2 emissions from human activities. There is no evidence that solar variations or volcanic activity are substantial drivers of recent climate change.

Climate scientists disagree about how much warming is associated with our emissions and whether this warming is larger than natural climate variability; “Variations in the sun and volcanic eruptions also have a substantial impact [on Earth’s climate], but these are simply unpredictable”.

1 – IPCC (2021). Sixth Assessment Report. 2 – Zhong and Haigh (2013) The greenhouse effect and carbon dioxide. Royal Meteorological Society Weather. 3 – PAGES 2K Consortium (2019) Consistent multidecadal variability in global temperature reconstructions and simulations over the Common Era. Nature Geoscience. 4 – Le Quéré et al. (2016) Global Carbon Budget 2016. Earth System Science Data. 5 – Knapp et al. (2010) The International Best Track Archive for Climate Stewardship (IBTrACS): Unifying tropical cyclone best track data. Bulletin of the American Meteorological Society. 6 – Lean et al. (2020) Solar irradiance variability: Modeling the measurements. Earth and Space Science. 7 – Gerlach (2011) Volcanic Versus Anthropogenic Carbon Dioxide. American Geophysical Union EOS. 8 – Sully et al. (2019) A global analysis of coral bleaching over the past two decades. Nature. 9 – Vicedo-Cabrera et al. (2021) The burden of heat-related mortality attributable to recent human-induced climate change. Nature. 10 – Lüthi et al. (2023) Rapid increase in the risk of heat-related mortality. Nature. 11 – Ballester et al. (2023) Heat-related mortality in Europe during the summer of 2022. Nature. 12 – Hausfather et al (2019) Evaluating the Performance of Past Climate Model Projections. Geophysical Research Letters. 13 – Robock (2000). Volcanic eruptions and climate. Reviews of Geophysics. Note: Scientists comments were lightly edited for clarity (i.e., information was added in brackets for context and minor punctuation changes were made).

On 15 April 2024, PragerU posted a short video on their website and YouTube titled “The Good News about Climate Change”, which gathered over 500,000 views combined as of the publication date of this review. The video features a former professor, Dr. Judith Curry, who makes claims about the current state of climate change knowledge – the knowns and unknowns, agreements and disagreements. Below we will share our investigation of some of these claims using scientific evidence, followed by evaluations of these claims from scientists with relevant expertise. Recent rises in global temperatures are being driven by CO2 emissions from human activity; evidence shows that natural variability cannot account for these changes In the video, Curry attempts to summarize what climate scientists agree and disagree about on climate change. She claims that they agree on the following: “the average global surface temperature has increased over the last 150 years; humans are adding carbon dioxide to the atmosphere by burning fossil fuels; and, carbon dioxide emissions have a warming effect on the planet.” The claims above do in fact represent some, but not all, of the findings shared by the Intergovernmental Panel on Climate Change (IPCC), the world’s leading authority on climate science. This is an important distinction because it is misleading to imply that these are the only three things that climate scientists agree on – or, more accurately, that the scientific evidence unequivocally shows. For instance the IPCC also reports that “rising greenhouse gas concentrations are driving profound changes to the Earth system, including global warming, sea level rise, increases in climate and weather extremes, ocean acidification, and ecological shifts.”[1] It is well established among scientists that humans are adding carbon dioxide (CO2) to the atmosphere by burning fuels, and that CO2 has a warming effect on the planet through the greenhouse effect. While remaining in the atmosphere, CO2 prevents heat from escaping and consequently warms the surface of Earth – a concept that is popularly known as the greenhouse effect. This is a consequence of the properties of CO2, which allow sunlight to pass through to Earth’s surface, but cause CO2 to absorb and re-emit the energy that returns (i.e., infrared radiation emitted from Earth’s surface after absorbing sunlight)[2] . It is also well established that global mean surface temperature (GMST) has been rising for over 150 years, as shown in Figure 1 below. In the most recent year, 2023, the National Oceanic and Atmospheric Association (NOAA) reported that “The average global land and ocean surface temperature for January–December 2023 was 1.18°C (2.12°F) above the 20th century average of 13.9°C (57.0°F)—the highest global land and ocean temperature for January–December in the 1850–2023 record.” Figure 1 – Observed global mean surface temperatures from 1850 to 2020 using four data sets. The horizontal lines represent different time ranges and are annotated to show the rise in GMST in the respective time periods. Source: IPCC (2021)[1] Although Curry’s claims above about agreement amongst climate scientists are scientifically supported, that ceased to be the case in her following claim that climate scientists disagree about “how much warming is associated with our emissions” and “whether this warming is larger than natural climate variability”. “This is absolutely not true”, explained Dr. Ella Gilbert, Regional Climate Modeller at the British Antarctic Survey, “we know unequivocally that human activity is responsible for the vast majority of observed warming, and that natural factors make up a very small proportion of the changes seen in the last few centuries.” Climate scientists know this because they have investigated the impact of natural inputs (e.g., solar, volcanic, etc.) and human CO2 emissions on global temperatures, and have also compared modern temperature trends to natural variations. This allows scientists to determine the relative contributions of these inputs to global warming and determine how modern global warming compares to natural variability. As shown below in Figure 2, greenhouse gases overall cause the most global warming of all the climate change drivers, and CO2 causes the most global warming of all the greenhouse gases. Figure 2 – The contributions of different drivers to global warming from the present time period (2010-2019) relative to the time period of 1850-1900. The estimates of warming (red) and cooling (blue) from radiative forcing studies (panel (c)) are based on both direct emissions into the atmosphere and their effect, if any, on other climate drivers. Source: IPCC (2021)[1] Scientists have also investigated which physical properties control the climate system and have quantified their influence on global temperatures. By incorporating all these physical properties in global climate models, they have been able to simulate the climate from 1850 to present day. As shown in Figure 3 below, the simulation that only included natural variables (solar and volcanic) was unable to match observed global temperature changes over the period of 1850-2020. However, the addition of human drivers – such as CO2 emissions – lead to a much closer match between simulated and observed temperatures. These simulations also show that human greenhouse gas emissions are the only variable that can reproduce observed temperatures; other natural phenomena (i.e., solar and volcanic influences) fail to explain the recent rise in global temperatures. Figure 3 – Observed and simulated changes in global surface temperature from 1850 to 2020. The black line represents 170 years of observed data and is compared to Coupled Model Intercomparison Project Phase 6 (CMIP6) climate model simulations. The brown area represents the temperature response to both human and natural drivers and the green area to only natural drivers (solar and volcanic activity). Solid colored lines represent the averages, and the shaded areas represent the very likely range for the models. Source: IPCC (2021)[1] The figures above help explain how human inputs, such as greenhouse gas emissions, have driven recent global temperature changes. However, scientists have also compared these changes to natural variations over longer time periods. After analyzing data from the past 2000 years, studies have shown evidence that modern global warming trends are unusual compared to past variations over this period. For example, PAGES 2K Consortium (2019), explains that over the last 2000 years “the largest warming trends at timescales of 20 years and longer occur during the second half of the twentieth century, highlighting the unusual character of the warming in recent decades.”[3]As shown in Figure 4 below, the black line – representing modern instrumental temperature records – shows that recent temperatures have exceeded the upper range of natural (pre-industrial) warming rates of the last 2000 years. Figure 4 – 2000 years of global warming/cooling rates averaged across 51 years and based on paleoclimate records. Modern instrumental temperature records shown in black. Data sourced from Neukom et al. (2019) and PAGES 2k Consortium (2019). Source: University of Bern Note that the warming/cooling rates above are averaged across 51 years; evaluating trends at these timescales (20 years and longer) is important because, as the IPCC explains, “over periods of a couple of decades or less, natural climate variability can dominate the human induced surface warming trend.”[1] That is to say that natural variability has less of an effect at timescales of decades to centuries. So looking at longer time periods allows scientists to better understand how human activities are impacting warming trends, without the ‘noisy’ ups and downs in temperature data observed at shorter timescales. As explained by the IPCC, “over the entire historical period (1850–2019), natural variability is estimated to have caused between -0.23°C and +0.23°C of the observed surface warming of about 1.1°C. This means that either the majority, or all, of the warming has been driven by human activities, particularly emissions of greenhouse gases”[1]. To conclude, Curry’s claim is at odds with the science on this point. Scientific knowledge has demonstrated that the vast majority of the observed warming can only be explained by the forcing created by greenhouse gases added to the atmosphere by human activities. Regarding scientific agreement among climate scientists, Dr. Kerry Emanuel, Professor Emeritus of Atmospheric Science at the Massachusetts Institute of Technology, explained: “There is a widespread scientific consensus that a strong signal of global mean temperature increase has emerged from natural background variability and that it is not caused by other kinds of radiative forcing changes, such as solar output. Of course, as in all scientific endeavors, there is a minority dissent, but in this case that has been reduced to typical background noise levels.” Evidence shows that recent climate change is not being driven by solar variability or volcanoes Over the years, claims continue to pop up regarding the impacts of solar activity and volcanoes on climate change. Science Feedback has addressed many of these in several past reviews, and in each case – now including this film – the claims were inconsistent with available evidence. See examples of these claims in the past reviews linked below: Review: 1: The sun isn’t responsible for current climate change, contrary to claims in Suspicious0bservers YouTube video Review 2: Low solar activity has little effect on Earth’s climate, contrary to claim in The Sun Review 3: Claim that current climate change can be explained satisfactorily by natural cycles and volcanic activity does not have scientific support Review 4: Evidence greenhouse gasses cause global warming denied by Willie Soon in Tucker Carlson interview, resulting in mass social media climate misinformation Curry claims that “Variations in the sun and volcanic eruptions also have a substantial impact [on Earth’s climate], but these are simply unpredictable”. Although this matter has been partially addressed above by comparing natural and human climate drivers, we will further investigate below. To gain expert insight on this matter, we interviewed Dr. Ian Richardson, Principal Research Scientist at the University of Maryland, who studies the interplanetary environment between the Sun and the Earth. After reviewing Curry’s claim, Dr. Richardson commented: “The solar influence on climate appears to be small. Changes in the solar visible and infrared irradiance are only ~0.1%, so the effect is not ‘substantial’ and tracks the 11-year solar cycle, so in this sense the changes are not ‘unpredictable’.” Dr. Richardson’s comment above aligns with evidence found in past Science Feedback reviews on this subject. For example, one of the Science Feedback reviews linked above explains that the rate and magnitude of modern global warming is too high to be caused by solar variability. As shown in Figure 5 below, solar irradiance and global temperatures show opposing trends; solar irradiance has shown no net increase since 1950, but temperatures have continued to rise. If changes in solar activity were a primary driver of recent climate change, we would expect to see global temperatures decrease with total solar irradiance, but the opposite has occurred in recent times. Figure 5 – Comparison of the global surface temperature changes (red) and the Sun’s energy that Earth receives (yellow) in watts per square meter since 1880. One can see that since the 1960s, the global temperature and solar activity have varied in opposite directions. Source: NASA/JPL-Caltech Regarding volcanic influences on Earth’s climate, the IPCC explains that large volcanic eruptions can actually have a cooling effect, as they release small particles into the upper atmosphere which reflect sunlight[1]. However, these effects are short lived; “Volcanic eruptions can cool the climate by a few tenths of a degree for a couple of years, but this is only a short-term effect compared to the long-term warming by human greenhouse gas emissions”, explained Dr. Georg Feulner, Deputy Head of Research Department at Potsdam Institute For Climate Impact Research. He also commented that Curry’s claim “overemphasizes the role of the sun and volcanic eruptions”. Feulner’s comments can be viewed in more detail near the bottom of this review. As shown earlier in Figures 2 and 3, other drivers – such as CO2 emissions from human activities – have had a far greater impact on Earth’s climate in recent times. Volcanic eruptions can also increase atmospheric CO2; however, as explained by Tobias Fischer, Volcanologist and Professor at The University of New Mexico, “during a typical year, volcanic eruptions contribute only about 0.006% of the global anthropogenic CO2 flux. The average CO2 emission of a person living in the USA is about 16 tons of CO2 per year[4] . Therefore, in any given year volcanic eruptions produce only about as much CO2 as 130,000 Americans, or less than the population of Wyoming—the state with the lowest population in the US.” More on this topic can be found in this linked review. Conclusion: and Final Remarks As we have shown above, the claims that Curry makes about climate change drivers are misleading and unsupported. Although Curry accurately listed some (but not all) of the unequivocal climate science findings (e.g., CO2 warms the planet, burning fossil fuels releases CO2, and global temperatures have been rising for 150 years), it was phrased in a misleading way that suggests that those were the only solid findings. This excludes many unequivocal findings that are outlined in the IPCC Sixth Assessment Report, for example. Additionally, her characterization of the uncertainties (i.e., disagreements among climate scientists) does not align with available scientific evidence. The evidence shows that CO2 emissions from human activities are the primary driver of recent rising global temperatures, and there is no evidence that natural variability can account for these changes. On the contrary, natural climate drivers such as solar variability and volcanic activity, have made a minimal impact compared to CO2 emissions from human activities. The information included thus far has addressed the claims that could be investigated using only scientific evidence, without discussion of policy options – which moves into ‘opinion’ territory. For this reason, we have not discussed the underlying message in the video which suggests that “all things considered, planet Earth is doing fine” and that if we focus only on adapting to effects of climate change, there is reason to be optimistic. However, as explained by Richardson, “choosing between either trying to change climate by moving away from fossil fuels or “adapting” to the effects is a red herring. You can do both.” This is why climate scientists discuss climate hazards in terms of both vulnerability (e.g., lack of proper infrastructure) and exposure (e.g., changing climate conditions). The IPCC explains that “continued GHG [greenhouse gas] emissions will further affect all major climate system components, and many changes will be irreversible on centennial to millennial time scales.”[1] They also explain that the available adaptation options will decrease as global warming increases. This provides further reason to focus on both aspects of risk mitigation – reducing known drivers of climate change and improving infrastructure. Scientists’ Feedback: Kerry Emanuel Professor of Atmospheric Science, MIT:There is a widespread scientific consensus that a strong signal of global mean temperature increase has emerged from natural background variability and that it is not caused by other kinds of radiative forcing changes, such as solar output. Of course, as in all scientific endeavors, there is a minority dissent, but in this case that has been reduced to typical background noise levels. On the more consequential question of whether this has caused increases in certain kinds of natural hazards, such as wildfires and hurricanes, there is no general answer that covers them all and we have to look at each hazard in each region. Since the mid 1990s, North Atlantic tropical cyclone activity, including landfalling storms, have been at levels not seen in records going back to 1900, even though there was some elevation of activity in the 1930s as well as the 1950s and 60s. Only about one third of North Atlantic tropical cyclones affect the continental USA, so we have a problem seeing trends with such small numbers, but the decade of the 2000s far surpassed the 1930s in US landfalling hurricane power [based on IBTrACS data][5]. Ian Richardson Research Scientist, NASA/University of Maryland:[In the video, ] there’s a lot of “cherry-picking” of what are generally facts in themselves that are strung together to try to make the point that we shouldn’t move away from fossil fuels. e.g., the Lake Chad example appears to be an inexpert politician not taking account for what appears to be the actual cause of the lake failing and says nothing about the reality of climate change. The 97% “per capita” decrease in the effect of bad weather is a rather meaningless statistic since there has been a huge increase in the population – and hence also in the number of people that are likely to be impacted by such a weather event. Choosing between either trying to change climate by moving away from fossil fuels or “adapting” to the effects is a red herring. You can do both. And it’s only practical to adapt so far. For instance, you can build sea walls, but not everywhere (and how do you choose where? – that’s an economic/political decision that may not be available to poor low-lying countries) and it’s not feasible to keep adding height as sea levels rise. Similarly for controlling water resources which are finite and subject to the effects of climate change. Any models used in science are imperfect but that doesn’t mean that they can’t provide insight and guidance and should be dismissed. Specifically, they may not include solar and volcanic effects because they are assessed to be unimportant. The solar influence on climate appears to be small. Changes in the solar visible and infrared irradiance are only ~0.1%, so the effect is not “substantial” and tracks the 11-year solar cycle, so in this sense the changes are not “unpredictable”. The irradiance has also declined since around 1980 as a result of the ~100 year Gleissberg cycle, whereas global temperature has risen during this time. Solar activity is somewhat “unpredictable” on short timescales[6] (days/weeks) and there is debate about whether for example variations in solar X-rays, ultraviolet radiation and energetic particles can influence the atmosphere and ionosphere on such timescales, but that’s confusing weather with long-term climate variability. Volcanoes are clearly unpredictable. There’s a useful summary at USGS [US Geological Survey]. The main issues with respect to climate change appear to be emissions of sulfur dioxide, which tends to cause atmospheric cooling, and carbon dioxide, which contributes to heating. However, the CO2 contributed by even large volcanoes is small compared to annual (2010) anthropogenic CO2, which is equivalent to 3500 Mount St. Helen’s or 700 Pinatubo eruptions and that volcanos add less than 1 percent of that produced by human activities[7]. Ella Gilbert Research Scientist, British Antarctic Survey:1. Curry’s claim: Climate scientists disagree about the most consequential issues: how much warming is associated with our emissions, and whether this warming is larger than natural climate variability. This is absolutely not true. We know unequivocally that human activity is responsible for the vast majority of observed warming, and that natural factors make up a very small proportion of the changes seen in the last few centuries. For example, the IPCC’s most recent report (AR6) contains the following in its working group 1 report summary for policymakers (section A1.3): “It is likely that well-mixed GHGs contributed a warming of 1.0°C to 2.0°C, other human drivers (principally aerosols) contributed a cooling of 0.0°C to 0.8°C, natural drivers changed global surface temperature by –0.1°C to +0.1°C, and internal variability changed it by –0.2°C to +0.2°C.”[1] i.e. that the contribution of natural factors to warming is *at very least* ten times smaller than that of greenhouse gases, and possibly very much smaller. The impact of natural drivers may not even be causing warming at all[1]. 2.Curry’s claim: “For the past 50 years, the global climate has been fairly benign. In the US, the worst heat waves, droughts, and hurricane landfalls occurred in the 1930s—much worse than anything we’ve experienced so far in the 21st century.” Climate change has been shown to increase the severity and intensity of extreme events such as wildfires, floods and heatwaves (IPCC, 2021). These kinds of events threaten ecosystems (for instance causing mass coral bleaching events, as have been reported recently[8] – see, e.g. Sully et al. 2019) and carry extreme risk to peoples’ lives (Vicedo-Cabrera, 2021; Lüthi et al., 2023)[9,10] – e.g. 70,000 people died in Europe during the heatwave of 2003 and more than 60,000 died in 2022’s European heatwave (Ballester et al., 2023)[11]. Extremes also threaten livelihoods, especially those based on agriculture and natural resource use. That the impacts of individual extreme events are now generally lower than in the 1930s is due to the fact that we are more prepared and have better tools to adapt and plan for extremes. Besides, people are less vulnerable in other ways (thanks to e.g. better health, fewer labour-intensive outdoor jobs and greater economic support), which means the death toll and losses associated with e.g. droughts, wildfires, heatwaves are lower. 3. Far from being “unreliable” and based on incorrect “assumptions”, models are actually very good at making predictions – Hausfather et al. (2019) shows how well even the oldest, simplest models have performed compared to observed climate change[12]. We *can* predict the big picture of climate change (and do so very successfully) – it’s the regional and small-scale changes that are less easy to predict. Georg Feulner Senior Scientist, Potsdam Institute for Climate Impact Research (PIK): Curry’s claim: Climate scientists disagree about the most consequential issues: how much warming is associated with our emissions, and whether this warming is larger than natural climate variability The first part of this statement is misleading, the second part is just wrong. Concerning the first part, the amount of warming associated with emissions is characterized by the climate sensitivity, i.e. the long-term warming after a doubling of the carbon-dioxide levels above pre-industrial concentrations. The latest IPCC assessment puts the climate sensitivity in a likely range of 2.5 to 4 degrees (high confidence)[1], so while we do not know precisely how much Earth will warm under continuing emissions, we are sure that it will warm. Concerning the second part of the statement, the warming already observed in the instrumental record has left the range of natural climate variability. Curry’s claim: “Variations in the sun and volcanic eruptions also have a substantial impact [on Earth’s climate], but these are simply unpredictable” – This statement overemphasizes the role of the sun and volcanic eruptions. Solar variability leads to fluctuations of Earth’s global mean surface temperature of about 0.1 degrees, compared to about 1.3 degrees of warming since the pre-industrial era. Volcanic eruptions can cool the climate by a few tenths of a degree for a couple of years[13], but this is only a short-term effect compared to the long-term warming by human greenhouse gas emissions. And the fact that we cannot predict the future behavior of the sun and volcanoes does not imply that we cannot include their effect in a statistical sense in future projections – in which the temperature change is dominated by human emissions in any case. Comments on other statements in the video: Curry’s claim: “inadequate climate models driven by unrealistic assumptions” Climate models are constantly improved and extensively validated against present-day observations and past climate change. They are based on our best knowledge of the physical, chemical, and biological processes in the Earth system and driven by measured (or reconstructed) input data (e.g. on greenhouse gas concentrations) in the past, and scenarios for future emissions for projections. While the models are not perfect (they would not be models, then), they provide important information about future climate change. Climate scientists typically compare the projections of many models to be able to assess robustness and quantify model uncertainty. On the Lake Chad example – one very specific counterexample of environmental change not caused by climate change does not disprove the multitude of expected negative climate change impacts around the world.

https://science.feedback.org/review/carbon-isotopes-do-not-show-humans-climate-impacts-too-small-notice-despite-the-daily-sceptic-inaccurate-claim/

Incorrect

Daily Sceptic, Chris Morrison, 2024-04-08

Human-caused carbon emissions’ effect on climate is ‘non-discernible’. Measurements of carbon isotope ratios in atmospheric CO2 indicate that it is the recent expansion of a more productive biosphere that has led to increased CO2 concentrations in the atmosphere.

Incorrect: Scientific studies demonstrate that fossil fuel emissions are the only cause that can explain both changes in carbon isotope ratios and increased CO2 concentrations in the atmosphere. Cherry-picking: The article supports its claim with only two papers while ignoring the vast body of existing evidence that disproves it. The two papers in question are written by authors with no background in climate science and have been debunked by scientists who showed that they relied on flawed methodologies and made fundamental errors. For example, a more productive biosphere would be a net carbon sink and therefore decrease CO2 concentrations in the atmosphere, rather than increasing them.

Carbon isotope ratios are actually one of the key measurements that show human-caused emissions are responsible for climate change. CO2 emissions from fossil fuels have lower concentrations of both carbon-13 and carbon-14 than CO2 placed in the atmosphere by the natural carbon cycle. Therefore, burning fossil fuels is linked to decreased concentrations of both isotopes in atmospheric CO2.

“Human-caused carbon emissions’ effect on climate is ‘non-discernible’. Measurements of carbon isotope ratios in atmospheric CO2 indicate that it is the recent expansion of a more productive biosphere that has led to increased CO2 concentrations in the atmosphere.”

1 – Graven et al. (2020) Changes to Carbon Isotopes in Atmospheric CO2 Over the Industrial Era and Into the Future. Global Biogeochemical Cycles. 2 – Hoffman and Rasmussen (2022) Absolute Carbon Stable Isotope Ratio in the Vienna Peedee Belemnite Isotope Reference Determined by 1H NMR Spectroscopy. Analytical Chemistry. 3 – Graven et al. (2017) Compiled records of carbon isotopes in atmospheric CO2 for historical simulations in CMIP. Geoscientific Model Development. 4 – Ritchie et al. Key Insights on CO2 and Greenhouse Gas Emissions. Our World in Data. 5 – Clark et al. (2021) SuessR: Regional corrections for the effects of anthropogenic CO2 on δ13C data from marine organisms. Methods in Ecology and Evolution. 6 – Francey et al. (1999) A 1000-year high precision record of δ13C in atmospheric CO2. Tellus B. 7 – Böhm et al. (2002) Evidence for preindustrial variations in the marine surface water carbonate system from coralline sponges. Geochemistry, Geophysics, Geosystems. 8 – Shervette et al. (2021) Radiocarbon in otoliths of tropical marine fishes: Reference Δ14C chronology for north Caribbean waters. PLOS One. 9 – Xiong et al. (2021). Time series of atmospheric Δ14CO2 recorded in tree rings from Northwest China (1957–2015). Chemosphere. 10 – Graven (2015) Impact of fossil fuel emissions on atmospheric radiocarbon and various applications of radiocarbon over this century. Proceedings of the National Academy of Science. 11 – Yu et al. (2022) Estimation of Atmospheric Fossil Fuel CO2 Traced by Δ14C: Current Status and Outlook. Atmosphere. 12 – Watson et al. (1990) Greenhouse Gases and Aerosols. Climate Change: The IPCC Scientific Assessment. 13 – Canadell et al. (2003) Global Carbon Budget 2023. Earth System Science Data. 14 – Suess (1955) Radiocarbon Concentration in Modern Wood. Science. 15 – Keeling (1979) The Suess effect: 13Carbon-14Carbon interrelations. Environment International. 16 – Anderegg et al. (2010) Expert credibility in climate change. Proceedings of the National Academy of Sciences.

Carbon comes in three naturally occurring isotopes on Earth: carbon-12, carbon-13, and carbon-14. Different carbon sources bear different mixtures of the three, and studying these isotopic signatures can help trace how carbon moves across the Earth. For instance, carbon-13 and carbon-14 are less abundant in fossil fuels than in atmospheric CO2, but the concentrations of the two isotopes in atmospheric CO2 have both dropped since the mid-20th century. A large body of scientific evidence has long attributed these declines to extra CO2 pumped into the atmosphere by humans burning fossil fuels[1]. An article authored by Chris Morrison in The Daily Sceptic, an outlet with a track record of scientifically unfounded messages, makes a conflicting claim: that changing isotope signatures in atmospheric CO2 result from the biosphere, rather than human causes like fossil fuel emissions. The article primarily cites “a new paper” published in February 2024 and supports its claim with a second paper published two years earlier. The article then upholds the two papers’ findings as scientific evidence that the human impact on climate change is “non-discernible”. Below, however, we show that the Daily Sceptic builds its claim on a scientifically shaky foundation. The two papers are at odds with decades of scientific results showing that these isotope changes are the direct result of CO2 emissions from human activity. Furthermore, both papers have received heavy criticism from climate scientists for drawing their conclusions from faulty analyses. Additionally, scientists contacted by Science Feedback emphasized that isotope concentrations are far from the only evidence pinning human activity as the primary cause of increased CO2 in the atmosphere. claim 1 (INCORRECT):A lack of carbon-13 is the biosphere’s problem The Daily Sceptic draws the core of its argument from a paper (“the Sci paper”) published in February 2024 in Sci, a journal published by MDPI, which has a reputation as a “predatory” publisher. The Sci paper analyzed historic data showing a decline in the ratio of carbon-13 to carbon-12, the element’s two stable isotopes, and blamed the change not on fossil fuel emissions but on a “more productive and expanded” biosphere. The carbon-13 to carbon-12 ratio is a common measurement in climate science. Carbon-12 accounts for about 99% of Earth’s carbon, and carbon-13 takes up almost all of the remaining 1%. Depending on the origin, the exact concentrations of each vary by a few fractions of a percent (Fig. 1). Climate scientists gauge these variations with δ13C, the deviation of a sample’s ratio of carbon-13 to carbon-12 from a standard benchmark originally derived from a particular type of limestone[2]. In other words, the lower a sample’s δ13C, the higher its carbon-12 content. Figure 1 – The δ13C values of different carbon sources and sinks. Note that fossil fuels have a distinctly lower δ13C than CO2 in the atmosphere and that the modern atmosphere has a lower δ13C than the atmosphere of only several hundred years earlier. Source: Graven et al. 2020[1] δ13C is a telling indicator when used to measure CO2 in the atmosphere (δ13CO2). Plants prefer to photosynthesize carbon-12, making the biosphere’s δ13C lower than δ13CO2. By extension, fossil fuels made from ancient biological matter also hold more carbon-12; when humans burn those fossil fuels, it also releases CO2 with lower δ13C than δ13CO2. The consequences are observed globally: δ13CO2has declined since the beginning of the Industrial Revolution (Fig. 2). Analyses have shown that, after accounting for exchanges between carbon in the atmosphere and carbon in the ocean and terrestrial biosphere, this decline matches the expected change from known fossil fuel emissions[1]. Figure 2 – Several measurements of δ13C from 1850 to 2015. The decline beginning in the late 20th century corresponds to a rise in anthropogenic CO2 emissions. Source: Graven et al. 2017[3] Instead, the Sci paper tried to explain the decline with a scenario that entirely ignored fossil fuel emissions. The paper attempted to calculate the relationship between CO2 and δ13CO2between 1520 and 1997 and noted that both measurements exhibited seasonal cycles as Earth’s biosphere became more active in the Northern Hemisphere spring, then declined in the Northern Hemisphere winter. The Sci paper then used this observation to claim that δ13CO2declined as a consequence of Earth naturally warming since the end of the Little Ice Age in about 1800, which the paper argues boosted the carbon cycle of the planet’s biosphere. The paper claimed the biosphere pumped low-δ13C greenhouse gas into the atmosphere, causing both a δ13CO2 decline and a rise in atmospheric CO2 levels. When Science Feedback asked scientists who studied isotope ratios to comment on the Sci paper, they pinpointed flaws in the paper’s methodology. For instance, although it is true that CO2 activity follows seasonal cycles, the paper’s model neglected to include several key processes impacting δ13CO2. The paper treated the atmosphere as a closed CO2 reservoir, ignoring two-way exchanges with the oceans and terrestrial biosphere that allow isotopic perturbations in the atmosphere to dissipate. More egregiously, the paper explicitly cited the known CO2 emissions from fossil fuels and their isotopic signature[4], then excluded them from its analysis and dismissed them as a driver of CO2 concentration and δ13CO2changes. “What is frustrating and confusing to me is that the author knows that human emissions have increased significantly during the industrial period, enough to explain the rise of CO2,” Sourish Basu, a research scientist at NOAA Global Monitoring Laboratory and an expert in carbon cycle, told Science Feedback in an email. “Early on, the author erroneously concluded that the biosphere must be the main driver behind the atmospheric CO2 budget and fossil fuel emissions must be negligible.” Heather Graven, a climate physicist at Imperial College London, echoed this criticism of the Sci paper. “What he does is he just tries to estimate the isotope composition of the source using a flawed method,” she told Science Feedback via telephone. “He doesn’t really perform a simulation taking into account all the factors.” Basu and Graven also questioned the validity of the Sci paper’s conclusion. “What we see in the atmosphere is because the biosphere and the oceans take up half of our emitted fossil CO2. The biosphere is a net sink, not a net emitter. The author gets this basic fact wrong,” Basu told Science Feedback. Therefore, the scenario that a more productive biosphere could simultaneously push down δ13CO2 and increase the amount of CO2 in the atmosphere makes little sense. “If [the carbon-12] were coming from the biosphere, we would have had to lose carbon,” Graven told Science Feedback. The Daily Sceptic derives the core of its claim from a paper that begins with flawed assumptions and uses a flawed model. Essentially, the paper ignores fossil fuel emissions to argue that they are not the root cause of declining δ13CO2. The paper then uses this flawed model to conclude that the biosphere is responsible for pumping CO2 into the air at unprecedented rates, something that contradicts the majority of available evidence. Meanwhile, numerous studies have explained that measurements of declining δ13CO2 correlate with and are caused by an increase in anthropogenic CO2 from fossil fuel emissions[5-7]. claim 2 (incorrect):Carbon-14 shows that fossil fuels emissions are a drop in the bucket The Daily Sceptic supports its erroneous claim by citing a second paper (“the Health Physics paper”), published in February 2022 in the journal Health Physics, a publication that has no significant relevance to climate science. The Health Physics paper examines carbon-14 data to conclude that fossil fuels are responsible for only a small fraction of atmospheric CO2. Climate scientists do use carbon-14 as an indicator. The isotope is extremely rare: about one in every 1012 carbon atoms is a carbon-14 atom. Carbon-14 is radioactive, with a half-life of about 5,700 years, meaning that fossil fuel carbon, which is hundreds of millions of years old, contains almost no carbon-14 whatsoever (Fig. 3) Therefore, the absence of carbon-14 is a flag for the presence of fossil fuel emissions. Figure 3 – The Δ14C values of different carbon sources and sinks. Note, again, that fossil fuels have a distinctly lower Δ14C than CO2 in the atmosphere. Thanks to nuclear weapons testing, atmospheric Δ14C in the modern day is higher than prior to the 20th century. Graven et al. 2020[1] Specifically, climate scientists use a measure called Δ14C, which is calculated from how much a sample’s carbon-14 concentration varies from that of atmospheric air prior to the invention of nuclear weapons[8]. A lower Δ14C indicates that less carbon-14 is present. In the 1950s and 1960s, carbon-14 released as fallout from nuclear weapons tests caused the Δ14C of atmospheric CO2 (Δ14CO2) to dramatically spike. But after the Partial Nuclear Test Ban Treaty largely ended above-ground tests in 1963, Δ14CO2began to decline just as drastically (Fig. 4). Figure 4 – Measurements of Δ14CO2over time. The decline beginning in the 1960scentury corresponds to the end of nuclear weapons testing and a large increase in human CO2 emissions. Source: Xiong et al. 2021[9] However, Δ14CO2 declined too quickly to be explained by carbon-14 decaying or being exchanged out of the atmosphere, indicating that carbon-14-free CO2 entered the atmosphere from fossil fuel emissions[1]. Multiple studies have clearly demonstrated that anthropogenic fossil fuel emissions are responsible for the ongoing decline in Δ14CO2[10,11]. The Health Physics paper’s three authors, none of whom have an obvious climate science background, created a model to match data on Δ14CO2 dating from between 1750 and 2018. Their model assumed that fossil fuel CO2 contained zero carbon-14 and that any given volume of CO2 cycled out of the atmosphere in about 4 years. The authors’ analysis determined that fossil fuel emissions only accounted for 12% of global CO2 as of 2018. The authors, then, concluded that fossil fuels could not have driven modern-day climate change. Like the Sci paper, the Health Physics paper garnered criticism from scientists for making false assumptions. One published comment in the same journal pointed out a major flaw in the Health Physics paper’s methodology: It conflated atmospheric CO2’s residence time (the amount of time a CO2 molecule actually spends in the atmosphere before being exchanged with the land or the water, which is about 4 years) with its adjustment time (the amount of time an extra volume of CO2 will stay in the atmosphere, which can be millennia). As a result, the Health Physics paper authors drastically underestimated how long fossil fuel CO2 would stay in the atmosphere. This is not a new error; as early as 1990, an IPCC report warned researchers against making it[12]. Furthermore, the comment stated, “Throughout [the Health Physics paper] the authors have failed to cite numerous related and relevant earlier publications in this field and demonstrated a lack of fundamental understanding of biogeochemical carbon cycle processes,” the comment stated. A second comment from a different group, published in the same journal, explained that — in addition to conflating residence time with adjustment time — the Health Physics paper used faulty Δ14CO2data and inadequately addressed the role of carbon-14 from nuclear weapons testing that remained in the atmosphere into the 21st century, both of which led them to further underestimate the fossil fuel contribution to Δ14CO2trends. This comment demanded that Health Science retract the paper, which the journal has not done. Much like the Sci paper, the Health Physics paper derived its conclusions from a flawed methodology. Moreover, the paper ignores that the volume of CO2 from fossil fuel emissions and its impact on the atmosphere at large are both very well-documented from methods such as air sampling[4]. The concentration of CO2 in the atmosphere has risen from about 280 parts per million (ppm) prior to the Industrial Revolution to about 420 ppm today; the Global Carbon Budget attributed about two-thirds of the excess to fossil fuel emissions and the remainder to human-caused land use changes like deforestation[13]. The body of evidence points to fossil fuel emissions as the culprit for atmospheric CO2 rise Despite the two papers’ flaws and their public debunking by scientists, the Daily Sceptic article champions them to assert a lack of a “discernible” human fingerprint on the climate and claims that carbon isotope signatures are an “interesting branch of climate science to investigate”. The reality is that it has been thoroughly investigated for decades. The study of carbon isotope ratios, in fact, predates any scientists reaching consensus about climate change. As early as the 1950s, chemist Hans Suess measured carbon-14 concentrations in wood and connected them to carbon-14-free fossil fuel emissions released starting from the Industrial Revolution[14]. By the late 1970s, climate scientists had measured shifts in δ13CO2and Δ14CO2 matched the predicted changes caused by then-known CO2 emissions[15]. It may be prudent to look at the isotope ratio changes in the bigger picture. We need a culprit that can explain all of the changes we have observed: a culprit that has lower δ13C than atmospheric CO2, a culprit that is sufficiently old for its carbon-14 levels to have decayed to effectively zero, and a culprit that can explain the dramatic increase in atmospheric CO2 concentrations since the industrial revolution. According to Basu, this allows us to rule out alternative carbon sources like volcanic outgassing, for example, which has a high δ13C; instead, the only suitable suspect is the emissions from humans burning fossil fuels. Moreover, the study of isotope ratios is only one branch of many clearly pointing at a human origin for climate change. Supporting this idea, Ralph Keeling, a climate scientist at the Scripps Institute of Oceanography, told Science Feedback in an email: “We don’t need to turn to measurements of isotopes to establish that the CO2 rise is caused by humans. In fact, we know quite well how much CO2 we’ve dumped into the atmosphere over the past 150 years through the burning of fossil fuels, and it’s more than enough to account for the observed rise. The rise started at the time of the dawn of the industrial revolution, and has accelerated since then. Overall, the CO2 rise is a bit similar to the buildup of trash in a landfill. The trash is obviously of human origin, because we know we put it there. There’s not much sense in questioning its human origins.” Indeed, scientists have clearly identified human causes as responsible for all of modern climate change activity[16], as Science Feedback has previously covered.

https://science.feedback.org/review/data-shows-temperatures-rising-greenland-world-current-global-warming-driven-co2-not-solar-activity/

Inaccurate

Daily Sceptic, Stephen Andrews, 2024-03-08

Ice cores from Greenland show no significant warming, casting doubt on the climate change theory

Factually inaccurate: The claim that there is no global warming signal from Greenland is in direct contradiction with available observations. Recent studies of ice cores from several locations in Greenland have shown that temperatures are warming faster than the natural variation of the last 1000 years. Rising temperatures in Greenland do not necessarily represent global changes. However, other studies have shown evidence of rising temperatures around the world. Unsupported: There is no evidence to support that solar cycle variation has a greater impact on rising global temperatures than increasing atmospheric CO2. In fact, solar intensity is currently declining while global temperatures are rising. Evidence shows that rising atmospheric CO2 from human activities is the primary driver of modern global warming. Cherry-picking: Ice core data from one location in Greenland is insufficient to represent the entire planet. Numerous recent studies with larger data sets and rigorous statistical analysis show a global warming trend around the world.

The effect of atmospheric CO2 concentrations on global temperatures is well established; as concentrations rise, global warming increases through the greenhouse effect. Scientific studies show that modern global warming is primarily driven by increasing CO2 emissions from human activities. Based on the available scientific evidence, solar variation has had no significant effect on modern global warming compared to rising atmospheric CO2 concentrations.

Ice cores from Greenland show no significant warming, casting doubt on the climate change theory; above a certain concentration of carbon dioxide, it has minimal direct impact on global temperature relative to solar cycles.

1 – Anderegg et al. (2010) Expert credibility in climate change. Proceedings of the National Academy of Sciences. 2 – Markle and Steig (2022) Improving temperature reconstructions from ice-core water-isotope records. Climate of the Past. 3 – Holme et al. (2019) Varying regional δ18O–temperature relationship in high-resolution stable water isotopes from east Greenland. Climate of the Past. 4 – Hörhold et al. (2023) Modern temperatures in central–north Greenland warmest in past millennium. Nature. 5 – Kaufman et al. (2020) Holocene global mean surface temperature, a multi-method reconstruction approach. Nature. 6 – IPCC (2021). Sixth Assessment Report. 7 – PAGES 2K Consortium (2019) Consistent multidecadal variability in global temperature reconstructions and simulations over the Common Era. Nature Geoscience. 8 – Santer et al. (2013). Human and natural influences on the changing thermal structure of the atmosphere. Proceedings of the National Academy of Sciences. 9 – Pierce and Adams (2009) Can cosmic rays affect cloud condensation nuclei by altering new particle formation rates?. Geophysical Research Letters 10 – Zhong and Haigh (2013) The greenhouse effect and carbon dioxide. Royal Meteorological Society Weather. Note: Scientists comments were lightly edited for clarity (i.e., information was added in brackets for context and minor punctuation changes were made).

The consensus among climate scientists is that modern global warming is primarily driven by increases in atmospheric CO2 from human activities[1]. A major component of studying global warming is comparing present conditions with those of the past. However, taken out of context, these data can be misinterpreted to draw conclusions that are inaccurate and unsupported. A recent example is in an article on The Daily Sceptic, which made several claims about global warming using a small subset of the available climate data, which we will investigate below. Based on ice core data from one part of Greenland, the article claims that “there is no significant global warming signal coming from one of the most sensitive parts of the planet”, and that these data–which show a rising temperature trend in modern times–fall within a normal (natural) variation. However, this claim is in direct contradiction with scientific findings, mischaracterizes the cited data, and excludes sufficient context about how global warming trends are studied. Evidence of Rising Temperatures in Greenland Scientists use climate proxies, such as ice cores, to help them reconstruct past conditions. For example, stable water isotope (δ18O) signals from ice cores can be used to determine past local temperatures[2]. This method was employed in the studies referenced by The Daily Sceptic article. However, the article leaves out critical details about the uncertainties in the data and mischaracterizes the findings. One study the article references has proxy data from 10,000 BCE to 1960 CE; however, this period excludes several recent decades of available climate data. The second paper the article references, Holme et al. (2019), studied proxy data from 1801-2014, which, as the article correctly points out, shows a rising trend in the δ18O signal. However, the article excludes an important conclusion from the study: “the linear δ18O–temperature relationship was unstable with time which implied that the annual-to-decadal variability of δ18O measured in an ice core could not be directly attributed to temperature variability.”[3] Therefore, there is less certainty when using these data to assess Greenland temperature trends over recent decades. There is a study, however, that analyzed recent temperature trends in Greenland compared to natural variation–the main topic of The Daily Sceptic article. Hörhold et al. (2023) analyzed ice core data from central and northern Greenland–a larger study area–to create a high-quality temperature reconstruction for the period of 1000-2011[4]. The study showed that “the warming in the recent reconstructed decade exceeds the range of the pre-industrial temperature variability in the past millennium with virtual certainty (P < 0.001)”[4] (Figure 1). The authors had greater confidence in these temperature trends due to the high correlation between the δ18O data and local temperature data–which was lacking in the Holme et al. (2019) study. Figure 1 – The top graph (solid black line) shows the record of δ18O and the inferred temperature time series from 1000-2011. Existing ice core data was extended to 2011 in this study by re-drilling ice cores–this data is highlighted in red on the top graph. Two trends from these data–1000 to 1800 and 1800 to 2011–are shown as black dashed lines. The number of firn cores used to collect the data are shown as a thin brown line below the top graph. The bottom blue graph represents arctic-wide data (not discussed here). Source: Hörhold et al. (2023)[4] Based on these findings, the claim made in The Daily Sceptic article regarding a lack of global warming signal from Greenland is inaccurate and a mischaracterization of the supporting data. The Hörhold et al. (2023) study–which analyzed more ice core data (with greater spatial coverage) and achieved high data correlation–found clear evidence of warming in Greenland which exceeded the natural variation of the last 1000 years[4]. Evidence of Rising Global Temperatures While proxy data from one location can be used to reconstruct past local temperatures, it is not necessarily sufficient to reconstruct past global temperatures. To explain this, Dr. Joanna Haigh, Emeritus Professor of atmospheric physics at Imperial College London, provided Science Feedback with the following comment about the article: “using one location to represent global warming is invalid. He [the author] refers to Greenland [as] being the most sensitive place without saying how that is defined. There is substantial evidence of larger variations in temperature at different locations [e.g. Dansgaard-Oescher events]. These are not fully understood but are not used to make statements on global parameters.” To better understand global climate change and reduce uncertainty in their studies, scientists use a variety of methods and analyze a greater number of samples. The Daily Sceptic article only cites data from one area in Greenland; however, there are studies which used more proxies and methods to reduce uncertainty. For example, a study by Kaufman et al. (2020) used 679 proxy sites (Figure 2) and five different statistical methods when reconstructing global mean surface temperatures (GMST) for the last 12,000 years[5]. This multi-method approach helped the researchers create an ensemble of global temperature reconstructions that account for the uncertainties of the different methods. By increasing the number of samples and locations they analyze, researchers also have greater confidence that the results better represent global changes, rather than local changes. Figure 2 – Locations of the 679 proxy data sites (green dots) for the 12,000 year temperature reconstruction. Source: Kaufman et al. (2020)[5] The Kaufman et al. (2020) study indicated that there were periods of cooling and fluctuation over the last 12,000 years (Holocene); however, it also showed a modern rise in global warming[5]. As the authors explain, “The distribution of peak global temperatures during the Holocene can also be compared with recent temperatures. The GMST of the past decade (2011–2019) averaged 1°C higher than 1850–1900. For 80% of the ensemble members, no 200-year interval during the past 12,000 years exceeded the warmth of the most recent decade.”[5] The results of this study (Figure 3) show that a rising global warming trend began in the industrial era and has continued to the present day. Figure 3 – Global mean surface temperature over 12,000 years using multiple reconstruction methods. The fine black line shows instrumental data collected from 1900 to 2010. The smaller inset graph shows the most recent 2000 years of data. Source: Kaufman et al. (2020)[5] Kaufman et al. (2020) explain that the comparisons they made between 200-year intervals of the Holocene and modern warming are conservative in the context of IPCC projections, which indicate that temperatures are likely to rise higher than 1°C above pre-industrial temperatures in the next century[5]. They then explain that the IPCC projections give a better comparison between warming in recent decades and the temperatures in the Holocene reconstructions. A number of other studies have also shown evidence that modern global warming trends are unusual compared to past variations. According to The Intergovernmental Panel on Climate Change (IPCC), the world’s leading authority on climate science, the last 1000 years of temperature data and their methods of reconstruction have been well-studied[6]. One of the studies the IPCC refers to, PAGES 2K Consortium (2019), explains that “the largest warming trends at timescales of 20 years and longer occur during the second half of the twentieth century, highlighting the unusual character of the warming in recent decades.”[7] Rising CO2 Has Driven Global Warming, Not Solar Cycle Variability The Daily Sceptic article also claimed that a lack of global warming signal from the data he provided “could be explained by the fact that the relationship of carbon dioxide to global temperature is logarithmic and above a certain concentration there is minimal direct impact relative to solar cycles.” However, this claim is inconsistent with available evidence. In fact, Science Feedback has done several investigations of similar claims about solar influence on climate change, a sample of which are linked below: Review: 1: The sun isn’t responsible for current climate change, contrary to claims in Suspicious0bservers YouTube video Review 2: Low solar activity has little effect on Earth’s climate, contrary to claim in The Sun Review 3: Claim that current climate change can be explained satisfactorily by natural cycles and volcanic activity does not have scientific support These reviews provide several lines of evidence that solar activity is not driving the rise in global temperatures. For example, one review explains that if the Sun were driving global warming, we should see temperatures rising at the surface of the Earth and throughout the Earth’s atmosphere. Instead, the data show Earth’s surface heating up, while the layers of the atmosphere are changing variably–lower altitudes heating, and higher altitudes cooling[8]. Another review found that the rate and magnitude of modern global warming is too high to be caused by solar variations[9]. The physics of both solar cycle variation and atmospheric CO2 are well understood. The IPCC explained that solar activity from the late 19th century to present was not exceptional compared to the last 9,000 years[6]. The IPCC also compared observed temperature changes to models that accounted for both human and natural influences (Figure 4). As shown below, in both the observed data and simulated cases, the addition of human drivers–such as CO2 emissions–lead to a greater rise in global temperatures. Figure 4 – Observed and simulated changes in global surface temperature from 1850 to 2020. The black line represents 170 years of observed and averaged data and is compared to Coupled Model Intercomparison Project Phase 6 (CMIP6) climate model simulations. The brown area represents the temperature response to both human and natural drivers and the green area to only natural drivers (solar and volcanic activity). Solid colored lines represent the averages, and the shaded areas represent the very likely range for the models. Source: IPCC (2021)[6] After reviewing the Daily Sceptic article’s claim about solar variability, Dr. Joanna Haigh provided the following comment: “He [the author] does not define ‘solar cycle’, normally used to refer to [the] 11-year activity cycle; he presumably means longer term solar activity which is currently declining so [it] can’t explain recent global warming.” And in response to the article’s claim of diminishing CO2 impacts, Dr. Haigh commented “Fig.6 in the paper [Zhong and Haigh (2013)] shows logarithmic response in radiative forcing of temperature to CO2 increase – but still rising. In that paper we used 389 ppm [parts per million] as [the] current CO2 concentration. It is now 425 ppm – higher than for millions of years and rising unremittingly.” Dr. Haigh’s explanation highlights that atmospheric CO2 concentration is increasing, and despite the response being logarithmic, global temperatures are, and will continue, rising with increasing CO2 (Figure 5). Figure 5 – Radiative Forcing of CO2 (relative to the atmospheric CO2 concentration of 389 ppm–the concentration at the time of the study). Source: Zhong and Haigh (2013)[10] In other words, the study shows that radiative forcing–the effect of Earth’s atmosphere receiving more energy from solar radiation that it emits back out to space–lessens gradually with increasing CO2 concentrations, but remains positive[10]. The Zhong and Haigh (2013) paper concludes that as CO2 increases in the atmosphere, there is no saturation point at which it will no longer cause radiative forcing–therefore, it will continue to be a factor in global warming. Conclusion: As shown above, the claims that the Daily Sceptic article made about Greenland temperature trends, global warming signals, CO2, and solar cycles are incorrect and unsupported. Scientific evidence on these subjects shows the following: temperatures in Greenland and around the world are rising, the primary driver is increasing atmospheric CO2 from human emissions, and solar variation has had no significant effect on rising modern global temperatures. Although the response is logarithmic, as CO2 concentrations increase, so will global temperatures. This is evident based on climate models and the physics of CO2, which are well understood. After analyzing and modeling the drivers of climate change, the IPCC found no evidence that solar variation can account for the rising trend of global temperatures. Several studies, which reviewed up to 10,000 years of climate proxy data, show that the current rate of global warming is unusual compared to past natural variations.

https://science.feedback.org/review/arctic-sea-ice-melting-over-past-decades-with-projections-summer-ice-free-conditions-mid-century/

Incorrect

The Epoch Times, Allan Astrup Jensen, 2024-02-06

Arctic sea ice is not melting and there is no indication that we should expect the Arctic sea summer ice to disappear completely, as predicted

Incorrect: Overall, Arctic sea ice extent and volume have been decreasing since the 1970s, a trend that scientists largely attribute to human-induced global warming. The author of the claim cherry-picks short term fluctuations due to natural variability to suggest otherwise. Scientists forecast the first ice-free summer for the 2050s.

Despite short-term fluctuations due to natural variability, the Arctic sea ice extent and volume has decreased over the past few decades. Scientists have established that this decrease is mostly the result of global warming due to human emissions of greenhouse gasses.

Arctic sea ice is not melting. There is no indication that we should expect the Arctic Sea summer ice to disappear completely, as predicted. CO2 levels don't drive Arctic sea ice decline.

1 – IPCC (2021) Ocean, Cryosphere and Sea Level Change. In Climate Change 2021: The Physical Science Basis. Contributions of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. 2 – Walsh et al. (2017) A database for depicting Arctic sea ice variations back to 1850. Geographical Review. 3 – Polyak et al. (2010) History of sea ice in the Arctic. Quaternary Science Reviews. 4 – Kinnard et al. (2011) Reconstructed changes in Arctic sea ice over the past 1,450 years. Nature. 5 – Halfar et al. (2013) Arctic sea-ice decline archived by multicentury annual-resolution record from crustose coralline algal proxy. Proceedings of the National Academy of Sciences. 6 – Johannessen et al. (2004) Arctic climate change: observed and modelled temperature and sea-ice variability. Dynamic Meteorology and Oceanography. 7 – Eyring et al. (2021) Human Influence on the Climate System. In Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. 8 – Perovich et al. (2007) Seasonal evolution and interannual variability of the local solar energy absorbed by the Arctic sea ice–ocean system. Geophysical Research Letters. 9 – Stroeve et al. (2014) Changes in Arctic melt season and implications for sea ice loss. Geophysical Research Letters.

Since the 1970s, satellites have been providing accurate measurements of sea ice extent in the Arctic, revealing a steady reduction in its surface. The yearly extent of Arctic sea ice that survives the entire summer has decreased by approximately 50% from 1979 to 2020 compared to its average extent during the period from 1981 to 2010. Under all Intergovernmental Panel on Climate Change (IPCC) scenarios, even the most optimistic one, the Arctic Sea is expected to reach a mostly ice-free state during some years in the summer as early as the 2040s. An article by The Epoch Times dated 6 February 2024 disseminated claims challenging the scientific observations of declining arctic sea ice and predictions of an ice-free summer in the Arctic, drawing on assertions from a single report and remarks by an independent consulting engineer. Arctic sea ice has been shrinking for decades The title of The Epoch Times article falsely claims that ‘the UN Says Melting Arctic Ice Is Key Indicator of Climate Change—But It’s Not Melting’. This statement is inaccurate, as scientific evidence consistently shows that Arctic sea ice is indeed melting and serves as a critical indicator of climate change. Arctic sea ice grows and shrinks with the seasons, melting from around March to September and reforming in the cold winter months. Scientists study the yearly minimum extent of Arctic sea ice because it provides critical insights into its seasonal cycle and its response to environmental changes. This measurement, taken at the end of the summer melting season, indicates the quantity of sea ice remaining. Satellite records have shown that Arctic sea ice extent has steadily declined over the last four decades. In the 1980s, the September average extent represented close to 50% of the March average; from 2013 to 2022, the ratio was only 35%. Reaching lower minimums indicates a weaker recovery in winter, showing that the Arctic is losing ice and failing to replenish it. In addition, this trend is further reinforced by the fact that sea ice volume is also decreasing. The IPCC notes that: “Current best estimates from reanalyses indicate that September Arctic sea ice volume has reduced by about 72% over the period from 1979 to 2016, […] a conservative estimate.”[1] Regarding the trend from the 2010s onwards, the IPCC explains in its report that there is “low confidence in the amount of decrease over this period […] primarily because of snow-induced uncertainties in the retrieval algorithms, the shortness of the record, and the small identified trend.” Arctic sea ice is forecasted to continue melting The Epoch Times article quotes a report by Allan Astrup Jensen, a chemical risk assessment specialist, claiming that “in the last 17 years, from 2007 to 2023, the [Arctic sea ice extent] downward trend has also been about zero […] Therefore, there is no indication that we should expect the Arctic Sea summer ice to disappear completely, as predicted, in one or two decades.” This assertion contradicts the majority of scientific literature on the subject projecting ice free summers later this century, which represents the best evaluation of human knowledge on the topic. Synthesizing this research, the IPCC reports that the current Arctic sea ice extent, both annually and during the late summer, is at its lowest level since at least 1850, with high confidence. In the same fact-sheet the IPCC states that, under all considered scenarios, the Arctic is expected to reach practically ice-free conditions at its summer minimum at least once before 2050. While Arctic sea ice extent has not declined at a constant rate from 1979 to 2007, the short term fluctuations do not invalidate the overall downward trend (see gray line in Figure 1) and the continued impact of warming expected in the future due to climate change. The last 17 Arctic sea ice yearly minimum extents are the lowest in the satellite record and summer Arctic sea ice loss since 1979 is unprecedented in 150 years, based on historical reconstructions[2] and more than 1000 years of paleoclimate evidence[3,4,5]. Figure 1 – Arctic Sea ice extent as measured by satellites between 1978 and 2022. The long-term trend for 1979 to 2021 is shown by the dashed gray line, while trends over shorter periods are shown in colors: red for 1979 to 1992, blue for 1993 to 2006, and dark green for 2007 to 2021. (source) How increasing CO2 concentrations impact Arctic sea ice? In The Epoch Times’ article, engineer Frank Geisel claims that we do not know whether increased atmospheric CO2 concentrations are driving a decline in sea ice extent and volume. The Epoch Times article’s author picks two CO2 concentration levels and Arctic minimum sea ice extent (in 1979 and 1996) that supposedly supports this claim. However, a physical connection between the two variables cannot be established or dismissed by just cherry-picking two data points, one has to look at all the available evidence and understand the physical mechanism explaining the connection. As explained below, scientists have established that human-induced climate change causes a decline in Arctic sea ice through various scientific observations and analyses. Firstly, observational data have shown a clear trend of shrinking sea ice extent and thickness, especially noticeable each September when the ice reaches its annual minimum. Model simulations show this decline correlates closely with rising global temperatures and increased greenhouse gas emissions, consistent with a direct link between increased greenhouse gases concentrations and diminishing sea ice[6]. The IPCC concluded that “it is very likely that anthropogenic forcing mainly due to greenhouse gas increases was the main driver of Arctic sea ice loss since 1979.”[7] Secondly, studies of the Arctic’s energy balance provide further evidence. Sea ice has a high albedo, meaning it reflects a significant amount of solar energy back into space. As climate change leads to warmer temperatures, sea ice melts, exposing darker ocean water that absorbs more solar energy, leading to further warming and ice loss in a reinforcing feedback loop. This mechanism, well-documented by climate scientists, further demonstrates how increased temperatures from greenhouse gasses directly contribute to the reduction of Arctic sea ice[8]. Lastly, the timing of the melt season has shifted, with ice melting earlier in the spring and freezing later in the fall, further supporting the impact of rising temperatures on sea ice[9]. Records show that increasing global temperatures are happening in tandem with increasing levels of carbon dioxide (see Figure 2, top), while the Arctic has been warming at an even faster rate than the rest of the globe (see Figure 2, bottom), which contributes to Arctic sea ice melting. Figure 2 – Top: yearly temperature anomalies compared to the twentieth-century average (red and blue bars) from 1880 to 2019, based on data from NOAA NCEI, and atmospheric carbon dioxide concentrations (gray line): 1880-1958 from IAC, 1959-2019 from NOAA ESRL (source).Bottom: cumulative/net trend in combined sea and ice surface temperature anomalies for the Arctic Ocean from 1993 to 2022. The cumulative trend is the rate of change (°C/year) scaled by the number of years (30 years). Based on satellite observations from the E.U. Copernicus Marine Service Information (source). Not all the decrease in Arctic sea ice extent is attributed to human induced climate change though. Researchers have found that natural variability accounts for about half of the sea ice decline observed so far; the other half coming from climate change. Therefore, a short period of stable Arctic sea ice extent trend is consistent with the models’ range of predictions. As National Snow and Ice Data Center (NSIDC) scientist Walt Meier pointed out in an article: “Natural variability has bigger effects at shorter timescales. It mainly plays a role over a time span of about 10 to 15 years. As the length of the observation period increases, natural variability has less effect, and the long-term forcing—greenhouse gas emissions—dominates. There is no escaping that we will see an Arctic with no summer sea ice this century if we continue to rapidly increase greenhouse gases in the atmosphere.”

https://science.feedback.org/review/optimal-atmospheric-co2-dinosaurs-plants-harmful-humans-current-concentration-higher-homo-sapiens-ever-experienced/

Misleading

Bright Insight, Jimmy Corsetti, 2024-02-04

High CO2 was fine for the dinosaurs and high CO2 benefits plants today in greenhouses, so more CO2 can’t be bad for humans

Flawed reasoning: The fact that elevated atmospheric-CO2 benefited the dinosaurs and benefits plants today does not mean it also benefits humans. In fact, there are potential human health risks from prolonged exposure to the optimal CO2 levels for dinosaurs and plants, in addition to the multiple negative environmental impacts for human society resulting from elevated CO2 and the enhanced greenhouse effect. Missing context: The optimal concentrations of CO2 for dinosaurs and plants would be far beyond the concentrations ever experienced by the human species naturally; they would dramatically change ecosystems. Even just the present level of CO2 in the atmosphere is already higher than it has been for millions of years, and Homo sapiens have only been around for 260-350 thousand years. The magnitude of change and the rate of change presents existential challenges for many species.

Elevated atmospheric-CO2 from human emissions enhances the greenhouse effect, which causes global warming and results in several other significant negative impacts on the ecosystems and natural processes on which humans depend. Plants and animals have different tolerances and responses to elevated CO2, and concentrations which are optimal for some species can be toxic for others. Human emissions have raised CO2 to levels never before experienced by our species, and not seen on Earth for millions of years.

Increasing carbon dioxide (CO2) is not bad for humans because it was much higher during the time of the dinosaurs and they were unaffected. High carbon dioxide also benefits plant growth, which is why CO2 is pumped into greenhouses to boost crop yields. Levels of CO2 are so low right now in comparison to the levels that were good for the dinosaurs and are good for plants, so an increase in CO2 can’t be bad for humans. CO2 is good for life and is not causing a climate crisis.

1 – Morris et al. (2018) The timescale of early land plant evolution. Proceedings of the National Academy of Sciences. 2 – Foster et al. (2017) Future climate forcing potentially without precedent in the last 420 million years. Nature Communications. 3 – Rae et al. (2021) Atmospheric CO2 over the past 66 million years from marine archives. Annual Review: of Earth and Planetary Sciences. 4 – Jacobson et al. (2019) Direct human health risks of increased atmospheric carbon dioxide. Nature Sustainability. 5 – Azuma et al. (2018) Effects of low-level inhalation exposure to carbon dioxide in indoor environments: A short review on human health and psychomotor performance. Environment International. 6 – Miller et al. (2005) The Phanerozoic record of global sea-level change. Science. 7 – IPCC (2019) Summary: for Policymakers. In: IPCC Special Report on the Ocean and Cryosphere in a Changing Climate 8 – Tierney et al. (2020) Past climates inform our future. Science. 9 – Zheng et al. (2018) The optimal CO2 concentrations for the growth of three perennial grass species. BMC Plant Biology. 10 – IPCC (2021) Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. 11 – Friedlingstein et al. (2023) Global carbon budget 2023. Earth System Science Data. 12 – Karnauskas et al. (2020) Fossil fuel combustion is driving indoor CO2 toward levels harmful to human cognition. GeoHealth. 13 – Lowe et al. (2018) Possible future impacts of elevated levels of atmospheric CO2 on human cognitive performance and on the design and operation of ventilation systems in buildings. Building Services Engineering Research and Technology. 14 – Diffenbaugh et al. (2013) Changes in ecologically critical terrestrial climate conditions. Science. 15 – IPCC (2023) Summary for Policymakers. In: Climate Change 2023: Synthesis Report. Contribution of Working Groups I, II and III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change

During Earth’s 4.5 billion year history, the atmosphere has undergone dramatic changes and only started to appear like it does today around 290 million years ago (mya). Today’s air is composed of several gasses with different concentrations, like nitrogen (78.08%), oxygen (20.95%), argon (0.93%), and carbon dioxide (0.04%). The air 600 mya, for example, had only about one-fifth of today’s oxygen level. Plants first appeared as far back as 500 mya[1]. Reptiles first appeared about 320 mya, and the dinosaurs only existed approximately from 243 mya until 66 mya. Mammals appeared about 225 million years ago, but anatomically modern humans, or homo sapiens, are only 260-350 thousand years old. Humans, dinosaurs, and plants all respire air, although plants do it very differently than mammals and reptiles. Considering these different evolutionary timelines under different atmospheric compositions, can we assume that animals, reptiles, and plants thrive breathing the same air? Is the optimal level of carbon dioxide for dinosaurs and plants also optimal, or at least feasible, for humans? Does all this mean anything for climate change? Youtuber Jimmy Corsetti, who’s channel Bright Insight has 1.61 million subscribers, suggested on X and Instagram that because dinosaurs and plants thrive under very high CO2, increasing in CO2 is good for life on Earth and not bad for humans. This means, according to Corsetti, “CO2 is Not causing a Climate Crisis”. Here we explore the reasons why this claim is misleading because it lacks context and uses flawed reasoning. Optimal carbon dioxide levels for dinosaurs and plants is toxic for humans over the long-term The atmospheric concentration of CO2 during the time of the dinosaurs was much higher than it is today, which currently stands at 422 parts per million (ppm). The article Corsetti screenshotted shows Dr. Paul Olsen’s response to the following question submitted by a reader: “How did plants and animals survive around 200 million years ago when the carbon dioxide concentration went up to 6,000 parts per million?”. Olsen, a geologist and paleontologist at Columbia Climate School’s Lamont-Doherty Earth Observatory, explains that the CO2 concentrations during the time of the dinosaurs (the Mesozoic Era) was in the 2000 to 4000 ppm range and that humans could potentially survive, but only with the help of technological innovations and not because of physiological ability. To be clear, the atmospheric concentration of CO2 during the time of the dinosaurs was never near 6000 ppm as Figure 1 shows[2], and it has never come close to that in the 66 million years since the dinosaurs went extinct[3]. Figure 1 – The rise and fall of atmospheric-CO2 (red trendline) over hundreds of millions of years (top x-axis), based on paleoclimatological reconstructions. Note the short timespan where Homo sapiens have existed, which has only featured low atmospheric-CO2 (right y-axis), especially compared to the Age of the Dinosaurs. Ice ages are indicated by blue shaded areas from the top x-axis. Based on reference [2], modified by Dr. Paul Olsen (source). According to Jacobson et al.’s (2019) recent synthesis of scientific literature from different fields exploring the impacts on CO2 air concentrations on humans, potential health risks can occur with exposure as low as 1000 ppm[4]. While concentrations above 5000 ppm are known to be harmful in both the short and long-term, research indicates that even concentrations below 5000 ppm “poses direct risks to human health”, including inflammation, reduced higher-level cognitive abilities, bone demineralization, kidney calcification, oxidative stress and endothelial dysfunction. Another literature review found physiological changes occur at CO2 exposures levels between 500 and 5000 ppm, effects on cognitive performance begin at 1000 ppm during short-term exposure, and respiratory symptoms are detected in children exposed to indoor CO2 concentrations higher than 1000 ppm[5]. Azuma et al. (2018) concluded that atmospheric CO2 concentration needs to be urgently suppressed to be able to efficiently control indoor concentrations. Most research on this topic is related to indoor environments, with humans under high exposure for limited time-frames corresponding to shift work in potentially hazardous workplace conditions. The Occupational Safety and Health Administration (United States Department of Labor) permissible exposure limit for CO2 is 5000 ppm over 8 hours. Concentrations above 40 000 ppm are considered immediately dangerous to life or health. There has been no research exploring prolonged human environmental exposure (weeks, months, years, lifespan) to elevated CO2 outdoors, especially for vulnerable demographics. Jacobson et al (2019) concluded that removing CO2 from the atmosphere will be necessary if emissions continue at current levels, based on their confirmation that “prolonged exposures as low as 1000 ppm CO2 affect human health and well-being”. In addition, during the Cretaceous period (145-66 mya) which ended when the dinosaurs went extinct, the average temperature was about 5-10°C higher than today and sea levels were 100 meters higher or more[6]. For comparison, the most extreme global warming future scenario (representative concentration pathway (RCP)) under consideration by the IPCC for the year 2100, called RCP8.5 or the “business as usual” scenario, implies a likely temperature increase of 3.2-5.4°C[7]. Figure 2 shows that the fossil-fuel intensive shared socio-economic pathway (SSP), called the SSP5-8.5 scenario, will lead to atmospheric-CO2 concentrations that match or even exceed Eocene or mid-Cretaceous levels[8]. It also illustrates just how unprecedented even a return to even just 1000 ppm CO2 would be, which has not been seen for tens of millions of years. Figure 2 – Comparing paleoclimates (past) with future climate scenarios side-by-side from the year 2020, including both global mean temperature (left y-axis, °C, only for the past) and global atmospheric-CO2 concentration (right y-axis, ppm, logarithmic scale, for the past and the future). Trendlines are smoothed to show long-term trends, and temperature colors are scaled related to pre-industrial levels. The small global maps on the right indicate different shared socio-economic pathway (SSP) scenarios (source). As for plants, Science Feedback has previously addressed flawed claims that because CO2 is used in greenhouses to promote plant growth, high CO2 in the atmosphere is good for the world’s plants and therefore not a concern for humans. Plants need more than just CO2 to photosynthesize and grow; they also need water, sunlight, and other plant nutrients like nitrogen and phosphorus. High CO2 in the atmosphere is directly linked to negative impacts on ecosystems through global warming which will constrain plant growth and limit any benefits from high CO2. For example, the increase in droughts in some regions or flooding in other regions are not beneficial for plants, regardless of high atmospheric CO2 (called the “CO2 fertilization effect”). Karin Kirk puts it simply with the title of her article for Yale Climate Connections: “More CO2 in the atmosphere hurts key plants and crops more than it helps”. But even if we ignore this (and all other climate related concerns of high CO2), and we focus just on maximizing plant growth as we do in greenhouses as referenced by Corsetti, the optimal CO2 levels for plants are still in conflict with human well-being. All plants respond differently to increased CO2, but they all generally follow a downward parabola (upside down “U”), increasing yield with increasing CO2 until reaching an optimal point (vertex) after which yield decreases with increasing CO2 (Figure 3, right). Different plants have different optimums, but many greenhouse recommendations reference ideal concentrations at or surpassing 1000 ppm, assuming no other limiting factors exist. For example, Figure 3 (left) shows how increasing CO2 concentrations helps three species of grasses grow, with their ideal concentrations for biomass yield at 915, 1178, and 1386 ppm[9]. Figure 3 – Left: The impact of elevated CO2 concentrations (x-axis) on above ground biomass (a), below ground biomass (b), and total biomass (c) of three species of perennial grasses as quantified in Zheng et al. (2018). Right: Generalized relationship between CO2 level and plant growth rate. Note that a CO2 concentration of 300 ppm was considered “Normal Air” at the time this illustration was first sketched by Roger H. Thayer (see here for an early version), which has been reproduced over the years despite the global average now being 422 ppm (e.g., like the figure above provided by the Oklahoma State University Extension). As mentioned above, these elevated levels of CO2 concentration in the atmosphere would be potentially harmful for humans when inhaled indefinitely without respite (every hour of every day), especially for vulnerable demographics. So not only does high CO2 raise new challenges for plant growth (such as drought and flooding) and ecosystem stability, the optimum CO2 level for plants is incompatible with human physiology over the long-term. The high CO2 enjoyed by dinosaurs and plants is just not relevant for human well-being, making Corsetti’s suggestions misleading. Because of human activities, carbon dioxide is now higher than our species have ever experienced CO2 is considered the most important greenhouse gas because it has such a long residence time in the atmosphere, it is by far the most abundant, and it contributes the most to global warming and climate change. The direct and indirect environmental impacts of high anthropogenic-CO2 emissions are not just related to temperature increases, but also other changes across different components of the Earth system. Aside from air temperature increase, climate change has been observed with the oceans getting warmer, ice sheets shrinking, glaciers retreating, snow cover decreasing, sea level rising, arctic sea ice decreasing, and extreme weather events increasing in frequency (see here for evidence provided by NASA). Relative to global concentrations in the year 1750, atmospheric CO2 has increased by more than 47% because of human activities[10]. As indicated in Figures 1 and 2, the current level of atmospheric-CO2 (422 ppm) is now higher than the human species has ever experienced. Air trapped in ancient ice cores has demonstrated that CO2 has not been this high for at least the past 800 000 thousand years (ice record limit). NOAA stated in 2022 that CO2 levels are now comparable to the Pliocene Climatic Optimum, between 4.1 and 4.5 million years ago. As a reminder, Homo sapiens have only been around for 260-350 thousand years. Rather than the steep reduction in CO2 emissions needed to meet climate goals and limit global warming, 2023 saw another slight increase compared to year before (+1.1%), increasing 1.5% since before the COVID-19 pandemic, and representing a 10-year plateau of sustained high emissions and no significant reductions[11]. Humans have emitted 40.7 gigatons of CO2 in 2022, with a similar amount estimated for 2023. Increasing anthropogenic CO2 emissions like this raises concerns for human cognition and well-being outside just like it does indoors[12]. Of course, not all regions of Earth have exactly the same CO2 concentration at all times, some can exceed others due to geographical factors. In dense urban areas, especially large cities in low-lying basins, CO2 can build up. And with CO2 concentration increasing by about 2.4 ppm in 2023 worldwide[11], geographically constrained urban areas with high populations like Mexico City and Athens could see local concentrations reaching harmful levels for humans by the end of the century[13]. Finally, claims that elevated CO2 concentrations are not bad for humans as Corsetti suggested in his post generally ignore one more critical aspect: the rate of change. The current rate of increase is estimated to be occurring 10 times faster than any other change of similar magnitude over the past 65 million years[14]. As this is much faster than plants, animals, and humans can evolve and adapt to (other than migration), and faster than ecosystems can sufficiently respond to, the risk of extinction is enormous in the coming decades (up to 29% of land plants and animals at risk of being wiped out with 3°C of warming; we are currently at 1.1°C of warming)[15]. CO2 by itself is not causing a climate crisis; elevated CO2 emissions from human activities are. Conclusion: The claim that because high CO2 was fine for the dinosaurs and high CO2 benefits plants today in greenhouses, high CO2 can’t be bad for humans is misleading. Firstly, the optimal carbon dioxide levels for dinosaurs and plants is, in fact, harmful for humans over the long-term. The age of the dinosaurs (the Mesozoic Era) had atmospheric-CO2 in the 2000 to 4000 ppm range, and plants typically grow best at 1000 ppm of CO2 or greater (like in greenhouses). Humans, on the other hand, can suffer mild health effects from CO2 as low as 1000 ppm even in the short-term, and the effects of permanent exposure to elevated CO2 levels are unknown. This is especially relevant for vulnerable populations, and anyone living in low-lying, densely populated urban areas. Humans as a species have never before experienced the high level of CO2 currently in the atmosphere, which is higher than it has been for as long as ice records can tell us (800 000 years). CO2 by itself is not causing a climate crisis; elevated CO2 emissions from human activities are.

https://science.feedback.org/review/study-calls-people-grow-their-own-food-years-come-despite-finding-higher-carbon-footprint-compared-conventional-agriculture/

Misleading

Facebook, The Atlas Society, Social media users, 2024-01-26

Study and headline saying homegrown food is more carbon intensive than conventional agriculture is meant to discourage and stop people from growing their own food

Misrepresents source: New study which quantified a higher carbon footprint of urban agriculture compared to conventional agriculture does not discourage or call for people to stop growing their own food. On the contrary, the study proposed multiple solutions to reduce carbon emissions and calls for maintaining and supporting urban agriculture, including home gardens, as long-term components of sustainable cities.

Although low-tech urban agriculture is expected to be a central component of sustainable cities in the future due to its many social, ecological, and nutritional benefits, new research demonstrates it is not necessarily less carbon intensive than conventional agriculture as commonly assumed. Scientists in general not only argue for long-term maintenance of urban agriculture as a tool for sustainable development, they also find ways to reduce the carbon footprint of home and community gardens, such as reusing the same infrastructure year-over-year. There is no evidence of scientists calling for the restriction of urban agriculture, home gardens, and citizen rights to growing their own food to reduce carbon emissions.

New study and article headline saying homegrown food is worse for the climate than conventional agriculture is ridiculous propaganda meant to discourage and ultimately ban people from growing their own food. Growing your own food in your garden will soon be prohibited in the name of climate change because they say it is more carbon intensive than conventional agriculture.

1 – Nicholls et al. (2020) The contribution of small-scale food production in urban areas to the sustainable development goals: A review and case study. Sustainability Science. 2 – Lee et al. (2015) Greenhouse gas emission reduction effect in the transportation sector by urban agriculture in Seoul, Korea. Landscape and Urban Planning. 3 – Azunre et al. (2019) A review of the role of urban agriculture in the sustainable city discourse. Cities. 4 – Appolloni et al. (2021) The global rise of urban rooftop agriculture: A review of worldwide cases. Journal of Cleaner Production. 5 – Goldstein et al. (2017) Contributions of local farming to urban sustainability in the Northeast United States. Environmental Science & Technology. 6 – Maureira et al. (2022) Evaluating tomato production in open-field and high-tech greenhouse systems. Journal of Cleaner Production. 7 – Ribeiro et al. (2023) Evidence on how urban gardens help citizens and cities to enhance sustainable development. Review: and bibliometric analysis. Landscape and Urban Planning. 8 – Hacking & Guthrie (2008) A framework for clarifying the meaning of Triple Bottom-Line, Integrated, and Sustainability Assessment. Environmental Impact Assessment Review. 9 – Ikeda et al. (2023) The Role of Urban Gardening in Global Cities: Three Case Studies in Berlin, Rome and Tokyo. In Sustainable Health Through Food, Nutrition, and Lifestyle. Springer Nature. 10 – Orsini & D’Ostuni (2022) The Important Roles of Urban Agriculture. Frontiers for Young Minds.

To meet global food challenges, such as increases in overall food demand alongside decreases in the natural resources needed for food production, urban agriculture is expected to play a critical role in the coming decades[1]. Because of the significant potential for transport carbon emissions reductions when food is grown close to the point of consumption[2], as opposed to in rural areas far away, there is the assumption that urban agriculture can be much less carbon intensive than conventional agriculture. As more scientific studies are performed, we gain more insight into urban agriculture’s full carbon footprint. Hawes et al. (2024) (“the Hawes study”) added more context to this topic by examining life cycle impacts of low-tech approaches in their new study published on 22 Jan. 2024. But what they found was unexpected: individual gardens are about five times more carbon intensive per serving of fruit or vegetables than conventional farming. The study was covered in an article in the Telegraph online, which started a wave of misrepresentation on social media. The Telegraph headline “Carbon footprint of homegrown food five times greater than those grown conventionally” was screenshotted and shared widely in multiple unique posts (such as this and this) alongside the general claim that the study implies urban agriculture is bad for the climate and, therefore, may be banned. One example from a Facebook group with 237 thousand followers has the caption: “Now will they come for your backyard veggie garden? #Reason #GlobalWarming”. Another example from a Facebook group with over one million followers asked: “Which country will be the first to declare home gardens a climate crime? This is absolute lunacy”. Joe Rogan (18.6 million Instagram followers) shared the Telegraph headline with the caption “Anyone that discourages people from growing their own food is not your friend” (over 410 thousand likes). As explained below, the claim that the study’s findings were meant to discourage and stop people from growing their own food misrepresents the original study. The claim is also unsupported within the context of the wider scientific community’s interest in promoting the multiple ecological and social benefits of urban agriculture, regardless of carbon related considerations[3-5]. These benefits were explicitly emphasized in the Hawes study, and again in their explainer article in The Conversation published on the same day, but they were not discussed in the Telegraph’s widely shared article. The Telegraph article also failed to mention that a quarter of home gardens studied outperformed conventional agriculture, which is clearly stated in the study’s publicly visible abstract. No statements against urban agriculture, home gardens, or citizen rights In the Hawes study, there are no statements nor calls against the use of urban agriculture or home gardens. There is also no indication whatsoever that people should not grow their own food. The carbon footprint of food produced using urban agriculture was found to be six times greater than conventional agriculture on average (see below for details). Even with their unexpected findings, the authors highlighted the situations where low-tech urban agriculture outperforms conventional agriculture from a carbon footprint perspective. They suggested best practices to keep low-tech urban farms, individual gardens and collective gardens as long-term fixtures in cities by making them more carbon-competitive. The Hawes study is emphatically not a call to discourage, limit, or criminalize people growing their own food. In an email with Science Feedback, lead and corresponding author Jason Hawes (School for Environment and Sustainability, University of Michigan) reiterated: “We did not call for a ban on urban farming and gardening…our team has more than a century of experience studying the many personal and community benefits that these urban food-growing sites produce…none of our recommendations involved banning the practice – in fact, we suggested that one key [best] practice would be to ensure long-term land tenure for urban agriculture sites.” In the study’s abstract, the authors clearly call for “maintaining [urban agriculture] sites for many years”. In the study’s conclusion, the authors stressed that because of urban agriculture’s many social, nutritional, and environmental benefits (explored below), it is likely to “have a key role to play in future sustainable cities”. There is no evidence that this study has been or will be used in any way, in policies or laws for example, to limit citizen rights to have home gardens as a new strategy to mitigate climate change. The claim that the study’s main finding, as headlined in the Telegraph, is meant as propaganda to discourage urban gardening and stop people from growing their own food is inaccurate. What did the study do, find, and propose? By partnering with individual gardeners, community garden volunteers and urban farm managers at 73 sites across five countries in North America and Europe, Hawes and colleagues tested the assumption that low-tech urban agriculture is less intensive than conventional agriculture. This assumption is mainly based on the fact that transportation emissions, which are very significant for conventional agriculture, are drastically and in some cases entirely reduced in urban agriculture. The study aimed to clarify previous uncertainties from earlier studies, and provide the first large-scale, comprehensive assessment of the full life cycle carbon footprint of different types of low-tech urban agriculture compared to conventional agriculture. Food product emissions were quantified from three types: urban farms (professionally managed, focused on food production), individual gardens (small plots managed by single gardeners) and collective gardens (communal spaces managed by groups of gardeners). For each country, the study included food produced using conventional agriculture both domestically and abroad, considering on-farm impacts, processing and transportation to the city. High-tech urban agriculture was not considered. The carbon footprint of food produced using urban agriculture on average (all three categories) was found to be six times greater than conventional agriculture (420 grams of carbon dioxide emissions equivalent (gCO2e) versus 70 gCO2e per serving), with the individual gardens category being about five times more carbon intensive (340 gCO2e, hence the Telegraph headline highlighting the term “homegrown food”). The main reason why urban agriculture was found to be more carbon intensive than conventional agriculture was the emissions associated with its infrastructure. This includes using raised beds, concrete walkways, small shelters like sheds, and so on, all of which add emissions that are not necessarily comparable to the wide-open fields of conventional farms which can produce food at-scale. In addition, only urban grown tomatoes and asparagus were less carbon intensive than conventionally grown versions among the crops considered. This is likely because conventional tomatoes are already very carbon intensive when grown (i.e., industrial greenhouses) and still need to be transported to the city, meaning urban grown versions are carbon-competitive[6]. Conventionally grown asparagus often requires air-freight importation and when this is factored in “the statistical difference between individual gardens and conventional agriculture vanishes”. Grouping all urban agriculture categories together, 17 of the 73 sites (23%) had less emissions than conventional agriculture, which helped the authors identify best practices to ensure the longevity and sustainability of urban farms, individual gardens and collective gardens in cities, contrary to the claims made on social media. They suggested that practitioners of urban agriculture and policy makers should: maximize the lifespan of farm infrastructure; promote urban waste streams as inputs, and, use farms as sites for education, leisure and community building. Based on the results and expertise of the authors, the Hawes study is in reality a call for people who grow their own food to explore how they can reduce their carbon footprint “by cultivating crops that are typically greenhouse-grown or air-freighted, maintaining [urban agriculture] sites for many years, and leveraging circularity (waste as inputs).” Scientists continue to research and call for more urban agriculture Urban agriculture, farming, and gardening refers to food production in urban areas, including animal husbandry, aquaculture, beekeeping, and horticulture. By enhancing vegetation cover in cities, which increases shade, evapotranspiration, and creates an urban cooling effect, urban agriculture is an internationally recognized option for climate change adaptation (e.g., featured since 2016 in the European Climate Adaptation Platform Climate-ADAPT). Hawes and colleagues are part of the wider scientific community investigating how to minimize the potential costs and maximize the already significant benefits of urban agriculture, especially low-tech approaches and home gardens. Senior researcher Dr. Johannes Langemeyer of the Integrated System Analysis of Urban Vegetation and Agriculture (URBAG) project provided Science Feedback with some insight into the wider context surrounding studies like the one by Hawes and colleagues, in relation to the unique functions of home gardens aside from food production. Based at the Institute of Environmental Science and Technology of Universitat Autònoma de Barcelona (ICTA – UAB), Dr. Langemeyer explained: “Commercial agriculture is primarily optimized for maximizing production yields. In contrast, urban gardening – distinct from urban agriculture – often does not prioritize food production as its primary goal, especially in regions like Europe, the US, and the UK. Urban gardening typically serves multifunctional purposes, such as fostering a connection to nature, providing educational opportunities, and facilitating leisure activities. Therefore, comparing CO2 emissions on the basis of production yield can be misleading, as the objectives of commercial agriculture and urban gardening are fundamentally different. A hypothetical reversal of this comparison might illustrate this point more clearly. For instance, if one were to compare commercial agriculture with urban gardening based on the leisure hours each provides, and possibly the CO2 emissions associated with these leisure hours, the contrast in objectives and outcomes would become more apparent. This perspective highlights the importance of considering the specific goals and functions of different agricultural practices when making such comparisons.” Scientists have been increasingly studying the role of different forms of urban agriculture, like urban community gardens, in driving sustainable development in cities (Fig. 1). There have been at least over 200 independent scientific studies exploring the different sustainable development aspects of urban gardens, with a drastic increase in recent years as scientists have recognized that “promoting urban gardens could be a relevant urban policy directed towards sustainable development”, as concluded by Ribeiro et al. (2023) following a comprehensive bibliometric analysis[7]. Figure 1. Visual overview of the Ribeiro et al. (2023) bibliometric analysis of the scientific literature on urban gardens as tools to promote sustainable development in cities, assessed using the triple-bottom-line framework (see reference [8]).Top: Publications meeting the analysis criteria according to the year of publication (x-axis), demonstrating growth in interest (number of publications indicated in the y-axis). Bottom: The cluster analysis of the publications selected with the most citations, based on the triple-bottom-line sustainable development pyramid. Urban farming can address 13 out of the 17 United Nations Sustainable Development Goals across economic, social and ecological vectors, as demonstrated by some of the outputs of the international GROOF (Greenhouses to reduce CO2 on Roofs) project. Although carbon emissions are a legitimate concern that must be quantified, just as Hawes and colleagues performed for low-tech approaches, urban gardens have been documented across different socio-cultural contexts to do more than just provide food. They also provide public spaces for citizens’ well-being, and serve as meeting places and as places of learning, especially in recent years during the COVID-19 global pandemic[9]. Scientists have even undertaken efforts to encourage the world’s youth to know about and participate in urban agriculture, for example with the article “The Important Roles of Urban Agriculture” published in the journal Frontiers for Young Minds[10]. Opinion articles with titles like “Urban gardening has taken root, and it’s time for cities to encourage new growth” by urban planning experts outside of traditional academia demonstrate the widespread support of urban agriculture as a permanent fixture in urban life, contrary to the claim on social media that studies like Hawes et al. (2024) imply experts want the opposite. The United Nations University even hosts a video series on the role of urban gardens in biodiversity conservation and sustainable development. But just like from the carbon footprint perspective, the social and community aspects of urban agriculture has both benefits and limitations (see here for an overview within the US context, including 40 references of studies by scientists exploring the critical value of urban agriculture). The growth in research interest in urban agriculture and the scientific debate surrounding potential risks and benefits were also outlined in a Global Sustainable Development Report brief in 2015. Overall, as far as we are aware at Science Feedback, there is no evidence of scientists making any efforts related to restricting urban agriculture, home gardens, and citizen rights to growing their own food by citing climate change related concerns. Conclusion: Although low-tech urban agriculture is expected to be a central component of sustainable cities in the future due to its many social, ecological, and nutritional benefits, Hawes and colleagues found it is not necessarily less carbon intensive than conventional agriculture as is commonly assumed. There are multiple ways to reduce the carbon footprint of different kinds of urban agriculture to make them more carbon-competitive with conventional agriculture, such as reusing the same infrastructure year-after-year. The claim that the study and article headline chosen by the Telegraph is meant to discourage and stop people from growing their own food has no support in reality. The study has been misrepresented on social media; there are no statements nor calls against the use of urban agriculture or home gardens within the study or anywhere else among the wider scientific community. On the contrary, Hawes and colleagues clearly call for “maintaining [urban agriculture] sites for many years”, and they concluded that urban agriculture will “have a key role to play in future sustainable cities”.

https://science.feedback.org/review/us-proposed-bills-hearings-dont-confirm-chemtrails-exist-not-geoengineering-strategy/

Inaccurate

Facebook, YouTube, Social media users, 2024-01-12

US state governments are banning chemtrails, confirming secret government programs using chemtrails for various purposes that harm the public and the environment

Factually Inaccurate: No US state government has passed laws banning chemtrails, which remain unproven and not supported by any scientific evidence. US congressional documents have been misattributed and misinterpreted as admissions of chemtrail existence. Proposed bills, citizen petitions, and committee geoengineering hearings do not prove the existence or use of chemtrails.

Contrails are trails of condensing water vapor left in the wake of airplanes. They do not contain harmful chemicals as proposed by "chemtrail" conspiracy theories, which are not supported by any evidence. Although some politicians have proposed bills to ban chemtrails or related conspiratorial concepts, they are not evidence of their existence and no such bills have been passed. Chemtrails are increasingly conflated with solar geoengineering strategies, like stratospheric aerosol injection, but these strategies are real proposals currently being explored by scientists to limit anthropogenic global warming and have not been implemented at scale.

There are secret government programs using chemtrails for various purposes that harm the public and the environment. This is confirmed by New Hampshire and Texas state governments referencing and forbidding chemtrails, and a Tennessee government hearing on the development of geoengineering projects like stratospheric aerosol injection. These sources prove chemtrails are real, harmful, and distinct from contrails. Climate change mitigation is not the real reason behind geoengineering.

1 – Shearer et al. (2016) Quantifying expert consensus against the existence of a secret, large-scale atmospheric spraying program. Environmental Research Letters. 2 – Burns et al. (2016) What do people think when they think about solar geoengineering? A review of empirical social science literature, and prospects for future research. Earth’s Future. 3 – Tingley and Wagner (2017) Solar geoengineering and the chemtrails conspiracy on social media. Palgrave Communications.

There is no credible, scientific evidence that chemtrails exist and are distinct from contrails. Claims that chemtrails exist have been addressed multiple times previously on Science Feedback (e.g., here). Yet, on 12 Jan. 2024, social media user “OFF GRID with DOUG and STACY” (701 thousand Facebook followers, 1.19 million YouTube subscribers) posted a video to their accounts claiming multiple US state governments have confirmed the existence of chemtrails in the text of bills and committee hearings designed to protect citizens from their negative effects, asking the question: “So, if they don’t exist, if there’s no such thing, why are they trying to ban them?” This post, which specifically references the US state governments of New Hampshire, Texas, and Tennessee, has been viewed over 200 thousand times between YouTube and Facebook, receiving tens of thousands of likes and shares. Several other similar claims are also being widely shared on different online platforms by other accounts currently. This review explains why this claim is based on inappropriate sources and is factually inaccurate, broken down by state. Misrepresented, misattributed, and exaggerated sources New Hampshire claim On 19 Dec. 2023, a New Hampshire House Bill was introduced by Rep. Jason Gerhard [R] (main sponsor) and Rep. Kelley Potenza [R] (co-sponsor). The bill (HB1700) was to be known as ‘The Clean Atmosphere Preservation Act’ but was voted “Inexpedient to Legislate” as of 31 Jan. 2024. This means that the bill is considered killed. The post author inaccurately claims “New Hampshire is now actively trying to ban chemtrails over their state.” The bill text does not refer to the term “chemtrails”. Instead, the bill is a proposal for “AN ACT prohibiting the intentional release of polluting emissions, including cloud seeding, weather modification, excessive electromagnetic radio frequency, and microwave radiation and making penalties for violation of such prohibition.” Terms like cloud seeding and other strategies of geoengineering have been publicly and openly debated for decades and are still under debate by scientists, who are uncertain whether the risks are comparable to unmitigated global warming. Chemtrails, on the other hand, have never been scientifically verified and therefore do not have a universally accepted definition that can be used to objectively verify if proposed bills like HB1700 are intended to ban them. The Merriam-Webster dictionary defines chemtrails as “a long-lasting airplane contrail believed to be composed of harmful chemical or biological agents that are dispersed as part of a conspiracy (as to manipulate the environment or the population)”. Contrails are streaks of condensed water vapor created in the air by an airplane or rocket at high altitudes (the factors of their formation are described further in a previous Science Feedback claim review). Chemtrails are not chemtrails, despite photos and videos of contrails continuously used as evidence for chemtrails. Most importantly, HB1700 was simply a proposal for a new law. Legislators in the US, like Rep. Jason Gerhard [R], are generally free to propose bills on a wide range of topics, regardless of their scientific foundation. Citizens, interest groups, and others can suggest a bill idea directly to legislators, but formal bill proposals must be sponsored by a legislator and go through many steps (outlined here), including potentially undergoing major changes and amendments. It can take months to years before a bill is either accepted or rejected. A bill proposal text is not to be taken literally because it must first be debated and approved by the New Hampshire General Court. But in the video post, HB1700 is taken for fact, for example with the post author repeating the specific text “The general court finds…” without providing viewers crucial context that this language is only true if the bill becomes a law. The post author inaccurately claims that New Hampshire is trying to ban chemtrails despite the fact that HB1700 does not refer to chemtrails and is simply a proposal that was sponsored by 2 of the 424 New Hampshire legislators. The progress of the bill can be reviewed here. Texas claim While appearing to read from an internet article from The People’s Voice (formerly known as Your News Wire, one of the most prolific sources of fake news on Facebook), the post author states that: “Texas made history last year when state representatives looked into changing a law to ban dangerous atmospheric aerosol spraying without prior approval and testing of the chemicals being sprayed.” This is inaccurate. In reality, The People’s Voice article refers to an online petition to “…prohibit the continuation of aerosolized spraying” of substances and particulates which “…is extremely harmful to our health and our environment”. Chemtrails are not referenced anywhere in the petition text, but it further states that there is a covert military program to control weather whereby “weather modification is frequently used to justify the spraying” of things like “aluminum oxide and other toxic metal compounds”. A previous Science Feedback claim review explained that allegations of secret large-scale atmospheric programs using chemtrails lack any supporting evidence (i.e., proof) and foundation (i.e., hypothetical basis)[1]. There are no scientific studies nor any existing data confirming elevated global atmospheric, soil, sediment, or water concentrations of the various chemicals that chemtrails are claimed to spread. With thousands of signatures and comments and featuring a photo of contrails, the petition webpage states that it is an initiative from “concerned Texas citizens who demand our State Legislators pass legislation to protect our families, pets, crops, water and environment from any and all negative side effects of…spraying of our sky”. Regardless of the lack of any legitimate and scientifically verifiable supporting evidence, the post author exaggerates the following: “They’re literally admitting they’re allowing people, willy-nilly, to spray in the skies chemicals that have not even been tested for human consumption, or what they could do to the environment, or anything else.” After claiming chemtrails are real and anyone stating otherwise is “gaslighting” later in the video, the post author introduces another bill proposal, saying “Now here’s Texas HR 2977”. However, HR 2977 was a Congressional Bill from the 107th Congress of the US Government (not Texas), proposed in 2001 by Ohio Rep. Dennis Kucinich [D] as the “Space Preservation Act of 2001”. It was intended to “preserve the cooperative, peaceful uses of space for the benefit of all humankind by permanently prohibiting the basing of weapons in space.” Bill HR2977 never passed, but it did explicitly refer to “chemtrails” among various so-called exotic weapons such as extraterrestrial weapons. The post author goes on to claim “I like how Texas actually concluded that little video segment there with the radio waves, mood altering stuff, chemtrails, the aluminum, all these kinds of things going on, all the things the conspiracy people have been talking about for quite a while are right in your face.” Once again, legislators can propose bills on a wide range of topics, regardless of their scientific basis. Bill proposals do not, in and of themselves, prove the existence of all terms included in the text. Tennessee claim The post author also claims that the Tennessee government held a major hearing about geoengineering, alluding to chemtrails being a form of geoengineering (discussed further below). In reality, the document that is quoted comes from an official hearing (see here for full hearing text, see here for hearing video footage) on the subject of geoengineering in 2009/2010 during the 111th Congress of the US Government (not Tennessee), specifically for the Committee on Science and Technology of the House of Representatives. Geoengineering to mitigate negative impacts from climate change and slow global warming are typically grouped into two categories: actively removing carbon dioxide from the atmosphere with different strategies to reduce the greenhouse effect; and reflecting sunlight from the planet to reduce heat inputs. Chemtrails, as generally defined, are not related to the topics that were discussed in the hearing. Chemtrails were mentioned in passing as a joke by subcommittee chairman Hon. Brian Bard, with reference to the need to be transparent with the public on geoengineering strategies if they are ever used in the future. In 2009, the potential risks, challenges and opportunities of geoengineering strategies had become more mainstream, which is why it was presented to the Committee on Science and Technology on the national stage at this hearing. It received wide dissemination in the public at the time, and is still openly explored in the public sphere. Additional context on chemtrails misinformation and their conflation with solar geoengineering The People’s Voice was one of the main sources of the misinformation on social media related to the inaccurate claims posted by OFF GRID with DOUG and STACY in January 2024. Its 19 Jan. 2023 story on the Texas citizen petition was misleadingly titled “Texas Becomes First State To Potentially Outlaw Chemtrails”. Nearly one year later, 3 Jan. 2024, The People’s Voice published another article inaccurately titled “New Hampshire Becomes Second U.S. State To Ban Chemtrails”, misinforming its readers on the New Hampshire proposed bill HB1700. Both articles were written by Your News Wire co-founder Sean Adl-Tabatabai who has a record of influential climate misinformation articles and who also founded The People’s Voice. These articles preceded multiple social media accounts repeating similar inaccurate claims in addition to the ones addressed above. For example, in the days since the most recent article from The People’s Voice, an Instagram account released three video posts on chemtrails as toxic climate/geoengineering, with the third on 19 Jan. 2024 claiming there are now two US states that have outlawed “climate engineering” while filming contrails. A post from another Instagram account repeated inaccurate claims from The People’s Voice article on the New Hampshire proposed bill HB1700, and repeated the inaccuracy that the bill had been passed and chemtrails have been banned. This is certainly not the first time government documents, whether hearings, bill proposals, policy agendas, or scientific reports, have been misrepresented as proof of the chemtrail conspiracy. Social media posts in recent years inaccurately claimed the UN is creating climate change using geoengineering and chemtrails, and the chemtrails are a key tool used to control the weather, with climate change being only a cover-up. Last year, the Mexican government announced a ban on solar geoengineering after an American start-up tested atmospheric sulfur injections from balloons over Mexico without any notice or approval. However, this ban was misrepresented on social media as a ban on chemtrails, despite chemtrails being unrelated to the new Mexican law and unsupported by any scientific evidence. Inaccurate claims that a 2022 CNBC story was actually as an admission of a secret chemtrail program went viral on social media. The story was about a new five-year plan assessing the use of solar and other interventions to mitigate climate change coordinated by the White House Office of Science and Technology Policy and US federal agencies, as directed by Congress. One intervention to be researched is stratospheric aerosol injection. Professor David Keith, a solar geoengineering expert leading a research group dedicated to this topic, told the Associated Press by email that aerosol injection would not leave contrails like those left by planes. Chemtrails remain unproven, unverified, and undiscovered by science. A 2016 study which surveyed of some of the world’s top atmosphere experts, consisting of atmospheric chemists with expertise in condensation trails and geochemists working on atmospheric deposition of dust and pollution, virtually every single respondent did not believe there is any scientific evidence for a secret large-scale atmospheric program using chemtrails[1]. Even when assessing data that conspiracy theorists claim is proof of chemtrails, such as elevated concentrations of specific elements in soils, sediments, and water bodies in remote locations, the overwhelming majority of the respondents stated that there are simpler and better supported explanations. As widely covered in the media, scientists are exploring the risks, rewards, and potential impacts of geoengineering technologies to mitigate climate change, including cloud seeding, solar geoengineering and carbon capture, none of which involve chemtrails. Solar geoengineering covers various hypothetical technologies and strategies that are meant to reflect sunlight out of Earth’s atmosphere to limit ongoing anthropogenic global warming. Ideas proposed for high altitudes, some of which being actively researched but not implemented, include placing a large mirror in orbit, thinning cirrus clouds, or spraying aerosols in the stratosphere (i.e., stratospheric aerosol injection) (Fig. 1). Figure 1 – Six of the most commonly proposed solar geoengineering options. They have different approaches, shortcomings, costs, and feasibility, but they are all designed to reduce the amount of solar radiation in Earth’s atmosphere and therefore limit ongoing anthropogenic global warming (source). There is a general unfamiliarity among the public with solar geoengineering[2]. Adding to the confusion and misinformation online, inaccurate conflations between chemtrails and solar geoengineering are increasing on social media. Science Feedback has addressed this issue in a previous claim review, pointing to the lack of any evidence for chemtrails and lack of evidence that solar geoengineering is happening and having a catastrophic effect on the ecosystems and human health. Tingley & Wagner (2017) found that between 30-40% of the general US public and as much as 60% of social media discourse believes in chemtrail conspiracy theories which “renders rational conversations around solar geoengineering and its potential role in climate policy even more difficult”[3]. Nevertheless, solar geoengineering proposals have been and continue to be publicly evaluated by scientists and government organizations (see here for scientists’ comments on some of the most popular strategies), weighing the pros and cons of each before recommendations are presented to elected officials, just like when they were discussed in front of the US Congress in 2009. Conclusion: Various accounts on social media inaccurately claim that US state and federal proposed bills and congressional hearings confirm the existence or use of chemtrails, with some states even banning chemtrails. However, no state governments have passed laws banning chemtrails, and bill proposals and the texts from congressional hearings are not evidence for the existence of chemtrails. Chemtrails as entities distinct from contrails remain unproven, unverified, and undiscovered by science. Chemtrails are increasingly conflated with solar geoengineering strategies, like stratospheric aerosol injection, which are real proposals currently being explored by scientists to mitigate climate change and limit anthropogenic global warming, but which have not been implemented. UPDATE (1 February 2024): We updated this review to indicate the new status of New Hampshire bill HB1700, which has been updated to “Inexpedient to Legislate” as of 31 Jan. 2024. This means that the bill is considered killed.

https://science.feedback.org/review/evidence-greenhouse-gasses-cause-global-warming-denied-willie-soon-tucker-carlson-interview-mass-social-media-climate-misinformation/

Incorrect

Tucker Carlson Network, Willie Soon, 2024-01-09

Carbon dioxide does not cause global warming, scientists are 90% sure it’s the Sun; The climate problems blamed on carbon dioxide (such as ocean acidification and negative impacts on polar bears) are not real

Incorrect: The hypothesis that the Sun is responsible for climate change is inconsistent with real-world observations. Scientific consensus based on overwhelming evidence shows that greenhouse gasses like carbon dioxide are the main cause of current global warming, beyond reasonable doubt. Inaccurate: Elevated atmospheric carbon dioxide causes the enhanced greenhouse effect which has multiple direct and indirect impacts on the hydrosphere and biosphere, including ocean acidification and the reduction of arctic sea ice, which affects polar bear populations. Flawed reasoning: The fact that Saturn’s moon Titan is much colder than Earth despite having more methane does not mean that methane does not cause global warming on Earth as a greenhouse gas. In fact, methane causes the greenhouse effect on Titan just as it does on Earth.

The causes of climate change and global warming are well-known among the international scientific community. Scientific consensus based on overwhelming evidence, beyond reasonable doubt, shows that anthropogenic greenhouse gas emissions are the main driver of current global warming, not the Sun. Elevated atmospheric carbon dioxide has multiple direct and indirect impacts on the hydrosphere and biosphere, including ocean acidification and arctic sea ice loss due to global warming which affects polar bears.

We don’t know what is causing climate change, but we are around 90% sure it’s the Sun. Methane is on Saturn’s moon Titan and it has no global warming; it is cold because it is far from the Sun. There’s also no consensus on the role of CO2. The climate problems of CO2 are artificial and made-up; it does not cause issues like ocean acidification or make any difference to polar bear populations.

1 – Lockwood (2008) Recent changes in solar outputs and the global mean surface temperature. III. Analysis of contributions to global mean air surface temperature rise. In Proceedings of the Royal Society of London A: Mathematical, Physical and Engineering Sciences. 2 – Santer et al. (2023) Exceptional stratospheric contribution to human fingerprints on atmospheric temperature. Proceedings of the National Academy of Sciences. 3 – Sloan et al. (2016) Cosmic rays, solar activity and the climate. Environmental Research Letters. 4 – IPCC (2021) Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. 5 – Friedlingstein et al. (2022) Global carbon budget 2022. Earth System Science Data Discussions. 6 – Gazeau et al. (2007) Impact of elevated CO2 on shellfish calcification. Geophysical Research Letters. 7 – Molnár et al. (2020) Fasting season length sets temporal limits for global polar bear persistence. Nature Climate Change. 8 – Stern et al. (2016) Sea-ice indicators of polar bear habitat. The Cryosphere. 9 – Bromaghin et al. (2015) Polar bear population dynamics in the southern Beaufort Sea during a period of sea ice decline. Ecological Applications. 10 – Lunn et al. (2016) Demography of an apex predator at the edge of its range: impacts of changing sea ice on polar bears in Hudson Bay. Ecological Applications. 11 – Hörst (2017). Titan’s atmosphere and climate. Journal of Geophysical Research: Planets. 12 – MacKenzie et al. (2021). Titan: Earth-like on the outside, ocean world on the inside. The Planetary Science Journal. 13 – Myers et al. (2021) Consensus revisited: quantifying scientific agreement on climate change and climate expertise among Earth scientists 10 years later. Environmental Research Letters 14 – Lynas et al. (2021) Greater than 99% consensus on human caused climate change in the peer-reviewed scientific literature. Environmental Research Letters 15 – IPCC (2023) Summary for Policymakers. In: Climate Change 2023: Synthesis Report. Contribution of Working Groups I, II and III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change

Review: Dr. Willie Soon, an astrophysicist and aerospace engineer who has received “much” of his research funding from the oil and gas industry, made multiple claims during an interview with Tucker Carlson denying the role of greenhouse gasses like carbon dioxide (CO2) and methane in driving global warming. The original video on the Tucker Carlson Youtube page from 9 Jan. 2024 has since been split into numerous snippets, shared, liked, and viewed millions of times across multiple social media platforms. The core of Soon’s claims are inconsistent with science, as we will demonstrate below for three main claims Soon makes within the first third of the interview. Greenhouse gasses drive recent global warming, not the Sun Soon: “We may not know exactly what is causing climate change, we suspect it’s the Sun. We have a lot of evidence to show that it’s probably the Sun. Very high percentage, you know like I would say 90% we are sure” (minute 12:47) The drivers of climate change and global warming are well-known among the international scientific community. There is a straightforward history spanning back to the mid-19th century of how scientists have reached the consensus on anthropogenic climate change, which is that CO2 and other greenhouse gasses like methane emitted by human activities are causing current global warming. Scientists have known for over a century that CO2, in particular, is a key greenhouse gas that is strengthening the greenhouse effect in the atmosphere. Like the other known infrared-absorbing greenhouse gasses, CO2 absorbs and re-emits heat and therefore maintains a higher temperature in the atmosphere than non-greenhouse gasses. Since the first experiments, like those of Eunice Newton Foote in 1856, countless more studies have tested and validated the warming effect of increased atmospheric-CO2. Solar irradiance (the amount of power per unit area of solar energy reaching the Earth in the form of electromagnetic radiation, measured in watts per meter squared, W m–2) and its influence on the climate are well-understood by scientists and the evidence shows clearly that solar variability cannot account for the recent warming[1]. The effect of rising rates of atmospheric greenhouse gasses, on the other hand, has been well established by decades of scientific research. The Sun’s activity has been monitored since the beginning of the 20th century, and although solar irradiance can have yearly fluctuations, there has not been a statistically significant increase in recent decades, as opposed to global temperatures (Fig. 1). Solar irradiance has decreased since the 1960’s while global temperatures have increased. The warming influence of CO2 has been much greater than that of the Sun over the past century. Figure 1 – Comparison of the global surface temperature changes (red) and the Sun’s energy that Earth receives (yellow) in watts per square meter since 1880. One can see that since the 1960s, the global temperature and solar activity have varied in opposite directions, which wouldn’t be the case if the Sun was responsible for global warming (source). Soon claims the Sun is causing global warming, which means it is causing the recent warming observed at the surface of the Earth (i.e., the troposphere). If this was true, we should be able to observe warming at every layer of the atmosphere, especially at the top which receives the most radiation. Solar radiation reaching the surface on a clear day is around 1000 W m–2, while at the top of the atmosphere it is 1361 W m–2. However, the upper layers of the atmosphere (i.e., the stratosphere) have not increased in temperature in tandem with the surface layer. The temperature in the lower stratosphere (high altitude) has actually fallen while the temperature of the lower troposphere (low altitude) has risen, one of the main “human fingerprints on atmospheric temperature”[2]. This observation is consistent with the enhanced greenhouse effect, where heat-trapping gasses like CO2 in the troposphere cause temperature to increase. This observation is inconsistent with Soon’s claim. Estimates of the potential contribution of solar radiation to recent global warming further contradict Soon’s claim. At the high end, a 2016 study concluded that “the contribution of changing solar activity either through cosmic rays or otherwise cannot have contributed more than 10% of the global warming seen in the twentieth century”[3]. The IPCC has compiled robust estimates of all of the contributors to observed global warming, concluding that solar activity was a virtually non-existent factor in comparison to anthropogenic greenhouse gasses (Fig. 2). When comparing the effective radiative forcing (ERF, aslo measured in units of watts per meter squared (W m–2)) of global warming contributors since 1750, CO2 has an ERF of 2.16 W m–2, and methane is at 0.54 W m–2. Because these values are positive, they represent energy added to the Earth system, unlike the insignificant ERF for solar (indistinguishable from zero). Figure 2 – Top: The contributions of different drivers to global warming from the present time period (2010-2019) relative to the time period of 1850-1900 (source). The estimates of warming (red) and cooling (blue) from radiative forcing studies (panel (c)) are based on both direct emissions into the atmosphere and their effect, if any, on other climate drivers. Bottom: Change in effective radiative forcing from 1750 to 2019 by greenhouse gasses, ozone, stratospheric water vapor, surface albedo, contrails and aviation-induced cirrus, aerosols, and solar. The anthropogenic total category represents the combined positive and negative effects of human activities (everything except solar). The solid bars represent best estimates with very likely (5–95%) ranges represented by the error bars (source). Multiple direct and indirect environmental impacts of elevated CO2 in the atmosphere Soon: “What we know now is CO2 ain’t gonna cause nothing. It’s not gonna change much of the climatic system…it won’t make any difference with the polar bear population…it won’t even cause what they call ocean acidification” (minute 8:39) CO2 is considered the most important greenhouse gas because it has such a long residence time in the atmosphere, it is by far the most abundant, and it contributes the most to global warming and climate change (Fig. 2). Relative to global concentrations in 1750, atmospheric CO2 has increased by 47%[4]. Methane, which breaks down into CO2 after around a decade in the atmosphere, has increased by 156%. Through the enhanced greenhouse effect, human emissions of these gasses have resulted in an increase in average global temperature of more than 1°C since record keeping began in the second half of the 19th century. As temperature is pivotal to Earth’s climate system, Soon’s general claim that CO2 “ain’t gonna cause nothing. It’s not gonna change much of the climatic system” is at odds with reality. The direct and indirect environmental impacts of high anthropogenic-CO2 emissions are not just related to temperature increases, but also other changes across different components of the Earth system. Aside from air temperature warming, climate change has been observed with the oceans getting warmer, ice sheets shrinking, glaciers retreating, snow cover decreasing, sea level rising, arctic sea ice decreasing, and extreme weather events increasing in frequency (see here for evidence provided by NASA). Soon’s specific claims that CO2 does not make any difference with the polar bear populations nor cause ocean acidification are inaccurate and explored in detail in Box 1. Box 1. The impacts of CO2on polar bears and ocean acidification. Contrary to what Soon claims, CO2is directly linked toocean acidification. Theocean has absorbed between 20-30%of total anthropogenic CO2emissions in recent decades[5]. The excess carbon that is absorbed makes the oceans more acidic because when CO2dissolves in seawater, it forms carbonic acid, which lowers the pH of the ocean. Global surface ocean waters have increased in acidity by about 30% (because of a pH drop of 0.1) since the beginning of the Industrial Revolution, matching increases in atmospheric-CO2from human emissions (Fig. 3). Ocean acidification also causes a decline in carbonate ion concentrations and the calcium carbonate saturation state. When this lowers, carbonate minerals will dissolve, which can have implications for organisms with exposed calcium carbonate shells and skeletons, from corals to oysters, clams, and mussels. It has already been shown from experiments that the structure and function of marine species, particularly organisms with calcium carbonate shells or skeletons, are affected by ocean acidification[6]. Figure 3 –Recent trends in surface (< 50 m) ocean carbonate chemistry over the period 1988–2015 at the Hawaii Ocean Time-series (HOT) Program in the North Pacific. The upper panel shows the similar increase in CO2(CO2, as concentration in air (ppm)) in the atmosphere (red points) and surface ocean (blue points). The bottom panel shows a decline in seawater pH (light blue points, primary y-axis) and carbonate ion (CO32−) concentration (green points, secondary y-axis) (source). By driving global warming and reducing arctic sea ice extent, it is also well established that global warming has and will continue to negatively impact polar bear populations. A 2020 study estimated that, “with high greenhouse gas emissions, steeply declining reproduction and survival will jeopardize the persistence of all but a few high-Arctic subpopulations [of polar bears] by 2100”[7]. Because polar bears depend on sea ice for hunting, and because their main prey seals also depend on sea ice for breeding and making dens, arctic sea ice loss is making it more difficult for polar bears to hunt[8]. Studies correlating local losses in sea ice habitat with polar bear populations found that some subpopulations have already been negatively affected[9-10]. Loss of sea ice is occurring in almost all polar bear subpopulations, with arctic sea ice extent trending downwards since reliable satellite record keeping began in 1979 (Fig. 4). The downward linear trend in Arctic sea ice extent for December over the over four decades of satellite records is 43 400 square kilometers per year, or 3.4 percent per decade relative to the 1981 to 2010 average. Based on the linear trend, December has lost 1.97 million square kilometers of ice since 1979, equivalent to three times the size of Texas. Leading polar bear population experts Dr. Andrew Derocher and Dr. Ian Stirling told Science Feedback in a previous claim review that “Current [polar bear] declines are due to climate change associated loss of sea ice”, and “Several [polar bear] populations…declined significantly as a direct result of climate warming causing steady loss of sea ice”, respectively. Figure 4 –Monthly December ice extent shows a decline of 3.4 percent per decade over the period from 1979 to present day (source). Titan is climatically distinct from Earth and yet methane still causes the greenhouse effect on both Soon: “Titan…it’s very cold by the way, so it’s minus 290 degrees Fahrenheit. Hint, hint, hint, where is the global warming there, right, if it’s full of methane?…because it’s far away from the Sun that’s what it is.” (minute 2:33) Titan is much colder than Earth because it is far from the Sun, but Soon uses flawed reasoning to claim this means methane does not cause global warming (on Titan or on Earth). Dr. Sarah Hörst, Associate Professor at John Hopkins University and one of the world’s leading experts on Titan’s atmosphere and climate[11], explained to Science Feedback that “Titan receives substantially less Sunlight than the Earth so it should be about 82 Kelvin (-191.15 °C) but the greenhouse effect provided by methane results in a surface temperature that is about 12 K warmer”. Titan orbits Saturn, which is 1.4 billion kilometers away from the Sun on average, compared to Earth’s average distance of 150 million kilometers. Titan’s average temperature is around -179 °C (-290 °F), compared to Earth’s at around +15°C. So, even though Titan is still very cold (-179°C) because it is so far from the Sun, it would be even colder (-191 °C) without methane causing the greenhouse effect like it does on Earth. Titan receives approximately 1% of the solar radiation that Earth receives. Furthermore, of the solar radiation reaching the top of Titan’s atmosphere, only 10% reaches the surface (compared to 57% for Earth). Titan’s distinct atmosphere to Earth actually features both a greenhouse effect (provided by methane and collision-induced absorption) and an anti-greenhouse effect (from the stratospheric haze layer). For comparison, an Earth without methane and all the other greenhouse gasses causing the greenhouse effect, would be around -33°C colder. There are other reasons why Soon’s comparison of Earth and Titan to deny methane’s role in the greenhouse effect is flawed. At Earth’s current temperature, the atmosphere is able to hold on average 0.4% water vapor ranging from 4% in the humid tropics to nearly 0% in the polar regions. Water vapor, a known greenhouse gas explored in a previous Science Feedback claim review, is responsible for about half of the natural greenhouse gas effect keeping Earth warm. Titan, on the other hand, has virtually no water vapor anywhere because it is so cold and it has no liquid water. Overall, Titan has a completely different atmospheric composition, pressure, and gravity than Earth. Both Titan and Earth have a stratified atmosphere with a troposphere, stratosphere, mesosphere, and thermosphere, but Titan’s is much more extended because of its lower surface gravity (reaching heights of 15–50 km compared to Earth’s 5–8 km)[12]. Although Earth and Saturn’s moon Titan are the only two astronomical bodies with significant atmospheres and surface seas with stable liquids in the solar system, Titan’s climate cannot be directly compared to Earth’s. Titan’s atmosphere is mostly molecular nitrogen (about 95%) and methane (about 5%), compared to Earth’s 78% and 0.00018%, respectively. There is no widely accepted answer for how so much methane appeared on Titan, but there is no mystery that hydrocarbons can exist without originating from organic lifeforms like fossil fuels from plants and animals. Methane exists off Earth as a gas, liquid, or as ice. It is found on Neptune, Uranus, and there’s so much on Titan that it rains methane and there are lakes and rivers of liquid methane (and ethane). It is one of the most abundant types of ice detected outside of our solar system too, and scientists have even managed to create methane in a laboratory under space-like conditions. Additional context As we have shown above, Soon made multiple incorrect claims about the science of how greenhouse gasses like CO2 and methane are driving global warming. In the video, Soon also claimed the scientific evidence for global warming driven by CO2 is “all artificial” and dreamed up by the “tyranny of the few”. First, as we have shown, the science of climate change is actually built on real evidence that has been studied and compiled by tens of thousands of scientists over decades. Second, climate contrarians like Soon are, in fact, the extreme minority who have a disproportionately large influence over public opinion. Nearly all scientists agree greenhouse gas emissions are the cause of global warming. Among scientists with the most climate-related expertise, the consensus reaches 100%[13]. A recent peer-reviewed scientific study analyzing thousands of other peer-reviewed scientific studies found that 99% of the scientific literature confirms human greenhouse gas emissions cause global warming[14]. In the most recent IPCC report (AR6), the very first text line (line A.1.) of the “Summary: for Policymakers” directly contradicts Soon by stating “Human activities, principally through emissions of greenhouse gasses, have unequivocally caused global warming”[15]. The report confirms there has been 1.1°C of global warming since the period 1850-1900 and it explicitly identifies CO2 from human emissions as the leading cause (Fig. 2). As an indication of the scientific robustness of AR6, just the contribution from Working Group 1 alone was written by 234 of the world’s leading climate scientists coming from 66 countries. It included nearly 4 000 pages of research based on more than 14 000 scientific papers as supporting references and was critiqued and revised by over 1 500 expert reviewers. Incorrect and inaccurate claims like those made by Dr. Willie Soon in his interview with Tucker Carlson reach millions of people, amplified across social media platforms; they become super-spreaders of climate misinformation.

https://science.feedback.org/review/eu-not-passing-law-seize-scrap-cars-under-climate-agenda-contrary-peter-sweden-claim/

Inaccurate

Twitter/X, Peter Imanuelsen (aka Peter Sweden), 2023-11-27

The EU could SEIZE and SCRAP your old car if it doesn't meet their criteria as part of their climate agenda.

Inaccurate: The EU Commission’s proposal does not mandate the seizure and scrapping of vehicles merely for failing to meet specific environmental criteria. Instead, it outlines how to assess and recycle vehicles that are neither economically repairable nor roadworthy, aiming to minimize environmental harm. Inaccurate: Retaining an old combustion engine car is less beneficial for the climate than replacing it with an electric vehicle (EV), which offsets the initial emissions in a few years (driving ~40,000 km), particularly when the EV is lightweight and equipped with a smaller battery.

The EU Commission’s proposal focuses on regulatory measures aimed at manufacturers and the automotive industry; it doesn’t target car owners or consumers. Increasing the circularity of car parts and materials is expected to reduce the need for production and shipping of new materials, thereby lowering greenhouse gas emissions associated with manufacturing and transport.

The EU could SEIZE and SCRAP your old car if it doesn't meet their criteria as part of their climate agenda. Repairing an already existing car with spare parts is by far the best thing to do if you care about carbon emissions.

1 – IPCC (2022) Chapter 10: Transport. In: Climate Change 2022: Mitigation of Climate Change. Contribution of Working Group III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change

In July 2023, the European Commission introduced a regulation proposal for end-of-life vehicles (ELV) to enhance vehicle life-cycle circularity in the European Union (EU). This initiative aims to ensure that vehicles are used to their fullest potential and that their components are recycled or repurposed at the end of their lifecycle. Following its announcement, numerous claims emerged on social media suggesting that the regulation would allow the EU to infringe on personal freedoms and threaten car ownership under the alleged guise of climate change and environmental concerns. The new end of life vehicles regulation targets the automotive industry, not consumers One such viral post was published by Peter Imanuelsen, also known as “Peter Sweden”, who has regularly shared climate change misinformation according to Climate Action Against Disinformation. Imanuelsen claimed that the EU could “SEIZE and SCRAP your old car if it doesn’t meet their criteria as part of their climate agenda.” His post further claimed that the state would dictate “how long you will be allowed to own your car”, suggesting there would be mandatory scrapping of vehicles that miss their regular EU checkup for two years or if the cost of repairing a car exceeds its market value. In reality, the EU Commission’s proposal does not mandate the seizure and scrapping of vehicles simply for not meeting certain environmental criteria. Instead, it provides guidelines for assessing vehicles that are neither economically repairable nor roadworthy, without stipulating specific consequences. In accordance with this, Annex 1 of the ELV proposal specifies that a vehicle is considered economically irreparable if its market value is lower than the cost of the necessary repairs required to meet road worthiness standards in the Member State where it is registered. This clause relates to evaluating the economic viability of repairing a vehicle; it does not enforce the seizure and scrapping of vehicles based solely on their condition. Furthermore, the EU Commission’s proposal does not specifically target car owners or consumers. The focus is on regulatory measures aimed at manufacturers and the automotive industry. In fact, the proposal is designed to promote new industrial practices in manufacturing and disposal, relevant only to the industrial sector. Thus, there is no evidence in the regulation’s terms that private cars could be seized and scrapped, contrary to Imanuelsen’s claim. Figure 1 – Extract detailing the proposal’s objectives, in the terms of the EU Commission’s proposal on circularity requirements for vehicle design and on management of end-of-life vehicles (source). Another document that reacted to the proposal is an online petition against it written by a Swedish bikers’ Magazine, which garnered over 12,000 signatures. The petition claimed that the proposal “concerns the purchase, sale, right to ownership of vehicles, parts and components, repair, renovation, restoration, preservation, and modification.” However, these claims are false, as the proposal does not introduce changes to the private rights related to car modifications. Indeed, the proposal focuses on transforming design and production industry requirements to increase both the quantity and quality of materials that are reused, remanufactured, and recycled (see Figure 1). The regulation’s potential impacts are openly available in an Impact Assessment Report, which is based on feedback from stakeholders. Would the regulation reduce carbon dioxide emissions? An overarching claim repeated several times in Imanuelsen’s post is that reducing carbon dioxide (CO2) emissions is merely a pretext for this proposal “to take away your freedom and control your life”. This new regulation is actually very likely to result in reducing carbon dioxide emissions as intended. The increased circularity of car parts and materials will reduce the need for production and shipping of new materials, thereby lowering greenhouse gas emissions associated with manufacturing and transport. This type of circular economy policy is indeed recognized by scientists as an “effective approach to mitigate industrial greenhouse gases emissions” in the latest IPCC assessment’s summary to policy-makers. Imanuelsen’s claim overlooks the very significant role of road vehicles in contributing to global greenhouse gas emissions. In 2019, direct greenhouse gas emissions from the transport sector accounted for 23% of global energy-related CO2 emissions, according to the IPCC’s latest assessment1. Most importantly, about 70% of direct transport emissions came from road vehicles (see category “Road” in Figure 2). Figure 2 – Evolution of the transport sector’s global greenhouse gases (GHG) emissions by transportation category from 1990 to 2019. Emissions are measured in gigatons, or billions of tons, of carbon dioxide equivalents (CO2-eq). This unit standardizes the climate effects of various greenhouse gases by equating their warming potential to that of carbon dioxide (source). While most CO2 emissions occur when a car is being driven, reducing emissions in the manufacturing phase still represents a significant opportunity, given the scale of the transport sector’s greenhouse gas emissions. According to the German Environment Agency, the manufacturing phase of an internal combustion vehicle, in case of a lifetime mileage of 168,000 km, has a share of 15% of the overall CO2 emissions (64% for the use-phase, 17% for fuel production and 4% for disposal and maintenance). The EU Commission has estimated that the proposed regulation would lead to an annual reduction of 12.3 million tons of CO2-equivalent in 2035. To put it into perspective, it can be compared to avoiding about 24 million flights from Paris to Helsinki a year, which emit about 0,5 tons of CO2-equivalent per passenger in Premium Economy class according to myclimate’s flight emissions calculator. Keeping an older car is not more beneficial for the climate Imanuelsen also claims that “repairing an already existing car with spare parts is by far the best thing to do if you care about carbon emissions”. However, replacing an old, inefficient vehicle with an electric vehicle (EV) does lead to a reduction in carbon dioxide emission. Although there is a bump in CO2 emissions during the production of an EV and its battery, the EV begins to offset these emissions after being driven for approximately 20,000 to 32,000 miles in the UK (equivalent to 32,000 to 51,000 kilometers), as illustrated in the chart below, according to a Carbon Brief analysis. Figure 3 – Lifecycle tonnes of CO2 (y-axis) per thousand miles of driving in the UK (x-axis) for an old pre-2015 petrol Ford Focus (grey trendline), old pre-2000 petrol Mercedes (black trendline), a new Tesla Model Y (red trendline) or new Nissan Leaf (peach trendline). Purchasing a new EV implies adding new CO2 emissions during its production and during the production of its battery (emissions accrued before the first mile driven, trendlines left of 0 on x-axis), but the lower emissions involved in the operation of an EV mean that these initial emissions are offset within a short period when compared to the continued operation of an old vehicle. After this crossover point (where trend lines cross in the gray shaded area), changing to and operating a new EV results in less total emissions than retaining an “old banger” (source). This analysis shows that a typical UK driver replacing an old vehicle, colloquially known as “bangers”, with a new electric vehicle (EV) will offset the initial carbon emissions from the EV purchase in about four years. The precise period for this carbon offset is dependent on several factors, including the fuel efficiency of the replaced car, the annual mileage of the driver, and the battery size of the new EV. Overall, retaining an old combustion engine car is not more beneficial for the climate compared to replacing it with an electric vehicle (EV), particularly when the EV is lightweight and equipped with a smaller battery. The regulation is expected to undergo several stages before it has a chance of being fully implemented. During this process, the proposal may be amended and will be subject to scrutiny by the European Parliament and the Member States. According to the proposal’s terms, it is acknowledged that implementation could take up to 8 years.

https://science.feedback.org/review/contrary-widespread-misrepresentation-new-study-finds-extremely-minimal-impact-human-breathing-climate/

Misleading

Daily Mail, Jonathan Chadwick, 2023-12-13

Scientists say human breathing is fueling global warming

Misrepresents source: A new study found that human breathing in the UK contributes only 0.0539 of the UK’s 417 megatons of greenhouse gas emissions. The study did not show human breathing is significantly fueling global warming or bad for the environment. In reality, the authors said the contributions of human breathing pales in comparison to fossil fuel burning and other major sources of emissions. Factually inaccurate: The Daily Mail’s claim that the gasses humans exhale contribute to 0.1% of the UK's greenhouse gas emissions is approximately eight times greater than the value the authors of the study estimated, which was 0.013%. In comparison, we have robust data quantifying the actual factors that fuel global warming, such as emissions from energy, transport, and land use.

Human breathing has been found to contribute around one hundredth of one percent of the total greenhouse gas emissions in the UK. Scientists do not claim we are fueling global warming by breathing. The human activities that are, such as greenhouse gas emissions from energy, transport, and land use, are well-known and must be reduced to mitigate the negative effects of climate change.

New study finds the gasses in air exhaled from human lungs are fueling global warming, contributing 0.1% of greenhouse gasses in the UK. Now scientists say breathing is bad for the environment.

1 – IPCC (2023) Summary for Policymakers. In: Climate Change 2023: Synthesis Report. Contribution of Working Groups I, II and III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change 2 – Polag & Keppler (2019) Global methane emissions from the human body: Past, present and future. Atmospheric Environment 3 – Mitsui et al. (1997) Effect of aging on the concentrations of nitrous oxide in exhaled air. Science of the Total Environment 4 – Van Der Geest et al. (2021) Slow-onset events: a review of the evidence from the IPCC Special Reports on Land, Oceans and Cryosphere. Current Opinion in Environmental Sustainability 5 – Wang et al. (1985). Potential climatic effects of perturbations other than carbon dioxide. In: Projecting the Climatic Effects of Increasing Carbon Dioxide. United States Department of Energy.

A new scientific study published on 13 Dec. 2023 quantified greenhouse gasses (GHG) emissions from human breathing in the UK and compared the results with other, more well-known known sources of emissions. Dawson et al (2023) found that only 0.05% and 0.1% of the UK’s methane and nitrous oxide emissions, respectively, can be attributed to people breathing. Overall, breathing is estimated to contribute 0.013% of GHG emissions in the UK. Despite these small percentages, over the next few days and weeks of this study being published, far-reaching online media sources (tabloids) and influential social media accounts misled the public by misrepresenting the study. Among the various headlines reaching millions of readers (a sample is listed further below), the Editorial Board of the New York Post published a piece about the study on 21 Dec. 2023 entitled “Climate fanatics now target BREATHING — proving how much they hate humanity”. Yet, on 13 Dec. 2023, the senior study authors stated explicitly “If you’re looking to reduce your climate impact, don’t hold your breath.” Multiple tabloids, websites and social media posts used the study to claim, whether sincerely or disingenuously, that breathing is causing and fueling global warming. Whatever the intended angle, these claims grossly misrepresent the study which estimated that humans breathing contribute roughly 1.3 of every 10 000 units of greenhouse gasses (0.013%). In particular, the Daily Mail (MailOnline) headline “​​Now scientists say BREATHING is bad for the environment: Gases we exhale contribute to 0.1% of the UK’s greenhouse gas emission” is inaccurate in its entirety. The study and its authors (Dawson and colleagues) never said or implied this, and this percentage value that Daily Mail presented their readers, who then shared it further online, is eight times greater than what the study actually found. The study’s corresponding author, Dr. Nicholas Cowan of the UK Centre for Ecology & Hydrology, has told Science Feedback that headlines like these are “a misinterpretation of what our study says and its message”. He adds: “The effect of human breathing would have extremely minimal impact on climate change – the overwhelming issue that should be the focus of efforts to mitigate global warming is the fossil fuels we burn, which our study made clear.” This claim review will put human breathing as a GHG source in context and outline more precisely what the authors found in comparison to the misleading and inaccurate viral claims which have ensued. Human breathing is not significantly fueling global warming There has been an increase in average global temperature of more than 1°C since record keeping began in the second half of the 19th century. Humans have caused all of the observed contemporary global warming. The main factors fueling global warming are clear; they all relate to increasing greenhouse gas emissions which results in the enhanced greenhouse effect. Roughly 79% of GHG emissions are linked to the energy, industry, transport, and building sectors, with the rest coming from the “agriculture, forestry and other land use” category[1]. An enhanced greenhouse effect means the atmosphere can maintain higher temperatures than before the GHG increase. The main GHGs which fuel global warming and which humans are responsible for are carbon dioxide, nitrous oxide, methane, and chlorofluorocarbons. Human activities like burning fossil fuels (for energy, transport, industry, etc.), cutting down forests, using intensive agricultural practices (especially involving nitrogen fertilizers and ruminant livestock), and using products that involve fluorinated gasses continue to raise GHG levels into unknown territories. Relative to 1750 levels, current atmospheric carbon dioxide has increased by 47% and methane by 156%, far exceeding the scale of natural changes over at least the past 800 000 years between glacial and interglacial periods[1]. Nitrous oxide has also increased by 23% since 1750. Carbon dioxide is considered the most important GHG because it has a long residence time, it is by far the most abundant, and it contributes the most to global warming (Fig. 1). Carbon dioxide causes about two-thirds of the final warming observed; it fuels global warming. Human breathing does not add carbon dioxide to the atmosphere. Figure 1 – Top: The contributions of different drivers to global warming from the present time period (2010-2019) relative to the time period of 1850-1900. The estimates of warming (red) and cooling (blue) from radiative forcing studies are based on both direct emissions into the atmosphere and their effect, if any, on other climate drivers. Y-axis indicates change in temperature in degrees Celsius (source). Bottom: Radiative forcing caused by major long-lived greenhouse gasses from 1979-2019 based on the change in concentration of these gasses in the Earth’s atmosphere since 1750. Radiative forcing is calculated in watts per square meter, which represents the size of the energy imbalance in the atmosphere. On the right side of the graph, radiative forcing has been converted to the Annual Greenhouse Gas Index (set to a value of 1.0 for 1990), which is a measure of the capacity of Earth’s atmosphere to trap heat as a result of the presence of long-lived greenhouse gasses (source). During breathing, human lungs oxygenate blood with atmospheric oxygen, in exchange for carbon dioxide which is cleared out from the lungs through exhalations (called gas exchange). However, the carbon dioxide we exhale is not relevant for global warming because it comes from the food we eat, which was produced using carbon dioxide that was already in the atmosphere. The amount of carbon we breathe out balances with the carbon we consume from plants and animals, with a little left to build and maintain our bodies. Human breathing adds virtually inconsequential amounts of GHGs The datasets we have for the big GHG emission sources, like those coming from land use or the energy and transport sectors, are robust because of their significance as drivers of global warming. But less important GHG sources receive less scientific attention. For example, we do not have much data on how much methane and nitrous oxide we exhale alongside carbon dioxide. The methane and nitrous oxide we exhale is newly added to the atmosphere, unlike carbon dioxide. Methanogenic flora in the human gut produce methane and denitrifying bacteria in the gut and oral cavity produce nitrous oxide. Previous studies estimate breathing contributes approximately 0.11% of methane and 0.16% of nitrous oxideemissions globally[2,3]. Although we already know emissions of these GHGs from breathing are very small, we do not have robust data on the exact quantities we exhale and what factors control them (e.g., our diet, age, gender, etc.). The new study by Dawson and colleagues was conducted to address this research gap and provide more data to compare. Of the 328 breath samples analyzed, they found 31% of people exhaled methane and all emitted nitrous oxide. Extrapolating their results to the full UK population of 68.2 million, they estimated 1.04 gigagrams (Gg) of methane and 0.069 Gg of nitrous oxide are exhaled annually, amounting to 53.9 Gg of CO2e (carbon dioxide equivalent units) in emissions. In relation to the total emissions of the UK, human breathing is estimated to account for 0.05% of the methane (2051 Gg of methane emitted in 2021) and 0.1% of nitrous oxide (72 Gg of nitrous oxideemitted in 2021). These findings are both smaller than previous study estimates for these gasses at the global scale[2,3]. Dr. Cowan explained to Science Feedback that “Emissions of these gases in human breath is not a new discovery and our own global estimates of emissions from the data are actually lower than previous estimates, which are all cited in the manuscript”. So, the Dawson study actually demonstrated breathing may be even less consequential for global warming than studies have previously thought, which was already very low. And yet, these previous studies did not result in viral tabloid and social media attention. Overall, when all of the 430 megatonnes of GHGs (CO2e) emitted in the UK in 2021 are considered, not just methane and nitrous oxide, human breathing contributes only 0.013% of that. The annual impact of breathing would be virtually invisible when stacked up alongside all the actual drivers of global warming in the UK. It would take up only 0.0539 Mt CO2e on the y-axis of Figure 2 which extends from 0 to 800 Mt CO2e. Figure 2 – Summary: of historical greenhouse gas emission estimates in the UK from all anthropogenic sources. Total net greenhouse gas (GHG) emissions in 2020 in the UK were 406 Mt CO2e. Carbon dioxide, which is not increased from human breathing, is the dominant GHG emitted, accounting for 79% of emissions in 2020. According to Dawson et al (2023), human breathing in the UK would only take up 0.0539 Mt CO2e on the y-axis of this figure. The estimated uncertainty in total net GHG emissions in 2020 was ± 3%, at a 95% confidence level. The unit “Mt CO2e” refers to the megatonnes of greenhouse gas emissions in carbon dioxide equivalent units (source). The study has been widely misrepresented; millions of people mislead Major sources of GHG emissions can be reasonably considered “bad for the environment” in reference to their effects on global temperatures, which can lead to a wide-range of climate change related impacts for the natural world. Slow-onset impacts include sea level rise, salinization, ocean acidification, glacial retreat, land degradation, desertification and loss of biodiversity[4]. Climate change has caused losses and damages on terrestrial, freshwater, and ocean ecosystems worldwide[1]. But as demonstrated above, even though human breathing does increase atmospheric concentrations of two GHGs, methane and nitrous oxide, breathing as a GHG source is virtually inconsequential for global warming (and the “environment”) in comparison to major sources like burning fossil fuels, deforestation, and intensive agricultural practices. The widely-shared Daily Mail article is not just a misrepresentation of the words of the study’s authors, it is also factually inaccurate. Science reporter Jonathan Chadwick, who had interviewed Dr. Cowan about the study, writes in the Daily Mail article that “Methane and nitrous oxide in the air we exhale makes up to 0.1 per cent of the UK’s greenhouse gas emissions, scientists say.” But the authors never said this. As Dr. Cowan, corresponding author of Dawson et al (2023), explains: “The total contribution to the UK’s greenhouse gas emissions from human breathing is estimated to be 0.013%, which was clearly communicated to the writer before publication of the article” Further down in the Daily Mail article, Mr. Chadwick contradicts the headline by stating that the 0.05% of methane and 0.1% of nitrous oxide emissions in the UK estimated to be from human breathing does not equate to “0.1% of the UK’s greenhouse gas emissions”. He writes: “Dr Cowan stresses that each of these percentages relate specifically to these respective gases, not all of the UK’s greenhouse gas emissions as a whole.” We reached out to Mr. Chadwick for comment and will update this review if new information becomes available. According to Bob Ward (Policy Director at Grantham Research Institute, LSE), the exploitation of the UK’s ineffective press regulation explains the long track record of climate misinformation from the Daily Mail. This would not be the first time the Daily Mail started a wave of inaccurate climate-related claims just from publishing one article. In 2017, a regulatory ruling led to the Daily Mail admitting multiple inaccuracies in an article on global warming, but the false information (including manipulated graphs since taken down from MailOnline) had already been widely shared and repeated in over 150 different articles. The Dawson study does not state or conclude that breathing is bad for the environment nor that breathing is, or may be, fueling global warming. Despite this reality, the following inaccurate headlines have been published by tabloid press, hyper-partisan websites, and others claiming the study authors say breathing is bad for the environment: Now scientists say BREATHING is bad for the environment: Gases we exhale contribute to 0.1% of the UK’s greenhouse gas emissions (Daily Mail (MailOnline))* ‘Anti-human’: Scientists claim breathing is ‘bad’ for the environment (Sky News Australia)* NEW “SCIENCE” — Humans Breathing Are Bad for the Climate (The New American) Inaccurate headlines published claiming the study authors say breathing is, or may be, fueling global warming include: Humans may be fueling global warming by breathing: new study (New York Post)* Study: Humans Contributing to Global Warming by Breathing (Breitbart News)* Humans Are Fueling Global Warming By Just Breathing, Study Claims (NDTV)* Humans breathing causes ‘global warming’, according to new study (The Post Millennial)* * indicates a mention, quote, or repetition of the inaccurate 0.1% value originating from the Daily Mail. The amount of people who were misled by the overall tabloid media’s inaccurate claims about the Dawson study was further increased on social media. Joe Rogan (7.2 million followers), one of the world’s most influential figures on social media (one of Time 100 Most Influential People, 2022), shared the New York Post article on Facebook. Daily Wire personality Michael J. Knowles (1.5 million followers) posted on Facebook the inaccurate claim that the study means humans have to stop breathing, in addition to the inaccurate claim that methane and nitrous oxide “allegedly contribute to global warming”, which has been well-known for decades based on established and fundamental physics[5]. This inaccurate claim was also made by Blaze Media in their article “UK researchers raise alarm that humans are contributing to ‘global warming’ — by breathing”. Pubity (36 million followers), repeated on Instagram the inaccurate claim that “humans may be fueling global warming by breathing”, and the inaccurate claim that “exhaled methane and nitrous oxide, in addition to carbon dioxide, make up around 0.1% of the UK’s greenhouse gas emissions”. This post alone has been liked over 234 000 times as of 12 Jan. 2023. On the same day the Dawson study was published (13 Dec. 2023), and before the majority of inaccurate and misleading claims appeared in the tabloid media and were shared widely on social media, senior authors Dr. Cowan and Dr. Heal also published an article in The Conversation to help the public understand the study’s main purpose, findings, and implications. In it they stated that the climate change impact of human breathing “pales in comparison to fossil fuel burning and other major sources of emissions”. Dr. Cowan reiterated to Science Feedback: “if you want to be responsible for releasing less greenhouse gasses into the atmosphere, you’d be better off breathing as normal and focusing on other more manageable activities”. Conclusion: The Dawson study found “extremely minimal” impact of human breathing on climate change in the UK, contributing approximately 0.013% of the total greenhouse gas emissions. The factually inaccurate value of 0.1% published by the Daily Mail has been shared and repeated widely. At no point did the authors say human breathing is bad for the environment and fueling global warming. In reality, the senior study authors have said the contributions of human breathing pales in comparison to fossil fuel burning and other major sources of emissions. We have robust data quantifying the actual factors that fuel global warming, such as emissions from energy, transport, and land use. Tabloid press, hyper-partisan websites, and others have misrepresented the scientists words and the study’s findings and implications, misleading millions of members of the public in the process.

https://science.feedback.org/review/claim-cow-burps-not-important-contributor-climate-change-ignores-full-range-greenhouse-gas-emissions-beef-production/

Misleading

Instagram, Social media users, 2023-12-19

Methane from cows is only a small percentage of total greenhouse gas emissions, it would be produced anyways without cattle, it is not an important contributor to climate change

Misleading: Estimates of livestock greenhouse gas emissions do not include land use related emissions, which is one of the most impactful aspects of beef production on climate change. Even so, the seemingly small percentage attributed to US livestock agriculture is still globally relevant because total US emissions are so high. Lacks context: Livestock burps, flatulence, and manure produce 32% of global anthropogenic methane emissions, which drives significantly more warming than carbon dioxide during its relatively short lifetime on a per molecule basis. As beef production increases, so do global methane emissions. Factually inaccurate: Cows are ruminants meaning their stomachs provide ideal anaerobic conditions for the production of methane. The high methane emissions due to the planet’s 1.46 billion domesticated cows would not occur without humans raising such a large number of them.

Reducing methane is critical to achieving global climate targets. Conventional beef and dairy production is a significant contributor to climate change through the release of greenhouse gasses like methane from cow burps. The EPA greenhouse gas estimate does not include land use related emissions from livestock agriculture, which is one of the most impactful aspects of beef production on climate change in addition to cow burps. Methane is a more potent greenhouse gas than carbon dioxide. As beef production increases, so do global methane emissions. The high quantity of cows and the high global warming potential of methane is what makes cow burps impactful on climate change.

Methane claims against cattle are overblown because all emissions from all livestock is only 3.9% of total US greenhouse gas emissions according to the EPA estimate. The emitted methane comes from grass, leaves the atmosphere after 10 years, and then returns to help grass grow. Much of the methane emissions would occur anyways outside the digestive tract of cows.

1 – Lazarus et al. (2021) The climate responsibilities of industrial meat and dairy producers. Climatic change 2 – Emery (2018) Without animals, US farmers would reduce feed crop production. Proceedings of the National Academy of Sciences 3 – Marvin et al. (2023) Natural climate solutions provide robust carbon mitigation capacity under future climate change scenarios. Scientific Reports 4 – Poore & Nemecek (2018) Reducing food’s environmental impacts through producers and consumers. Science 5 – Xu et al. (2021) Global greenhouse gas emissions from animal-based foods are twice those of plant-based foods. Nature Food 6 – IPCC (2023) Chapter 7: Agriculture, Forestry, and Other Land Uses (AFOLU). In: Climate Change 2023: Synthesis Report. Contribution of Working Groups I, II and III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change 7 – Ojima et al. (2020) A climate change indicator framework for rangelands and pastures of the USA. Climatic Change 8 – Hristov (2012) Historic, pre-European settlement, and present-day contribution of wild ruminants to enteric methane emissions in the United States. Journal of Animal Science 9 – Reisinger et al.(2021) How necessary and feasible are reductions of methane emissions from livestock to support stringent temperature goals?. Philosophical Transactions of the Royal Society A

Agriculture is the largest anthropogenic source of methane (CH4) emissions. Livestock agriculture which takes up 80% of global agricultural land but produces less than 20% of the world’s supply of calories, represents about a third of these emissions. It has a much larger emissions profile and impact on climate change than just cow burps. Conventional beef and dairy production results in significant amounts of greenhouse gas (GHG) emissions, which is why improving practices and reducing meat consumption are recognized strategies to mitigate climate change. But in a recent viral Instagram post from 19 December 2023 liked more than 4,000 times, it was claimed that cattle livestock agriculture is not a significant contributor of greenhouse gas emissions. We explain below how this claim is misleading because it fails to account for the full range of emissions linked to beef and dairy production, in addition to methane from cow burps. We also outline how the post caption contains other statements that lack necessary context and are factually inaccurate. The total emissions profile of livestock agriculture is larger than EPA estimates because of land use impacts Agriculture contributes around 10% of all US GHG emissions. In the latest US Environmental Protection Agency’s (EPA) GHG inventory report, livestock agriculture contributed 4.4% of the 6,340.2 million metric tons of CO2-equivalent (CO2-eq) the US emitted in 2021, mostly from enteric fermentation (cow burps) and manure management. The high total emissions of the US may create the impression that livestock agriculture is a relatively small contributor; research has shown that the US meat and dairy industry uses this to undermine climate-related policies[1]. However, 4.4% is still 278.3 million metric tons emitted by US livestock agriculture alone, equating to 69% of the GHG emissions of France for all sectors for the same year, for instance. Furthermore, the use of these EPA estimates to downplay the impact of livestock agriculture on climate change is misleading because they do not include all indirect emissions of CH4, nitrous oxide (N2O), and carbon dioxide, which are significant in the agricultural sector. In addition to enteric fermentation (e.g., cow burps), livestock agriculture involves multiple greenhouse gas emissions sources, such as emissions from manure management (e.g., manure lagoons), feed production (e.g., fertilizer emissions), the energy required to maintain livestock production (e.g., ventilation), and livestock processing and retail (e.g., slaughter and packaging). These all relate to livestock agriculture, but one of the largest emissions sources is still missing: land use impacts. Many GHG estimates typically do not consider the land use impacts of livestock agriculture, despite the fact that it requires extensive land resources. This is the case for the EPA’s estimates. The croplands dedicated to growing livestock feed in the US alone, which is unsuitable for human consumption, cover around three-quarters of the country and involve intensive practices that prioritize yields and negatively affect much of the country’s soils and waterways[2]. Land use impacts in livestock agriculture are especially important for beef production (see Figure 1). Figure 1 – Greenhouse gas emissions for the full supply chain, including land use change impacts, for major animal-based food products measured in kilograms of carbon dioxide-equivalents (CO2-eq) per kilogram of food. Cows are separated as either for beef or dairy production. When land use change impacts and other non-farm sources are included, beef meat production has notably higher greenhouse gas emissions (source). Such extensive land resources dedicated to intensive and environmentally degrading livestock agriculture are blocked from being used to maximize ecosystem carbon sequestration above- (trees and plant biomass) and belowground (soil organic matter). Natural carbon sinks from landscape conservation and restoration are a vital piece of the climate change mitigation puzzle to reduce the impacts of other major sources of GHG emissions, like the transport sector[3]. Land used to intensively grow livestock feed is also land that could be used for producing food suitable for humans to offset meat consumption reductions or crops to foster biofuel production. Expansion of grazing lands and croplands for livestock feed production means less natural vegetation and often much less carbon storage and more carbon emissions. Increases in the demand for beef products within the US can also result in deforestation for pastures in other countries, as beef is a global commodity. Beef production is the leading driver of tropical deforestation, with 2.1 million hectares converted to pastures each year. The lost opportunities for natural carbon sinks and the GHG emissions from land use changes within and beyond the US linked to beef consumption is not represented in the EPAs 4.4% estimate. Including land use and land use change impacts from livestock would significantly increase its emissions profile estimate. For example, considering the average American is ranked second globally for total meat consumption and third for beef consumption, the World Resources Institute estimated the total GHG emissions from the average American-style diet. By including indirect emissions from land-use-change in addition to direct emissions, the total was found to be within the range of per capita energy-related emissions. This indicates that agriculture, primarily because of the total emissions profile of livestock agriculture, can be as impactful for climate change as one of the largest sectors: energy. The total (all direct and indirect emissions) impact US livestock agriculture on top of the EPA’s limited estimate of 4.4% has not yet been robustly calculated. Fortunately, we do have some ideas on how including land use impacts change livestock emission values on the global stage. The FAO estimated that livestock agriculture alone contributes 12% of global GHG emissions in its latest data analysis, with 3.6 billions of tons (Gt, gigaton) of CO2-eq of direct emissions and 6.2 Gt CO2-eq of total emissions (when the full supply chain is considered). Peer-reviewed studies estimate livestock’s contribution at around 15-19% of global emissions, much higher than the EPA’s limited estimate of 4.4%[4-5]. The broader category of “agricultural, forestry, and other land use” is responsible for more than a fifth of the world’s GHG emissions according to the latest IPCC report[6]. This is mainly from land use change (e.g., deforestation for pasture), enteric fermentation (e.g., cow burps), poor pasture and manure management, and nitrogen fertilization. All these factors are linked to beef production. The entire food system, from cultivation, transport, processing, retail, and consumption, contributes 34% of global GHG emissions. Nearly three quarters of that comes from agriculture and its indirect land impacts. Overall, it is clear that cow burps (beef production) are indeed a significant contributor to climate change because they are a major component of agricultural sector emissions when all direct and indirect sources are considered. Cow methane emissions contribute to global warming and would not occur naturally to the same extent Cows are ruminant animals along with goats and sheep; they all release methane (CH4) through burps and flatulence as they digest plants like grass as a result of enteric fermentation. Their burps, flatulence and manure is estimated to contribute 32% of anthropogenic CH4 emissions, and about 40% of global GHG emissions from the agricultural sector in 2011. Contrary to popular belief, cow burps release far more methane than their flatulence. Manure CH4 and N2O emissions represent 7% of global agricultural GHG emissions in 2011. Although CH4 only lasts around 10 years in the atmosphere, it is a much more potent greenhouse gas compared to CO2 and causes long-term damage to climate change mitigation efforts. After being released and within those 10 years, CH4 naturally degrades in the atmosphere through methane oxidation. Chemically, CH4 reacts with ozone to form carbon dioxide and water. Methane-consuming bacteria (methanotrophs) in soil and water can also remove CH4 if in contact. The CO2 and water byproducts of atmospheric CH4 oxidation can then be taken up by ecosystems, for example by photosynthesis in grass to then be consumed by cows, completing this small part of the biogenic carbon cycle. However, this relatively short lifespan and the potential uptake of its oxidized byproducts by plants does not mean CH4 has a neutral impact on global warming. Some context is missing that demonstrates why CH4 methane emissions from cow burps are a significant driver of climate change. First and foremost, the 10 year lifespan of CH4 in the atmosphere is less important than its global warming potential. Why else would one of the world’s largest agribusinesses, Cargill, be investing in cow wearables (i.e., masks) to “tackle methane emissions in the dairy industry”? One molecule of CH4 is over 80 times as potent as one molecule of CO2 in trapping heat in the atmosphere and strengthening the greenhouse effect in the short-term. Even after CH4 oxidizes into CO2, the global warming effect of the original cow burp will continue as CO2 until it is finally photosynthesized by plants. Considering the short-timeframe left for emissions reductions to limit global temperature increase to 1.5°C, any new CH4 emitted to the atmosphere from cows has negative and immediate consequences for climate change mitigation. Second, the fact that CH4 is released by ruminants naturally does not mean it is not an anthropogenic source of CH4 emissions. By drastically increasing beef and dairy production globally, humans have expanded the impact of ruminant CH4 emissions on the atmosphere. Simply put, more cows means more burps and manure which means more CH4 in the atmosphere, in addition to more of the other associated livestock agricultural emissions driving global warming such as land use impacts (e.g., CO2 and N20). The absolute increase and quantity of GHGs is what is most relevant. All human activities have more than doubled atmospheric CH4 over the past 200 years. A single cow produces between 70-120 kg of CH4 gas per year. There are 62% more cows in 2021 than there were in 1961. When all the burps and associated agricultural emissions are added up for today’s 1.46 billion cows, they were responsible for 3.8 Gt of CO2-eq in GHG emissions in 2015. It is also important to clarify that quantities of CH4 emitted by cows in livestock agriculture are not comparable to natural ecosystem CH4 emissions, like from wetlands, geologic seepage, wild animals, termites, wildfires, and permafrost. As CH4 emissions from livestock is an anthropogenic GHG emissions source, this means humans can modify it in an effort to mitigate negative impacts of climate change. Modifying truly natural global-scale CH4 emissions is outside human capabilities, both technologically and logistically. But most importantly, the same scale of CH4 emissions from cow burps would not have occurred naturally as inaccurately claimed in the post. The digestive systems of ruminants like cows provide the optimal anaerobic conditions for CH4 production during enteric fermentation in the specialized “rumen” chamber, the largest part in their stomach (see Figure 2). As plant tissues ferment in the rumen by methanogen microbes for further digestion later, CH4 is produced and released as burps. This process does not occur easily outside of the rumen in landscapes where human managed cows, sheep, and goats consume vegetation. Figure 2 – The global domesticated cow population enabling beef and dairy production is a significant anthropogenic source of CH4 emissions which would not otherwise exist without human involvement. The rumen in the cow digestive system provides the optimal anaerobic conditions for CH4 production via methanogen microbes (source). Non-ruminant CH4 production depends on environmental conditions. Anaerobic bacteria need to decompose biomass under anaerobic conditions, which occurs best in the water-logged soils of wetlands (the largest natural source of CH4 emissions). This would not happen naturally in the open grasslands and pastures used for ruminant grazing. In the US, most rangelands and some pastures occur in semiarid to arid climate zones, while the rest of pastures occur in humid and marginally semi-arid environments[7]. Wetlands are not conducive for livestock agriculture. More cows digesting and fermenting plant tissues means more burping and manure production over pastures and in intensive feedlots. This results in new, additional atmospheric-CH4 that would not have been chemically produced at the same location and to the same extent even when wild ruminants are considered. Wild ruminants in the US like bison, elk, and deer only emit around 4.3% of the emissions from domesticated ruminants, and even pre-settlement wild ruminants only emitted around 86% of today’s domesticated ruminants[8]. Despite misleading claims that cow emissions is just existing carbon that is cycled whereas fossil fuel emissions is new carbon that is added, both of these sources add new carbon to the atmosphere that would not have otherwise been released without human involvement. Any new CO2 and CH4 carbon in the atmosphere will have a warming effect until they are cycled into other carbon pools, regardless of their origin. Emissions are only carbon neutral if they are in equilibrium with the cycle, but human activities have added more carbon than natural cycles can remove, which is why atmospheric GHG concentrations have risen so significantly. Conclusion: Research has shown that reducing CH4is critical to achieving global climate targets, both from fossil fuel sources and from livestock agriculture[9]. Conventional beef and dairy production in particular is a significant contributor to climate change through the release of greenhouse gasses like methane from cow burps. The claim that livestock agriculture, and the burps from cows resulting from beef and dairy production, are not as impactful for climate change as believed is misleading because it is based on GHG estimates that do not include land use related emissions. Even without land use impacts considered, the seemingly small percentage attributed to US livestock agriculture is still globally relevant because total US emissions are so high. Context is also missing in the claim that CH4 from cow emissions has a short-lifespan and is therefore not impactful. In reality, it drives significantly more warming than carbon dioxide during that time on a per molecule basis. As beef production increases, so do global methane emissions. The high quantity of cows and the high global warming potential of methane is what makes cow burps impactful on climate change. Finally, the claim that the same CH4 emissions would occur naturally without beef and dairy cows is factually inaccurate. The enteric fermentation process is unique to ruminants like cows and the methane emissions they produce would not otherwise occur in the pastures and grasslands where cows are raised. Overall, cows are managed by humans so their burps are an anthropogenic source of emissions.

https://science.feedback.org/review/uncertainties-about-future-climate-change-1970s-does-not-invalidate-today-evidence-reality-global-warming/

Inaccurate

Facebook, Facebook users, 2023-12-09

Scientists predicted global cooling and were wrong, so they are wrong about global warming

Inaccurate: During the 1970’s, it was unclear if global cooling linked to atmospheric aerosols would override global warming linked to elevated atmospheric greenhouse gasses. There was no scientific consensus, although more scientists forecasted a future warming than a cooling. Nowadays, available scientific evidence decisively supports the forecast that temperature will continue to increase–and not cool–in the near future.

Some climate scientists in the 1970’s were concerned about the cooling effect of atmospheric aerosols and explored the hypothesis that it might lead to a cooling of the Earth. However, the majority of scientists at that time were actually forecasting global warming for the future. In fact, scientists have warned that elevated greenhouse gasses would cause global warming since the 19th century. Overwhelming observational evidence has resulted in the scientific consensus that global warming is real and human activities, primarily through the emissions of greenhouse gasses, is the main driver.

Scientists in the 1970’s predicted there would be global cooling and a new ice age in the coming decades, but they were wrong. This means they are wrong again about present and future global warming.

1 – Peterson et al. (2008) The myth of the 1970s global cooling scientific consensus. Bulletin of the American Meteorological Society 2 – Sawyer JS (1972) Man-made carbon dioxide and the “greenhouse” effect. Nature 3 – Hansen et al. (1978) Mount Agung eruption provides test of a global climatic perturbation. Science 4 – Lynas et al. (2021) Greater than 99% consensus on human caused climate change in the peer-reviewed scientific literature. Environmental Research Letters 5 – Myers et al. (2021) Consensus revisited: quantifying scientific agreement on climate change and climate expertise among Earth scientists 10 years later. Environmental Research Letters 6 – IPCC (2023) Summary for Policymakers. In: Climate Change 2023: Synthesis Report. Contribution of Working Groups I, II and III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change 7 – Hausfather et al. (2020) Evaluating the performance of past climate model projections. Geophysical Research Letters

In the 1970’s, some popular media outlets were reporting on the supposition that a new ice age could be coming in the following decades. Of course, this never came to pass. We are now in the midst of rapid global warming, largely due to anthropogenic emissions of greenhouse gasses. Multiple temperature records indicate an increase in average global temperature of at least 1.1°C since record keeping began in the second half of the 19th century. However, these historical popular media reports are often used today to challenge global warming and climate change science. In social media posts such as the one featured below in Box 1, it is claimed that because some scientists were studying the possibility of a global cooling that did not end up happening, science must be wrong today about global warming. But scientists in the 1970’s were not entirely certain that global temperatures would increase or decrease in the coming decades. Global warming due to elevated greenhouse gasses was already being modeled, but new research indicating the potential cooling effects of atmospheric aerosols made it necessary to study whether their cooling effect or the warming effect would dominate in future climate change. That said, more scientific studies were forecasting a future warming than a cooling during the 1970’s. A scientific consensus was eventually reached on the fact that the warming influence of greenhouse gasses dominates the cooling effect of aerosols. There was no scientific consensus on global cooling in the 1970’s The idea that scientists in general were predicting an impending global cooling in the 1970’s is wrong[1]. In 2008, a study investigated whether there was any agreement on this topic in the scientific literature. The authors reviewed scientific studies published between 1965 to 1979 projecting or estimating any aspect of climate change and climate forcing over time scales from decades to a century. Only seven of the papers they found projected cooling, whereas 44 projected warming and twenty either projected no change or did not provide an estimate at all (noted as ‘Neutral’ on Fig. 1). Figure 1 – Papers published during the period from 1965 to 1979 classified as projecting, implying, or providing supporting evidence for future global cooling or global warming[1]. The cooling papers also received less citations in the years immediately following publication, indicating less scientific impact and validation as climate science advanced. British meteorologist John Sawyer’s 1972 global warming projection stands-out among the studies reviewed; his projection that the year 2000 would be 0.6°C warmer turned out to be off by less than 0.1°C[2] (see also Fig 3). The lack of scientific consensus on global cooling in the 1970’s is also confirmed in a national survey of scientists in the United States called “Climate Change to the Year 2000: A Survey of Expert Opinion”. Following the especially cold 1976/1977 winter in the eastern U.S., 24 leading climate scientists across the country were surveyed in 1978 by the National Defense University and collectively “tended to anticipate a slight global warming rather than a cooling”. The leading theory on future climate change in the decades before, during, and after the 1970’s has been that of a climate warming due to greenhouse gasses. Ever since the first demonstrations of the greenhouse effect over a century ago and the awareness that humans increasingly emit greenhouse gasses, scientists have consistently warned about global warming. In the defense of the climate scientists who were concerned about a global cooling trend, global temperatures decreased by about 0.1°C from 1940-1970 and it was legitimate to investigate the causes of this trend and whether it would reverse or not. Atmospheric aerosols from anthropogenic air pollution played an important role in some of the local cooling that was observed (i.e., locally over the industrial areas where they are released). But as air pollution aerosols were reduced, emissions of greenhouse gasses continued, and temperature measurement coverage expanded globally, the cooling trends observed over industrial land areas in the northern hemisphere were no longer significant. By the end of the 1970’s, researchers were beginning to understand that any cooling effects from aerosols, which was one of the main supporting points for global cooling projections, were actually outweighed by the warming effects from the increasing concentrations of atmospheric greenhouse gasses[3]. In fact, the reduction of air pollution aerosols and their cooling effects is now a recognized potential driver of global warming scientists follow closely today. The claim that scientists have repeatedly predicted false environmental catastrophes since the 1970’s has already been shown to be inaccurate by Science Feedback. One of the original global cooling popular media stories was a piece written by reporter Peter Gwynne in Newsweek in 1975. Today, Gwynne is amazed how his nine paragraphs on page 64 are still “misused and misinterpreted” by popular climate change contrarians to somehow contend with several decades of proven climate science. Gwynne has tried to clear the air, writing “it’s time for deniers of human-caused global warming to stop using an old magazine story against climate scientists” in his Inside Science article entitled “My 1975 ‘Cooling World’ Story Doesn’t Make Today’s Climate Scientists Wrong”. While his article exploring the possibility of a cooling due to aerosol pollution was justified at the time it was published, it would not be anymore given the information that has become available since then. The reality of global warming projections and observations since the 1970’s Another important point of context to have in mind is that climate science was advancing in the years leading up to the 1970’s; there was uncertainty on the state of the climate because temperature records at the global scale were lacking. The first satellite measurements were starting by the late 1960’s, but we were not yet sure if temperatures were trending up or down and what the main drivers were. Today, there is overwhelming evidence and scientific consensus that global temperatures are increasing. We have robust records of air temperatures over land and the oceans worldwide thanks to the efforts of thousands of data collectors, scientists, meteorologists, and other researchers. Various research organizations that record global temperature using different data processing methods have reached the same results: temperature is rising. Efforts to independently and impartially analyze temperature records, on behalf of skeptics, have confirmed their veracity repeatedly. When we combine temperature records of indirect proxy measurements over the last two millennia (Fig. 2.top), with all the temperature records taken by direct measurements since 1880 (Fig. 2.middle), the increase in average global temperature of at least 1.1°C is clear. There is strong agreement between multiple independent temperature records; they all show that the globe has warmed (in comparison to the average temperature during the period 1951-1980). Compared to the entire 20th century’s average temperature, every decade since the 1970’s have been comparatively warmer (Fig. 2.bottom). This shift from colder to warmer years follows an observed increase in atmospheric-CO2 concentrations, which is the most significant driver of global warming through the elevated greenhouse effect. Figure 2 – Top: Comparison of temperature record (degrees Celsius) going back in time over 2000 years. Temperature records that are based on indirect proxy measurements are indicated by the blue trendline, while temperature records that were directly measured are indicated by the red trendline (source). Middle: Comparison of consolidated temperature records (degrees Celsius) of multiple datasets and methodologies. The data represents temperature differences (plus or minus numbers on y-axis representing change in degrees Celsius) between the recorded year (x-axis) and a common baseline temperature average for the period 1951-1980 (represented as 0 on the y-axis) (source). Bottom: Yearly temperature compared to the twentieth-century average (red bars mean warmer than average, blue bars mean colder than average) from 1850–2022 and atmospheric carbon dioxide amounts (gray line): 1850-1958 (source). Beyond demonstrating global warming is real through years of global temperature measurements and global change observations, like sea level rise from melting ice caps and glaciers, scientists have also demonstrated and are in agreement that humans are the main cause of global warming through greenhouse gas emissions like CO2. A recent peer-reviewed scientific study analyzing thousands of other peer-reviewed scientific studies found that 99% of the scientific literature confirms human greenhouse gas emissions cause global warming[4]. Among scientists with the most climate-related expertise, the consensus reaches 100%[5]. In the most recent IPCC report (AR6), the very first text line (line A.1.) of the “Summary: for Policymakers” confirms there has been 1.1°C of global warming since the period 1850-1900 and it explicitly identifies CO2 as the leading cause[6]. As an indication of the scientific robustness of AR6, just the contribution from Working Group 1 alone was written by 234 of the world’s leading climate scientists coming from 66 countries. It included nearly 4 000 pages of research based on more than 14 000 scientific papers as supporting references and was critiqued and revised by over 1 500 expert reviewers. Some of the earliest attempts at using computer models to understand climate change in the 1970’s not only projected warming, they were also reasonably accurate. In a study comparing the projections of seventeen historical climate model projections (seven of which from the 1970’s) with actual temperature observations since 1970, all of the models projected warming and the majority were consistent with reality (Fig. 3)[7]. Only three of the models projected temperature changes there were too far from reality and were therefore incorrect (observations fell outside their ranges of uncertainty): two projected more warming and one projected less. Figure 3 – Comparison between global climate model projections (red dots) and temperature observations (blue dots). Model projections are expressed as the change in temperature versus the change in radiative forcing, the “implied TCR”, to provide meaningful model-observation comparisons even if the forcing differs between models. As all models have a positive implied TCR value (y-axis), they have all projected an increase in global temperature. The model name and length of time represented are indicated on the x-axis (source). Box 1. Example of an inaccurate claim that global warming is not real because some scientists once predicted global cooling In this post on Facebook from 9 December 2023, it is claimed that global warming is a paranoia that climatologists created after their predictions of extreme global cooling leading to a new ice-age did not materialize. The caption of the Facebook Reel lists various statements labeled as “facts”, including the inaccurate claims that “Science is wrong on Global Warming” because “Science was wrong on Global Cooling”. This post has been shared hundreds of times and reached thousands of viewers who may not know that global cooling was not a mainstream climate theory in the 1970’s. As we explained above, there were more scientists at that time projecting and modeling future global warming. In addition, the claim that “Science is wrong on Global Warming” is inaccurate because the reality of global warming has been unequivocal for years, verified by overwhelming observational evidence resulting in the scientific consensus. Hypotheses that were investigated in the past by scientists, like the one on global cooling, do not invalidate today’s proven scientific concepts that accurately represent observed reality, like current global warming. Conclusion: Some climate scientists in the 1970’s investigated the possibility of a global cooling that they thought could result from the effects of atmospheric aerosols, but the majority of scientists were actually projecting future global warming. In fact, scientists have warned about global warming for a long time. We now know that 1970’s projections of global warming were reasonably accurate, and average temperatures have increased by at least 1.1°C since record keeping began. Overwhelming observational evidence has resulted in the scientific consensus that global warming is real and human activities, primarily through the emissions of greenhouse gasses, is the main driver.

https://science.feedback.org/review/water-vapor-greenhouse-gas-not-major-driver-global-warming/

Incorrect

Climate Change is Crap, Facebook users, 2023-11-18

Water vapor is the most abundant greenhouse gas so it is the main cause of recent global warming

Flawed Reasoning: Water vapor, which lasts only days in the atmosphere, is ultimately controlled by air temperature and pressure according to thermodynamics. Long-term changes in temperature driven by other greenhouse gasses supersedes water vapor feedbacks. Misleading: Water is only relevant for maintaining the natural greenhouse effect. It is a negligible contributor to the enhanced greenhouse effect which is responsible for global warming.

Water vapor is fundamentally different from the other greenhouse gasses which directly cause global warming. It leaves the atmosphere in a matter of days and its atmospheric concentration is ultimately governed by temperature. It is critical for the natural greenhouse effect, but it is a negligible contributor to the enhanced greenhouse effect. We already know, beyond any reasonable doubt, that human emissions of the other greenhouse gasses is the primary cause of global warming.

Water vapor is the main cause of recent global warming because it is the biggest contributor to the greenhouse effect and the most abundant greenhouse gas by weight and volume. Water vapor is natural and the greenhouse effect is natural, so recent global warming is natural.

1 – IPCC (2021) The Earth’s Energy Budget, Climate Feedbacks, and Climate Sensitivity. In Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. 2 – Sherwood et al. (2018) The global warming potential of near-surface emitted water vapour. Environmental Research Letters. 3 – Gimeno et al. (2021) The residence time of water vapour in the atmosphere. Nature Reviews Earth & Environment. 4 – Cawley (2011) On the atmospheric residence time of anthropogenically sourced carbon dioxide. Energy & fuels. 5 – Kiehl & Trenberth (1997) Earth’s annual global mean energy budget. Bulletin of the American meteorological society. 6 – Soden & Held (2006) An assessment of climate feedbacks in coupled ocean–atmosphere models. Journal of climate. 7 – Anbar et al. (2016) Addressing the Anthropocene. Environmental Chemistry. 8 – Broecker (2012) The carbon cycle and climate change: memoirs of my 60 years in science. Geochemical Perspectives.9 – Kunzig & Broecker. (2009) Carbon scrubbers: taking CO2 out of the air. New Scientist.

Although water vapor is the most abundant greenhouse gas (GHG) by weight and volume, it is not a major driver of long-term climate change and the recent global warming we are experiencing. The opposite is often claimed as a challenge to anthropogenic climate change because it is the most important gas maintaining the greenhouse effect and it is naturally occurring. So, as this claim goes, human emissions of GHGs are not to blame. For example, in this Facebook post from 18 November 2023 a table of data is presented that misleads viewers towards this conclusion. We address that post specifically in Box 1 at the bottom of this article. In the next few sections, we will review more generally why this claim is based on flawed reasoning. Water vapor is different than the other greenhouse gasses There are a few differences between GHGs that are driving global warming, like carbon dioxide (CO2) and those that do not, like water vapor. The ability of a gas to add to or reduce global warming is represented by its effective radiative forcing value (ERF, measured in units of watts per square meter (W.m–2)). The ERF is the energy added (heating) or subtracted (cooling) from the Earth system due to a change in that gasses’ concentration and also their global warming potential, which represents the gasses’ ability to trap heat in the atmosphere compared to CO2 as the standard. The ERF is based on radiative transfer models that account for the gasses’ specific absorption and emission properties. The concept implies a change from the norm; a change in radiative forcing from the conditions that we should normally be experiencing under the natural greenhouse effect which makes Earth liveable. We can estimate the ERF of the main greenhouse gasses, including water vapor, over the industrial era to get an idea of the main drivers of the recent global warming we are experiencing (Fig. 1). From the years 1750 to 2019, out of a total anthropogenic ERF value of 2.72 W.m–2, atmospheric-CO2 has been the most important single driver, contributing 2.16 W.m–2 [1]. The next largest drivers are methane contributing 0.54, ozone at 0.42, nitrous oxide at 0.21, and halogens at 0.41. Stratospheric water vapor, resulting from the oxidation of methane emitted from humans, has an ERF of only 0.05 W.m–2. It is among the least powerful greenhouse gasses humans directly or indirectly emit. As a reminder, because these ERF values are all positive, they represent energy added to the Earth system and increased global warming. Figure 1 – Change in effective radiative forcing from 1750 to 2019 by greenhouse gasses, ozone, stratospheric water vapor, surface albedo, contrails and aviation-induced cirrus, aerosols, and solar. The anthropogenic total category represents the combined positive and negative effects of human activities (everything except solar). The solid bars represent best estimates with very likely (5–95%) ranges represented by the error bars (source). Near-surface water vapor has a similarly low ERF and negligible effect on driving global warming as stratospheric water vapor[2]. Because any increase in water vapor near the surface does not reach the upper-troposphere, the potential positive contribution to global warming is negated by the increased reflectance from humidity-induced low cloud cover. This results in a net-zero or even cooling effect from increased water vapor. In addition to the ERF of GHGs (which considers concentration and global warming potential), we also need to consider how long they stay in the atmosphere contributing to global warming. This is known as the atmospheric residence time, or the average time a molecule of that gas remains in the atmosphere before changing or being removed by natural processes. Gasses with longer residence times will have more time to let their ERF impact global climate conditions, whether they increase (e.g., like CO2) or decrease (e.g., like aerosols) global warming. In a sense, we can assume that the longer the residence time in the atmosphere, the greater the cumulative effect of the gas on the greenhouse effect. The atmospheric residence time of water vapor is extremely short compared to the other GHGs. Water vapor cycles through the atmosphere through evaporation and precipitation within 8–10 days on average (median residence time of 4–5 days)[3]. The average residence time of methane is around 10–12 years, nitrous oxide lasts over 100 years, while fluorinated gasses last weeks to thousands of years. Fluorinated gasses, like hydrofluorocarbons, perfluorocarbons, sulfur hexafluoride, and nitrogen trifluoride, are not only the longest lasting, they are also the most powerful GHGs emitted by human activities (thousands of times greater global warming potential than CO2). For CO2, one molecule may leave the atmosphere after about 5 years, but it is replaced by another CO2 molecule from the ocean or biosphere. The global carbon cycle, with its tight budget of sources and sinks (or stocks), is such that it can take hundreds to thousands of years to really “lock away” the excess CO2 that humans have emitted (primarily through burning fossil fuels which was carbon previously locked away). Therefore, atmospheric-CO2 has a much more lasting impact as a GHG than methane and even nitrous oxidebecause its increase in the atmosphere is independent of its actual residence time[4]. Excess water vapor molecules are gone in the blink of an eye comparatively. This is why water vapor is not a major driver of global warming, even if it is the most abundant GHG. The enhanced greenhouse effect and water vapor feedbacks The previous section discussed the ERF of GHGs and estimated negligible values for stratospheric and near-surface water vapor. This water vapor comes from the oxidation of methane emitted from human activities or from irrigation practices, meaning it is water vapor that we ultimately added to the atmosphere (i.e., a change from the norm). But what about all the water vapor that exists naturally in the atmosphere, evaporating from the land and oceans, condensing as clouds and returning as rain and snow? We’ve known for decades that natural water vapor returns much more infrared radiation to the Earth’s surface than other gasses like CO2[5]. Water vapor is what keeps this planet habitable and keeps us warm; it alone causes around half of the natural greenhouse effect[6]. While fluorinated gasses may have the highest global warming potential and CO2 is driving global warming the most, naturally occurring water vapor is indeed the most important greenhouse gas in the atmosphere. The properties of water vapor have also helped keep the Earth’s temperature stable. For at least two thousand years, average global temperatures barely fluctuated more than a few tenths of a degree Celsius before the industrial revolution (based on proxy data like ice cores). But now there is no question that global temperatures have rapidly risen over the last few decades, resulting from the increased anthropogenic greenhouse gas emissions. The planet is currently more than 1°C warmer than the pre-Industrial average with CO2 alone increasing by 50% over this period. This is known as the enhanced greenhouse effect (Fig. 2). When it comes to understanding recent global warming, it is solely the enhanced greenhouse effect which matters. Figure 2 – Illustration of the global energy balance as affected by the natural greenhouse effect (left) and the enhanced greenhouse effect (right). Water vapor (H2O) plays an important role in maintaining the natural greenhouse effect, not driving the enhanced greenhouse effect. Incoming solar shortwave radiation is represented by the yellow arrows and outgoing terrestrial longwave radiation is represented by the red arrows (source). The claim that because both water vapor and the greenhouse effect are natural, global warming is natural is an example of flawed reasoning. It is an oversimplification which disregards the current understanding that human activities, particularly the burning of fossil fuels, have significantly enhanced the natural greenhouse effect by adding more GHGs to the atmosphere. The enhanced greenhouse effect caused by human activities is impacting global temperatures more than what would have occurred naturally with the pre-Industrial concentrations of GHGs. Water vapor is not relevant when it comes to creating the enhanced greenhouse effect because it is a byproduct of temperature change and not a driver, governed by the Clausius–Clapeyron relation. While the other GHGs remain as gasses in the atmosphere, water vapor is easily condensable. It condenses into precipitation and evaporates back into water vapor as a function of the current temperature and air pressure. So any excess water vapor that should not be there precipitates quickly, and any deficit in water vapor is restored by evaporation as soon as possible. Atmospheric-CO2, on the other hand, does not disappear under normal climate conditions in a matter of days like water vapor. In fact, atmospheric-CO2 has been repeatedly shown to be the primary factor controlling global temperature anomalies (changes). These relationships illustrate that it is not water vapor that drives temperature; it is the reverse. So, unlike the other GHGs, human activities do not significantly increase water vapor directly. Any water vapor that is emitted directly or indirectly (e.g., from irrigation or methane oxidation) is not long-lasting, as described above. Human activities cannot directly control how much water vapor is in the atmosphere because ocean and air temperature does. This is also unlike the other GHGs. Warmer temperatures will create warmer surfaces which promote more evaporation and increases in atmospheric water vapor. Colder air temperatures hold less water vapor, resulting in more precipitation and decreases in atmospheric water vapor. Human activities can influence atmospheric water vapor very indirectly by continuing to drive global warming, raising the atmosphere’s capacity to hold water vapor. There is a clear feedback loop between water vapor and global temperature, where an increase in one leads to an increase in the other. It is one of the most dominant climate feedbacks, explaining why global temperatures are so sensitive to changes in the long-lived greenhouse gasses. As the oceans warm because of the enhanced greenhouse effect resulting from increases in atmospheric-CO2, for example, there will be more water evaporation and more water vapor released to the atmosphere. This excess water vapor can trap even more heat and encourage more evaporation. According to the laws of thermodynamics, water vapor concentration should increase by roughly 7% in the atmosphere with every degree Celsius rise in temperature. So, water vapor does indeed contribute to global warming by reinforcing the enhanced greenhouse effect. But it was the initial contributions of the other anthropogenic GHGs that started this feedback. The reduction of GHGs like CO2 can also reverse the water vapor-climate feedback loop by reducing air temperatures which reduces the amount of water vapor in the atmosphere. Earth’s air temperature does not directly affect the concentrations of the other GHGs; their feedback loops with global warming are different. Ultimately, water vapor is very important for maintaining habitable temperatures and it can have a reinforcing feedback with rising temperatures, but it is simply not in the driver’s seat when it comes to creating and maintaining the enhanced greenhouse effect. Box 1. Example of a misleading claim that water vapor is driving recent global warming. In this 18 November 2023post by the Facebook group “Climate Change is Crap”, a table of data is presented that misleads viewers towards the conclusion that water vapor is driving recent global warming. The post is an image of an undated presentation slide from thelate Dr. Wallace Broecker, American geochemist and Professor at Columbia University. The table features different greenhouse gasses and their relative contributions to the greenhouse effect. While the data is outdated and lacking scientific sources, this slide does illustrate the significant role of water vapor in maintaining the natural greenhouse effect and the negligible amount of water vapor in the atmosphere that humans are responsible for. However, the table is not describing the enhanced greenhouse effect, which is the core issue of global warming and climate change. Without context on the difference between the natural and the enhanced greenhouse effect, viewers are misled to believe that water vapor is driving recent global warming and therefore it is a natural phenomenon and not the result of the human emissions of the other greenhouse gasses. The viewers of this post are further misled to believe that this conclusion is supported by climate scientists like Dr. Broecker, who is explicitly attributed to this post. Ironically, Dr. Broecker is credited with coining the term“global warming” as far back as 1975. He was a strong proponent of reducing greenhouse gas emissionsuntil the end of his life, stating in his final academic talk that humanity is not moving quickly enough to slow the production of CO2that is warming the Earth. Broecker regularlyspoke about solving the “CO2crisis”andpublished numerous research articleson the urgent need to reduce atmospheric-CO2concentrations to slow the enhanced greenhouse effect through any means feasible[7-9]. Conclusion: Water vapor may be the most abundant GHG keeping the planet habitable, but it is not a major driver of long-term climate change and the recent global warming we are experiencing. It is incorrect to claim that because water vapor is natural and the greenhouse effect is natural, recent global warming must be natural. Water vapor is fundamentally different from the other GHGs which directly cause global warming. It has a negligible ERF, it leaves the atmosphere in a matter of days, and it is ultimately governed by temperature rather than human emissions. It is more of a consequence of global warming than a cause. We already know beyond any reasonable doubt that anthropogenic emissions of the other GHGs like CO2, methane, and nitrous oxide, is the primary cause of global warming. Water vapor is not relevant when it comes to the enhanced greenhouse effect in the context of recent global warming.

https://science.feedback.org/review/video-ian-plimer-incorrectly-states-human-co2-emissions-not-responsible-for-increased-atmospheric-co2-concentrations-global-warming/

Incorrect

Conservative Political Action Conference, Ian Plimer, 2023-10-03

Increases in atmospheric CO2 is mainly from natural causes, like ocean outgassing, and not from humans who emit so little in comparison

Inaccurate: Though annual human CO2 emissions are much smaller than natural carbon cycle fluxes, they have steadily accumulated in the atmosphere over the past few centuries because their removal by natural carbon sinks has not increased to the same extent. The present-day anthropogenic CO2 increase is unprecedented in rate and magnitude compared to at least the last 800,000 years. Incorrect: Ocean outgassing, which amplifies natural climate variations on timescales of hundreds-to-thousands of years, cannot explain the magnitude of the present-day atmospheric CO2 increase or the fact that ocean carbon has also been rapidly increasing since the beginning of the industrial era. Atmospheric measurements pinpoint fossil fuel emissions as the primary source of the rapid buildup of atmospheric CO2.

Multiple independent lines of evidence indicate that the present-day increase in atmospheric CO2 is caused by human emissions from fossil fuels and land use change. A significant fraction of annual CO2 emissions remains in the atmosphere each year and has steadily accumulated since the onset of the industrial era, driving global warming. Ocean temperature-CO2 feedbacks are important in millennial-scale glacial-interglacial transitions but do not explain the current atmospheric CO2 increase.

Human emissions could not be driving global warming since they are a small fraction of natural emissions. Temperature actually drives CO2, not the inverse. So the current rise in atmospheric CO2 is caused by ocean outgassing, not human emissions.

1 – Grantham Research Institute on Climate Change and the Environment (2022) Why does climate change get described as a stock-flow problem? 2 – Friedlingstein et al. (2022) Global Carbon Budget 2022. Earth System Science Data 3 – Lan et al. (2023) Trends in globally-averaged CO2 determined from NOAA Global Monitoring Laboratory measurements 4 – IPCC (2021) Global Carbon and other Biogeochemical Cycles and Feedbacks. In Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change 5 – IPCC (2021) The Earth’s Energy Budget, Climate Feedbacks, and Climate Sensitivity. In Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change 6 – DeVries (2022) The Ocean Carbon Cycle. Annual Review: of Environment and Resources 7 – Henry (1803) Experiments on the quantity of gases absorbed by water, at different temperatures, and under different pressures. Philosophical Transactions of the Royal Society of London 8 – Bauska et al. (2021) Abrupt changes in the global carbon cycle during the last glacial period. Nature Geoscience 9 – IPCC (2021) Changing State of the Climate System. In Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change 10 – Keeling and Graven (2021) Insights from Time Series of Atmospheric Carbon Dioxide and Related Tracers. Annual Review of Environment and Resources 11 – Graven et al. (2022) Radiocarbon dating: going back in time. Nature

Dr. Ian Plimer, a former mining geologist, spoke at the Australian Conservative Political Action Conference (CPAC) in Sydney on 2 October 2022. A video clip of the talk was posted on Facebook a year later, and as of 1 December 2023, it has been liked over 5,200 times and shared over 3,700 times. CLAIM 1 (Inaccurate):: “No one has ever shown that human emissions of CO2 drive global warming … and if it could be shown, then you would have to show that the 97% of emissions which are natural do not drive global warming.” While anthropogenic fossil fuel carbon dioxide (CO2) emissions are indeed only a small fraction of annual natural emissions, they play a disproportionately powerful role in driving global warming. This may seem counterintuitive, but it becomes more apparent when we treat atmospheric CO2 as a stock-flow problem[1]. In this framework, the atmospheric CO2 content is the stock while the input and removal of CO2 to the atmosphere are the flows. The issue is that since the onset of the industrial era, human emissions have increased the input of CO2 to the atmosphere, whereas CO2 removal through natural processes has not increased to the same extent. The result of this annual flow imbalance is an increasing stock of atmospheric CO2, driving global warming. The carbon cycle describes how carbon moves between different reservoirs or stocks in the earth system. On timescales up to millennia, the most important natural exchanges are between the atmosphere, ocean, and terrestrial biosphere. Each year, CO2 is released to the atmosphere through ecosystem respiration and fire, and a nearly equal amount is taken up through photosynthesis; there are also air-sea CO2 fluxes largely balanced in both directions. These processes were more or less in equilibrium in the two millennia before the industrial era such that atmospheric CO2 concentrations remained relatively stable (Fig. 1, top). Geologic exchanges typically occur on much longer timescales via sediment burial, volcanic outgassing, and rock weathering. However, since the beginning of the industrial era, human activity through burning fossil fuels has rapidly released carbon stored in geologic reservoirs directly to the atmosphere, with emissions steadily increasing up to the present. Human-induced land-use changes (mainly deforestation) have also transferred carbon from the terrestrial biosphere to the atmosphere much more rapidly than pre-industrial conditions. Though natural removal processes of land and ocean CO2 uptake, or sequestration, have also steadily increased, they have not fully kept pace with increased emissions, taking up around 55% of the total anthropogenic perturbation[2]. The atmospheric CO2 stock reflects this net flow imbalance. Annually-averaged CO2 concentrations have risen without interruption since the beginning of atmospheric measurements in 1958, and the rate of increase is also growing[2,3]. Atmospheric CO2 concentrations have increased from approximately 278 parts per million (ppm; equivalent to 590 gigatons of carbon (GtC) as 1 ppm = 2.124 GtC) in 1750[2] to 417 ppm (886 GtC) in 2022 (Fig. 1, top)[3]. These concentrations are unprecedented in the last 2 million years, and the rate of CO2 increase over the past century is at least 10 times faster than at any other time during the last 800,000 years[4]. This CO2 increase is estimated to contribute to a global surface air temperature warming of 1.01°C since 1750 (90% confidence interval of 0.74°C to 1.41°C), the largest-magnitude climate perturbation over the industrial period[5]. Figure 1 – Atmospheric CO2 concentrations (ppm, top) and global surface temperature anomaly (°C, bottom) over the past 2000 years. From Climate Lab Book. For a more detailed picture, we can examine the specific flows between reservoirs causing the present-day atmospheric CO2 increase using a recent best-estimate assessment of the global carbon cycle for the 2012–2021 decade (Fig. 2)[2]. Average annual fossil fuel emissions over this period are estimated to be 9.6 GtC yr−1 (GtC per year). Dividing this value by the average annual CO2 fluxes from the land (130 GtC) and ocean (80 GtC) yields an estimate of a fossil fuel perturbation of around 4%, comparable to Dr. Plimer’s 3% value (they would be closer using older data as emissions have been increasing). Adding land-use changes (1.2 GtC yr−1) and subtracting sequestration by terrestrial (3.1 GtC yr−1) and marine (2.9  GtC yr−1) carbon sinks yields an average 2012–2021 atmospheric CO2 increase of 5.2 GtC yr−1, or 2.46 ppm yr−1. Figure 2 – Carbon cycle reservoirs (GtC, filled circles) and average annual fluxes (GtC yr−1, arrows) for 2012–2021 (from Figure 2 of reference 2). Thin arrows show the background natural carbon exchanges (estimated around 1750) and thick arrows show the anthropogenic perturbation. CLAIM 2 (Incorrect):: “It’s not CO2 that drives temperature; it’s the exact inverse.” We’ve known for 200 years from chemistry the inverse solubility of CO2, that warm water holds less CO2 as it warms. “We see it from the ice cores … when we have natural warming, some 650–6000 years later we have an increase in CO2.” In his second claim, Dr. Plimer posits that the present-day atmospheric CO2 increase is from the ocean releasing CO2 in response to past natural warming, not human emissions. However, this claim fundamentally overlooks multiple sources of evidence showing a massive influx of anthropogenic CO2 to the climate system. While the ocean does respond to warmer temperatures by outgassing CO2 during glacial-interglacial transitions on timescales of hundreds-to-thousands of years, this mechanism does not explain observations of the rapid and unprecedented rise of atmospheric CO2 concentrations since the onset of the industrial era. The ocean reservoir contains tremendous amounts of dissolved carbon (Fig. 2, circles), owing to the chemistry of CO2 in seawater which allows it to be partitioned across different ions[6]. Like many gases, the solubility of CO2 decreases with temperature, which indeed has been known for over 200 years[7]. A consequence of this inverse solubility relationship is that the ocean is able to hold less carbon as it warms, assuming other conditions are held fixed[6]. This mechanism contributes to amplifying high-latitude temperature changes on timescales of hundreds-to-thousands of years. Due to the slow timescales of deep ocean circulation, the ocean takes centuries to equilibrate to the initial surface temperature perturbation. For example, recent paleoclimate studies indicate that Antarctic temperatures generally precede atmospheric CO2 changes by around 500–650 years (90% confidence interval) during glacial-interglacial transitions, at the far low end of Dr. Plimer’s range[4],[8]. Though important for paleoclimate variations, this mechanism is unable to account for the recent staggering rise of atmospheric CO2 (Fig. 3), which has reached levels unprecedented over the last 2 million years and is increasing at least 10 times faster than at any other time during the last 800,000 years[4]. Moreover, the several centuries prior to the rapid rise of atmospheric CO2 in the industrial era featured slight global cooling[9] (Fig. 1, bottom), contrary to Dr. Plimer’s hypothesized warming. Figure 3 – Atmospheric CO2 concentrations (ppm, top) and Antarctic temperature anomaly (°C, bottom) over the past 800,000 years. From British Antarctic Survey. A glaring problem with Dr. Plimer’s claim is that ocean carbon has been increasing since the industrial era. The schematic Fig. 4 shows a recent best-estimate assessment of the anthropogenic global carbon cycle perturbation for cumulative 1850–2021 changes (left side) and average fluxes over the 2012–2021 decade (right side)[2]. For cumulative 1850–2021 changes (left side), ocean carbon content – estimated from several ocean biogeochemistry models and observation-based data products – increased by 175±35 GtC (mean±1 standard deviation). During that time, total emissions from fossil fuels and land-use change were 670±65 GtC, while atmospheric CO2 concentrations increased by only 275±5 GtC and terrestrial carbon storage by 210±45 GtC. Even considering uncertainties, it would be extremely difficult to close the remaining carbon imbalance without ocean CO2 uptake. Average fluxes for the recent 2012–2021 period (right side) indicate that the rate of ocean carbon sequestration has increased, with uptake rates almost 3 times faster than the 1850–2021 average. Figure 4 – Anthropogenic global carbon cycle perturbation (from Figure 14 of reference 2). Left: cumulative 1850–2021 changes (GtC). Right: average fluxes over 2012–2021 (GtC yr−1); note that these correspond to the thick arrows in Figure 2. Several atmospheric measurements provide further corroboration that human emissions are the source of rising global atmospheric CO2 concentrations[4],[10]. Figure 5, top, shows observations of monthly CO2 concentrations at Mauna Loa Observatory and the South Pole, with concentrations at both stations continuously increasing since measurements began in the late-1950s. Another feature is that CO2 concentrations at Mauna Loa have increased by a few ppm compared to the South Pole, indicating higher CO2 input from the land-dominated northern hemisphere, where most industrialized regions are located. Furthermore, measured atmospheric oxygen (O2) concentrations have been steadily decreasing globally since regular observations began around 1990 (Fig. 5, bottom). Atmospheric O2 concentrations are not affected by ocean CO2 outgassing, so the decreasing O2 concentrations indicate that increasing atmospheric CO2 is primarily driven by an oxygen-consuming process, namely combustion, but also respiration. Figure 5 – Top: Monthly average atmospheric CO2 concentration (ppm) at Mauna Loa Observatory, Hawaii (black) and South Pole (red). From Scripps CO2 program. Bottom: Atmospheric O2 concentrations (expressed as the O2/N2 ratio) at Mauna Loa Observatory. From Scripps O2 Program. Isotope measurements provide additional evidence for a fossil fuel source of increased atmospheric CO2 concentrations[10],[11]. Carbon has two stable isotopes: around 99% exists as carbon-12 (12C) and 1% as carbon-13 (13C). Plants preferentially take up 12C through photosynthesis, so plants and fossil fuels (which are derived from organic matter) are enriched in 12C compared to atmospheric CO2. The global 13C/12C ratio has been decreasing since atmospheric measurements began in the late-1970s (Fig. 6), indicating a plant or fossil fuel source of increasing atmospheric CO2. Furthermore, the unstable radioactive isotope carbon-14 (14C or radiocarbon) is naturally produced in extremely small amounts in the upper atmosphere and is absent from fossil fuels. There has been a long-term decrease in the 14C/12C ratio (interrupted by a pulse from atmospheric nuclear testing), indicating an enhanced 12C source from fossil fuel emissions. Figure 6 – Monthly average 13C/12C ratio (expressed as δ13C) at Mauna Loa Observatory (black) and South Pole (red). From Scripps CO2 program. Conclusion: Dr. Plimer’s claims are incorrect and inaccurate. Overwhelming evidence from carbon budget accounting and atmospheric measurements implicate anthropogenic fossil fuel burning as the main source of the present-day atmospheric CO2 increase. Though relatively small on an annual basis compared to natural fluxes, the steady input of anthropogenic CO2 emissions with only partial removal from natural carbon sinks has resulted in an unparalleled increase of atmospheric CO2 concentrations since the onset of the industrial era. The scientific consensus and evidence for the clear links between human CO2 emissions, the greenhouse effect, and global warming have also been recently addressed in another claim review of Science Feedback. Trends in atmospheric measurements, such as CO2 concentrations increasing faster in the northern hemisphere, decreasing O2 concentrations, and decreasing 13C/12C and 14C/12C ratios, can only be explained by emissions from fossil fuel combustion in the industrialized northern hemisphere.

https://science.feedback.org/review/global-warming-matches-model-predictions-well-misconstrued-claims-new-photosynthesis-study/

Inaccurate

Twitter/X, Steve Milloy, 2023-11-18

New photosynthesis study shows that Earth is not warming as predicted by climate models

Factually Inaccurate: Observations of the increases in global temperature match the uncertainty ranges of leading climate models. In some cases, observed warming exceeds predictions. Misrepresentation of sources (strawman): New research shows increased photosynthesis potential of plants under global warming scenarios; it does not imply observed global warming: 1) is not happening; 2) is not happening as much as predicted; or, 3) will not continue to happen.

Climate models have forecasted global warming well since the 1970s. New insights on plant photosynthesis under global warming do not invalidate climate models; rather, they help reduce uncertainty in model predictions of future climate change resulting from human emissions of greenhouse gases.

Earth not warming as predicted by (junk) climate models because plant photosynthesis is absorbing more CO2 than imagined. Climate change is a hoax.

1 – Hausfather et al. (2020) Evaluating the performance of past climate model projections. Geophysical Research Letters 2 – Kim et al. (2020) Evaluation of the CMIP6 multi-model ensemble for climate extreme indices. Weather and Climate Extremes 3 – Carvalho et al. (2022) How well have CMIP3, CMIP5 and CMIP6 future climate projections portrayed the recently observed warming. Scientific Reports 4 – Gudasz et al. (2021) When does temperature matter for ecosystem respiration?Environmental Research Communications 5 – Marcolla et al. (2020). Patterns and trends of the dominant environmental controls of net biome productivity. Biogeosciences 6 – Samset et al. (2023) Steady global surface warming from 1973 to 2022 but increased warming rate after 1990. Communications Earth & Environment

A recent scientific study illustrating the increasing role of photosynthesis under global warming scenarios has been misconstrued to promote climate change denialism. In a November 18th Twitter post, Steve Milloy inaccurately claims the Earth is not warming as predicted by climate models because plant photosynthesis will absorb more CO2 than imagined. Milloy has ties to and defended the tobacco, chemical, and oil and gas industries for years; he considers climate change to be a hoax. His claims are based on his understanding of the study and a November 17th Telegraph article covering the study and have reached over 1.1 million viewers on Twitter. Before addressing the claim inaccuracies, it is necessary to state that they fall outside the scope of the study, which does not investigate current or future global warming. The study’s lead and corresponding author Dr. Jürgen Knauer (Western Sydney University) confirmed to Science Feedback that Milloy’s claims are unrelated to the study and “any conclusions on what our study means with respect to future global warming remain speculative.” Global climate models continue to predict global warming well The Earth is warming as predicted by climate models, contrary to Milloy’s central claim. In fact, we know now that even the first attempts at using early computer models in the 1970’s to predict global warming were reasonably accurate. In a study comparing the predictions of seventeen historical climate model predictions with actual temperature observations since 1970, the majority were consistent with reality (Fig. 1)[1]. After ensuring the performance of each model can be compared fairly (by accounting for differences in historical climate forcings), the results showed that 14 of the models predicted the warming that has been observed (i.e., observations within the uncertainty range). Only three of the models were off: two predicted more warming and one predicted less. Figure 1 – Comparison between global climate model predictions (red dots) and temperature observations (blue dots). Model predictions are expressed as the change in temperature versus the change in radiative forcing, the “implied TCR”, to provide meaningful model-observation comparisons even if the forcing differs between models. The model name and length of time represented are indicated on the x-axis (source). In addition to the overall assessments presented in Figure 1, the successful track record of climate models can also be observed on a yearly scale starting from the first predicted year. In 2017, Carbon Brief produced visualizations comparing several original model predictions and actual observed warming for each year since John Sawyer’s (British meteorologist) early 1970’s prediction that the year 2000 would be 0.6°C warmer (he was off by less than 0.1°C). Despite various computational and theoretical limitations as the models developed from simple (energy balance) to advanced (fully-coupled Earth System Models), these predictions have closely matched observations. More visual examples comparing past predictions, or model forecasts, with actual observations of global temperatures can be found here. Another way we can see how well global climate models have performed is to take them as a whole: a multi-model ensemble. Dozens of institutes and labs around the world model past, present and future climate change effects, each developing their own climate model using different approaches. The Coupled Model Intercomparison Project (CMIP) uses a standard experimental framework to average out the predictions of all these coupled models (ocean-atmosphere coupled) as an ensemble of models, which allows us to get statistically more robust predictions with greater confidence and less uncertainty. We can also see where the models agree or disagree and explore why[2]. The most recent multi-model ensemble, CMIP6, featured 49 climate modelling groups and 100 individual climate models. The CMIP3 predictions, for example, have clearly survived the test of time (Fig. 2.top). Multiple records of global temperature data observations follow the multi-model average forecasted by CMIP3 from the year 2000, with all observations falling within the uncertainty range. With the ensemble model developed as part of CMIP5 for the 2014 IPCC AR5, we see that the multi-model averages capture historical and recent warming (Fig. 2.bottom). Figure 2 – Top: Global temperature anomalies (observations, coloured trend lines updated to January 2023) compared to CMIP3 individual simulations performed in 2004 with forcings extrapolated from the year 2000 (black trend line) with model ensemble 95% confidence interval (source). Bottom: Global surface temperature anomalies on a monthly scale (observations, red trend line) compared to CMIP5 climate model predictions (multi-model average, black trend line with 95% confidence interval) until the year 2030 using a baseline period of 1900-2000 (source). Observational data that falls outside the multi-model 5th-95th percentile range can be considered unsuccessfully modelled, and should therefore statistically be observed in one in twenty times due to the variability of Earth’s climate system (e.g., El Niño and La Niña behaviour–which can exercise large influences on global mean surface temperature). The vast majority of temperature observations in Fig. 2.bottom have been within uncertainty ranges of the historical, present, and future (in the case of CMIP5’s pre-2014 simulations) multi-model predictions. There are even some indications that CMIP predictions up to 2020 have underestimated the magnitude of warming we have since observed[3]. Potential increase in photosynthesis does not imply global warming is not happening By also claiming “Hoaxers now blaming plants for absorbing more CO2 than imagined”, Steve Milloy not only promotes climate change denialism, but he misrepresents Dr. Knauer’s study. This is the strawman fallacy. Together with Dr. Knauer, we will briefly explain how the original study is unrelated to and does not support Milloy’s claims. Let’s recall a few concepts. Terrestrial ecosystems play an important role in the global carbon cycle, acting as both sources and sinks of carbon dioxide (CO2). Therefore, terrestrial ecosystems, including plants, affect atmospheric-CO2 levels, which determine the strength of the greenhouse effect and global warming. The ebb and flow of carbon between the atmosphere and ecosystems is called net biome productivity (NBP), featuring the carbon taken up by plants through photosynthesis, called gross primary productivity (GPP), and the carbon released back to the atmosphere, called ecosystem respiration (ER). The difference between these two flows, or fluxes, determines whether an ecosystem is a net sink or source of carbon, in addition to other factors like fires and land use practices. Carbon sinks imply a reduction of atmospheric-CO2 and, possibly, reduced global warming, but an increase in GPP alone is not enough information to tell us if global warming overall will be impacted. There are many questions. Dr. Knauer states how his study is unrelated to Milloy’s inaccurate claims: “In our study we looked only at GPP. We didn’t look at ER or the actual land sink (NBP). Thus we cannot make definite statements on how future increases in GPP, even if they are stronger than expected, influence NBP or global temperatures.” Understanding NBP as a whole can help us add up the global carbon budget and improve our projections of future global warming. It is true that because GPP is fundamental to NBP, any change in GPP will affect NBP and the overall carbon balance of ecosystems. But this relationship is indirect; there are several factors that will influence how much a change in GPP will result in a change in NBP. For example, ER is closely tied to temperature, especially at higher temperatures above 20°C[4]. As temperatures rise, biological processes accelerate and so do respiration rates. If respiration increases under global warming more than photosynthesis (GPP) increases, it would offset the atmospheric-CO2 reductions. Fires, droughts, and other ecosystem disturbances can also influence the difference between GPP and ER. As Dr. Knauer explains: “Since GPP is one component of NBP, a stronger than expected increase in GPP could also lead to a stronger than expected increase in NBP. But there are a couple of reasons why NBP might not follow the same trajectory as GPP. For example, respiration has a strong temperature response and is likely to show a stronger increase than GPP with global warming. Then there are other factors such as fires, droughts, and other disturbances that could increase in frequency and intensity in the future and affect NBP.” So, while plant photosynthesis can be an indicator of potential atmospheric-CO2 reductions, we also need to consider other factors affecting NPB before we can reasonably predict changes to future global warming[5]. Changes in ER and multiple ecosystem disturbances need to be accounted for. Over time, these new insights on the response of plants and ecosystems to climate change can be incorporated into global climate models to further improve our predictions of future global warming. When new data and insights arise like those in Dr. Knauer’s study, scientists revise models in search of even greater accuracy; see here for some of their thoughts on the process. Ultimately, Milloy’s inaccurate claims that the Earth is not warming as predicted by (junk) climate models because plant photosynthesis is absorbing more CO2 than imagined misconstrued Dr. Knauer’s study: “In summary, our study suggests that GPP can be higher than previously expected under future climate change. Our study did not look at how NBP will change with climate change and how that could feed back on global warming. Hence, any conclusions on what our study means with respect to future global warming remain speculative.” Conclusion: Steve Milloy’s claims are inaccurate and unsupported. Climate model predictions have been evaluated and tell us that the global warming we are experiencing today is within the ranges we predicted it to be. Even decades old predictions still hold-up. If anything, evidence suggests warming estimates may have been a bit too conservative and the rate of global warming may be increasing faster than predicted[6]. Milloy’s claims misconstrue and misrepresent the study he uses as support. Increases in photosynthesis, based on new scientific insights, does not imply that global warming is not happening, is not happening as much as predicted, or will not continue to happen.

https://science.feedback.org/review/wall-street-journal-questions-decades-scientific-evidence-demonstrating-elevated-atmospheric-co2-causes-global-warming/

Inaccurate

The Wall Street Journal, Holman W. Jenkins, 2023-11-03

We do not know if CO2 is the cause of global warming

Inaccurate: Evidence has allowed scientists to conclude, beyond reasonable doubt, that elevated atmospheric-CO2 from human emissions is the main driver of global warming. Scientists have quantified how much CO2 has strengthened the greenhouse effect by absorbing and radiating heat and this warming effect matches the observed global temperatures increase.

We know that CO2 causes global warming through the greenhouse effect based on overwhelming evidence from data collected over decades of investigation. There is international scientific consensus that elevated atmospheric-CO2 from human emissions is not just a cause of global warming, it is the leading cause of global warming.

We do not know if CO2 is the cause of global warming because global climate models and temperature records are unreliable.

1 – Myers et al. (2021) Consensus revisited: quantifying scientific agreement on climate change and climate expertise among Earth scientists 10 years later. Environmental Research Letters 2 – Lynas et al. (2021) Greater than 99% consensus on human caused climate change in the peer-reviewed scientific literature. Environmental Research Letters 3 – IPCC (2023) Summary for Policymakers. In: Climate Change 2023: Synthesis Report. Contribution of Working Groups I, II and III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change 4 – IPCC (2021) The Earth’s Energy Budget, Climate Feedbacks, and Climate Sensitivity. In Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change 5 – Romps et al. (2022) Why the forcing from carbon dioxide scales as the logarithm of its concentration. Journal of Climate 6 – Vose et al. (2021) Implementing full spatial coverage in NOAA’s global temperature analysis. Geophysical Research Letters

In the Wall Street Journal (WSJ), opinion columnist Holman W. Jenkins claims we do not know if carbon dioxide (CO2) is the cause of global warming. Jenkins bases his November 3rd article“The Earth Is Warming, but Is CO2 the Cause?” largely on a recent report from the national statistics agency of Norway. Dozens of other outlets and blogs similarly covered that report. The claim that we do not know if CO2 is the cause of global warming is inaccurate based on a comprehensive body of scientific work, diverse methodologies and data sources, and fundamental physics, as we explain below. A consensus of scientific evidence confirms CO2 from human emissions causes global warming It takes more than the claims of one report to overturn decades of evidence and the international scientific consensus that CO2 causes global warming. There is a long and straightforward history of how we have reached the consensus on anthropogenic climate change, or that CO2 and other greenhouse gas emissions from humans are causing global warming. Nearly all scientists agree humans are causing global warming through greenhouse gas emissions. Among scientists with the most climate-related expertise, the consensus reaches 100%[1]. A recent peer-reviewed scientific study analyzing thousands of other peer-reviewed scientific studies found that 99% of the scientific literature confirms human greenhouse gas emissions cause global warming[2]. Last week, the Fifth National Climate Assessment of the USA (a congressionally mandated interagency report featuring 500 expert contributors) concluded that “global warming observed over the industrial era is unequivocally caused by greenhouse gas emissions from human activities”. The report goes on to explain that CO2 is the primary greenhouse gas humans emit and the principal greenhouse gas that affects Earth’s radiative balance. On the global stage, the reports from the United Nations Intergovernmental Panel on Climate Change (IPCC) represent humanity’s best attempts to synthesize and summarize climate change science. With each IPCC report released, thousands of experts are involved in making sure the statements are accurate and robustly supported in the scientific literature. In the most recent IPCC report (AR6), the very first text line (line A.1.) of the “Summary: for Policymakers” states “Human activities, principally through emissions of greenhouse gases, have unequivocally caused global warming”[3]. The report confirms there has been 1.1°C of global warming since the period 1850-1900 and it explicitly identifies CO2 as the leading cause (Fig. 1). As an indication of the scientific robustness of AR6, just the contribution from Working Group 1 alone was written by 234 of the world’s leading climate scientists coming from 66 countries. It included nearly 4000 pages of research based on more than 14 000 scientific papers as supporting references and was critiqued and revised by over 1 500 expert reviewers. Figure 1 – The contributions of different drivers to global warming from the present time period (2010-2019) relative to the time period of 1850-1900 (source). The estimates of warming (red) and cooling (blue) from radiative forcing studies (panel (c)) are based on both direct emissions into the atmosphere and their effect, if any, on other climate drivers. Clear links between human CO2 emissions, the greenhouse effect, and global warming We have high resolution records of CO2 increase across the globe in more recent decades, with even relatively robust proxy records before and since the start of the Industrial Revolution (which was when humans started to really harness fossil fuels like coal, petroleum, natural gas). As we burned fossil fuels throughout the industrial era, we released CO2. With current global atmospheric-CO2 concentrations now approaching 420 parts per million, human emissions have increased CO2 concentrations in the atmosphere by 50% since the year 1750 (Fig. 2). Figure 2 – Human emissions of CO2 (grey line, right y-axis) from activities like burning fossil fuels, deforestation, and intensive agricultural land use practices represent only a small portion of total annual emissions on Earth (human and natural emissions), but they have accumulated enough year-over-year to increase atmospheric concentrations significantly (blue line, left y-axis) (source). We have known for over a century that CO2 is a key greenhouse gas that can and is strengthening the greenhouse effect in the atmosphere. Like the other known infrared-absorbing greenhouse gases, CO2 absorbs and re-emits heat and therefore maintains a higher temperature in the atmosphere than non-greenhouse gases (Fig. 3). Since the first experiments of mid-19th century scientists, countless more studies have tested and validated the warming effect of increased atmospheric-CO2. Figure 3 – The surface and atmosphere of the Earth absorbs solar radiation from the Sun and re-radiates it as longwave radiation. Some of the longwave radiation makes it back to space (blue shaded section). The radiation that does not, gets trapped in the atmosphere by greenhouse gases like CO2, which all have different radiative forcing strengths based on the frequencies (or wavelengths) they affect and their atmospheric concentration, among other factors. This is the greenhouse effect (red shaded section), because more longwave radiation persisting in the atmosphere produces higher air temperatures (source). Global temperature records resulting from the efforts of thousands of data collectors, scientists, meteorologists, and other researchers across the planet, demonstrate a clear increase in temperature in recent decades that is unprecedented (Fig. 4). Various government, academic, and independent research organizations that record global temperature using varying data processing methods have reached the same results: temperature is rising. These methods and the datasets themselves are based on the gold standard of scientific publication involving peer-review critiques and re-analysis from external experts. Efforts to independently and impartially analyze temperature records, on behalf of skeptics, have confirmed their veracity repeatedly. This is how we can say the data is reliable and represents our best scientific efforts. Figure 4 – Top: Comparison of temperature record (degrees Celsius) going back in time over 2000 years. Temperature records that are based on indirect proxy measurements are indicated by the blue trendline, while temperature records that were directly measured are indicated by the red trendline (source or source). Bottom: Comparison of consolidated temperature records (degrees Celsius) of multiple datasets and methodologies. The data represents temperature differences (plus or minus numbers on y-axis) between the recorded year (x-axis) and a common baseline temperature average for the period 1951-1980 (represented as 0 on the y-axis) (source). So, we know elevated CO2 comes from human activities, which strengthens the greenhouse effect, and there has been a significant increase in global temperatures as a result. In the IPCC AR6, greenhouse gases are quantified to be (very likely) the main driver of global warming among all the different drivers (Fig. 1). Other greenhouse gases, such as methane, have been heating the atmosphere since 1850 due to their increased concentrations, but most of the temperature increase can be attributed to CO2. Each greenhouse gas has a specific effective radiative forcing (ERF, measured in units of watts per square meter (W.m–2)) which represents the energy added (heating) or subtracted (cooling) from the Earth system due to their change in concentration and their global warming potential (GWP). Calculations of the ERF of CO2 since 1850 place it at 2.012 ± 0.241 W.m–2, while the next largest is methane (CH4) at 0.496 ± 0.099 W.m–2, followed by nitrous oxide (N2O) at 0.201 ± 0.030 W.m–2. Because these values are all positive, they represent energy added to the Earth system. They are calculated from a combined approach that uses the stratospheric-temperature-adjusted radiative forcing from radiative transfer models and adds the tropospheric adjustments derived from Earth system models[4]. The relationship between CO2 and global temperatures is so clear that we can trace recent global warming alongside recent atmospheric-CO2 increases and even predict temperatures based on the concentration of atmospheric-CO2. With each doubling of CO2, its radiative forcing increases by about 4 W.m–2, meaning there should be a logarithmic relationship between temperature and atmospheric-CO2 concentration[5]. When we plot both with CO2 on logarithmic scale and incorporate a time lag for global temperatures to respond, this is exactly what we see (Fig. 5). Figure 5 – Top: Comparison of yearly global surface temperatures (left y-axis) with atmospheric-CO2 concentrations (grey line, right y-axis) since 1850. Yearly temperature bars are relative to average temperature from 1850-2022 with blue bars indicating a cooler than average year and red bars indicating a warmer than average year (source). Bottom: Global temperatures versus atmospheric-CO2 on a logarithmic scale (as described in a previous claim review on Climate Feedback). This is why we know CO2 causes global warming. It traps infrared radiation near the Earth’s surface and is the most important driver of global warming. It may not have the highest GWP, but its concentration has increased the most in the atmosphere (in absolute terms) and it has the highest ERF. From 1990 to 2022, CO2 caused approximately 78% of the increase in global warming attributed to greenhouse gases. In summary, the greenhouse gases overall cause the most global warming of all the climate change drivers, and CO2 causes the most global warming of all the greenhouse gases (Fig. 1). Climate change misinformation is fuelled by misconceptions, but the science is clear Jenkins’ inaccurate claim in the WSJ refers heavily to only one source, a recent report published by Statistics Norway entitled “To what extent are temperature levels changing due to greenhouse gas emissions?”. The report authors, who do not have significant expertise in climate science, think that global climate models are probably unable to detect anthropogenic climate change. However, this climate change skepticism talking point has been addressed regularly over the years. The Statistics Norway report is problematic for numerous reasons, as demonstrated by both Dr. Rasmus Benestad, who is a senior scientist at the Norwegian Meteorological Institute with a background in physics and statistics, and by Dr. Stefan Rahmstorf, who is a physicist, oceanographer, and professor at Potsdam University. Among the main issues with the report, the authors conflate methods of statistical models with physics-based models and misunderstand the purpose, methods, and effects of model calibration or “tuning”. Their claim that solar activity can be an explanation for global warming has long been investigated and the observations are incompatible with the hypothesis that the Sun could be the cause of global warming. In fact, the amount of energy received from the sun has decreased while the climate has warmed over the last few decades. The authors also disregard physical evidence of global-scale climate change, like sea level rise, and CO2’s greenhouse gas physical properties (proven in laboratories and by physics) by claiming local “noise” in temperature datasets makes it “impossible to determine how much of the temperature increase is due to emissions of CO2”. Local-scale datasets cannot always be expected to reflect global warming trends due to the chaotic nature of local weather. If it was only random fluctuations in temperature at the global scale, then we would expect as many decreases in temperature as increases. In reality, almost all weather stations show warming because the natural variability at the local scale, or the noise, is drowned out. The limited selection of data analyzed in the report is a poor representation of the global situation and leads to cherry picking data. This enables one to find spurious correlations or conceal significant correlations to support pre-existing biases. The authors also propose changes in Earth’s orbit as an explanation for recent climate change. While climate scientists have long been aware that changes in Earth’s orbit have caused past climate change over long periods of time, this is not something that can explain recent global warming, which is happening at a much faster rate. Both the IPCC AR6 and the NCA5 report outline how natural climate change drivers throughout the industrial era, like solar radiation and volcanic aerosols, have had negligible and regionally variable climate effects. Jenkins also inaccurately claims that temperature records are dishonestly managed and unreliable (claims previously addressed by Climate Feedback here and here). Despite stating “the Earth is warming” in the title of his opinion piece, Jenkins contradicts himself by later writing “a future climate scandal” might in fact reveal the opposite. Claims that temperature datasets are corrupted are regularly debunked. The temperature records maintained by NOAA come from a mix of sources and have been compiled over the years to ensure full global and historical coverage. These methods are tested and verified by other bodies and researchers independent of NOAA. With each expansion of the dataset to include earlier years, more geographic locations, and higher-quality data, NOAA and other researchers using the data publish and explain the new methods and the impacts of their results. For example, researchers recently investigated new NOAA data reaching back to the year 1850 and found even more warming in the Arctic than previously estimated[6]. It is with these updates that we improve climate science and reduce the range of temperature uncertainties, which are inevitable in any effort to quantify natural phenomena at the global scale. Conclusion: In America’s second largest print newspaper, with an online audience of millions of subscribers, Jenkins questions whether we know if CO2 drives global warming. The two authors of the Statistics Norway report claim we cannot know. However, the evidence that has been analyzed by thousands of leading scientists around the world has allowed them to conclude that, to the best of human knowledge and beyond reasonable doubt, we know that increased atmospheric-CO2 from human activity is causing global warming. UPDATE (30 November 2023): We updated this review to include a link to Dr. Stefan Rahmstorf’s rebuttal on RealClimate, published on 29 November 2023, and added a sentence to further explain the differences between analyzing local and global temperature datasets.

https://science.feedback.org/review/claim-current-climate-change-explained-natural-cycles-volcanic-activity-does-not-have-scientific-support/

Incorrect

Twitter/X, Social media users, 2023-09-02

The cyclical activity of the Sun as well as other variations in solar and earth activity, and NOT anthropogenic CO2 emissions, are responsible for climate change

Incorrect: There is no evidence that natural variation in the Sun’s energy output, changes in the position of the Sun relative to the Earth, or volcanic activity on Earth can account for ongoing climate change. By contrast, all observations are consistent with the fact that human emissions of greenhouse gases are causing ongoing global warming.

Solar energy output does change slightly over short-term as well as long-term cycles. However, the expected effects due to these natural cycles are far below the threshold that could account for current climate change.

The cyclical activity of the Sun as well as other variations in solar and earth activity, and NOT anthropogenic CO2 emissions, are responsible for climate change

IPCC (2023) Climate Change 2023 Synthesis Report. Date accessed September 15 2023 Crowley (2000) Causes of climate change over the past 1000 years. Science Santer et al. (2013) Human and natural influences on the changing thermal structure of the atmosphere. Proceedings of the National Academy of Sciences Joshi and Jones (2009) The climatic effects of the direct injection of water vapour into the stratosphere by large volcanic eruptions. Atmospheric Chemistry and Physics Hall and Waugh (1997) Tracer transport in the tropical stratosphere due to vertical diffusion and horizontal mixing. Geophysical Research Letters

In a post on X (formerly Twitter) on September 2, a social media user (Robin Monotti) posits that the primary reason for climate change is the cyclical activity of the Sun and the Earth, with volcanic activity also playing a role. Overall, it appears that Monotti’s aim is to imply that while human activity and CO2 emissions might be playing some role in climate change, these are not the main factors. As of the date of publication of this review, the post has been reposted about 5 thousand times and viewed over 1.2 million times. However, in its most recent report on climate change, which constitutes an authoritative review of scientists’ work around the world, the Intergovernmental Panel on Climate Change (IPCC) explains that, compared to the 19th century, global surface temperature has increased by more than 1°C, and this increase can be entirely explained by the influence of human activities. In contrast, the impact of natural (solar and volcanic) drivers on global temperatures is estimated to be 0 plus or minus 0.1°C over this same period[1] (Figure 1). Figure 1 – Drivers of global warming for the period 2010–2019. The figure shows that the observed warming is consistent with the warming that can be calculated from human influence, the warming being mostly a consequence of added greenhouse gases (GHG). Taken from Figure 2.1 from the Climate Change 2023 Synthesis Report of the IPCC. In his post, Monotti does not specifically state how the cyclical activity of the Sun as well as other factors can cause climate change, but he implies that variation in solar activity and in the Sun’s orbit relative to other celestial bodies, and changes in the Earth’s orbit are sufficient to explain ongoing climate change without recourse to greenhouse gas emissions and human activity. However, there is no evidence that any of these factors can explain the magnitude of the change in the earth’s climate that we are currently experiencing[2]. To address these claims, it is instructive to consider why scientists agree that climate change is man-made and why there is a consensus that it is due to greenhouse gases. On the one hand, this conclusion rests on direct measurements of greenhouse gases in the atmosphere. These measurements have shown that atmospheric CO2 increased by more than 40% from 1800 to 2019. How do we know that this increase is due to human activity? First, the circumstantial evidence: CO2 levels have increased most precipitously since 1970, which was a period that also witnessed a pronounced increase in global energy consumption. Further, the conclusion is based on analysis of the different carbon isotopes detected. Carbon comes in three naturally occurring isotopes: 12, 13, and 14. These numbers refer to the numbers of neutrons in the nuclei of these different isotopes, and the different isotopes are derived from different sources. Plant material is enriched in 12C (Carbon 12), and it is precisely this isotope that has become enriched in the atmosphere. The only valid explanation is that this enrichment is due to the burning of fossil fuels and the release of 12C. The changes in climate, meanwhile, are based on scientists’ understanding of how heat is trapped by greenhouse gases. Models that seek to explain changes in climate and their causes have identified anthropogenic greenhouse gas emissions as the only factor that can reasonably explain the observed global warming. Of course, natural causes and variations can affect the earth’s climate, as they have done in the past over long periods of time. However, calculations that only take these natural factors into account do not predict any significant warming of the Earth’s climate over the past century. Monotti implies that the positions of the Earth and the Sun relative to each other, as determined by cyclical changes over the short and long-term, could explain climate change. Put simply, long-term changes to the Earth’s orbit occur in the timeframe of 10,000-100,000 years. This is too long to explain the short-term changes to climate observed today. The Sun also undergoes its own short- and long-term cycles. Here again, the problem with this claim is that while long-term phenomena (thousands of years) do influence the climate over long periods of time, the changes to the climate that we are seeing are both drastic and very recent, i.e., +1°C between pre-industrial times and today. The 11-year solar cycle does indeed result in changes in the Sun’s energy output. However, these are modest (up to 0.15%) and cannot explain the magnitude of change observed. One overarching argument against changes in solar activity being responsible for climate change is that if this were the case, that is if the Sun’s energy output had increased, then all layers of the atmosphere should be warmer. Instead, however, measurements from different layers of the atmosphere show that the lower atmosphere or troposphere has gotten warmer, while the middle layer of the atmosphere or stratosphere has in fact gotten cooler[3](Figure 2). This is wholly consistent with a model in which CO2 mixes throughout the atmosphere but only traps heat closer to the Earth’s surface, due to the absorption of energy from the Earth’s surface. Figure 2 – Changing temperatures in the Earth’s atmosphere. Between 1986 and 2022, temperatures dropped in the higher levels of Earth’s atmosphere (starting at top left, blue shades); conversely, temperatures in those atmospheric layers closest to Earth have increased (bottom row, red shades). Image credit: Benjamin Santer/UCLA. Accessed from UCLA newsroom. Monotti also references volcanic activity and specifically the Hunga-Tonga Hunga underwater volcanic eruption of January 2022 as a source of climate change. Volcanoes can contribute to global warming in two ways, through CO2 emissions and, in cases of underwater eruptions, through release of water vapor into the atmosphere[4], which then traps heat. The Hunga-Tonga Hunga underwater volcanic eruption was indeed unprecedented in the amount of water vapor that was released into the atmosphere. However, this effect, while potentially marked, is temporary as the increased water vapor is expected to dissipate within a decade[5].

https://science.feedback.org/review/clintel-group-inaccurately-represents-climate-science-declaration-no-climate-emergency-once-again/

Incorrect

Clintel, The Epoch Times, Benoit Rittaud, Naveen Athrappully, Viv Forbes, Richard Lindzen, Patrick Moore, Ian Plimer, Guus Berkhout, Christopher Monckton, 2023-08-19

Global warming is just the end of the Little Ice Age; Warming is slower than climate models forecasted; Carbon dioxide is beneficial to Earth; Global warming is not intensifying or increasing the frequency of natural disasters

Incorrect:Observations show that global mean surface temperature has increased since 1850. Among other lines of evidence, climate models that have been skillful at simulating global mean surface temperature indicate that human activity–and, notably human emissions of carbon dioxide–is responsible for this increase, rather than the end of the Little Ice Age. Scientific evidence supports the finding that climate change influences various extreme weather events, which adversely impact plants and agriculture, contrary to the unsupported claims made in this letter and its coverage that suggest otherwise.

Scientists have investigated all potential causes of climate change and concluded that human activity is responsible for modern warming, not the end of the Little Ice Age. Climate change has adverse impacts on plants and agriculture, including through its influence on extreme weather events.

“The Little Ice Age ended as recently as 1850. Therefore, it is no surprise that we now are experiencing a period of warming.”; Warming is far slower than predicted”; “Climate models have many shortcomings…”; “CO2 is plant food, the basis of all life on Earth”; “There is no statistical evidence that global warming is intensifying hurricanes, floods, droughts and suchlike natural disasters, or making them more frequent.“

A letter published on August 14 by CLINTEL, a group that claims to have the support of “1,609 scientists and professionals”, repeats a series of familiar myths about climate science to arrive at its declaration that “there is no climate emergency”. The group has published similar claims about climate science in the same letter format in 2022 and 2019, both of which were previously analyzed by Climate Feedback, here and here. This year’s edition of the letter was covered by dozens of online blogs and news sites, including the Epoch Times, an outlet that has also previously published science misinformation. The letter first claims that “it is no surprise that we are now experiencing a period of warming” because the “Little Ice Age ended as recently as 1850”. The Little Ice Age refers to a period of slight cooling, typically defined as occurring from the mid-16th to mid-19th century that was particularly strongly expressed in the northern hemisphere (Fig. 1)[1]. Scientists have proposed a variety of explanations for the cause of the Little Ice Age, including reduced solar activity[2], variations in atmospheric circulation patterns[1], changes in North Atlantic ocean circulation and ice dynamics[3], large volcanic eruptions[4], and even human-driven land-use change triggered by European colonialism[5]. Figure 1. Reconstructions and observations of global temperature change over the last two millennia. The magnitude of temperature change during the Little Ice Age, denoted by the blue-shaded region of the plot, is far outweighed by current warming. Source: Climate Lab Book Here, the letter is implying that post-industrial warming resulted naturally from the end of this cool interval, which climate scientists say is not accurate. Climate scientists have parsed out the influence of human-caused and natural factors on global mean surface temperature, and have concluded that contemporary warming is due to human activity (Fig. 2)[6,7]. As Timothy Osborn, a climate scientist at the University of East Anglia, remarked in comments to Climate Feedback for a previous review of a similar claim, “[N]atural warming after the Little Ice Age was complete by the late 1800s. The warming from the late 1800s to the present is all due to human-caused climate change, because natural factors have changed little since then and even would have caused a slight cooling over the last 70 years rather than the warming we have observed” (Fig. 2). Figure 2. (left) Unprecedented rate of warming since 1850 and (right) observed (black) and simulated temperature change since 1850 with (brown) and without (green) human factors. Note that natural factors alone are insufficient to explain the unprecedented post-industrial rate of warming as documented in observations. Source: IPCC AR6 The letter goes on to claim that “warming is far slower than predicted” and that “[t]he world has warmed significantly less than predicted by IPCC [the Intergovernmental Panel on Climate Change] on the basis of modeled anthropogenic forcing”. However, the results from IPCC models shown in Fig. 2 indicate that the current suite of IPCC Sixth Assessment Report (AR6) models accurately captures the observed warming since 1850. Earlier climate models have also generally been skillful at simulating global mean surface temperature (Fig. 3)[8]. While some models have overestimated warming, others have underestimated it. As the authors of a 2019 paper[8]that explored the performance of projections by climate models over the last several decades put it, “We find no evidence that the climate models evaluated in this paper have systematically overestimated or underestimated warming over their projection period”. By suggesting that climate models have exclusively overestimated warming, the CLINTEL letter is engaging in cherry-picking–selectively reporting on only the results that match a desired outcome while excluding other pieces of relevant scientific evidence. Figure 3. Average of model-simulated temperature change from the IPCC’s first assessment report published in 1990 (black) against various temperature observations (colors). Source: Carbon Brief According to the letter, carbon dioxide (CO2), the greenhouse gas that is predominantly responsible for modern warming, is “plant food” that is both “favorable for nature” and “increas[es] the yield of crops worldwide”. However, scientists say that this claim oversimplifies the relationship between plants and CO2. “The benefit[s] of increasing CO2 concentrations for plant growth are increasingly being outweighed by the negative impacts, especially of global warming”, said Sara Vicca, a plant biologist and biogeochemist at the University of Antwerp, in comments to Climate Feedback for a previous article on the topic. “This is true for natural as well as agricultural ecosystems”. While satellite observations indicate that increasing levels of atmospheric CO2 have supported plant growth over the last few decades, these terrestrial (and marine) CO2 sinks do not remove all of the anthropogenic CO2 from the atmosphere. The uptake of carbon by terrestrial and marine plants together helps to slow the rate of warming. What’s leftover, however, causes climate change, which has a variety of adverse impacts on plants and agriculture. According to the latest IPCC report, human influence on climate has created physical conditions likely to increase the occurrence and severity of some extreme weather events (such as heavy precipitation, compound flooding, fire weather, and agricultural and ecological drought),[6]contrary to the letter’s claim that climate change “has not increased natural disasters”. Attribution scientists have even been able to identify the influence of climate change on individual extreme weather events in some cases. For example, scientists have found that the occurrence of the 2021 heatwave in the Pacific northwest region would have been “virtually impossible” without the existence of anthropogenic climate change.[9] These events, scientists say, put additional stress on plants and agriculture. “We are already seeing the first signs of a decline in the land CO2 sink and increasing extreme heatwaves and droughts seem to be a key reason behind this”, Vicca noted. One meta-analysis identified negative relationships between warming and the yields of maize, rice, wheat, and soy–four major agricultural crops.[10]Elevated levels of CO2 could also lower the nutritional value of rice, according to a 2016 study.[11] The author of the Epoch Times article purports that the CLINTEL letter contains the signatories of “over 1,600 scientists”. However, as in previous iterations of this letter, this claim is misleading because many of the letter’s 1,609 signatories are non-scientists and include people with the self-reported credentials of “retired teacher and manager of a small business”, “Senior Ship Designer”, and “Financial Advice Specialist”. Additionally, very few of the signatories who identify as scientists report credentials in climate science.References: 1 – Mann (2002). Little Ice Age. In: Encyclopedia of Global Environmental Change 2 – Mauquoy et al. (2002). Evidence from northwest European bogs shows ‘Little Ice Age’ climatic changes driven by variations in solar activity. The Holocene 3 – Lapointe et al. (2021). Little Ice Age abruptly triggered by intrusion of Atlantic waters into the Nordic Seas. Science Advances 4 – Miller et al. (2012). Abrupt onset of the Little Ice Age triggered by volcanism and sustained by sea-ice/ocean feedbacks. Geophysical Research Letters 5 – Koch et al. (2019). Earth system impacts of the European arrival and Great Dying in the Americas after 1492. Quaternary Science Reviews 6 – IPCC (2023). Summary: for Policymakers. In: Climate Change 2023: Synthesis Report. IPCC 7 – Tett et al. (2007). The impact of natural and anthropogenic forcings on climate and hydrology since 1550. Climate Dynamics 8 – Hausfather et al. (2020). Evaluating the performance of past climate model projections. Geophysical Research Letters 9 – Philip et al. (2022). Rapid attribution analysis of the extraordinary heat wave on the Pacific coast of the US and Canada in June 2021. Earth System Dynamics 10 – Moore et al. (2017). New science of climate change impacts on agriculture implies higher social cost of carbon. Nature Communications 11 – Zhu et al. (2016). Carbon dioxide (CO2) levels this century will alter the protein, micronutrients, and vitamin content of rice grains with potential health consequences for the poorest rice-dependent countries. Science Advances

https://science.feedback.org/review/three-decades-chemtrail-haarp-geoengineering-conspiracy-theory-remains-popular-despite-lack-evidence-no-scientific-basis/

Incorrect

Facebook, Facebook users, 2023-08-07

Global weather is controlled by secret geoengineering programs using chemtrails and ionosphere heating facilities.

Incorrect: Weather forms mainly in the troposphere and is driven by energy from the Sun. Research facilities like HAARP only influence a small area of the ionosphere directly above them, which is tens to hundreds of kilometers above where weather forms and occurs. Unsupported: There is no evidence for the existence of chemtrails nor is there evidence for the saturation of Earth’s atmosphere with any substances from chemtrails. The energy that research facilities like HAARP transmit to the atmosphere is billions of times smaller than the energy needed to power most weather systems such as mid-latitude cyclones.

While it is possible to change the Earth’s long-term climate through elevated atmospheric greenhouse gases, humans lack the scientific, technological, and logistical capabilities to control short-term weather events at the global scale. There is no evidence for the existence of chemtrails, nor for their claimed impact on global atmospheric chemical composition and physical properties. The Sun drives weather and sends far more energy to Earth than ionosphere heating facilities like HAARP can transmit. These facilities are radio transmitters that can only excite small areas of the ionosphere directly above them, whereas weather occurs primarily in the troposphere and all over the planet.

Global weather is controlled by secret geoengineering programs using chemtrails and ionosphere heating facilities. There is no natural weather at this point.

1 – IPCC (2021) Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change 2 – Shearer et al. (2016) Quantifying expert consensus against the existence of a secret, large-scale atmospheric spraying program. Environmental Research Letters 3 – Mironova et al. (2015) Energetic particle influence on the Earth’s atmosphere. Space Science Reviews 4 – Li et al. (2017) Analysis of ionospheric disturbances associated with powerful cyclones in East Asia and North America. Journal of Atmospheric and Solar-Terrestrial Physics 5 – Abshaev et al. (2022) Rain Enhancement Through Cloud Seeding. Unconventional Water Resources

Introduction Can humans control the weather on a global scale as periodically claimed by viral social media posts? Let’s review the basics. Weather is short-term atmospheric conditions, while climate is long-term atmospheric trends. Changing the climate is a bit like water eroding rocks in a river; it’s possible but requires long-term effort. By increasing atmospheric greenhouse gas concentrations over many decades, human activity has changed Earth’s climate and increased average global temperatures[1]. However, changing daily weather on demand would be like carving and cutting through rocks with a high-power waterjet. If it’s possible, it would require a huge amount of energy to pull off. Weather is a complex, dynamic, and high-energy system driven by the 430 quintillion joules (430 followed by 18 zeros) of energy the Sun sends to Earth every hour. That’s more energy in one hour than all the energy humans can produce and use in a year. Using the recent film Oppenheimer for reference, it’s equivalent to nearly 7 million Hiroshima atomic bombs (blast yield of 63 trillion joules) exploding every hour to keep weather functioning as we know it. With such stark difference in scales between human energy production and the energy pools and fluxes involved in the global weather system, it’s clear that controlling daily weather is beyond human capabilities. Still, one popular geoengineering conspiracy claims that we do already, and it has persisted from the early days of the internet to now flourish in the age of social media: the chemtrail-HAARP conspiracy theory. In a recent example from 7 Aug. 2023, a video posted on Facebook presents this theory as part of a global geoengineering conspiracy involving a secret large-scale atmospheric program (SLAP). It describes the saturation of the atmosphere with chemical and metal particulates from airplane chemtrails which has supposedly enabled weather manipulation using a network of ionosphere heating facilities, such as HAARP. Having been viewed over 500 thousand times, this is just one of several social media posts on this topic that have become viral in recent months, such as this, this, and this. The ultimate goal, according to some proponents, is to influence global geopolitics through targeted weather events. For a conspiracy of this scale to be plausible, many logistical, socioeconomic, governmental, and legal challenges would need to be first addressed. But by exploring only some of the physical aspects mentioned in this clip, this claim review demonstrates the insurmountable scientific challenges already invalidating the chemtrail-HAARP conspiracy theory. No evidence for chemtrails and their supposed effects The unidentified narrator in the clip begins by explaining that chemtrails are “what we see happening in the sky, this is weather modification on a global scale”. As a popular anchor point in geoengineering conspiracy theories since the 1990’s, the concept of chemtrails is inspired by a very real phenomenon called contrails. Contrails, or condensation trails, occur when water vapor and soot particulates from airplane exhaust freeze mid-air and form ice crystals. These are the long white lines crisscrossing the sky after planes have flown by. Differences in the level of humidity at the time and location of the airplane’s flight determines the visibility and longevity of its contrails, which is why not every plane you see will have them. Figure 1 – Left: Factors in the formation of contrails. The moisture and temperature at the time and location of the flight determines the visibility and persistence of a contrail. Conspiracy theorists who fail to understand the physical origin of this variability use it as evidence of an ongoing secret chemtrail program (source). Right: Examples of persistent contrails that visibly appear different despite occurring in the same location. Scenarios like this are also used as proof of chemtrails, but in reality they appear different because they formed at slightly different times and at different altitudes with different moisture and temperature conditions (photo: Ron Smith). Chemtrails, on the other hand, have never been demonstrated in any scientific study. Chemtrail conspiracy theorists generally claim that there are secret programs, whether run by government, military, or other, that use airplanes to spread toxic chemicals throughout the atmosphere. According to the theory, the cloud-like streaks in the sky that airplanes leave behind them are not just contrails, they can also be visible proof of chemtrails. But without in-situ sampling, in-depth investigations, or scientific studies proving chemtrails exist, distinguishing them from contrails remains a matter of faith. Aside from being used to enable geoengineering and weather control, chemtrails are also believed to be used as a means of mass sterilization, mass poisoning, and even mind control on targeted populations. According to the narrator, this secret large-scale atmospheric program (SLAP) starts with spreading chemtrails to achieve a global “…saturation of the atmosphere with various chemical and metal particulates” which “…ionizes the atmosphere, makes the atmosphere more conductive”. But in a 2016 study which surveyed of some of the world’s top atmosphere experts, consisting of atmospheric chemists with expertise in condensation trails and geochemists working on atmospheric deposition of dust and pollution, virtually every single respondent did not believe there is any scientific evidence for a SLAP using chemtrails[2]. Even when assessing data that conspiracy theorists claim is proof of chemtrails, such as elevated concentrations of specific elements in soils, sediments, and water bodies in remote locations, the overwhelming majority of the respondents stated that there are simpler and better supported explanations. In addition, there are no scientific studies nor any existing data confirming elevated global atmospheric, soil, sediment, or water concentrations of the various chemicals that chemtrails are claimed to spread. There is also no evidence of a more conductive atmosphere over the last two to three decades, and no scientific basis for the possibility of human activities to “ionize the atmosphere”. Atmospheric ionization, especially at the altitudes where weather occurs, is instead a result of the Sun’s radiation (extreme ultraviolet and X-rays) and the atmosphere being bombarded with energetic precipitation particles such as aural electrons, radiation belt electrons, solar protons, and galactic cosmic rays[3]. These outstanding issues do not support the claims made in this clip, which also fails to provide any references to data or studies that would support the claims made. Ionosphere heaters do not influence the weather The second component of the chemtrail-HAARP conspiracy theory involves the use of radio wave transmitters, specifically ionosphere heating facilities which are designed to study plasma turbulence and the behavior of the ionosphere and upper atmosphere. The High-frequency Active Auroral Research Program(HAARP) in Alaska, USA is the most famous such facility, especially for being a popular subject of conspiracy theories since its inception in 1990. In addition to weather modification events, HAARP has been also been blamed for recent disaster events like the 2023 Hawaii wildfires and Turkey–Syria earthquake. Originally a joint research facility of the United States Air Force and the University of Alaska-Fairbanks, HAARP has been operated exclusively by the university since 2015. The narrator of the clip mentions HAARP in Alaska as being just one HAARP facility of “at least 18 around the globe, possibly with 3 more being built in Antarctica right now” as part of the SLAP. But regardless of how many facilities do or do not exist in reality, this theory overlooks several conceptual problems. Ionosphere heaters are radio transmitters and therefore only manipulate electrical charges and currents. As the storms in the ionosphere caused by the Sun do not interfere with surface weather, the far less powerful experiments of facilities like HAARP are a non-factor. HAARP can transmit up to 3.6 megawatts into the upper atmosphere and ionosphere with a transmission efficiency of only 45%. Even at 100% efficiency, HAARP’s transmission capability is negligible considering the 1.5 million megawatts of kinetic energy and 6 hundred million megawatts in latent energy produced by a single hurricane per day. Furthermore, HAARP’s high-frequency signal reaches the ionosphere at around 14 milliwatts per square meter (at 200 km altitude based on this example), almost a hundred thousand times less intense than the Sun’s natural electromagnetic radiation constantly hitting Earth (known as the solar constant, roughly 1.361 kilowatts per square meter). These are some of the reasons why this geoengineering conspiracy theory is baseless: ionosphere heating facilities like HAARP simply aren’t powerful enough to alter the atmosphere significantly and influence the weather. Almost all weather occurs in the troposphere where 75% of all the air in the atmosphere and almost all of the cloud and rain-forming water vapor are found. There is no known link between ionosphere heating experiments and weather behavior in the troposphere at the site of the ionosphere heating facility, let alone at the global scale. These facilities were intentionally designed for, and therefore technologically limited to, interacting with the electrons and ionized atoms and molecules that make up the ionosphere. They are not able to interact with weather related properties at lower altitudes, such as water in clouds in the troposphere. Spanning from about 80 kilometers above the surface of the Earth to the edge of space, the ionosphere does not overlap with the range of the troposphere (between 6 km at the poles to 20 km at the equator) according to NASA and NOAA. Figure 2 – The layered structure of the Earth’s atmosphere, from the surface to outer space. The ionosphere spans from the mesosphere to the exosphere (left panel source; right panel source). Even if we assume there are elevated “chemical and metal particulates” in the atmosphere due to chemtrails and that the atmosphere has been “ionized” by humans, there is still no explanation for how this will help ionosphere heating facilities affect global weather. While extreme weather in the troposphere can influence the ionosphere[4], there is no scientific explanation for how the transmissions from these facilities could cause weather events under this hypothetical “more conductive” atmosphere. And then, even if we assume there is a scientific explanation with empirical support, the energy required to counteract ongoing natural weather phenomena normally driven by the Sun’s non-stop solar energy would be enormous and beyond our capabilities. Afterall, ionosphere heating facilities have limited and well-known energy transmission capacities, and they can only heat up a tiny space directly above them compared to the planetary scale of the atmosphere. Again, even with 18 or more locations, there is no explanation for how these small experimental plots can expand to control weather across the Earth’s entire troposphere tens to hundreds of kilometers below. Despite the narrator’s unsupported claim that “the entire weather system globally is virtually being thwarted”, this geoengineering conspiracy theory relies on too many conceptual and theoretical leaps to hold any water. So, can we control the weather? It is a fair scientific and ethical question that deserves asking. In fact, with all the gargantuan challenges delegitimizing the chemtrail-HAARP conspiracy theory of global weather control, there is already a widely known example of attempted local weather modification. You may remember seeing Chinese military personnel operating cannons aimed at the sky during the 2008 Beijing Summer Olympics. They were on-guard, ready to perform cloud-seeding. Also known as “blueskying”, cloud-seeding is the introduction of small particles of, for example, silver iodide or dry ice to clouds to promote rain or snow formation by providing a surface for water droplets to collect on or ice crystals to freeze around. It is no guarantee of precipitation, but it’s interesting enough for the Chinese government to spend billions of dollars in cloud-seeding research to ensure agricultural regions receive rain when needed and large public events are sunny and cloudless. This approach was apparently used successfully to pre-rain the Beijing sky and reduce air pollution before the 100th anniversary celebrations of the Chinese Communist Party in 2021. In the United States, the US Bureau of Reclamation recently committed over two million dollars in 2023 to combat drought in the Upper Colorado River Basin using cloud-seeding. But there’s a big difference from cloud-seeding in one single location of the world to give clouds a microphysical nudge in the right direction towards precipitation, and being able to cause or prevent storms, hurricanes, blizzards, floods, or droughts anywhere in the world and at any time. Even the effectiveness of cloud-seeding is still uncertain[5] with several potential unintended consequences, but at least it is a legitimate weather modification theory with a reasonable scientific basis for experimentation and evaluation. Controlling weather at the global scale, on the other hand, is currently far beyond human scientific, technological, and logistical capabilities. The chemtrail-HAARP geoengineering conspiracy theory is guilty of overlooking these limitations, making multiple unsupported assumptions, and ignoring the Sagan standard “extraordinary claims require extraordinary evidence”.

https://science.feedback.org/review/magnetic-poles-reversals-not-cataclysmic-events-adam-and-eve-theory-jimmy-corsetti-joe-rogan-podcast/

Incorrect

The Joe Rogan Experience, TikTok, Spotify, Joe Rogan, Jimmy Corsetti, 2023-01-18

Magnetic poles reversals involve the Earth flipping vertically and momentarily stopping its rotation, causing cataclysmic events during 6 days.

Unsupported: There is no evidence that magnetic reversals have any impact on climate nor is there scientific basis for the claim that the planet flips on itself within six days. Misunderstanding of science: Speculation on the imminent possibility of the next magnetic poles' reversal happening is based on confusing averages with a normal. Scientists estimate that the probability of the Earth’s magnetic field reversing within the next 20 000 years is extremely low.

Magnetic poles reversals do occur, but don’t involve the earth’s poles physically changing positions. The liquid core of the planet moves, generating variations of the magnetic field and occasionally, magnetic poles shift. There is no evidence that magnetic poles' reversal have had any influence on climate in the Earth’s history or generated the kind of extreme weather events claimed, by contrast carbon dioxide concentration has been shown to influence global climate in the past and present.

Shifts in the planet’s magnetic poles involve the earth doing a 90° flip, with the planet remaining still for 6 days. During this short period, cataclysmic events happen, involving heat, wind, floods, and climate change.

[1] Singer et al. (2019). Synchronizing volcanic, sedimentary, and ice core records of Earth’s last magnetic polarity reversal. Science Advances. [2] Brown et al. (2018). Earth’s magnetic field is probably not reversing. Proceedings of the National Academy of Sciences. [3] Buffet et al. (2018). A Probabilistic Assessment of the Next Geomagnetic Reversal. Geophysical Research Letters.

The planet’s magnetic field acts as a shield surrounding the Earth, protecting its surface from solar radiations. It is generated within the Earth’s liquid core, and varies according to the movement of molten iron present in it. The core creates currents of electricity featuring a direction, giving us the north and south, and an intensity, which is strongest near the poles. Many variations of the Earth’s magnetic field in Earth’s history have been recorded in solidified lava or sediments, from displacement of the magnetic poles to full magnetic poles swap. In a recent podcast episode, Comedian and Ultimate Fighting Championship commentator Joe Rogan and YouTuber Jimmy Corsetti talked about the so-called “Adam and Eve” theory. Even though this theory has no support in science, as we will show below, Corsetti and Rogan discussed it as if it were credible. Corsetti appears to believe that when magnetic poles reverse, the Earth flips over itself and stops rotating for six days. Corsetti also claimed that the next reversal should happen in a very near future, and that it would be cataclysmic. A clip from this interview was viewed over twenty millions times on TikTok, and several other clips were widely shared on social media. Magnetic poles reversals are not a “planet flip” The “Adam and Eve” theory laid out in the interview suggests that magnetic poles’ reversal includes the Earth doing a “flip”, involving North and South poles physically changing positions. In reality, no scientific evidence indicates that the Earth ever performed such flips. This claim is extremely implausible, as there is hardly anything that could flip the Earth in such a way, apart from a collision with planets or other astronomical bodies. According to Corsetti’s explanation, magnetic poles reversals would take place over a six days period. However, measurements show that the time taken for a magnetic poles’ reversal is on the order of thousands of years. Geologists found that the most recent field reversal, some 770,000 years ago, took at least 22,000 years to complete, for instance[1]. A duration of six days for the reversal of the Earth’s magnetic field is not close to any scientific observation. Corsetti also claimed that, during these six days, the planet would stop rotating, but he doesn’t explain where a force strong enough to stop the Earth’s rotation would come from. “A magnetic reversal causes a change in electric currents within the liquid metal core. These currents can alter the forces inside the liquid metal core, but this cannot stop the rotation of the Earth” explains University of California Berkeley professor Bruce Buffett in an email to Science Feedback. “As an analogy, you can’t literally pull yourself up by your bootstraps.” Forecasting the next magnetic poles’ reversal Jimmy Corsetti claims that the next magnetic pole shift is likely to happen soon “as we are 200000 years overdue”. The last reversal took place 780000 years ago, according to NASA scientist Alan Buis’ article on magnetic fields. On average, the time interval between reversals is 300 000 years, but it varies greatly. Yet Corsetti’s claim misunderstands this average time between reversals with a regular pattern. Past magnetic fields can be recorded in rocks or sediments, and many were analyzed: they show a large variability of the intervals between reversals of polarity measured in sediments. Figure 1 shows that polarity reversals haven’t followed a regular pattern. Short intervals have a duration of an order of tens of thousands of years, while exceptionally long intervals with a single polarity last 10 million years and are called superchrons. For instance, the Cretaceous Normal superchron lasted approximately 40 million years. So there is no indication that, because more than 300 000 years passed since the last reversal, the next one could be expected anytime soon. Figure 1 – Geomagnetic polarity over the past 169 million years, trailing off into the Jurassic Quiet Zone. Dark areas denote periods of normal polarity, light areas denote reverse polarity. Credit: Public domain. Source : NASA Global Climate Change. Scientists have looked at the probability of magnetic pole shifts occurring in the near future. Records show that the geomagnetic fields’ strength decreases before reversal events, and such a decreasing trend has indeed been observed over the past centuries. So it is legitimate to wonder whether a reversal is likely to happen soon. However, a few centuries is still a very short period of time on the scale of such variations. A scientific study found that the Earth “is not in an early stage for a reversal”[2]. Another scientist not involved in this study also agrees: “My own theoretical estimate, based on geological estimates of past behavior, is that the chance of a magnetic reversal in the next 20,000 years is only about 2%” adds Professor Bruce Buffett. Climate change and magnetic fields According to the claim, extreme weather events such as the sun staying in the same spot causing “heating like we’ve never experienced” or “1000 miles per hour (ca. 1,609 kilometers per hour)” winds would happen as a result of magnetic poles’ reversal. In reality, the only significant risk known to impact society is that a reversal temporarily weakens the magnetic shield protecting us from bursts of radiations from the sun, called solar flares. Solar flares can disrupt satellite communications, but theyare not the kind of cataclysmic events described by Corsetti. “There is no evidence that magnetic reversals have any impact on climate” emphasizes UC Berkeley professor Bruce Buffett. “We might be more impacted by solar flares, but there is no evidence that this alters climate. As far as I know, there is no proposed mechanism that would allow this to happen.” Scientists have examined this question in numerous studies, but the results haven’t demonstrated a causal link between magnetic poles reversals and climate. As reminded by NASA scientist Alan Buis on the agency’s website, “electromagnetic currents exist within Earth’s upper atmosphere. […] In the long run, the energy that governs Earth’s upper atmosphere is about 100,000 times less than the amount of energy driving the climate system at Earth’s surface. There is simply not enough energy aloft to have an influence on climate down where we live.” The unsupported “Adam and Eve” theory, along with Corsetti’s speculations on an imminent reversal, leads Joe Rogan to claim that climate change is of lesser importance. Rogan claimed climate change is “this narrative that just gets repeated over and over and over and this fear mongering and everyone gets freaked out”. He then compared it to the “Adam and Eve” theory, “If the f***ing magnetic poles might shift […] we might have bigger problems.” As explained above, both claims of impact on climate and of a potential reversal occurring soon are unsupported and go against available evidence. When comparing risks, Rogan doesn’t appear to be aware of scientists’ very high confidence in the fact that reaching a global warming of 1.5 °C above pre-industrial levels in the near-term “would cause unavoidable increases in multiple climate hazards and present multiple risks to ecosystems and humans”, as noted by the International Panel on Climate Change (IPCC). There are 127 key risks associated with climate change identified by the IPCC, and their impacts in the mid and long term “are up to multiple times higher than currently observed”. So a magnetic poles reversal is far from being a more important risk than climate change, contrary to Rogan’s belief. Scientists’ Feedback: Bruce Buffett Professor, University of California, Berkeley: A magnetic reversal causes a change in electric currents within the liquid metal core. These currents can alter the forces inside the liquid metal core, but this cannot stop the rotation of the Earth. As an analogy, you can’t literally pull yourself up by your bootstraps. There is no evidence that magnetic reversals have any impact on climate. The overall strength of the magnetic field decreases during a reversal. This allows charged particles from the Sun (known as solar wind) to penetrate deeper into the atmosphere. We might be more impacted by solar flares, but there is no evidence that this alters climate. As far as I know, there is no proposed mechanism that would allow this to happen. Reversals occur at irregular intervals in the geological past, based on the magnetization of igneous rocks. If we average over the past few million years, the typical recurrence interval is about 250,000 to 300,000 years. The last one was 780,000 years ago, so you might argue we are overdue. In fact, there have been recent suggestions that we are entering the next geomagnetic reversal. My own theoretical estimate, based on geological estimates of past behavior, is that the chance of a magnetic reversal in the next 20,000 years is only about 2%[3]. A reversal lasting only 7 days would be difficult to detect in the geological record, but this is not realistic. A more typical estimate for the duration of a reversal is in excess of 10,000 years (depending a little on how you define a reversal; is it the time to flip the orientation of the magnetic field or the time required to flip the orientation and bring the amplitude back up to the average value?). Flipping the magnetic field orientation to the reversed state and back to the original state in 7 days would require absurdly large fluid velocities in the liquid metal core. Let’s suppose that the Earth stopped rotating. The centrifugal acceleration associated with rotation would disappear. This acceleration is presently responsible for the equatorial bulge of the solid part of the planet, as well as the oceans. The solid part of the Earth would have an abrupt elastic response of several kilometers when rotation stopped. Similarly, the oceans would respond on timescales of a few days. I would expect to see kilometers of sea level change as the solid earth and ocean adjust by different amounts over short times. It would be hard to miss this change.

https://science.feedback.org/review/headline-temperatures-on-earth-are-increasing-and-the-rise-is-drastically-outpacing-previous-natural-changes-in-the-planets-climate/

Inaccurate

Media Research Center, Ian Plimer, 2023-05-02

“We have been cooling down for the past 4000 years”; the Earth has cooled since the ‘medieval warming’, “It’s all about when you start the measurements”

Factually inaccurate: Earth’s surface has not been cooling in recent times - both global average and Greenland temperatures have rapidly increased since the beginning of the industrial era. Misleading: The most recent temperature datapoint that the claim references corresponds to 1855, which is misleading since warming caused by humans occurred mostly after this time.

Temperature data indicate that global temperatures are already higher than at any other period in the past several thousand years. Multiple independent lines of evidence indicate that the Earth is currently warming at a rate that is much faster than past changes in climate. Increasing atmospheric carbon dioxide levels due to human activities are a key driver of this change, as has been consistently shown by a consensus of scientific data.

“We have been cooling down for the past 4000 years”; the Earth has cooled since the ‘medieval warming’, “It’s all about when you start the measurements”

1 – Alley (2000) The Younger Dryas cold interval as viewed from Central Greenland Quaternary Science Reviews 2 – Hörhold (2023) Modern temperatures in central–north Greenland warmest in past millennium Nature 3 – Wilson (2016) Last millennium northern hemisphere summer temperatures from tree rings: Part I: The long term context Quaternary Science Reviews 4 – IPCC (2021) Climate change widespread, rapid, and intensifying – IPCC 5 – Cuffey and Clow (1997) Temperature, accumulation, and ice sheet elevation in central Greenland through the last deglacial transition Journal of Geophysical Research 6 – More et al. (2017) Global risk of deadly heat Nature Climate Change 7 – Im et al. (2017) Deadly heat waves projected in the densely populated agricultural regions of South Asia Science Advances

Information about Earth’s past climate can provide insights for the trends we are currently experiencing. Historical temperature conditions can be reconstructed from archives such as ice cores and tree rings that contain proxies for temperature. Although records exist of measured temperatures that date back to 1659 (Figure 1), direct records predating the 1880s are too sparse for the purposes of climate studies at a global scale, hence the need to rely on proxies. Figure 1 – Mean temperature anomalies for each full year in the Central England Temperature series against 1961-1990 climatology. While these data also show temperature increases since the industrial era, they are too sparse for climate studies at a global scale. Source: HadCET (2023) Ian Plimer, a former mining geologist who has previously made unsupported claims about climate change, recently claimed “we have been cooling down for about the past 4000 years”, implying that this somehow contradicted what scientists know about recent global warming. In the video, Plimer falsely claims that there has been no change in temperature over the past 38 years, in direct contradiction to available data (see Figure 2). Plimer also claims that the global temperature has been cooling since the “medieval warming”, which he can only conclude by ignoring any data after the 1850s; this claim has previously been debunked on Science Feedback. Figure 3 shows that current temperature increase is happening at higher rates than past changes in climate over the last 2,000 years. Figure 2 – Global temperature estimates compiled by Berkeley Earth Figure 3 – Global Warming/cooling rates averaged across 51 years and based on paleoclimate records. Modern thermometer records shown in black. Source: University of Bern Plimer points to temperature data over almost 10,000 years taken from one ice core extracted from the Greenland Ice Sheet, Greenland Ice Sheet Project 2 (GISP2), citing a 2000 paper[1] by Richard Alley, Professor of Geosciences at Pennsylvania State University. However, this dataset does not capture the past 170 years, which is the period after which the Earth began warming due to human activities. In addition, since the data dates back to the 1990s and was extracted from just one ice core using assumptions that are now questioned and analysis optimized for studies of tens of thousands of years rather than the past two centuries, it is not a suitable reference for discussions of current climate change and more recent data extracted with more modern analysis techniques exist. “The curve misses the point as it is not showing the context of recent global warming,” Anders Svensson, Associate Professor in Physics of Ice, Climate and Earth at the University of Copenhagen told Science Feedback, pointing out that the time scale shows years before 1950 CE and that the most recent point is 1855. The current rising temperatures due to human activities that are causing concern mostly occurred after 1855. In response to Plimer’s emphasis on the importance of timeframes temperature comparisons are made within, Maria Hörhold, a senior researcher in the Department for Glaciology at the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research pointed out that looking at a longer time frame would be more useful for showing the seesaw pattern of temperatures in glacial and interglacial periods. In her own study[2] on more recent analysis to extract temperature data from Greenland ice cores, she and her colleagues also point out that their data show temperatures cooling down until the industrial era hit in the nineteenth century. It is at this point that human activities led to global warming. In addition this is not on a par with the previous rate of cooling but at a much higher rate, as shown in Figure 4 below. NASA’s Earth Observatory website quantifies current warming at 10 times faster than previous warming after the last ice age. “The natural system has cooling and warming”, she told Science Feedback. “That is not under debate, no-one is arguing against that”. However, the fact that climate changed naturally in the past in no way invalidates scientific understanding that current emissions of greenhouse gases by human activities are also causing the global climate to change now. Figure 4 – The graphs show temperatures for Greenland (NGT, the North Greenland Traverse) taken from ice cores, compared with temperatures from the broader Arctic region (north of 60°N) and measured meltwater run off. It shows how recent warming due to human activities drastically outpaces the previous natural cooling trend. Source: Hörhold et al. (2023)[2] Temperature data in the recent Nature study[2] by Hörhold and colleagues cover the period 1000-2011 AD and identify a clear warming trend, with temperatures over 2001-2011 exceeding temperatures over any other period in the past thousand years. Temperature reconstructed from tree rings show the same trend[3], and an estimated warming of approximately 1.1°C since the industrial era was reported[4] in 2021 by the Intergovernmental Panel on Climate Change (IPCC) – an organization that synthesizes the best available research carried out by scientists globally. Data processing challenges There are numerous challenges in extracting reliable temperature data from ice cores as described at length in this article by Carbon Brief. One of the main issues is the noise, that is, fluctuations in the data that make it harder to identify a trend. This can be local due to wind blowing snow around the surface of the ground before it is compacted into ice, or it can result from natural fluctuations in weather. There are now recognized ways of dealing with this noise for modern day studies that can extract more reliable temperature data that holds for the region from which the ice cores are taken. One approach, as used by Hörhold and colleagues to amplify the signal of any trend in the temperature data over the noise, is to combine the data from several ice cores taken from different points. “In the data from Cuffey and Clow[5] used in the Younger Dryas paper[1], [that is, the 2000 paper that the graph Plimer cites is taken from] there is some smoothing applied, and, the data shown were optimized to capture the change from ice age to today, not to capture shorter-lived changes more recently,” Alley told Science Feedback, flagging the limitations of the data when looking at shorter time frames. He also notes that despite many reconstructions that have been made for more recent times, this particular misinterpretation “keeps coming back”. “So, it [the dataset Plimer cites] is not global”, he adds. “It is smoothed in a way that is not best for the purpose of looking at recent changes, it is not the right data set if you are concentrating on recent changes, and it is no longer the most up-to-date data set. Careful scholars simply would not be making any interpretation of recent temperatures based on this old publication.” As Alley told Andrew Revkin for an article in the New York Times 13 years ago, “using GISP2 data to argue against global warming is, well, stupid, or misguided, or misled, or something, but surely not scientifically sensible.” Current human activities are causing global warming Alley also points out that over the course of Earth’s long history spanning hundreds of millions of years, there have been many periods that are hotter than now, so hot that large regions would have been uninhabitable to unprotected humans. “The high temperatures in those past times were primarily caused by high CO2 levels”, said Alley. “Those were caused naturally, and the warming occurred at much slower rates than what we’re doing. The current rise is not natural, but caused by us.” Hörhold also highlights how temperature variations correlate with CO2 concentrations. Historic CO2 concentrations can be measured from ice cores too and naturally vary from 280-320 ppm. Looking at global CO2 levels for the past year for instance at CO2.Earth, reveals concentrations around 420 ppm. “Much higher than this natural variation,” adds Hörhold. On account of these increased CO2 concentrations, the historical correlation with temperature, and the increased temperatures in modern day measurements, scientists no longer doubt that we are in a period of global warming due to human activities that emit greenhouse gases like CO2. Conclusion: In summary, Plimer cherry-picks one old dataset that is a proxy for the temperature at a single point in Greenland to falsely imply that the Earth as a whole has cooled since the ‘medieval warming’ or the past 4000 years. When scientists reconstruct Earth’s surface temperature, they show that global temperatures have warmed rapidly over the past century, largely exceeding the slow and local temperature variations during the ‘medieval warming’ or the little ice age. Scientists’ Feedback: Richard Alley Professor, PennState University: Scientific studies have shown that, under strong human-caused warming, we could approach or reach temperatures in some places this century that would be fatal for unprotected humans—someone sitting naked in the shade in the wind drinking water would still die of heat stroke. Well before that, impacts of heat likely would drive many people away by stressing them and their crops and farm animals[6,7]. I frequently meet people who say “Climate has always changed naturally, so we should not worry about people changing climate.” I have never met someone who said, “Fires have always occurred naturally, so we should not worry about arson.” I have never met someone who said, “People have always died, so we should not worry about murder.” Climate has always changed, which proves climate is changeable. Climate change has always affected living things, which shows that climate change is important. Climate has changed for many reasons, but especially because of changing CO2, which focuses special attention on our release of CO2 to the atmosphere from fossil-fuel burning and other activities. When authoritative bodies look at the history of climate and use that knowledge to help inform understanding of possible futures, they find that releasing more CO2 to the atmosphere will change the climate in many ways, and these will overall make life harder for humans. Very strong scholarship shows that using this knowledge effectively can help the economy as well as the environment.

https://science.feedback.org/review/antarctic-ice-coverage-not-increasing-record-levels-nor-continent-getting-colder-contrary-to-curry-easterbrook-cfact-movie/

Inaccurate

CFACT, Instagram, Don Easterbrook, Judith Curry, 2023-04-16

Antarctic sea-ice extent is increasing to record levels. Antarctica is getting colder; its sea ice and ice cap are not melting

Cherry-picking: Antarctic sea-ice extent reached a record high in 2014, but that was not the sign of a long term trend of expansion since a precipitous decline followed, with the sea ice extent reaching its lowest value in 40 years.Factually Inaccurate: The consensus of scientific evidence shows that the average temperature over the Antarctic has not been getting colder. Some of the world’s fastest warming is observed in regions of the continent.

Despite a period of slight growth between 1979 and 2014, Antarctic sea ice cover is not increasing to record levels. The trend reversed in 2014 and ice cover started to decrease vigorously. Many long-term measurements from Antarctic research stations show no significant warming or cooling trends over the whole continent, but parts of the continent are among the regions experiencing the fastest warming in the world, and the ice cap is losing mass.

We’re seeing record set for antarctic sea ice extent. Climate models predict that antarctic should be losing sea ice, and it’s exactly the opposite of what’s happening. The antarctic ice cap is not melting, the average annual temperature there is 58 degrees below 0°. There’s not melting going on in the first place, it’s actually growing. The sea ice is at record high because it’s getting colder

Science has shown consistently that adding CO2 to the atmosphere is changing the climate in various ways, including raising the surface temperature of the oceans and atmosphere. As a consequence, scientists anticipate that polar sea ice would decline. This has been observed in the Arctic, which shows a 40% reduction in minimum sea-ice extent over the past 44 years[1]. However, the situation in the Antarctic is more complex because the continent is more isolated from the influence of global warming as explained in this article. This complexity has been seized by climate contrarians to try and cast doubt on the scientific understanding of the impacts of climate change. The claims that the Antarctic sea ice cover is increasing and that the average temperatures in the continent are getting colder are taken from the 2016 film Climate Hustle, produced by CFACT, an organization part of the climate change countermovement according to a climate change polarization study[2]. A short video snippet from this film has been shared on social media. One post on Instagram received 30 000 likes over a single week in April 2023. Former climatologist Judith Curry, who called into question the fact that humans are the dominant cause of recent climate change in Congressional Testimony, first claims that “Antarctica sea ice extent is increasing to record levels”. Sea ice extent refers to the cumulative area of all ocean surfaces where water is covered with ice. On the other hand, the terms ice cap and ice sheet refer to ice covering terrain such as land or bedrock. In order to understand the trends in sea ice extent, scientists study its area in February and September, respectively the periods in which the ice cover retreats and peaks. The most accurate data available to detect trends in Antarctic ice coverage are satellite observations, with records starting in the late 1970s. A study compiling 40 years of such records published in 2021 by NASA Research Scientist Claire L. Parkinson found that the Antarctic sea ice cover has been growing very slightly on average until 2014, at which point it started to decrease vigorously at rates “far exceeding the more widely publicized decay rates experienced in the Arctic”[3] (see Figure 1 below). So despite a period of growth between 1979 and 2014, the data shows clearly that the Antarctic sea ice cover is not increasing to “record levels”. Figure 1 –Time series of monthly mean Antarctic Sea ice extent anomalies for all February months from 1979 to 2023. The anomalies are expressed as a percentage of the February average for the period 1991-2020. Source In the video snippet, Judith Curry also claims that “climate models predict that the Antarctic should be losing sea ice, and it’s exactly the opposite of what’s happening”. This statement comprises correct and incorrect claims. Overall, climate models did predict a decrease in Antarctic sea-ice cover[4]. For instance, scientists ran the HadCM3 model in 2002 to simulate past sea ice extent between 1970 and 1999. The model simulated Antarctic Sea ice extent decreasing to 12.5 million km2 in 1999 while observations in 1999 showed sea ice extent grew over 14 million km2. Authors of the study attribute the difference with observations to the scarcity of data on the Southern Ocean around Antarctica. By comparison, the model accurately simulated a 2.5% decrease per decade trend in average Arctic sea ice extent for 1970–1999, which is very similar to observations[5]. Nonetheless, current observed trends do not totally contradict these projections, since a shift occurred from a period of sea-ice growth (1979-2014) to a period of sea-ice decline (2014-2022). Moreover, one purpose of models is for scientists to test their understanding of complex issues, and the Antarctic ice coverage is one of those. “Antarctic sea ice has puzzled modelers for a while. They expected a decrease in sea ice, not a slight increase; and the abrupt change in 2016 was not expected.” comments Eric Rignot, Earth System Science Professor and Chair at UC Irvine, in an email to Science Feedback. Even though the individual elements driving sea ice evolutions are fairly understood, the case for modeling the Antarctic sea ice coverage is especially difficult because of their interactions. “Complex feedbacks involving not only the sea ice and its snow cover but also the ocean, atmosphere and ice sheet (as well as biogeochemical processes)” are the main causes, according to scientist Kyle Clem’s article on Antarctica sea ice predictions[6]. Yet, this subject is not a blind spot in scientific research as, for more than 20 years, numerous scientists have examined reasons for sea ice coverage increase during the 1979-2014 period, formulating different hypotheses[7-10]. In any case, the complexity in modeling Antarctic sea ice extent isn’t enough for undermining all climate models’ accuracy. Indeed, climate models can’t forecast every variable perfectly, but they still skilfully forecasted the evolution of global temperatures. After testing the most prominent climate models predicting global temperature used since 1973, climate scientist and journalist Zeke Hausfather found that “they all show outcomes reasonably close to what has actually occurred”. Later in the same video, former Geology Professor Don Easterbrook then claims that “the Antarctic ice cap is not melting, [because] the average annual temperature there is 58 degrees below 0°” and then adds “I think it’s getting colder, very simple”. First, according to measurements reviewed by scientists John Turner and Thomas Bracegirdle in an article for the British Antarctic Survey, there is no evidence to support the claim that it’s getting colder. “Many long-term measurements from Antarctic research stations show no significant warming or cooling trends, and temperatures over most of the continent have been relatively stable over the past few decades” they write[11]. Moreover, temperatures vary greatly depending on the location of the weather station within the Antarctic, which is twice the size of Australia. According to the World Meteorological Association (WMO), in 2022 the average annual temperature ranges from about −10°C (14°F) on the Antarctic coast to −60°C (-76°F) at the highest parts of the interior[12]. Second, surface temperature is not the only factor responsible for ice cap melt. Don Easterbrook shows a lack of understanding of ice caps dynamics with his claim that ‘if the temperature is below 0°C, it cannot melt’. Ice caps are masses of ice formed on the Antarctic’s bedrock, and ice mass changes are dominated by changes in snowfall and glacier flow[13]. Additionally, the ice cap’s grounding lines and the bordering ocean’s temperatures also contribute to mass changes. Contrary to Easterbrook’s claims, observations show that Antarctic’s ice caps can lose mass (i.e. ‘melt’) at current temperatures. In fact, between 2003 and 2013 Antarctica’s ice caps have been losing mass at an estimated rate of 84 gigatons per year, according to a study by University of Bristol researcher Alba Martín-Español[14]. It is also important to note that some regions of the Antarctic are indeed warming. “The Antarctic Peninsula (the northwest tip near to South America) is among the fastest warming regions of the planet, almost 3°C over the last 50 years” said meteorologist Petteri Taalas in an article for the WMO in June 2021[15]. Significant warming is also occurring in the Southern Ocean, bordering the Antarctic. “For what matters most to us, which is sea level rise from melting Antarctica, the air/ocean temperature is increasing in a lot of regions along the coast” confirms Earth Systems Science researcher Eric Rignot. Influencing the Antarctic’s air temperatures, winds, and ice shelves, the Southern Ocean’s warming is yet another evidence of climate change impacting the frozen continent[16].Reviewers’ Feedback: Eric Rignot Professor, University of California Irvine & Jet Propulsion Laboratory: The Antarctic sea ice cover has been growing very slightly on average until about 2016*, at which point it started to decrease vigorously. Year to year fluctuations are expected and are not indicative of long term trends. To detect trends, you need multiple years and decades. The mean ground/air temperature in Antarctica is not getting colder. It also depends on whether you are looking at the coastline or the Antarctic plateau. For what matters most to us, which is sea level rise from melting Antarctica, the air/ocean temperature is increasing in a lot of regions along the coast. The Antarctic is part of the global climate system and also impacts the global climate system. The evolution of Antarctic sea ice has puzzled modelers for a while. They expected a decrease in sea ice, not a slight increase; and the abrupt change in 2016 was not expected. Overall, a decrease in sea ice cover since the 1970s was expected and observed. There are several interpretations of the recent record of Antarctic sea ice and its switching to a rapid decrease. I will not delve into this because the debate is still open on the thorough interpretation of these observations. I would simply say that it is consistent with a warming signal in Antarctica and the rest of the planet. *Editor’s note : 2016 is when the average Antarctic sea ice extent for November set a record low. The growth trend previously mentionedstarted to reverse in 2014.REFERENCES: 1 – NASA (2023). Arctic Sea Ice Minimum Extent. Global Climate Change Vital signs of the planet. Date accessed April 15 2023 2 – Farrell (2016). Corporate funding and ideological polarization about climate change. Proceedings of the National Academy of Sciences. 3 – Parkinson (2019). A 40-y record reveals gradual Antarctic sea ice increases followed by decreases at rates far exceeding the rates seen in the Arctic. Proceedings of the National Academy of Sciences. 4 – Turner et al. (2017). Solve Antarctica’s sea-ice puzzle. Nature. 5 – Gregory et al. (2002). Recent and future changes in Arctic sea ice simulated by the HadCM3 AOGCM. Geophysical Research Letters. 6 – Clem et al. (2022). Antarctic sea ice# 3: trends and future projections. Antarctic Environments Portal. 7 – Thompson et al. (2002). Interpretation of recent Southern Hemisphere climate change. Science. 8 – Stammerjohn et al. (2008). Trends in Antarctic annual sea ice retreat and advance and their relation to El Niño–Southern Oscillation and Southern Annular Mode variability. Journal of Geophysical Research: Oceans. 9 – Bintanja et al. (2013). Important role for ocean warming and increased ice-shelf melt in Antarctic sea-ice expansion. Nature Geoscience. 10 – Swart et al. (2013). The influence of recent Antarctic ice sheet retreat on simulated sea ice area trends. Geophysical Research Letters. 11 – John Turner et al. (2022). Antarctica and climate change. British Antarctic Survey. Date accessed April 21 2023. 12 – World Meteorological Organization (WMO) (2021). Antarctic heat, rain and ice prompt concern. World Meteorological Organization. Date Accessed April 21 2023. 13 – Pörtner et al. (2019). The ocean and cryosphere in a changing climate. IPCC special report on the ocean and cryosphere in a changing climate. 14 – Martín-Español et al. (2014). Spatial and temporal Antarctic Ice Sheet mass trends, glacio-isostatic adjustment, and surface processes from a joint inversion of satellite altimeter, gravity, and GPS data. Journal of Geophysical Research: Earth Surface. 15 – WMOs Evaluation Committee (2021). WMO verifies one temperature record for Antarctic continent and rejects another. World Meteorological Organization. Date Accessed April 21 2023. 16 – Holland et al. (2020). The southern ocean and its interaction with the Antarctic ice sheet. Science.

https://science.feedback.org/review/strands-cloud-behind-aeroplanes-trails-condensed-water-contrails-not-chemtrails-some-believe/

Inaccurate

Facebook, William Deagle, 2023-03-18

Chemtrails contain toxic substances such as barium salts that are 10 thousand times more toxic to your nervous system than lead

Factually inaccurate: The consensus of scientific evidence shows that atmospheric barium levels have not increased due to deliberate programs to deposit barium salts in the atmosphere. Inadequate support: There is no evidence of a program to deliberately deposit chemicals into the atmosphere via so-called “chemtrails”. Misleading: Barium salts are not 10,0000 more toxic for the nervous system than lead. Although some barium salts are toxic, their toxicity is comparable to lead.

Aeroplanes sometimes leave a trail of condensed water – a contrail – in their wake depending on factors such as altitude and weather conditions. The water condenses as the hot exhaust from the engine hits air, which is cold at high altitude. Some people have pointed to these as evidence of chemtrails but they are water vapour. There is no evidence of chemicals including barium salts deliberately deposited in the atmosphere to counter climate change or for any other reason.

Chemtrails contain toxic substances such as barium salts that are 10 thousand times more toxic to your nervous system than lead

1 – Federal Environment Agency (2011) Chemtrails – Dangerous Atmospheric Experiments or Just Fiction? 2 – Moore et al. (2017) Biofuel blending reduces particle emissions from aircraft engines at cruise conditions Nature 3 – Voigt et al. (2021) Cleaner burning aviation fuels can reduce contrail cloudiness Communications Earth and Environment 4 – Shearer et al. (2016) Quantifying expert consensus against the existence of a secret, large-scale atmospheric spraying program Environmental Research Letters 5 – US Department of Health and Human Services (2007) Toxicological profile for barium and barium compounds 6 – Compounds, Agency for Toxic Substances and Disease Registry (last reviewed: October 21, 2014) Medical Management Guidelines for Barium (Elemental) and Selected Barium 7 – Centre for Disease Control (Last Reviewed: December 2, 2022) Blood Lead Reference Value

The claims that aeroplanes are deliberately depositing chemicals in the sky in chemtrails containing barium salts 10,000 times more toxic than lead are taken from a four hour long lecture by self-proclaimed prophet Dr Bill Deagle at the Granada Forum in 2006. The snippet has been posted multiple times on social media including Facebook, where one post received over 37,000 likes and 33,000 shares in March 2023. Despite the lack of evidence for chemtrails as demonstrated below, the idea retains a small but persistent following. A previous claim by GeoengineeringWatch.org allegedly proving that “Global climate engineering operations are a reality” and “the lingering, spreading jet aircraft trails, so commonly visible in our skies, are not just condensation” has already been reviewed by Climate Feedback. The consensus of the scientific community has not changed. When asked to comment on the claim in the current video, a spokesperson from the UK Met Office confirmed, “There is no such thing as a ‘chemtrail’, this is a conspiracy theory where people think commercial aircraft are spraying the population with chemicals. The vapor trails left behind aircraft in certain atmospheric conditions are called contrails, as an abbreviation for condensation trails.” Andreas Schütz, Head of Communication and spokesperson for the German Aerospace Centre responded with a link to the Federal Environment Agency’s own article: “Chemtrails – Dangerous Atmospheric Experiments or Just Fiction?”[1] where they clarify the issue (in German). The contrails sometimes mistaken for chemtrails form naturally as the hot exhaust from the aeroplane engines hit the cold air in the upper atmosphere. Christiane Voigt, Head of Department for Cloud Physics at the German Aerospace Center Institute of Atmospheric Physics, described the process in more detail: “Contrails are ice crystals, small snow particles and mainly contain water ice. The water condenses from the ambient atmosphere. The ice nucleates [starts to grow] on particle emissions from aircraft engines, mainly soot from the burned hydrocarbon compounds in the kerosene, ice nucleates and is persistent in cold and humid conditions. Contrails only form in 5% of the flights which have this cold and humid conditions mainly related to frontal weather systems”. Voigt has closely investigated the formation of contrails for her research, which has looked at how different compositions of fuel can affect aircraft induced cloud formation[2,3] from contrails. Although she highlights the potential climate impact of contrails, as she told Science Feedback, “Contrails are not toxic as they mainly constitute water.” A survey of experts In 2016 a group of researchers in California led by University of California, Irvine, Earth System Scientist Steven Davis, undertook one of the most comprehensive investigations of chemtrail claims[4]. They were concerned about the absence of scientific studies attempting to engage with claims of chemtrails despite the number of believers in the theory – 2.6% of an international survey of 3105 people at the time of the study. “There have been few attempts to seriously and scientifically evaluate the claims of its proponents”, report the authors of the paper. They hoped that an independent scientific appraisal of the claims would help to disambiguate them. They sent surveys to hundreds of experts in either atmospheric science and specifically condensation trails, or geochemistry and specifically atmospheric deposition of dust and pollution on the Earth’s surface. They defined experts as researchers who were authors of at least one of the top 100 most cited papers in the field. The surveys included various observations that have been cited as evidence that a program to deposit chemicals in the atmosphere – a secret large scale atmospheric program (SLAP) – is in operation, such as photos of trails left by aeroplanes and analysis of the concentration of elements including barium present in samples of pond sediment, airborne particles and snow. The elemental analyses indicate that the measured element concentrations in the airborne particles are above the maximum contaminant levels, but as one expert pointed out, “The concentrations per unit mass look like average soil or desert dust. The MCL [maximum contaminant levels] values are not relevant, and look to be based on drinking water standards.” On receipt of 49 responses to the contrail survey and 28 responses to the survey on atmospheric deposition, they found the experts unanimously disagreed with the chemtrail theory as “the most parsimonious [simplest] explanation for the depicted phenomena” in the photos of aeroplane trails. None of the experts noted unusual concentrations of barium. When asked to reflect on past experience, which includes their past observations of elemental concentrations from samples, 1 expert cited an observation that did not rule out the existence of chemtrails while the remaining 76 of the 77 experts who responded simply stated they “had not encountered evidence that indicates the existence of a secret, large-scale atmospheric spraying program (SLAP)”. Lead author Davis told Science Feedback that they were not surprised by the scientific consensus in response to the study. ”It takes a lot more effort to explain contrails and soil survey results by a secret large-scale spraying campaign than by natural phenomena.” Despite the strength of the conclusions he said that it was never the goal to settle the debate about chemtrails. “Our paper was intended to provide a scientific counter to conspiracy claims for those in the public who were seeking information on the issue, not to persuade conspiracy theorists who already had strongly held beliefs.” Barium salts are not 10,000 times more toxic than lead As for the claim that barium salts are 10,000 times more toxic than lead, this exaggerates the toxicity of barium salts. Some salts such as barium sulphate are insoluble and not readily absorbed. They are used as contrast agents for medical images, for instance to make x-rays of the gastrointestinal tract clearer. Over exposure to barium salts can lead to “vomiting, abdominal cramps, diarrhoea, difficulties in breathing, increased or decreased blood pressure, numbness around the face, and muscle weakness”[5,6] and excessive quantities can be fatal. However the toxicity does not grossly outweigh that of lead[7] as suggested in the video. Conclusion: Over the course of multiple studies by atmospheric scientists and geochemists for various projects there remains no evidence that chemicals are deliberately dumped in the sky by passing aeroplanes. There is good evidence for the simple explanation that these are ‘condensation of water’ trails. On these points experts in the field agree. In addition, barium salts are not 10000 times more toxic than lead. In summary the highlighted claims in Dr Beagle’s video are false or unsupported.

https://science.feedback.org/review/pre-human-changes-climate-not-negate-contemporary-human-influence-modern-warming/

Flawed reasoning

Instagram, Social media users, 2023-01-17

Climate changed naturally in prehistoric eras, modern climate change is a naturally occurring phenomenon

Flawed reasoning: Climate change has occurred in the past without human influence. However, this does not indicate that non-human causes are driving modern warming, for which a consensus of scientific evidence shows that greenhouse gas emissions are responsible.

Scientists study all potential causes of climate change and have concluded, based on several independent lines of evidence, that modern warming is driven by human emissions of greenhouse gases. Other variables, such as orbital, solar and tectonic variations, contributed to climate change in earth’s geological history. However, these processes do not vary sufficiently fast to explain the rate of modern warming.

“Climate change is a naturally occurring phenomenon that can be tracked throughout prehistoric eras…Yes the planet is changing but that’s a constant part of life on this earth.”

A recent Instagram post alleges that “climate change is a naturally occurring phenomenon,” and that such change represents “a constant part of life on this earth.” While evidence shows that climate has been influenced by multiple factors in the past, scientists have found, through several independent lines of evidence, that modern climate change is driven by human emissions of greenhouse gases.[1-3] These greenhouse gases, like CO2, prevent heat from escaping from the atmosphere, which results in the warming of the surface of the planet. Other variables that may influence climate include volcanic eruptions, which simultaneously release particles that can cool the planet and greenhouse gases that warm the planet,[4]and the amount of energy released by the sun. Climate scientists study all potential causes of climate change by investigating the individual climatic influence of these different variables. When calculating the impact of each conceivable climate variable on global surface temperature, scientists have found that modern warming is impossible to explain without the greenhouse gases derived from human activities (see Figure 1).[1] By contrast, the sun–the preferred explanation for climate change in the Instagram post–contributes negligibly to modern warming (Fig. 1). Figure 1. Modeled influence of different climate forcing mechanisms on global mean surface temperature since 1850. Observations (dots) show a clear warming trend, which is consistent with the forcing resulting from increased greenhouse gas emissions (red). Without greenhouse gases added by human activities, the observed warming would not exist. Source: Carbon Brief. What about climate change in the past, prior to human influence? Scientists note that other variables played a more important role than CO2 on these different timescales. On the order of tens to hundreds of millions of years ago, key differences in the climate system included “the distribution of continents and ocean on the planet, the amount of volcanic activity (blocking out sunlight), and the brightness of the sun,” noted James Renwick, a climate scientist at Victoria University of Wellington in a previous review of a similar claim. “CO2 is very important for the energy budget of the earth, but it is not the only factor on very long time scales,” continued Renwick. On the order of tens to hundreds of thousands of years ago, earth’s orbit also played an important role in regulating the amount of solar energy received by the planet and global climate.[5] Invoking the notion that climate change has occurred in earth’s geological history without human influence in order to advance the narrative that humans are not responsible for modern climate change is a popular technique among climate contrarians. However, scientists say that this argument is flawed. “Here are logically identical arguments: ‘The New England Patriots scored touchdowns before Rob Gronkowski, so Rob Gronkowski can’t score touchdowns,’“ explained Mark Richardson, a climate scientist at Colorado State University in a previous review of a similar claim. “Or more simply: ‘Fires happened before humans, so humans can’t cause fires.’“ The 2017 US National Climate Assessment summarized the science on the cause of climate change this way: “This assessment concludes, based on extensive evidence, that it is extremely likely that human activities, especially emissions of greenhouse gases, are the dominant cause of the observed warming since the mid-20th century. For the warming over the last century, there is no convincing alternative explanation supported by the extent of the observational evidence.”References: 1 – Hausfather (2017). Analysis: Why scientists think 100% of global warming is due to humans. Carbon Brief 2 – Harries et al. (2001). Increases in greenhouse forcing inferred from the outgoing longwave radiation spectra of the Earth in 1970 and 1997. Nature 3 – Feldman et al. (2015). Observational determination of surface radiative forcing by CO2 from 2000 to 2010. Nature 4 – UCAR. How volcanoes influence climate 5 – Hays et al. (1976). Variations in the Earth’s orbit: pacemaker of the ice ages. Science

https://science.feedback.org/review/link-between-co2-earth-temperature-well-established-despite-claims-fox-news-tom-harris/

Inaccurate

Fox News, Tom Harris, 2022-10-12

Scientists have found no consistent correlation between CO2 and temperature; scientists do not know whether earth will warm or cool in future

Inaccurate:Past climate data show a correlation between CO2 concentration and global temperature, and physics shows CO2 is a greenhouse gas that strongly influences the temperature of the Earth’s surface. Unsupported: Research has shown that solar activity variations are not enough to offset human-caused warming.

The link between global warming and atmospheric CO2 levels is well-established; in fact, increases in CO2 have warmed the planet multiple times over the last million or so years. Science shows unambiguously that current climate change is caused by human-emitted greenhouse gases. Based on this knowledge, scientists are confident that any grand solar minimum will not result in a cooling trend, as changes in total solar irradiance are not projected to be enough to offset human-caused warming.

Scientists have found “No consistent correlation between carbon dioxide and earth’s temperature”; “It’s all based on models that don’t work”; “we don’t even know whether it’s going to warm or cool in the future”; various scientists show “we’re headed into a grand solar minimum around 2060, and that we’ll see gradual cooling over the next few decades”

In an interview with Fox News on 12 October, International Climate Science Coalition Executive Director Tom Harris made multiple misleading and inaccurate claims about climate change. The International Climate Science Coalition disputes the scientific consensus that human activities are causing the planet to warm. Harris, who has a background in mechanical engineering, quoted a university professor who Harris claimed found that there was “no consistent correlation between carbon dioxide and earth’s temperature.” “At times, CO2 was 1300% of today, and we were stuck in very cold conditions,” Harris said. On the contrary, paleoclimate data from the last 800,000-plus years show that the link between temperature and CO2 is well-established. Scientists discovered CO2’s role in warming the planet in the mid-19th century, noted James Renwick, Professor, Victoria University of Wellington, in a previous review of a similar claim. “Through the past 2.6 million years, the period of recent ice ages, carbon dioxide has gone up and down in step with temperature, bottoming out at around 180 parts per million in the depths of a “glacial maximum” and peaking at around 280 parts per million in the warmer interglacial periods, he said in the review. “Going back further, CO2 levels were certainly higher than present, but so were temperatures.” Figure 1 shows that CO2 concentrations have oscillated in conjunction with Earth’s temperature for the last 800,000 years. Figure 1 –Graphs show CO2 and temperature oscillations over the last 800,000 years for the global average and Antarctica. Credit: Ben Henley and Nerilie Abram, The Conversation. The Ordovician Period, which began 485.4 million years ago, saw CO2 levels that were 8 times higher than today.[1] Based on paleoclimate data, the later part of this period experienced glaciation – though that coolness does not invalidate the link between CO2 and warming, and was likely aided by a less-bright sun; the placement of the continents, which at that time were bunched together; and a drawdown of CO2. “There were periods of times when CO2 was very high, likely as high as 1500-2000 ppm,” Katrin Meissner, Professor, University of New South Wales, said in a previous review. “The ecosystems and biogeochemistry were adapted to these conditions, and they looked very different from today. There were no humans, many of the mammals around us did not exist. Not to mention that the sun’s energy output was slightly smaller during that time.” The last time the planet experienced CO2 levels this high was more than 3 million years ago. During that time – called the Mid-Pliocene Warm Period – the planet’s surface temperature was 4.5–7.2 degrees Fahrenheit (2.5–4 degrees Celsius) warmer than during the pre-industrial era, according to NOAA Climate.gov. Scientists are confident in the finding that increased CO2 concentrations are causing Earth’s temperature to rise.[2] As CO2 and other greenhouse gases are emitted into the atmosphere, they trap more of the sun’s energy, leading to warming. “It is unequivocal that human influence has warmed the atmosphere, ocean and land,” the IPCC notes in its Sixth Assessment Report.[3] While remaining in the atmosphere, CO2 prevents heat from escaping and consequently warms the surface of Earth – a concept that is popularly known as the greenhouse effect. This theory predicts that the increase in temperature will be proportional to the logarithm of the concentration of CO2, with a time-lag of about 20 years. Figure 2 shows that this is precisely what the data shows, hence providing a strong validation of the theory, in addition to other lines of evidence. Meanwhile, Figure 3 shows how global average annual temperature has increased in tandem with CO2 concentrations since 1880. Figure 2 –Global temperature plotted against atmospheric CO2 concentration. Note the logarithmic scale of the x-axis is due to the nature of the relationship between greenhouse gases and temperature.[7] Source: Berkeley Earth via a previous Climate Feedback review. Figure 3 – Global annual average temperature (as measured over both land and oceans) has increased by more than 1.5°F (0.8°C) since 1880 (through 2012). Red bars show temperatures above the long-term average, and blue bars indicate temperatures below the long-term average. The black line shows atmospheric carbon dioxide (CO2) concentration in parts per million (ppm). Credit: globalchange.gov. Harris also claimed that climate science is based on “models that don’t work.” Climate science is based both on observations – including temperature and other weather records – and models. Climate models simulate the earth’s climate system, and use mathematical equations to project how the planet may respond under different scenarios (i.e. low greenhouse gas emissions, business as usual emissions, etc.) as well as to recreate the climate at different times in the planet’s past. These models are complex: According to the National Centre for Atmospheric Science, “there are so many mathematical equations involved that a typical climate model includes enough code to fill 18,000 pages of printed text.” These models have proved to be accurate – though imperfect – tools. In fact, a 2019 study found that climate models have been skillful in projecting changes in the Earth’s temperature.[4] “Climate models published over the past five decades were generally quite accurate in predicting global warming in the years after publication, particularly when accounting for differences between modeled and actual changes in atmospheric CO2 and other climate drivers,” the study notes.[4] Scientists test models through a process called hind-casting, during which scientists run the model in the recent past and compare what the model shows to the observed climate and weather during that time period. This way, scientists are able to see how closely the model’s projections line up with actual weather and climate results – and, if needed, adjust the model accordingly. “Climate models are imperfect representations of nature that represent just one tool scientists use to understand how and why Earth’s climate varies,” Timothy Myers, Postdoctoral Researcher at Lawrence Livermore National Laboratory, said in a previous review. “Climate models are good at simulating some physical processes and deficient in their simulation of other processes. Simply because the climate is complex does not mean we cannot reasonably model or understand it.” Harris also claimed that experts aren’t sure whether the globe will warm or cool in the future, and that “various people that study the sun” say that Earth is headed towards a grand solar minimum, which will result in gradual cooling. Research, however, disputes this claim of future cooling. A 2016 study found that human emissions would delay the next ice age by about 50,000 years.[5] And a 2013 study found that a grand solar minimum would slow down global warming – but that the rate of warming would go back up once total solar irradiance started to rise again.[7] “Therefore, results here indicate that such a grand solar minimum would slow down and somewhat delay, but not stop, human-caused global warming,” the study concludes.[6] Figure 4 – Rise of global temperature for two different emission scenarios (A1B, red, and A2, magenta). The dashed lines show the slightly reduced warming in case a Maunder-like solar minimum should occur during the 21st century. The blue line represents global temperature data. Source: Potsdam Institute for Climate Impact Research; taken from a previous Climate Feedback Review. NASA agrees that if a grand solar minimum were to occur in the next few decades, it would not be enough to offset human-caused warming. “The warming caused by the greenhouse gas emissions from the human burning of fossil fuels is six times greater than the possible decades-long cooling from a prolonged Grand Solar Minimum,” NASA writes in a 2020 article. “Even if a Grand Solar Minimum were to last a century, global temperatures would continue to warm. The reason for this is because more factors than just variations in the Sun’s output change global temperatures on Earth, the most dominant of those today is the warming coming from human-induced greenhouse gas emissions.” References: [1] Pancost et al. (2013) Reconstructing Late Ordovician carbon cycle variations. Geochimica et Cosmochimica Acta. [2] Stips et al. (2016) On the causal structure between CO2 and global temperature. Scientific Reports. [3] IPCC (2021) Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. [4] Hausfather et al. (2019) Evaluating the Performance of Past Climate Model Projections. Geophysical Research Letters. [5] Ganopolski et al (2016) Critical insolation–CO2 relation for diagnosing past and future glacial inception. Nature. [6] Meehl et al. (2013) Could a future “Grand Solar Minimum” like the Maunder Minimum stop global warming? Geophysical Research Letters. [7] Huang et al. (2004). Why logarithmic? A note on the dependence of radiative forcing on gas concentration. Journal of Geophysical Research: Atmospheres.

https://science.feedback.org/review/scientists-found-modern-climate-change-caused-entirely-by-human-activity-contrary-recent-speculation-joe-rogan-experience/

Flawed reasoning

The Joe Rogan Experience, Joe Rogan, 2022-10-02

“The question is, ‘how much of an impact do we have on [climate]?’ That has not totally been quantified”; climate change is happening anyway, “The ice age happened without us…It’s probably this constant cycle”.

Flawed reasoning: Scientists have quantified human influence on the climate system and found it to be responsible for the entirety of modern warming. Other non-human factors are capable of influencing Earth’s climate, as has occurred previously in Earth’s history. However, Earth’s climate has been stable for 11,000 years before humans started releasing large amounts of greenhouse gasses and scientists have determined that natural factors are insufficient to explain modern warming.

In quantifying the impact of different possible drivers of climate change, scientists have identified that human activity is responsible for the entirety of modern global warming. There is no scientific evidence available to support an alternative explanation. While Earth’s climate has changed in the past due to “natural” (non-human) causes, such changes occurred over much slower timescales compared to present-day warming.

“Temperature has always been up and down.”; “The question is, ‘how much of an impact do we have on [climate]?’ That has not totally been quantified. They’re not exactly sure. They know it’s a significant impact, but [climate change] is happening anyway [without human influence]…The ice age happened without us…It’s probably this constant cycle”.

In a recent podcast episode, Comedian and Ultimate Fighting Championship commentator Joe Rogan questioned the extent to which human activity impacts climate. “The ice age happened without us”, Rogan noted, later suggesting that modern climate change could be part of a “constant cycle”. Human influence on the climate system is multifaceted. Emissions of greenhouse gasses, such as CO2, warm the lower atmosphere and the surface of the planet. Changes in land use may affect the planet’s ability to sequester carbon, further impacting our climate. Anthropogenic aerosols–tiny solid or liquid particles suspended in the atmosphere–may both cool or warm the Earth depending on their properties.[1] Non-human variables, such as changes in the sun and volcanic activity, can also influence climate. Scientists have studied all of these possible causes of climate change, or forcing mechanisms. This is done by calculating the climatic impact of each individual forcing mechanism over time and then comparing it with observations of temperature change. When all of the forcing mechanisms are put together, it becomes evident that anthropogenic greenhouse gas emissions are the only mechanism that can reproduce the observed warming trend (Fig. 1). By contrast, the impact of all other factors (e.g., solar activity and aerosols) on climate has been relatively minor since 1850 (Fig. 1). In fact, without anthropogenic greenhouse gas emissions, these other factors would have resulted in a slight cooling trend, rather than the observed warming.[2] Figure 1. Modeled influence of different climate forcing mechanisms on global mean surface temperature since 1850. Observations (dots) show a clear warming trend, which is consistent with the forcing resulting from increased greenhouse gas emissions (red). Without greenhouse gases added by human activities, the observed warming would not exist. Source: Carbon Brief. “The empirical evidence that increases in greenhouse gas concentrations (from fossil fuel burning) are the primary cause of century-scale warming is that observed global temperatures have risen in line with what would be expected from the observed increase in greenhouse gas concentrations and observations of natural drivers of climate change (e.g. solar output and volcanic eruptions) indicate that natural drivers are not causing warming”, said climate scientist Patrick Brown in a previous review. Brown’s comments are reflected in the findings of the world’s most comprehensive climate change report by the Intergovernmental Panel on Climate Change (IPCC), which was prepared by hundreds of independent scientific experts in 2021 and concluded that it is “unequivocal that human influence has warmed the atmosphere, ocean and land.”[3] What of the ice ages, then? Referencing claims by his former podcast guest, Steve Koonin, a physicist who previously authored a book that misrepresents climate science, Rogan goes on to say that “[temperature] has always been up and down” according to “core samples”, or reconstructions of Earth’s past climate based on geological proxies. Paleoclimate evidence indicates that the Earth’s climate has been stable for the last 11,000 years, a period known as the Holocene, which allowed human civilization to flourish.[4] The Holocene began at the end of the most recent ice age, during which global temperature dropped by an average of about 4°C[4] Variations between ice ages, also called glacial periods, and warmer intervals between them, called interglacials, are a feature of Earth’s climate over the last 2.6 million years. What causes these major paleoclimate shifts? Changes in astronomical dynamics–the eccentricity of Earth’s orbit around the sun, the precession of the equinoxes and axial tilt–result in differences in the distribution of solar energy on Earth, which influences global temperature and ice volume. Thus, astronomical variability has been referred to as the “pacemaker of the ice ages”.[5] However, this isn’t the full picture. Rather, initial orbital-driven climate change can trigger multiple synergistic shifts in the Earth system, which affect the exchange of CO2 between the ocean and the atmosphere. Scientists have therefore concluded that this greenhouse gas, which is responsible for all of modern warming, was also an important mechanism for amplifying climate change initiated by astronomical processes in the geological past.[4] This is supported by ice core records, which show a tight link between atmospheric CO2 concentration and temperature over the last 800,000 years[6,7] (Fig. 2). Figure 2. Atmospheric CO2 (top) and temperature change (bottom) over the last 800,000 years. Note that high levels of CO2 are associated with high temperatures and low levels of CO2 are associated with low temperatures. Chart modified from Data from the University of Copenhagen Centre for Ice and Climate. Prior to human influence, CO2 varied from approximately 200 to 300 ppm over thousands of years. However, the situation today, in which CO2 levels exceeded 400 ppm in the course of several decades, is unprecedented in the past million years (Fig. 3). Figure 3. Atmospheric CO2 concentration over the last 800,000 years. Note that modern levels of >400 ppm, driven by anthropogenic emissions, are a notable departure from pre-human variability. Source: NASA. Climate contrarians frequently invoke the fact that Earth’s climate has changed in the past, without human influence, to cast doubt upon the consensus of scientific evidence[8,9] that points to modern warming driven by human activity. However, this argument is flawed, noted Mark Richardson, a climate scientist at Colorado State University. “Here are logically identical arguments: ‘The New England Patriots scored touchdowns before Rob Gronkowski, so Rob Gronkowski can’t score touchdowns,’ said Richardson. “Or more simply: “‘Fires happened before humans, so humans can’t cause fires.’” Contrary to Rogan’s speculations, all of the scientific evidence indicates that human emissions of greenhouse gas are driving modern climate change.References: 1 – NOAA Geophysical Fluid Dynamics Laboratory. Aerosols and Climate 2 – Hausfather (2017). Analysis: Why scientists think 100% of global warming is due to humans. Carbon Brief 3 – IPCC (2021). Sixth Assessment Report 4 – Hausfather (2020). Explainer: How the rise and fall of CO2 levels influenced the ice ages. Carbon Brief 5 – Hays et al. (1976). Variations in the Earth’s orbit: pacemaker of the ice ages. Science 6 – Lüthi et al. (2008). High-resolution carbon dioxide concentration record 650,000–800,000 years before present. Nature 7 – EPICA Community Members (2004). Eight glacial cycles from an Antarctic ice core. Nature 8 – Oreskes (2004). The scientific consensus on climate change. Science 9 – Cook et al. (2013) Quantifying the consensus on anthropogenic global warming in the scientific literature. Environmental Research Letters

https://science.feedback.org/review/the-epoch-times-prints-range-of-inaccurate-misleading-claims-climate-changes-impacts-causes-patrick-moore/

Incorrect

The Epoch Times, Patrick Moore, 2022-09-06

CO₂ is not the cause of our current warming trend; Arctic sea ice has expanded in recent years; Polar bears’ population is growing and is not threatened by climate change; CO₂ is good for plant life

Incorrect: The data is clear that carbon dioxide emitted by human activities is driving current rates of climate change. Misleading: Long-term records of Arctic sea ice show a consistent decline. Inaccurate: Polar bear populations are estimated at 22,000 - 30,000 individuals, not 50,000. Research shows that climate change threatens polar bear populations by disrupting their hunting habitat. Misleading: Plants need CO2 to survive, but the buildup of CO2 in the atmosphere is leading to numerous climatic changes, including heat waves, drought and wildfires, that are damaging for plants and the rest of the planet.

Climate change has led to a decades-long decline in Arctic sea ice, putting polar bears – and other Arctic organisms – at risk of significant population declines. Meanwhile, based on all existing evidence, scientists are confident that the buildup of carbon dioxide and other greenhouse gases in the atmosphere is driving current climate change, which is leading to a range of negative impacts for plant, animal and human populations.

”If carbon dioxide was the main cause of warming, then there should be a rise in temperature along the carbon dioxide curve, but it doesn’t“; “They say the polar bear will go extinct in 2100... In fact, this past winter in the Arctic saw an expansion of ice from previous years, and Antarctica was colder during the last winter than in the past 50 years“; “We do not know the cause of these periodic fluctuations in temperature, but it was certainly not CO2; A study in 2013 found that increased levels of carbon dioxide (CO₂) have helped boost green foliage across the world’s arid regions over the past 30 years.“

The Epoch Times laid out a range of inaccurate and misleading claims from Canadian industry consultant and former activist Patrick Moore in a September article, outlining statements from Moore taken from emails between himself and South Korean professor Seok-soon Park in late 2021. Polar bears and melting sea ice In the article, Moore claims that the polar bear population has “increased from 6,000 to 8,000 in 1973 to 30,000 to 50,000 today,” and that the polar bear is not threatened by melting sea ice in the Arctic. In fact, as of 2015, which was the last time the animal was assessed, the IUCN estimates the total population of polar bears at 22,000 to 31,000 individuals.[1] Recent research has found that polar bears face an uncertain future as Arctic sea ice melts: Because the animals depend on sea ice for hunting, and because seals, their prey of choice, also depend on sea ice for breeding and making dens, sea ice loss is making it more difficult for polar bears to hunt. A 2020 study estimated that, “with high greenhouse gas emissions, steeply declining reproduction and survival will jeopardize the persistence of all but a few high-Arctic subpopulations [of polar bears] by 2100.”[2] (Climate Feedback evaluated New York Times coverage of this study in 2020 and found it to be correct. We also evaluated a claim similar to Moore’s in 2020, which asserted that polar bear populations were “growing” and “thriving,” and found it to be incorrect). Numerous other studies have warned of the threat posed to polar bear populations by melting sea ice. A 2021 study published in Earth’s Future predicts, for instance, that under high warming (over 2°C) scenarios, “seals will not be able to den (Hezel et al., 2012); [and] polar bears will not have sufficient marine food sources,” due to loss of ice in the Arctic Circle.[3] In addition some studies have already documented negative impacts of sea ice loss, including lower survival rates, in polar bear subpopulations.[8-9] How climate change impacts the Arctic and Antarctic Moore also claims that “this past winter in the Arctic saw an expansion of ice from previous years, and Antarctica was colder during the last winter than in the past 50 years.” Scientists keep records on Arctic sea ice minimums (the lowest amount of cover that the sea ice reaches in summer) and maximums (the highest amount of cover sea ice reaches in winter). This February, the region’s winter sea ice extent was the 10th-lowest in the satellite record maintained by the National Snow and Ice Data Center. Though it’s true that that’s a slightly higher cover than last year – which ranked 7th-lowest in the satellite record – Arctic sea ice extent has been trending downwards since reliable satellite record keeping began in 1979, with minimum extents declining at about 13% per decade.[4] Figure 1: Graph shows decline in August Arctic sea ice extent from 1979 – 2022. Credit: National Snow and Ice Data Center. Figure 2: Graph shows decline in average February sea ice extent from 1979 – 2022. Credit: National Snow and Ice Data Center. The Amundsen-Scott South Pole Station did experience a record-cold six-month stretch between April and September 2021. As Reuters notes in a 2021 fact-check, however, this six-month period does not invalidate the decades of data on global planetary temperature trends. Climate change’s impact on Antarctica also differs greatly from its impact on the Arctic, a fact that scientists are still working to understand. While sea ice thickness and extent has declined over the last few decades, sea ice in Antarctica has remained stable. There are numerous contributing factors to this dichotomy, including differences in geography, wind strength and ice thickness between the two regions, but the differences do not cast doubt on the globe’s overall warming trend. In addition, the sea ice loss trends in the Arctic dwarf the slight growth trends Antarctica experienced up until 2014. “Looking at the trend in annual mean ice extent over the full period we have satellite data for (1979 to the end of 2021), the trends in the Antarctic are nearly ten times smaller than those in the Arctic (as well as being positive, not negative),” Caroline Holmes, Polar Climate Scientist at the British Antarctic Survey, said in a previous Climate Feedback review. “This is a fair comparison, as the average ice extent over those periods is similar.” CO2: A known driver of climate change Moore also claims that “the world has been warming since about the year 1700, 150 years before we were using fossil fuels.” He also references the Little Ice Age and Medieval Warm Period, which research has suggested were both prompted by natural causes: The Medieval Warm Period was drivenlargely by an increase in solar radiation and decrease in volcanic eruptions, while the Little Ice Age may have been triggered by warm Atlantic water entering the Nordic seas.[10] However, one study examined the Little Ice Age and Medieval Warm Period and found that the time periods were not as “globally coherent” as previously assumed, and could be considered more regional climate events.[11] The study states: “Against this regional framing, perhaps our most striking result is the exceptional spatiotemporal coherence during the warming of the twentieth century. This result provides further evidence of the unprecedented nature of anthropogenic global warming in the context of the past 2,000 years.” Moore cast doubt on the consensus that current rates of climate change are being driven by Carbon Dioxide and other greenhouse gases. He provided a graphic of CO2 levels graphed against temperatures in Central England and noted: “If carbon dioxide was the main cause of warming, then there should be a rise in temperature along the carbon dioxide curve, but it doesn’t.” In reality, global records show a clear link between increasing levels of Carbon Dioxide and increasing temperatures. They also show that this current rate of temperature increase is far fasterthan past changes in temperature.Figure 3: Yearly temperature compared to the twentieth-century average (red and blue bars) from 1880–2019, based on data from NOAA NCEI, plus atmospheric carbon dioxide concentrations (gray line): 1880-1958 from IAC, 1959-2019 from NOAA ESRL. Original graph by Dr. Howard Diamond (NOAA ARL), and adapted by NOAA Climate.gov. Caption credit: Climate.gov. According to NASA, industrial activities “have raised atmospheric carbon dioxide levels by nearly 50% since 1750.” Scientists know that the CO2 building up in the Earth’s atmosphere is from human activities because of its isotopic fingerprint, which indicates that the CO2 originated from ancient plant material – i.e. fossil fuels. Accurate global temperature records date back to 1880, with temperature data from years prior to 1880 estimated using “proxies” – things like tree rings and fossilized pollen. Research has traced human-caused warming to the 1830s – towards the end of the industrial era, which began in the mid 1750s.[5] The preindustrial era, which is hard to define definitely but which one study set as 1720–1800, was “0.55°–0.80°C cooler than 1986–2005 and that 2015 was likely the first year in which global average temperature was more than 1°C above preindustrial levels.”[6] Figure 3: Changes in the temperature of the Northern Hemisphere from surface observations (in red) and from proxies (in black; uncertainty range represented by shading) relative to 1961-1990 average temperature. These analyses suggest that current temperatures are higher than seen globally in at least the last 1700 years, and that the last decade (2001 to 2010) was the warmest decade on record. (Figure source: adapted from Mann et al. 2008). Caption and graphic Courtesy globalchange.gov. Moore references research that has found that excess levels of CO2 in the atmosphere can lead to global greening – an increase of leaf cover across the planet. Research does support this claim: A 2016 study, for instance, found that from 1982–2009, the globe showed “a persistent and widespread increase of growing season integrated LAI [Leaf Area Index] (greening) over 25% to 50% of the global vegetated area.”[7] But, as Climate Feedback explained earlier this year, that doesn’t mean that CO2 is harmless. “The benefit[s] of increasing CO2 concentrations for plant growth are increasingly being outweighed by the negative impacts, especially of global warming,” Sara Vicca, assistant professor at the University of Antwerp, told Climate Feedback in a previous review. “This is true for natural as well as agricultural ecosystems.” Science Feedback has reviewed inaccurate claims by Patrick Moore about climate change’s causes before. As cataloged by Open Feedback, the Epoch Times has been shown to have published misinformation in the past. Update: A previous version of this post stated that Arctic sea ice maximums were declining by 13% per decade. In fact, Arctic sea ice minimums are declining by 13% per decade, while maximums are declining by about 2.8% per decade. This post has been updated to reflect this fact. References: [1] Wiig et al. (2015) Ursus maritimus. The IUCN Red List of Threatened Species. [2] Molnár et al. (2020) Fasting season length sets temporal limits for global polar bear persistence. Nature Climate Change. [3] Newton et al. (2021). Defining the “Ice Shed” of the Arctic Ocean’s Last Ice Area and Its Future Evolution. Earth’s Future. [4] How is Arctic sea ice changing? (2020). National Snow and Ice Data Center. [5] Abram et al. (2016) Early onset of industrial-era warming across the oceans and continents. Nature. [6] Hawkins et al. (2017) Estimating Changes in Global Temperature since the Preindustrial Period. Bulletin of the American Meteorological Society. [7] Zhu et al. (2008). Greening of the Earth and its drivers. Nature. [8] Lunn et al (2016) Demography of an apex predator at the edge of its range: impacts of changing sea ice on polar bears in Hudson Bay. Ecological Applications. [9] Regehr et al (2007) Effects of earlier sea ice breakup on survival and population size of polar bears in Western Hudson Bay. The Journal of Wildlife Management. [10] Lapointe et al. (2021) Little Ice Age abruptly triggered by intrusion of Atlantic waters into the Nordic Seas. Science Advances. [11] Neukom et al. (2019). No evidence for globally coherent warm and cold periods over the preindustrial Common Era. Nature.

https://science.feedback.org/review/scientific-evidence-indicates-modern-warming-driven-by-co2-contrary-to-richard-lindzen/

Incorrect

Climate Change is Crap, Richard Lindzen, 2022-08-30

“Believing CO2 controls the climate is pretty close to believing in magic.”

Incorrect: Several independent lines of scientific evidence based on observational datasets and modeling indicate that current climate change is driven by human emissions of greenhouse gases such as CO2. Scientific evidence shows that changes in all other potential climate variables are insufficient to explain modern warming.

Climate change is not only evidenced by increased global average temperature, but also by increased ocean-heat content, Arctic sea ice decline and sea level rise. All of the scientific evidence, including observational datasets and climate models, indicates that the warming and disruption of Earth’s climate system since the onset of the industrial era is due to human emissions of greenhouse gases such as CO2.

“...What is the likelihood of the climate (which, itself, consists of many variables and not just globally averaged temperature anomaly) is controlled by this 2% perturbation in a single variable?”; “Believing CO2 controls the climate is pretty close to believing in magic.”

A quote on Facebook attributed to Richard Lindzen, a retired meteorologist who has received funding from fossil fuel interests, claims that climate change cannot likely be caused by a “single variable” such as CO2 due to the complexity of the climate system. Climate is indeed a complex system consisting of multiple variables. However, its complexity does not indicate that scientists do not understand the main variables that are driving contemporary warming. Since 1950, atmospheric CO2 concentrations have climbed from just above 300 parts per million (ppm) to over 400 ppm (Fig. 1). This change, caused by fossil fuel use, is particularly startling in the context of past atmospheric CO2 concentrations, which ice core reconstructions indicate have fluctuated between around 200 and 300 ppm over periods of thousands of years during the last 800,000 years (Fig. 1).[1,2] While remaining in the atmosphere, CO2 prevents heat from escaping and consequently warms the surface of Earth – a concept that is popularly known as the greenhouse effect. This theory predicts that the increase in temperature will be proportional to the logarithm of the concentration of CO2, with a time-lag of about 20 years. Figure 2 shows that this is precisely what the data shows, hence providing a strong validation of the theory, in addition to other lines of evidence. “The role of CO2 in warming the Earth was discovered in the mid-19th century,” says James Renwick, a climate scientist at Victoria University of Wellington in a previous review of a similar claim. Figure 1. Variations in atmospheric CO2 concentration over the last 800,000 years. Source: NASA. Figure 2. Global temperature plotted against atmospheric CO2 concentration. Note the logarithmic scale of the x-axis is due to the nature of the relationship between greenhouse gases and temperature.[3]Source: Berkeley Earth. But how can scientists be certain that CO2 is driving today’s warming and not, as Lindzen argues, one of the other several variables of Earth’s climate system? Scientists have calculated the influence of individual variables on Earth’s climate, and consistently find that human activities, dominantly CO2 emissions, have driven warming following the onset of the industrial era (Fig. 3). Figure 3. Time series of effective radiative forcing (warming) caused by various mechanisms. Note that carbon dioxide (gray) contributes more to warming than all of the other well-mixed greenhouse gases (WMGHG). Note also that the majority of warming is caused by carbon dioxide and other greenhouse gases. Source: U.S. Fourth National Climate Assessment. “The warming from the late 1800s to the present is all due to human-caused climate change, because natural factors have changed little since then and even would have caused a slight cooling over the last 70 years rather than the warming we have observed”, noted Timothy Osborn, a climate scientist at the University of East Anglia, in a previous review. Atmospheric observations also support warming driven by greenhouse gases. The scientific understanding of greenhouse gas physics predicts that CO2 would selectively warm the lower section of the atmosphere, called the troposphere, while cooling the upper part of the atmosphere, called the stratosphere. Thus, if CO2 is responsible for Earth’s temperature increase, we would expect to see a simultaneous warming of the troposphere and cooling of the stratosphere[4-6], which is exactly what the data show (Fig. 4). Figure 4. Global temperature variations in the upper atmosphere (top graph) and in the lower atmosphere (bottom graph) since the 1960s. We observe a warming at the surface and a cooling above, which is consistent with the effect of added greenhouse gases in the atmosphere. Source: Met Office Hadley Centre.If you are interested in learning more about how carbon dioxide can have such an important effect on global climate when its concentration is so small, read this article in The Conversation.Updates: 9 September 2022: Content related to Lindzen’s “2% perturbation” statement was removed due to a lack of clarity about what perturbation the author refers to. References: 1 – Lüthi et al. (2008). High-resolution carbon dioxide concentration record 650,000–800,000 years before present. Nature 2 – EPICA Community Members (2004). Eight glacial cycles from an Antarctic ice core. Nature 3 – Huang & Shahabadi (2004). Why logarithmic? A note on the dependence of radiative forcing on gas concentration. Journal of Geophysical Research: Atmospheres. 4 – Lockwood & Fröhlich (2007) Recent oppositely directed trends in solar climate forcings and the global mean surface air temperature. Proceedings of the Royal Society of London A: Mathematical, Physical and Engineering Sciences. 5 – Lockwood (2008) Recent changes in solar outputs and the global mean surface temperature. III. Analysis of contributions to global mean air surface temperature rise. Proceedings of the Royal Society of London A: Mathematical, Physical and Engineering Sciences. 6 – Santer et al. (2013). Human and natural influences on the changing thermal structure of the atmosphere. Proceedings of the National Academy of Sciences.

https://science.feedback.org/review/letter-there-is-no-climate-emergency-repeats-inaccurate-claims-about-climate-science-daily-sceptic-toby-young/

Incorrect

Daily Sceptic, Toby Young, 2022-08-18

“Natural variation explains a substantial part of global warming observed since 1850;” no statistical evidence that global warming is intensifying natural disasters, or making them more frequent.

Incorrect: Natural (non-human) drivers of climate change have been mostly stable since the onset of modern warming and all the available scientific evidence implicates human greenhouse gas emissions as the primary culprit. Scientific evidence also indicates that climate change is contributing to intensified or more frequent natural disasters such as heatwaves, drought and heavy rainfall.

Scientific evidence shows that climate change is driven by human activities, as recognized by the world’s authoritative scientific bodies such as the U.N.’s Intergovernmental Panel on Climate Change, the U.S. National Academy of Sciences and the U.K. Royal Society. These scientific bodies, composed of experts in the field of climate science, have concluded that climate change is predominantly driven by human emissions of greenhouse gases. The “World Climate Declaration” group, largely composed of non-experts, relies on several inaccurate claims about the science to arrive at an alternative conclusion.

“The political fiction that humans cause most or all climate change and the claim that the science behind this notion is ‘settled’, has been dealt a savage blow by the publication of a ‘World Climate Declaration (WCD)’ signed by over 1,100 scientists and professionals.” “Natural variation explains a substantial part of global warming observed since 1850;” “There is no statistical evidence that global warming is intensifying hurricanes, floods, droughts and such-like natural disasters, or making them more frequent.”

An article authored by Toby Young in the Daily Sceptic, a website with a history of publishing scientifically unfounded claims, reports on an open letter signed by “1,200 scientists and professionals.” The letter, entitled the “World Climate Declaration,” is claimed to have “dealt a savage blow” to the notion that human emissions of greenhouse gases are responsible for climate change. The World Climate Declaration group, which has links to fossil fuel interests, has made similar allegations in the past, which were previously analyzed by scientists and found to be inaccurate. Young and the letter argue that, rather than greenhouse gas emissions, today’s warming may be a natural event following the end of the Little Ice Age, an interval of particularly cold conditions between around 1400 to 1700.[1] Young quotes Antonio Zichichi, a physicist with ties to the Heartland Institute think tank who does not have a background in climate science: “Natural variation explains a substantial part of global warming observed since 1850…the Earth’s climate has varied for as long as the planet has existed, with natural cold and warm periods.” While natural variations can impact climate, invoking the existence of such natural variability (i.e., non-human factors such as solar variability and volcanic activity) to explain contemporary warming is scientifically unsound. Examining all plausible climate drivers reveals that natural variability has exerted a relatively minor influence on total climate change since the industrial era (Fig. 1). By contrast, human emissions of CO2 and other greenhouse gases are the dominant factors that have driven warming over this interval.[2,3]Figure 1. Time series of effective radiative forcing (warming) caused by various mechanisms. Note that carbon dioxide (gray) contributes more to warming than all of the other well-mixed greenhouse gases (WMGHG). Note also that the majority of warming is caused by carbon dioxide and other greenhouse gases. Source: U.S. Fourth National Climate Assessment. “The warming from the late 1800s to the present is all due to human-caused climate change, because natural factors have changed little since then and even would have caused a slight cooling over the last 70 years rather than the warming we have observed”, said Timothy Osborn, a climate scientist at the University of East Anglia, in a previous review of a similar claim. “Climate scientists study the causes of warming and cooling periods and calculate their effects on our climate. These studies show that natural warming after the Little Ice Age was complete by the late 1800s,” added Osborn. Scientists estimate the effects of various potential climate drivers by running model simulations, mathematical representations of the climate system. The effectiveness of climate models is evaluated by their ability to capture real-world climate trends. Models used by the IPCC have been faithfully predicting climate since the 1970s, which gives researchers confidence in their performance.[4] Modeling results consistently indicate that the observed increases in surface temperature and ocean heat content are not possible to explain with natural variability alone and rather demonstrate that human activities are responsible for the warming trend (Fig. 2).Figure 2. IPCC climate model simulations of land and ocean surface temperatures in addition to ocean heat content since the beginning of the twentieth century using natural and anthropogenic (e.g., greenhouse gas emissions) climate forcings (red) and non-anthropogenic forcings alone (blue). Black lines denote observations. Source: IPCC AR5. Young’s article later repeats another claim about the merits of CO2 with a quote from the letter, calling the greenhouse gas “beneficial for nature” and responsible for “greening the Earth.” This narrative was explored in a recent Climate Feedback insight article, in which scientists like Sara Vicca, a carbon-cycle expert at the University of Antwerp, were featured. While it is true that plants need CO2, this does not indicate that warming driven by greenhouse gas emissions is harmless. “The benefit[s] of increasing CO2 concentrations for plant growth are increasingly being outweighed by the negative impacts, especially of global warming,” said Vicca. For example, extreme events associated with CO2-driven warming, such as drought, can adversely impact plant life.[5] The letter also contests a relationship between climate change and extreme events, claiming that “there is no statistical evidence that global warming is intensifying hurricanes, floods, droughts and such-like natural disasters, or making them more frequent.” Such a claim is at odds with the most recent IPCC report,[2] which states in its summary for policymakers that “human-induced climate change is already affecting many weather and climate extremes in every region across the globe.” The IPCC further notes that “evidence of observed changes in extremes such as heatwaves, heavy precipitation, droughts, and tropical cyclones, and, in particular, their attribution to human influence, has strengthened since AR5 [Assessment Report 5, a previous IPCC report].” Moreover, the IPCC states with high confidence that “increases in frequency, intensity and severity of droughts, floods and heatwaves, and continued sea level rise will increase risks to food security in vulnerable regions from moderate to high between 1.5°C and 2°C global warming level [the maximum level of warming that the Paris Agreement calls for], with no or low levels of adaptation” (Fig. 3). Figure 3. Severity of various climate impacts occurring (right) under different scenarios of warming. Note that extreme weather events (RFC2) are expected to intensify with warming. Source: IPCC AR6. Given the volume of inaccurate claims made in the letter and Young’s article, it is perhaps surprising that “1,200 scientists and professionals” agree with its content. It is, however, instructive to examine the credentials of the signatories. Of the 1,200, only a handful mention having a background in climate science. Some of these individuals claim that they have a master’s degree in the subject matter while others identify as “independent researchers” without mentioning specific credentials. Many signatories have degrees in unrelated fields (i.e., psychology) or work in the fossil fuel industry. Such findings are similar to Climate Feedback’s review of the signatories to the previous letter.References: 1 – Mann et al. (2009) Global Signatures and Dynamical Origins of the Little Ice Age and Medieval Climate Anomaly. Science. 2 – IPCC (2021) Sixth Assessment Report. 3 – US Fourth National Climate Assessment, Climate Science Special Report 4 – Hausfather et al. (2019) Evaluating the Performance of Past Climate Model Projections. Geophysical Research Letters. 5 – Xu et al. (2019) Increasing impacts of extreme droughts on vegetation productivity under climate change. Nature Climate Change

https://science.feedback.org/review/carbon-dioxide-emissions-humans-major-driver-climate-change-jerome-corsi-claims-cbn-news/

Incorrect

CBN News, Jerome Corsi, 2022-07-29

Carbon dioxide is not a climate heat driver; we had an ice age when the Earth had extraordinarily larger amounts of carbon dioxide; in the 1970s scientists thought we were going to have a new ice age.

Incorrect: As a greenhouse gas, additional carbon dioxide in the atmosphere, driven by human emissions, exerts a warming effect on the planet and has been demonstrated to be the dominant driver of modern global warming and climate change. Misleading: Carbon dioxide is the dominant driver of contemporary warming, which is happening very rapidly. However, other factors were also responsible for regulating Earth’s climate on longer timescales in the geological past, such as the distribution of continents, volcanic activity and the brightness of the sun. Misleading While a few studies in the 1970s speculated about the possibility of global cooling, the majority of the climate research community indicated that future warming would occur.

Earth’s climate is a complicated system with multiple potential driving mechanisms. However, scientists have evaluated all possible driving mechanisms of contemporary global warming and have consistently concluded that human emissions of greenhouse gases are the primary culprit. While climate change has occurred in Earth’s geological history independently of humans, it is misleading to invoke these relatively slow changes under very different Earth-system conditions (e.g., variability in tectonics, solar forcing, orbital conditions and volcanism) in order to discredit the findings of climate science.

“[Carbon dioxide] is about 0.0003 or 0.0004% of the atmosphere…it is not a climate heat driver…when the Earth had extraordinarily larger amounts of carbon dioxide in the atmosphere, we had an ice age and there were no human beings here…They [climate scientists] thought in the 1970s we were going to have a new ice age.”

A recent video published on CBN News’ Facebook page alleges that carbon dioxide is not responsible for driving contemporary global warming. Jerome Corsi, a former political scientist with a history of promoting unfounded conspiracy theories, claims that carbon dioxide is a “trace element” in Earth’s atmosphere and not a “climate heat driver.” Corsi goes on to argue that “when the Earth had extraordinarily larger amounts of carbon dioxide in the atmosphere, we had an ice age and there were no human beings here.” According to Corsi, carbon dioxide has been unjustifiably “picked on” as a driver of global warming by environmental activists and political figures. He also claims that, in the 1970s, climate scientists were warning of “global cooling” rather than global warming. It is true that carbon dioxide is a minor constituent of Earth’s atmosphere by percentage. However, it is just above 0.04% today, while Corsi falsely claims carbon dioxide represents 0.0003 to 0.0004% of the atmosphere. Importantly, though, the relatively low percentage weight of atmospheric carbon dioxide does not indicate that its role in regulating climate is negligible. As James Renwick, a climate scientist at Victoria University of Wellington, notes, “carbon dioxide is the major ‘climate heat driver,’ in terms of the radiation budget of the planet.” Indeed, a consensus of scientific evidence[1,2] indicates that contemporary global warming is caused by human emissions of carbon dioxide and other greenhouse gases. This finding is also substantiated by various national and international climate reports such as the U.N. International Panel on Climate Change (IPCC) Sixth Assessment Report[3] and U.S. Fourth National Climate Assessment[4]. Carbon dioxide is a greenhouse gas – a type of gas that prevents heat from leaving the atmosphere and warms the Earth. “There are other gases that are more effective than carbon dioxide at absorbing and re-radiating heat (e.g. methane), but carbon dioxide wins in the long term because of its long lifetime of hundreds to thousands of years,” says Renwick. In addition to its long atmospheric residence time, or the amount of time a carbon dioxide molecule remains in the air, it also constitutes a majority of total greenhouse gas emissions. As such, carbon dioxide is in fact responsible for most of the warming observed since the mid 20th century (Fig. 1). Figure 1. Time series of effective radiative forcing (warming) caused by various mechanisms. Note that carbon dioxide (gray) contributes more to warming than all of the other well-mixed greenhouse gases (WMGHG). Note also that the majority of warming is caused by carbon dioxide and other greenhouse gases. Source: U.S. Fourth National Climate Assessment. While 0.04% of the atmosphere may seem small, it is important to note that carbon dioxide comprised less than 0.03% of the atmosphere prior to the onset of human emissions during the industrial revolution (Fig. 2). This change represents a dramatic departure from natural changes in atmospheric carbon dioxide, which typically varied between approximately 0.02% (200 ppm) to 0.03% (300 ppm) during the last 800,000 years and changed over periods of tens of thousands of years. Figure 2. Atmospheric carbon dioxide concentration over the last 800,000 years. Note that modern levels of >400 ppm (>0.04%), driven by anthropogenic emissions, are a rapid departure from natural variability. Source: NASA. But what about temperature over this period? Corsi claims that we had an “ice age” under “larger amounts of carbon dioxide.” While he does not invoke a specific example in Earth history, paleoclimate research has found that Earth’s glacial-interglacial cycles, periods of relative cooling (ice growth) and warming (ice melt), have indeed occurred in concert with changes in atmospheric carbon dioxide (Fig. 3), at odds with Corsi’s claim. Figure 3. Atmospheric carbon dioxide (top) and temperature change (bottom) over the last 800,000 years. Note that high levels of carbon dioxide are associated with high temperatures and low levels of carbon dioxide are associated with low temperatures. Source: Time Scavengers. Carbon dioxide is, however, just one of many climate forcing mechanisms. For example, while glacial-interglacial changes do correspond to changes in carbon dioxide, they also correspond to changes in Earth’s orbit and tilt. As such, explanations for what drives glacial-interglacial variations typically invoke a synergy of different mechanisms, including changes in Earth’s orbit, ocean circulation and atmospheric greenhouse gases[5,6,7]. Looking further back in time, paeloclimate research also generally supports a relationship between atmospheric carbon dioxide concentration and Earth’s surface temperature over the last 66 million years[8] (Fig. 4). Figure 4: Reconstructed changes in Earth’s surface temperature (top) and atmospheric carbon dioxide (bottom) over the last 66 million years. Source. Such associations do not necessarily indicate that carbon dioxide was always the main mechanism regulating changes in climate, particularly at periods in Earth’s more distant geological past. “If you go back far enough, over 100 million years ago, you can find periods where it looks as though there were high carbon dioxide levels and cool temperatures, though again the uncertainties are large,” says Renwick. “At those times though, many things were very different, such as the distribution of continents and ocean on the planet, the amount of volcanic activity (blocking out sunlight), and the brightness of the sun. Carbon dioxide is very important for the energy budget of the Earth, but it is not the only factor on very long time scales.” It is, however, misleading to invoke drivers of geological-scale climate change in order to discredit the driving role of carbon dioxide in modern climate change. Climate scientists from different disciplines have evaluated the influence of all modern climate forcing mechanisms and have repeatedly and consistently concluded that greenhouse gases are the dominant cause[3]. This is not the only misleading argument made by Corsi. He goes on to claim that climate scientists in the 1970s were warning that “we were going to have a new ice age.” This claim is commonly repeated in climate contrarian circles in an effort to undermine the reliability of climate scientists. However, a survey[9] of the climate literature between 1965 and 1979 found that only 7 studies projected future cooling. By contrast, 44 studies projected warming. Climate science has evolved dramatically since the 1970s and all of the available scientific evidence continues to support projected warming driven by human emissions of greenhouse gases[3]. Scientists’ Feedback: James Renwick Professor, Victoria University of Wellington: Jerome Corsi is right that carbon dioxide is a minor element of the atmosphere, it currently makes up around 0.04% of the air (this is however more than he claims). However, it is crucially important for regulating earth’s energy budget and surface temperatures. But he is not right about much else. Carbon dioxide is the major ‘climate heat driver,’ in terms of the radiation budget of the planet. There are other gases that are more effective than CO2 at absorbing and re-radiating heat (e.g. methane), but carbon dioxide wins in the long term because of its long lifetime of hundreds to thousands of years. This has been understood for a long time – the role of CO2 in warming the earth was discovered in the mid-19th century. It has not been ‘picked on’ recently by climate activists. The warming of the globe from increasing carbon dioxide concentrations in the air was first calculated in 1896. A good source on the history of the science is Spencer Weart’s book ‘The Discovery of Global Warming.’ Through the past 2.6 million years, the period of recent ice ages, carbon dioxide has gone up and down in step with temperature, bottoming out at around 180 parts per million in the depths of a “glacial maximum” and peaking at around 280 parts per million in the warmer interglacial periods. Going back further, CO2 levels were certainly higher than present, but so were temperatures (Fig. 3). As Corsi says, CO2 levels dropped from 500M or so years ago to the beginning of our ice age period 2.6M years ago. There were lots of ups and downs along the way, and the atmospheric concentration did not start at 7500 parts per million CO2, it was closer to 700ppm. It probably did go above 1000ppm over 100M years ago, but the uncertainties are large: Atmospheric carbon dioxide concentration over the last 400 million years. Source: Earth.org. In any case, in broad terms, yes, CO2 levels have dropped from the ‘hothouse conditions’ of 50 million years ago to the ‘icehouse conditions’ of the last few million years. In that period of time, temperatures have risen and fallen with CO2, as they have done through the recent ice ages (Fig. 3). With current emissions, we’ll be back at the “hothouse” level next century if we don’t take action. That would be catastrophic for humanity. If you go back far enough, over 100 million years ago, you can find periods where it looks as though there were high CO2 levels and cool temperatures, though again the uncertainties are large. At those times though, many things were very different, such as the distribution of continents and ocean on the planet, the amount of volcanic activity (blocking out sunlight), and the brightness of the sun. CO2 is very important for the energy budget of the earth, but it is not the only factor on very long time scales. The last point about the ‘ice age scare’ in the 1970s… yes, there were a few papers published in the 1970s wondering about this, after a couple of decades of slight global cooling. The media picked up on this and there were articles published in Time magazine and elsewhere talking about the possibility of an impending ice age. But, in the climate research community, the vast majority of papers published through the 1970s were about global warming, not global cooling. There’s a good discussion here[9].” References: 1 – Oreskes (2004) The scientific consensus on climate change. Science. 2 – Cook et al. (2013) Quantifying the consensus on anthropogenic global warming in the scientific literature. Environmental Research Letters. 3 – IPCC (2021) Sixth Assessment Report. 4 – U.S. Fourth National Climate Assessment, Climate Science Special Report. 5 – Denton et al. (2010) The Last Glacial Termination. Science 6 – McManus et al. (1999) A 0.5-Million-Year Record of Millennial-Scale Climate Variability in the North Atlantic. Science 7 – Raymo et al. (1997) The timing of major climate terminations. Paleoceanography 8 – Rae et al. (2021) Atmospheric CO2 over the Past 66 Million Years from Marine Archives. Annual Review: of Earth and Planetary Sciences 9 – Peterson et al. (2008) The myth of the 1970s global cooling scientific consensus. Bulletin of the American Meteorological Society

https://science.feedback.org/review/the-sun-isnt-responsible-for-current-climate-change-contrary-claims-suspicious0bservers-ben-davidson/

Incorrect

Suspicious0bservers, Ben Davidson, 2022-07-14

Scientists have neglected the effect of solar particles, cosmic rays, the interplanetary magnetic field and Earth's weakening magnetic field to conclude climate change is due to human activity

Incorrect: Scientists have established that human activities are responsible for the climate change observed over the last several decades and ruled out the possible influence of the sun or Earth’s magnetic field.

Though the sun does go through regular solar cycles, changes in its activity – or in the Earth’s magnetic field – cannot account for our planet’s observed climate change. The sun has, historically, played a role in changes to the Earth’s climate, but the rate and magnitude of the Earth’s current warming is too high to be linked to changes in the sun or Earth’s orbit. The effect of rising rates of atmospheric greenhouse gases, on the other hand, has been well established by decades of scientific research.

“They're able to blame us for climate change because they do not properly factor in the sun, how its activity has changed over the centuries…there's not one single paper in existence blaming humans for global warming which accounts for solar particles, cosmic rays, the interplanetary magnetic field and Earth's weakening magnetic field.”

On 14 July, 2022, YouTuber Ben Davidson published a video on his channel Suspicious0bservers which claims that the sun is at the root of the global warming that has been observed by scientists since the Industrial Revolution. Davidson, whose channel has more than 600,000 subscribers, claims that current climate science does not account for “solar particles, cosmic rays, the interplanetary magnetic field and Earth’s weakening magnetic field.” But scientists haven’t found a link between those factors and significant changes to the planet’s climate, said Georg Feulner, Deputy Head of Research Department at the Potsdam Institute for Climate Impact Research. The warming effect of greenhouse gases, on the other hand, has been well established – as is the link between human activities and Earth’s current warming.[1] “There is absolutely no doubt in the scientific community that the current climate crisis is due to human activities,” Feulner said in an email to Science Feedback. One of the factors Davidson points to as driving current rates of climate change are coronal mass ejections (CMEs), phenomena defined by NOAA’s Space Weather Prediction Center as “large expulsions of plasma and magnetic field from the Sun’s corona.” Davidson cites a 2002 paper published in the Journal of Geophysical Research: Space Physics to support his claim that the sun produced twice the number of CMEs from 1940 to 2005 as it did a century earlier. In its abstract, the 2002 study notes: “We surmise that the coronal mass ejection (CME) rate for recent solar cycles was approximately twice as high as that for solar cycles 100 years ago.”[2] Ian Richardson, a research scientist at NASA and the University of Maryland College Park and lead author of the 2002 study, told Science Feedback that that statement was a hypothesis of his – and, looking back on it now, probably an incorrect one. “This was really just one hypothesis that I was considering to explain (unsuccessfully) the increase in geomagnetic activity in the first part of the 20th century, and is based on the simplest assumption that the CME rate is proportional to the sunspot number as suggested by studies published at that time based on direct observations of CMEs first available in the 1970s,” Richardson said in an email. “It is unreasonable to suggest that it’s an established fact as in the video.” Coronal mass ejections aren’t associated with measurable changes to Earth’s temperature, because the magnetic field surrounding the Earth reflects the massive energy that CMEs put out back into space. This magnetic field, as NASA notes, “shields us from erosion of our atmosphere by the solar wind (charged particles our Sun continually spews at us), erosion and particle radiation from coronal mass ejections (massive clouds of energetic and magnetized solar plasma and radiation), and cosmic rays from deep space.” Davidson, however, claims that a weakening of the Earth’s magnetic field has made it easier for the sun’s energy to warm the planet. According to NASA, Earth’s magnetic field has weakened by about 9 percent on average in the last 200 years – but “paleomagnetic studies show the field is about as strong as it’s been in the past 100,000 years, and is twice as intense as its million-year average.” And scientists don’t have reason to believe that, as Davidson claims, the Earth’s poles will be flipping anytime soon: Pole reversals take place over hundreds to thousands of years, and there is no guarantee that the Earth’s current magnetic field will continue weakening.[3] “CMEs are short-lived events, and there is no evidence that the charged particles released from CMEs have a significant effect on the global climate, irrespective of the state of the Earth’s magnetic field,” Feulner said. Davidson also points to a graph of the last four centuries of sunspot observations as evidence that the sun is playing a major role in current observed climate change. Sunspots are locations on the sun’s surface that are cooler than the rest of the sun, and their number tends to vary in approximately 11-year cycles. When sunspot activity is at a maximum, there tends to be a small increase in the sun’s energy output. But that output isn’t associated with major temperature changes: According to NOAA Climate.gov, scientists estimate that slight increases in levels of sunlight between the late 1800s and mid-1900s contributed to up to 0.1°C at most of the planet’s 1.0°C of warming since the pre-industrial era. “The fact that solar activity based on the sunspot number has been falling during the last four ~11 year solar cycles might pose a problem for those who are arguing for a relation between global warming and solar activity, in that warming continues to increase,” Richardson said. “Seemingly dramatic variations in say the sunspot number, and related phenomena such as the rate of CMEs do not then result in major influences on the Earth – just large changes in a very small component of the energy input.” Figure 1 – Graph shows sunspot numbers from 1700 – present. Courtesy Ian Richardson (Credit: Royal Observatory of Belgium). Contrary to Davidson’s claims, scientists have evaluated the sun’s potential impact on climate change and found that it is dwarfed by the impact of human activities. A 2016 study concluded that, of the tests done to determine solar activity’s impact on observed climate change, “all indicate that the contribution of changing solar activity either through cosmic rays or otherwise cannot have contributed more than 10% of the global warming seen in the twentieth century.”[4] Solar radiation accounts for “more than 99.9% of the energy entering Earth’s system,”[5] and climate models do take into account for total solar irradiance – the amount of solar energy the Earth receives – as does the IPCC. According to NASA: “Since 1750, the warming driven by greenhouse gases coming from the human burning of fossil fuels is over 50 times greater than the slight extra warming coming from the Sun itself over that same time interval.” Aside from TSI, the sun also emits energetic particles, including galactic cosmic rays, which were at one point hypothesized to influence cloud formation and thus global temperature. However, research has determined that galactic cosmic rays aren’t strongly tied to cloud formation.[6-8] Figure 2 – Comparison of the global surface temperature changes (red) and the Sun’s energy that Earth receives (yellow) in watts per square meter since 1880. One can see that since the 1960s, the global temperature and solar activity have varied in opposite directions. Source: NASA/JPL-Caltech One of the reasons scientists know the sun is not responsible for our current observed warming is the rate and magnitude of our current warming is too high to be linked to changes in the sun or Earth’s orbit. Additionally, if the sun were responsible for climate change, scientists would expect to see warming from the surface of the Earth up to the stratosphere (the Earth’s second layer of atmosphere). Instead, records show that the Earth’s surface is warming, while the stratosphere is cooling. Scientists’ Feedback: The statements quoted below are from the video; comments are from the reviewers (and are lightly edited for clarity). “It wasn’t just the sun spots, it was the coronal mass ejections. The sun pounded out twice the CMEs that it was producing just a century earlier. Not only did the sun give us much more over the last century but it had an easier time getting in. Earth’s magnetic field is weakening and its poles are shifting.” Georg Feulner Senior Scientist, Potsdam Institute for Climate Impact Research (PIK):The changing number of Sun spots are an indicator of solar activity. Climate studies looking at the historic and future evolution of Earth’s climate take the small changes in the Sun’s brightness due solar activity into account, but it is scientifically well established that their impact on the global mean temperature is only a few tenths of a degree, much less than the observed global warming of currently more than one degree. Moreover, solar activity and global warming show opposing trends over the last few decades: While solar activity has been decreasing overall, global temperatures are rising quickly. CMEs are short-lived events, and there is no evidence that the charged particles released from CMEs have a significant effect on the global climate, irrespective of the state of the Earth’s magnetic field. Climate studies that tie current climate change to human activities do not account “for solar particles, cosmic rays, the interplanetary magnetic field and Earth’s weakening magnet field in the modern pole shift.” Georg Feulner Senior Scientist, Potsdam Institute for Climate Impact Research (PIK):Climate studies do not have to take these effects into account because science could not find a link between these effects and significant changes in the Earth’s climate. In contrast, the warming effect of greenhouse gases like carbon dioxide is known since the 19th century, is known to hold over Earth’s long history and can fully explain the observed warming (in combination with the other greenhouse gases, aerosols, changes in land use as well as all natural climate forcings like volcanic eruptions and changes in solar activity). There is absolutely no doubt in the scientific community that the current climate crisis is due to human activities. Ian Richardson Research Scientist, NASA/University of Maryland:I had actually forgotten about the comment that the coronal mass ejection rate might have been around twice as large now than at the beginning of the 20th century in my 2002 paper. This was really just one hypothesis that I was considering to explain (unsuccessfully) the increase in geomagnetic activity in the first part of the 20th century, and is based on the simplest assumption that the CME rate is proportional to the sunspot number as suggested by studies published at that time based on direct observations of CMEs first available in the 1970s. Because of the lower sunspot number at the beginning of the 20th century, this might suggest that the CME rate was decreased then by ~50%. But there were no observations of CMEs or the solar wind at that time and so no direct proof that this hypothesis is correct or not. On the other hand, the last solar cycle (2008-19) was the smallest in 100 years (see below) and we can compare directly the CME rate observed by spacecraft in this and the previous stronger cycle. For example, Zhang et al. (2021, Progress in Earth and Planetary Science (2021) 8:56 https://doi.org/10.1186/s40645-021-00426-7) show that the CME rate in cycle 24 was not as low as would be expected based on the lower sunspot number (see their Figures 5a and 6a). This suggests that my simple assumption that the low sunspot number at the start of the 20th century might imply a ~50% lower CME rate then was probably incorrect, and is not supported by recent CME observations. Certainly, it is unreasonable to suggest that it’s an established fact as in the video. Of course, the fact that solar activity based on the sunspot number has been falling during the last four ~11 year solar cycles (see above), might pose a problem for those who are arguing for a relation between global warming and solar activity, in that warming continues to increase. I suppose in the video, this would be accounted for by the claimed “30 year delay” in the influence of the Sun on global warming, such that the effect of the reduced solar activity in recent decades is not yet showing up in the climate record. This figure also shows nicely the known ~100 year periodicity in solar activity (e.g., smaller activity cycles tends to occur around the start of each century). Another point to bear in mind is that identifying long-term trends in the sunspot number, as in the video, is problematic. Observations of sunspots have been made over centuries by different observers with different instruments and different ways of counting sunspots (e.g., do you count every small sunspot or not?), so the sunspot record is extremely uneven. There has been a huge effort in recent years to unearth observatory records and previously unknown observations and try to adjust for these different influences (for details see https://sidc.be/silso/newdataset). The plot above is the currently accepted best estimate of the history of the sunspot number, whereas so far as I can tell, the video uses the “old” number without the corrections. This is convenient because it gives the impression that the sunspot number in the 20th century is larger than in previous centuries, but that’s largely because observing techniques were improved. In the above plot, the solar cycles in each century are much more even, and those in the 20th century aren’t especially larger than those in previous centuries. Also note that there are typical sized cycles in the 1700s following the Maunder minimum highlighted in the video which are not evident in the plot in the video. Of course, the climate deniers would probably claim this reassessment of the sunspot number is all a fraud to cover up the large cycles in the 20th century, but I know firsthand that this has been a large undertaking by an international team that are simply interested in learning more about the physics of our star, not to satisfy the climate change community. The conclusions using the longer-term reconstructed sunspot number shown in the video are probably also suspect. Yes, it does suggest that the sunspot number is currently the highest it has been for a long period, but that’s the only true data point we have. Any other conclusions depend on the accuracy of the assumptions made to reconstruct the sunspot number series (why can deniers hold the results of certain studies as facts but claim others as fraud when all science has uncertainty?). The supposed neglect of effects such as CMEs, solar particles, cosmic rays, etc. on climate change is first that they are only minor direct energy inputs into the Earth system compared to direct visible/infrared radiation. The video does highlight studies showing solar variability, and there is no dispute that this is a real phenomenon (as in the above figure). However, seemingly dramatic variations in say the sunspot number, and related phenomena such as the rate of CMEs do not then result in major influences on the Earth – just large changes in a very small component of the energy input. The effects, such as geomagnetic storms, can be dramatic but are also short term, lasting just a few hours or days and hence not an obvious contributor to long-term variations. In contrast, the much larger energy input at visible wavelengths varies only slightly over the sunspot cycle. However, the Sun, solar wind, solar energetic particles and cosmic rays do produce effects in the Earth’s magnetic field, radiation belts, ionosphere, thermosphere and troposphere (where weather occurs), and it has become increasingly clear from recent research that phenomena in these regions are strongly coupled in complex ways. There is a lot of ongoing research in this area, and it is possible that there are subtle ways in which the Sun influences climate via coupled processes in these regions. So rather than the effects of the Sun being neglected, they are being actively studied, but until the pathways by which these effects might occur are identified and assessed (including the possible influence of changes Earth’s magnetic field, which are well recognized and can be taken into account), it is not possible to consider including them in climate models. There is probably also some reluctance on the part of the climate change community to consider ideas that are from a different perspective using different science and methods/models, but I do see encouraging signs of collaboration that may shed further insight into this question e.g. at American Geophysical Union meetings. References: [1] IPCC (2021) Climate Change 2021: The Physical Science Basis. Contributions of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. [2] Richardson et al. (2002) Long-term trends in interplanetary magnetic field strength and solar wind structure during the twentieth century. Journal of Geophysical Research: Space Physics [3] Nilsson et. al (2022). Recurrent ancient geomagnetic field anomalies shed light on future evolution of the South Atlantic Anomaly. Proceedings of the National Academy of Sciences [4] Sloan et. al (2016) Cosmic rays, solar activity and the climate. Environmental Research Letters. [5] Dudok de Wit et al. (2018) Better data for modeling the Sun’s influence on climate. Eos. [6] Pierce and Adams (2009) Can cosmic rays affect cloud condensation nuclei by altering new particle formation rates? Geophysical Research Letters [7] Agee et al (2011) Relationship of Lower-Troposphere Cloud Cover and Cosmic Rays: An Updated Perspective. Journal of Climate [8] Dunne et al (2016) Global atmospheric particle formation from CERN CLOUD measurements. Science

https://science.feedback.org/review/warming-earths-surface-oceans-continues-apace-contrary-to-claims-daily-sceptic-chris-morrison/

Incorrect

Daily Sceptic, Chris Morrison, 2022-05-19

”Global warming started to run out of steam over two decades ago… Half of the apparent global temperature increase from January 1910 to January 2000 is due to administrative adjustments.”

Incorrect: Continuous warming of the Earth’s surface and oceans has been measured since the 1960s by multiple independent and peer-reviewed datasets. All of the available evidence indicates that global warming has not stopped, with 2016 and 2020 being the warmest years on record. Ocean heat content data also indicate an increase from 1998 to 2012.Misleading: Adjustments to the NASA GISS surface temperature dataset are made to accommodate new stations and updated algorithms. When adjusted annual temperature data from NASA GISS are compared against raw temperature data, the adjusted dataset actually diminishes the warming trend from ~1940 to present.

Global warming has been a persistent signal in all relevant climate datasets from ~1960 to present. The 1998 to 2012 interval has received attention by climate contrarians due to an apparent warming slowdown in surface temperature datasets, which may be due to a combination of natural and internal variability as specifically noted in the Intergovernmental Panel on Climate Change’s Sixth Assessment Report. However, warming did occur throughout this interval and continues to the present day as shown in measurements of surface temperature, ocean heat content, glacier melt and sea-level rise.

”In a major re-evaluation of data from meteorology balloons rising through the troposphere, the scientists confirmed that temperatures have mostly paused since around 1998. In July 2013, the Met Office published a paper about the [1998 to 2012] pause, although its main argument that the heat had disappeared into the ocean does not seem to have stood the test of time. Professor Humlum looked at the adjustments to the NASA GISS [surface temperature] dataset and found that ‘half of the apparent global temperature increase from January 1910 to January 2000 is due to administrative adjustments to the original data since May 2008.’”

In a recent article in the Daily Sceptic, a website with a history of publishing scientifically unfounded claims, Chris Morrison repeats a common claim in contrarian circles that “global warming has slowed dramatically” since 1998. Morrison, who presents himself as a former financial journalist, further goes on to downplay past warming, claiming that “half of the apparent global temperature increase from January 1910 to January 2000 is due to administrative adjustments to the original [NASA Goddard Institute for Space Studies (GISS) surface temperature] data since May 2008”. This claim that global warming is due to data adjustment has been shown false in the past, as re-explained below. Temperature corrections are made to accommodate new stations and updated algorithms used to produce the dataset, says Gavin Schmidt, a climate scientist and director of GISS. Schmidt also notes that changes in temperature among different versions of the dataset are “very small compared to the changes over time because of climate” (Fig. 1). Moreover, the corrections applied to the NASA GISS dataset actually reduced the temperature increase from ~1940 to present, rather than accentuated it, as claimed by Morrison (Fig. 2). Figure 1. Different versions of the GISS global mean temperature time series. Note that the small adjustments to the dataset invoked by Morrison are not sufficient to negate the clear warming trend. Source: NASA GISS.Figure 2. NASA GISS adjusted temperature anomalies (teal) compared to raw unadjusted data (black). Note that the adjustments made to the GISS time series suppress the warming trend since ~1940, rather than accentuate it as claimed by Morrison. Source: NASA Climate.Then how did Morrison and Ole Humlum, a geographer at the University of Oslo quoted in the article, conclude that these corrections resulted in much larger impacts on the final dataset when comparing temperatures for January 1910 and January 2000? “This is just a cherry pick,” says Schmidt. “There is a lot of noise in the monthly data, and this particular comparison is just the largest adjustment he could find. If he had looked at January 1881, the adjustments reduced the difference to Jan 2000 by about 0.1 ºC.” “Regardless of what record you look at, [warming] trends have continued through 1998. In all records, 2016 or 2020 were the warmest years on record,” says Schmidt (Fig. 3). Continued warming is indeed reinforced by findings from the latest national and international climate reports such as the U.S. National Climate Assessment[1], the Intergovernmental Panel on Climate Change’s Sixth Assessment report (IPCC AR6)[2], the American Meteorological Society’s State of the Climate in 2020 report[3]and the World Meteorological Organization’s State of the Global Climate 2021 report[4]. The available evidence is therefore in clear contrast to Morrison’s claim that “temperatures have mostly paused since around 1998.” Figure 3. Temperature anomalies from different datasets since the late 1970s. Note that the warming trend continues from 1998 to present, in clear contrast to claims made by Morrison. Source: RealClimate.Fabio Madonna, an atmospheric scientist at the Italian National Research Council and lead author of the study[5]invoked by Morrison, agrees with Schmidt. “In my paper, it is never mentioned that temperatures have mostly paused since around 1998,” says Madonna. “The analysis of the time series of upper-air data shows that in 1998 something happened (likely boosted by a strong El Niño [a shift in Pacific Ocean circulation patterns that impacts temperature records[6]]) with a slow down of the warming of the upper troposphere in the northern hemisphere only.” There are therefore two major problems with Morrison’s argument: first, it relies exclusively upon data from the upper troposphere in only a portion of the northern hemisphere, which is not representative of global climate trends. As Victor Venema, a climate scientist at the University of Bonn, says, “[Morrison’s] ‘evidence’ seems to be his own eye-ball estimate of warming for a small part of the Earth, the air 9-km up in the northern hemisphere between 20 and 70 °N, which is not global. Compared to the actual global temperature this would be missing the strong warming we have recently seen in the Arctic.” Secondly, using 1998 as a starting point is problematic, note climate scientists Andrea Steiner and Stephen Po-Chedley. “The positive temperature anomalies due to the strong El Niño leads to a trend dominated by this large peak,” says Steiner. Thus, Morrison’s reliance upon this time period is an example of cherry picking: selectively picking a particularly warm year as a baseline in order to downplay the warming trend. Morrison continues to write that the Met Office’s “main argument that the heat [from 1998 to 2012] had disappeared into the ocean does not seem to have stood the test of time.” Morrison’s claim, however, is again in contradiction with ocean heat content data published by NOAA that show continuous warming of the upper 700 meters of the ocean since ~1990 (Fig. 4).Figure 4. Time series of ocean heat content (upper 700 m). Note that the positive trend continues from 1998 to 2012, in contrast to Morrison’s claims of a warming “pause”. Source: NOAA.Further, the IPCC AR6[2]provides specific comments on this particular interval, noting that the slower increase in surface temperature, “was a temporary event induced by internal and naturally-forced variability that partly offset the anthropogenic warming trend over this period. Nonetheless, the heating of the climate system continued during this period, as reflected in the continued warming of the global ocean (very high confidence) and in the continued rise of hot extremes over land (medium confidence).”Annotations: The statements quoted below are from the article; comments are from the reviewers (and are lightly edited for clarity). Daily Sceptic claim: “Temperature [increase] has mostly paused since around 1998” Gavin Schmidt Director, NASA Goddard Institute for Space Studies: Not true. Regardless of what record you look at (satellite or surface or reanalyses (like ERA5)), trends have continued through 1998. In all records, 2016 or 2020 were the warmest years on record (see Fig. 3).Andrea Steiner Professor for Climate Analysis and Director, Wegener Center for Climate and Global Change, University of Graz, Austria: This is a misleading statement. Using 1998 as a starting point with the positive temperature anomalies due to the strong El Niño leads to a trend dominated by this large peak. Current best estimates of atmospheric temperature trends have been published in several peer-reviewed journals and assessed by the recent IPCC 6th Assessment Report[2]of WG I. Chapter 2 of the report shows the observed changing state of the climate system. Fig. 2.12 shows atmospheric temperature trends. Temperature increase has definitely not paused, the troposphere has been warming (Table 2.5). For more information and also surface trend estimates see chapter 2.3.1.Fabio Madonna Scientist, Italian National Research Council: The IPCC AR6 considered the totality of evidence to conclude that the troposphere has warmed since at least the 1950s. In the tropics, the upper troposphere has warmed faster than the near-surface temperatures since at least 2001. This is the most general view agreed by the scientific community. In my JGR paper[5], it is never mentioned that “temperatures have mostly paused since around 1998.” The analysis of the time series of upper-air data shows that in 1998 something happened (likely boosted by a strong El Niño) with a slow down of the warming of the upper troposphere in the northern hemisphere only. Moreover, the results at 300 hPa in the tropics show, instead, a significant warming after 2000 at 300 hPa in line with the statements by IPCC. After 2015 the warming has largely sped up globally: this is also accompanied by an increase of relative humidity in the southern hemisphere (again likely boosted by another strong El Niño). This is also commented on in my paper. The last 5-6 years of strong warming are also reported in several bulletins and journal papers. The warming/cooling in the upper-troposphere is not immediately related to the near surface temperature trends: if from one side there is a correlation among different vertical regions in the atmosphere, from another side it is also true that changes are reflected in each region with different “sensitivities”. For example, in the JGR paper, where I do not investigate any near surface temperature data, I show that at 300 hPa in the Northern Hemisphere, the decadal temperature trend in the period 1978 – 2018 is 10-20% smaller than the trends at 850 hPa (about 1.5 km of altitude), while in the tropics the warming trend at 300 hPa is 40-50 % larger than the trend at 850 hPa. Investigating trends is a very delicate task because uncertainties affecting the trend estimation are very often larger than the trend themselves. Moreover, the interpretation of trends values must be seen in a global context and over a long time period to ensure that the data analysis may clearly reveal the “fingerprints” of climate change.Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: First, the Earth is warming due to anthropogenic emissions of greenhouse gases. The rate of warming is influenced by natural variations in the Earth’s climate (e.g., volcanic eruptions and El Niño events). Consideration of longer time periods reduces the impact of natural variations in Earth’s climate on anthropogenic warming. Choosing a starting point of 1998 is cherry picking and misleads readers (there was a large El Niño over 1997 – 1998). Second, despite the above disclaimer, it is not true that temperature changes have paused since around 1998. Across all lower tropospheric datasets (UAH, RSS, ERA5, JRA-55, RATPAC, RICH, and RAOBCORE) used in the State of the Climate Report[3](the peer-reviewed version, not the version by the Global Warming Policy Foundation think tank cited in the article) there is warming over 1998 – 2021. On average, the post-1998 warming is 0.22 K per decade (with a range of 0.11 – 0.30 K per decade across datasets). Note that other papers that consider radio occultation measurements (available over 2002 – 2018) also show rapid tropospheric warming[7]. The new dataset and publication cited by the Daily Sceptic did not analyze the period after 1998 and does not purport that temperature change has paused.Victor Venema Scientist, University of Bonn, Germany: This is not supported by the evidence. For example the recent IPCC report shows consistent warming over the last 4 to 5 decades. See figure below, which is Figure 2.11c from the IPCC (2021) report[2]: The only new information the article presents is not about global warming, which normally points to the warming of the surface temperature, but about the upper air temperature (around 9 km up in the air). And the “evidence” is only one dataset of many. The upper air temperature is valuable for many applications, but a much less reliable source for long-term trend computations. Measuring upper air temperature is much harder and instruments change regularly. It uses one-way instruments, which need to have a dynamic range of up to 100 °C, operate in clouds and with little ventilation in harsh sunlight. Also radiosondes are mostly launched over land and the data is really spare for the Southern Hemisphere. The article cites this new radiosonde dataset with upper air temperature data to claim “Further scientific evidence that global warming starting to run out of steam over two decades ago has been presented by an international group of leading scientists.” However, the article does not make any claims about slowing warming in the last 20 years. It even makes the opposite claim about the tropics: “For temperature (Figure 8) in the [Northern Hemisphere], IGRA, RHARM [The new dataset of this study], and ERA5 show a similar positive trend of 0.38, 0.39 and 0.43 K da −1 [that is degree per decade], respectively, while in the tropics at 300 hPa the trend is of 0.17, 0.25, 0.20 K da −1, with a more pronounced trend increase starting around 1997.” Chris Morrison shows a plot from the study. Thus his actual “evidence” seems to be his own research eye-ball estimate of warming for a small part of the Earth, the air 9-km up in the Northern Hemisphere between 20 and 70 °N, which is not global. Compared to the actual global temperature this would, e.g., be missing the strong warming we have recently seen in the Arctic.Daily Sceptic claim: “Professor Humlum looked at the adjustments to the NASA GISS dataset and found that ‘half of the apparent global temperature increase from January 1910 to January 2000 is due to administrative adjustments to the original data since May 2008’” Gavin Schmidt Director, NASA Goddard Institute for Space Studies: This is just a cherry pick. There is a lot of noise in the monthly data, and this particular comparison is just the largest adjustment he could find. If he had looked at Jan 1881, the adjustments reduced the difference to Jan 2000 by about 0.1ºC. But all of these adjustments – which happen because we’ve added stations, updated algorithms etc. – are very small compared to the changes over time because of climate (Fig. 2).Victor Venema Scientist, University of Bonn, Germany: The term “administrative adjustments” is not used in science and comes from a report Humlum wrote for an anti-science Think Tank, the Global Warming Policy Foundation [GWPF]. This computation does not make much sense, but the same graph could have been used to claim that there was effectively no change in the “administrative adjustments” over the full period of the dataset. So even if the measure made sense, the claim would be a misleading cherry pick of a specific period. The claim seems to correspond to the often used conspiracy theory that an open group of thousands of scientists from all over the world and numerous disciplines are conspiring against humanity by pretending that the world warms more than it actually warms. An inconvenient fact for this conspiracy, which is normally not mentioned by people making the claim, is that the “homogenization adjustments” scientists make result in a smaller global warming estimate than the one one would make based on raw data without adjustments[8] (see Fig. 2). Had it been the other way around, it would still not have been sufficient to call it suspicious. Also, then it would have required an engagement with the science, the published reasons for the adjustments and the published evidence they make the warming estimates more accurate.Andrea Steiner Professor for Climate Analysis and Director, Wegener Center for Climate and Global Change, University of Graz, Austria: Data records are continuously reprocessed and subject to improved quality control. There are several different groups that produce surface data sets, reaching similar conclusions while using different methods. The mentioned State of the Climate report of Prof Humlum [written for the GWPF] is not an independently peer-reviewed report according to scientific standards. The original “State of the Climate” report is an international peer-reviewed report in BAMS [Bulletin of the American Meteorological Society], written by dozens of scientists[3].The most recent report on the year 2021 is still under peer-review. There is also the “State of the Global Climate” report by the World Meteorological Organization (WMO)[4].Daily Sceptic claim: The argument that the heat [from 1998 to 2012] had disappeared into the ocean does not seem to have stood the test of time Gavin Schmidt Director, NASA Goddard Institute for Space Studies: The change of ocean heat is tracked by NOAA and sees continuous increases over this time (Fig. 4).Andrea Steiner Professor for Climate Analysis and Director, Wegener Center for Climate and Global Change, University of Graz, Austria: See the statement below from Chapter 3 of the IPCC AR6 WGI[2], Cross Chapter Box 3.1: “With updated observation-based GMST [Global Mean Surface Temperature] datasets and forcing, improved analysis methods, new modelling evidence and deeper understanding of mechanisms, there is very high confidence that the slower GMST and GSAT [Global mean Surface Air Temperature] increase inferred from observations in the 1998–2012 period was a temporary event induced by internal and naturally-forced variability that partly offset the anthropogenic warming trend over this period. Nonetheless, the heating of the climate system continued during this period, as reflected in the continued warming of the global ocean (very high confidence) and in the continued rise of hot extremes over land (medium confidence). Considering all the sources of uncertainties, it is impossible to robustly identify a single cause of the early 2000s slowdown[9,10]; rather, it should be interpreted as due to a combination of several factors.[11,12,13]”References: 1 – U.S. National Climate Assessment (2018). Fourth National Climate Assessment. 2 – IPCC (2021). Sixth Assessment Report. 3 – American Meteorological Society (2021). State of the Climate in 2020. 4 – World Meteorological Organization (2021). The State of the Global Climate. 5 – Madonna et al. (2021). The New Radiosounding HARMonization (RHARM) Data Set of Homogenized Radiosounding Temperature, Humidity, and Wind Profiles With Uncertainties. JGR Atmospheres. 6 – NOAA (2016). El Niño and La Niña: Frequently asked questions. 7 – Steiner et al. (2020). Observed Temperature Changes in the Troposphere and Stratosphere from 1979 to 2018. Journal of Climate. 8 – Karl et al. (2015). Possible artifacts of data biases in the recent global surface warming hiatus. Science. 9 – Hedemann et al. (2017). The subtle origins of surface-warming hiatuses. Nature Climate Change. 10 – Power et al. (2017). Apparent limitations in the ability of CMIP5 climate models to simulate recent multi-decadal change in surface temperature: implications for global temperature projections. Climate Dynamics. 11 – Huber and Knutti (2014). Natural variability, radiative forcing and climate response in the recent hiatus reconciled. Nature Geoscience. 12 – Schmidt et al. (2014). Reconciling warming trends. Nature Geoscience. 13 – Medhaug et al. (2017). Reconciling controversies about the ‘global warming hiatus’. Nature.

https://science.feedback.org/review/earths-surface-warm-due-greenhouse-gas-christopher-monckton-watts-up-with-that/

Incorrect

Watts Up With That?, Christopher Monckton, 2022-04-04

“...Seven and a half years have passed since there was any trend in global warming at all” If global warming was caused by human emissions, temperature would rise at a steady rate

Incorrect: Global warming describes the long-term increase in global average surface temperature due mainly to human emissions of greenhouse gasses that trap infrared radiation. Short-term fluctuations around that trend due to natural variability are observed, but it is incorrect to conclude that the Earth’s current long-term warming trend is due to natural processes such as El Niño events. Misleading: Monckton claims that there has been a “pause” in global warming since 2015 based on a surface temperature dataset. This claim ignores that global warming continues, as documented in datasets of ocean heat content, global ice cover and sea-level rise among other sources.

To accurately measure global warming, it is necessary to look at all of the available evidence over several decades. A popular technique of climate science contrarians is to focus on short timescales during which surface temperatures reflect interannual variability in order to mask the overall warming trend observed in numerous climate datasets over the last several decades. Taken together, the evidence suggests that the rate of global warming has actually increased, not paused.

“...Seven and a half years have passed since there was any trend in global warming at all” “[Temperature] has been rising in occasional spurts in response to natural events such as the great Pacific shift of 1976 and the subsequent strong El Niño events, rather than at the somewhat steadier rate that one might expect if our continuing – and continuous – sins of emission were the primary culprit.”

A recent article in Watts Up With That, a blog with a long history of publishing scientifically unfounded claims, authored by Christopher Monckton argues that there has not been any global warming over the last 7 and a half years. Monckton, a former British politician with formal training in classics and journalism, further claims that past increases in temperature have been caused by natural processes such as “the great Pacific shift of 1976 and the subsequent strong El Niño events”. The argument that global warming has paused or stopped is not a new one. Climate science contrarians previously made this argument over a decade ago, using an apparent warming hiatus from 1998 to 2010 in an attempt to discredit emissions-driven global warming. Such claims, which have been previously assessed and debunked by NASA climate scientist Gavin Schmidt[1], rely upon a limited selection of data and ignore the long-term warming trend in global mean surface temperature (Fig. 1). Schmidt notes that this technique is disingenuous and statistically flawed because “looking at only 8 years of data is looking primarily at the ‘noise’ of interannual variability rather than at the forced long-term trend. This makes as much sense as analyzing the temperature observations from 10-17 April to check whether it really gets warmer during spring.”[1] Monckton’s recent claim is no exception, as the author uses only 7 and a half years of surface temperature data (from 2015 to 2022) in order to cast doubt on the large consensus of scientific evidence which demonstrates that surface temperatures are warming due to human greenhouse gas emissions.[2-5]This is an example of cherry picking data, selecting only a small subset of the available data in order to advance the author’s narrative, and leads Monckton to make the erroneous claim that natural shifts in climate, such as those caused by variations in the Pacific Ocean, have been responsible for surface temperatures rising “in occasional spurts”. However, global surface temperature observations reveal an unabated increasing trend since the early 1960s (Fig. 1), with only short term fluctuations around the trend.Figure 1. Global mean surface temperature (GMST) trend over the last 170 years. Black dots represent monthly temperature observations. The yellow line represents the modeled human contribution to temperature rise whereas the blue line represents the influence of natural (non-human) variability on temperature. The red line represents the combined modeled temperature response to both human-caused and natural temperature change. The fact that temperature observations track the red line but not the blue line indicates that human activities such as greenhouse gas emissions can explain modern global warming, but natural processes cannot. Source: Globalwarmingindex.org.Robert Jnglin Wills, a scientist at the University of Washington who studies the role of atmospheric and oceanic circulation in climate, commented, “It is well understood that global temperature changes result from a combination of anthropogenic greenhouse gasses and internal climate variability such as El Niño [a source of natural variability in the Pacific Ocean invoked by Monckton]. Anthropogenic global warming dominates the multi-decadal trends, while internal variability is important for trends up to a few decades.” El Niño events are a part of a natural variation in Pacific Ocean circulation patterns called the El Niño Southern Oscillation (ENSO). Two phases of ENSO exist: the El Niño mode and the La Niña mode, which give rise to distinct weather conditions around the planet.[6] During an El Niño event, trade winds weaken. These winds are responsible for driving the circulation of relatively warm surface waters from South America to Asia, and so weaker winds under an El Niño event result in an accumulation of warmer surface waters in the eastern Pacific but relatively less warming in the deeper parts of the ocean. By contrast, strong trade winds characteristic of a La Niña event result in an increase in temperature in deeper parts of the western Pacific but cooler conditions at the surface. In the tropical Pacific Ocean, sea surface temperatures are therefore relatively warmer during El Niño events but relatively cooler during La Niña events (Fig. 2). Due to the enormous size of the Pacific Ocean, sea-surface temperature variations in this region strongly influence globally averaged surface temperature datasets.[6]Figure 2. Departures in sea surface temperatures from average conditions during a La Niña event in 1988 and an El Niño event in 1997. Source: NOAA.As such, it is typical for the warmest year in a given decade as recorded by surface measurements to correspond to an El Niño event whereas the coolest year in a given decade is usually associated with a La Niña event (Fig. 3). Importantly, this does not indicate that the planet gains heat during an El Niño event or loses heat during a La Niña event, but rather that there is a redistribution of heat between the deep ocean (which is warmer than average during a La Niña event) and the planet’s surface/lower atmosphere (which is warmer than average during an El Niño event).Figure 3. Annual globally averaged surface temperature separated by decade. Note that most of the warmest surface temperature years in a given decade occur during El Niño events (red dots) and that most of the coldest surface temperature years in a given decade occur during La Niña events (blue dots). This is due to the vast size of the Pacific Ocean, which strongly influences globally averaged surface temperature datasets. Source: NOAA.Despite the transient influence of these events on globally averaged surface temperature during a given year, the data clearly demonstrate an increase in surface warming regardless of ENSO activity (Fig. 2). Monckton’s claim that large El Niño events after 1976 drove recent increases in surface temperature is therefore not supported by the data. In fact, a recent study by Cheng et al. found that ocean surface temperatures actually reached another all-time high in 2021 despite the cooling effect derived from the concurrent La Niña event.[7] So, what about that “pause” in global warming over the last 7 and a half years that Monckton discusses? In the blog post, the author uses a relatively stable trend in satellite temperature measurements and the HadCRUT4 dataset, a global compilation of surface temperature data produced by the Met Office Hadley Centre and Climatic Research Unit at the University of East Anglia[8], from 2015 to present as evidence for such a pause. However, because an El Niño event occurred from 2015 to 2016, some cooling relative to 2015 is expected and so choosing this year as a baseline is problematic. As Inglis notes, the interval selected by Monckton is “…cherry-picked to maximize the cooling trend following the El Niño event relative to the long-term anthropogenic warming trend.” Further, had Monckton included data from the subsurface ocean, which stores most of Earth’s excess heat (Fig. 4), the author would have identified a relatively linear increase in warming (Figs. 4 and 5). In fact, when considering all relevant climate indicators such as ocean heat content, sea-level change and global ice cover, the World Meteorological Organization identified an acceleration in the rate of climate change from 2015 to 2019, not a pause.[9] It is therefore misleading to claim that global warming has not occurred since 2015 and Monckton’s exclusion of additional climate datasets is another example of cherry picking.Figure 4. Time series of excess energy in the ocean, land, ice and atmosphere. The vast majority of excess energy caused by global warming is stored in the upper 700 m of the ocean. Note that ocean heat content has increased since 2015, contrary to Monckton’s claim that global warming has “paused” over this period. Source: von Schuckmann et al. (2020).[10]Figure 5: Time series of global ocean heat content from 0 to 700 m depth (where most ocean heat storage occurs). Note that ocean heat content has increased linearly since 2015, contrary to Monckton’s claim that global warming has “paused” over this period. Source: NOAA.As has been documented by an overwhelming consensus of scientific evidence[2-5], anthropogenic greenhouse gas emissions are the main driver of modern global warming. This was recently verified again by the Sixth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC), which states that “it is unequivocal that the increase of CO2, methane (CH4) and nitrous oxide (N2O) in the atmosphere over the industrial era is the result of human activities and that human influence is the principal driver of many changes observed across the atmosphere, ocean, cryosphere and biosphere” including global warming.[11] Monckton’s alternative conclusion that greenhouse gas emissions cannot be responsible for modern global warming is rooted in the author’s misrepresentation of equilibrium climate sensitivity, the level of global warming expected from a doubling of CO2 emissions. Citing Zelinka et al. (2020)[12], Monckton claims that climate scientists base their predictions of emissions-driven warming by first “imagining” that all warming is driven by CO2 and then back-calculating the impacts of emissions on absolute temperature. The author goes on to use an invented formula involving absolute temperature to assert that the impacts of CO2 on warming are negligible, a claim which is not supported by the scientific literature[11]. According to Wills, Monckton’s technique to recalculate emissions-driven warming is flawed because “whether it is calculated from models or observations, [equilibrium climate sensitivity] is a calculation about how the climate system responds to a perturbation away from an equilibrium state (e.g., warming in response to greenhouse gas emissions) and the absolute temperature is not a part of the calculation.” Indeed, this is true of the climate models evaluated in both Zelinka et al. (2020)[12] and the compilation of estimates from models and observations in the latest IPCC report.[11] Note that this article was updated on April 14, 2022 to include additional comments from Mark Richardson. Reviewers’ Feedback: Robert Jnglin Wills Research Scientist, University of Washington Department of Atmospheric Sciences: This article relies on cherry-picking and misconstruction of our knowledge of the climate system to argue that the role of anthropogenic greenhouse gasses in global warming has been overblown. It is well understood that global temperature changes result from a combination of anthropogenic greenhouse gasses and internal climate variability such as El Niño. Anthropogenic global warming dominates the multi-decadal trends, while internal variability is important for trends up to a few decades. The article selects a 7-year period following a large El Niño event in 2015-16, which is cherry-picked to maximize the cooling trend following the El Niño event relative to the long-term anthropogenic warming trend. It then acknowledges that cherry-picking and responds by further cherry-picking, calculating a trend back to 1850, which is muted by the weak greenhouse gas forcing prior to the 20th century, and comparing that against a somewhat high estimate of 1.8°C global warming by 2030 from the IPCC first assessment report in 1990.[13] Methods to estimate the future warming trend have improved since 1990, but this early estimate is still within the range of global temperature changes of 1.2-1.8°C (relative to 1850-1900; very likely range) that are predicted for the 20-year period 2021-2040 by the most recent IPCC report[11], showing just one example of how accurate early predictions of global warming were (one that was cherry picked because it was not as good as others). This article then goes on to misconstrue the physical understanding of global warming based on climate feedbacks, arguing that climate scientists ignore the warming of the earth by pre-industrial (non-anthropogenic) greenhouse gasses and the sun. In contrast, understanding of the role of greenhouse gasses and solar forcing in setting the pre-industrial temperature is foundational to the understanding of how much global temperature will rise in response to anthropogenic CO2 emissions.Mark Richardson Research Associate, Colorado State University/NASA JPL: This blog misleads readers with simple statistical mistakes and a discussion of climate physics that is basically gobbledygook. The latest data shows ongoing global warming[17], here is data with a statistical fit that has been shown to accurately estimate longer-term changes.[18] The 1.2 °C (2.2 °F) warming is obviously not a straight line[19], and the last decade rate is around 2.2 °C per century. The blogger mistakenly uses a straight line to claim just 0.5 °C per century recently, and also incorrectly calculates statistical uncertainties.[20] Smaller year-to-year temperature jumps are often related to the Pacific El Niño-La Niña cycle. The figure below shows global temperatures in red and an El Niño dataset in blue.El Niño spikes trigger short-term warming, like in 1997/98 and 2015/16. The blogger claims some “great El Niño shift” in 1986 that isn’t in the data, and research has found that the Pacific has not acted to accelerate warming.[21,22] The blogger begins one part of their analysis near the strong warming El Niño event of 2015/16 and ends during the recent extended La Niña event. By picking a short period with a strong El Niño-La Niña switch, the long-term trend is temporarily hidden. Notably, if you only look at years that were strongly affected by La Niña, 2021 is the warmest of them all. El Niño and La Niña events have less effect on the Earth’s heat buildup. The left panel below shows measured ocean heat, and the right panel satellite-measured sea level changes. These show clearly that global warming is continuing.The blog’s later claims about how climate models calculate climate change, with a reference to a 2020 study by Dr. Mark Zelinka and colleagues[12]and others are just detached from the reality of what those researchers did, and are so nonsensical that it’s not possible to judge them scientifically.Annotations: The statements quoted below are from the article; comments are from the reviewers (and are lightly edited for clarity). “IPCC (1990, p. xxiv) confidently predicted 1.8 K global mean anthropogenic warming from 1850-2030.”Robert Jnglin Wills Research Scientist, University of Washington Department of Atmospheric Sciences: The value quoted is the “best estimate” from that IPCC report and does not include the full range of predicted values. For example, the most recent IPCC report[11] predicts 1.2-1.8°C of global warming (relative to 1850-1900; very likely range) for the 20-year period 2021-2040, with a best estimate of 1.5°C, and 2.8-4.6°C of global warming (relative to 1850-1900; moderately high emissions scenario; very likely range) for the 20-year period 2081-2100, with a best estimate of 3.6°C. For context, the IPCC Special Report on Global Warming of 1.5°C[14] compiles evidence that extreme heat, extreme rainfall, drought, ocean acidification, and associated impacts on ecosystems and human society will be greater at 2°C of global warming than at 1.5°C of global warming. “To forestall the usual whingeing about “cherry-picking” from the climate-fanatical trolls, here is the entire HadCRUT4 record of monthly global mean surface temperature anomalies for the 172 years 1850-2021. The trend is a not particularly catastrophic half a degree per century equivalent. ” Robert Jnglin Wills Research Scientist, University of Washington Department of Atmospheric Sciences: Looking at the NASA GISTEMP observational temperature data between 1880 and 2018, Parsons et al. (2020)[15] show that 100-year trends have ranged between 0.35 °C/100 years (1880–1979) and 1.0 °C/100 years (1919-2018), with a median value of 0.69 °C/100 years. The higher trends in later periods reflect the increase in greenhouse gas emissions rate over time and show that the 0.54 °C/century reported in this article is on the lower end of what has been observed. Parsons et al. (2020)[15] also show that no climate model simulates 100-year trends as large as that observed over 1919-2018 unless they include anthropogenic greenhouse gas emissions. “For 1850, the system-gain factor, by which one multiplies a direct warming (or reference sensitivity) to allow for feedback response and derive final warming (or equilibrium sensitivity) is not, as Hansen (1984), Schlesinger (1988) or Lacis (2010, 2013) absurdly imagined, 32 / 8 = 4. Instead, it is (255 + 32) / (255 + 8) < 1.1. Their error is as elementary as that.” Robert Jnglin Wills Research Scientist, University of Washington Department of Atmospheric Sciences: This is not how the equilibrium climate sensitivity (ECS) – the global warming in response to a doubling of CO2 – is calculated. The 4°C value given in Zelinka et al. 2020[12] is calculated from a mean of multiple climate models, and the models have an ECS range of 1.8 to 5.6°C. However, the IPCC Sixth Assessment Report[11] considers multiple lines of evidence including observations and states that there is high confidence that ECS is within the range of 2.5°C to 4°C, with a best estimate of 3°C. Whether it is calculated from models or observations, ECS is a calculation about how the climate system responds to a perturbation away from an equilibrium state (e.g., warming in response to greenhouse gas emissions) and the absolute temperature is not a part of the calculation. “For every hillside is infested with whomping windmills – 14th-century technology to address a 21st-century non-problem. Birds, bees and bats by the billion are being blended or batted out of the sky.”Robert Jnglin Wills Research Scientist, University of Washington Department of Atmospheric Sciences: “The State of the Birds 2014” Report estimates that 234,000 birds per year are killed by wind turbines in the U.S. compared to 2.4 billion per year killed by cats in the U.S. and 599 million per year killed by building windows in the U.S.[16] “It will make no difference to global temperature. Even if all the nations bound by the Paris discords actually achieved net-zero emissions by 2050, as Mr Johnson fatuously proposes, the global warming abated would be little more than a twentieth of a degree, for most countries are not bound by it.” Robert Jnglin Wills Research Scientist, University of Washington Department of Atmospheric Sciences: This is misleading, because it talks about a scenario where only countries bound by the Paris Agreement reduce their greenhouse gas emissions, when the Paris Agreement is a framework for setting emissions targets and does not itself have binding emissions targets. The IPCC Sixth Assessment Report on the Mitigation of Climate Change estimates that a scenario with an 85% reduction in global greenhouse gas emissions by 2050 would reduce global warming by more than 1°C compared to a scenario with a global 5% emissions reduction by 2050 (Global Emissions Pathway Category C1 vs. C6).[11]References: 1 – Schmidt (2008). Uncertainty, noise and the art of model-data comparison. RealClimate. 2 – Oreskes (2004) The scientific consensus on climate change. Science. 3 – Anderegg et al. (2010) Expert credibility in climate change. Proceedings of the National Academy of Sciences. 4 – Cook et al. (2013) Quantifying the consensus on anthropogenic global warming in the scientific literature. Environmental Research Letters. 5 – Cook et al. (2016) Consensus on consensus: a synthesis of consensus estimates on human-caused global warming. Environmental Research Letters. 6 – NOAA (2021). El Niño and La Niña: Frequently asked questions. 7 – Cheng et al. (2021). Another Record: Ocean Warming Continues through 2021 despite La Niña Conditions. Advances in Atmospheric Sciences. 8 – Met Office (2016). HadCRUT4. Hadley Centre observations datasets. 9 – World Meteorological Organization (2019). Global Climate in 2015-2019: Climate change accelerates. 10 – von Shuckmann et al. (2020). Heat stored in the Earth system: where does the energy go? Earth System Science Data. 11 – IPCC (2022). Sixth Assessment Report. 12 – Zelinka et al. (2020). Causes of higher climate sensitivity in CMIP6 models. Geophysical Research Letters. 13 – IPCC (1990). First Assessment Report. 14 – IPCC (2018). Special Assessment Report on the Impacts of Global Warming of 1.5 °C. 15 – Parsons et al. (2020). Magnitudes and Spatial Patterns of Interdecadal Temperature Variability in CMIP6. Geophysical Research Letters. 16 – State of the Birds (2014). The State of the Birds Report. 17 – Richardson (2022). Prospects for Detecting Accelerated Global Warming. Geophysical Research Letters. 18 – Clarke and Richardson (2021). The Benefits of Continuous Local Regression for Quantifying Global Warming. Earth and Space Science. 19 – Cahill et al. (2015). Change points of global temperature. Environmental Research Letters. 20 – Thiébaux and Zwiers (1984). The Interpretation and Estimation of Effective Sample Size. Journal of Applied Meterology and Climatology. 21 – England et al. (2014). Recent intensification of wind-driven circulation in the Pacific and the ongoing warming hiatus. Nature Climate Change. 22 – Zhou et al. (2016). Impact of decadal cloud variations on the Earth’s energy budget. Nature Geoscience.

https://science.feedback.org/review/robust-scientific-evidence-supports-human-activity-drives-global-warming-contrary-to-claims-co2-coalition-blog-post-andy-may/

Incorrect

CO2 Coalition, Andy May, 2022-03-03

"There is no evidence, other than models, that human CO2 emissions drive climate change and abundant evidence that the Sun, coupled with natural climate cycles, drives most, if not all, of recent climate changes"

Incorrect: Solar irradiance has had a negligible impact on Earth’s climate since the industrial era. Atmospheric observations do not support the hypothesis that the Sun has driven modern warming. There is a consensus of scientific evidence that warming is driven by human greenhouse gas emissions. Misleading: While models do play a role in attributing warming to human emissions, this claim ignores the abundance of scientific evidence based on independent observations that also point to the same conclusion. Inaccurate: The Climate Model Intercomparison Project 5 (CMIP5) suite of climate models discussed by May have been shown to reliably reproduce historical trends in climate without evidence of a warming bias.

All available scientific evidence, including independent physical observations, indicates that global warming is driven by human greenhouse gas emissions and that solar forcing plays an extremely minor role in contemporary climate.

"There is no evidence, other than models, that human CO2 emissions drive climate change and abundant evidence that the Sun, coupled with natural climate cycles, drives most, if not all, of recent climate changes"

A recent blog post by Andy May published by the CO2 Coalition, a nonprofit organization funded largely by fossil-fuel interest groups, claims that the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC)[1] relies upon model evidence to conclude that greenhouse gas emissions, such as CO2, drive contemporary global warming. May, who presents himself as a retired geologist, goes on to say that these models employ “circular proof” to attribute warming to CO2 emissions and argues that there is “abundant evidence that the Sun, coupled with natural climate cycles, drives most, if not all, of recent climate changes”, rejecting the consensus of scientific evidence that global warming is caused by human greenhouse gas emissions[2-5]. The “abundant evidence” that May invokes is a single article published in a journal unrelated to climate science by Connolly et al. (2021), which uses simple linear regression (itself a basic statistical model) to establish links between solar irradiance and the surface temperature of select northern-hemisphere locations. “It is ironic…that they consider these fairly rigorous and physical model-based methods [of the IPCC] to be disqualifying and yet in the next sentence celebrate Connolly et al’s (2021) ‘simple linear regression’ of surface temperature records against total solar irradiance [which is also a model] as ‘abundant evidence’ that the Sun drives climate change,” commented Henri Drake, a postdoctoral fellow at Princeton University and NOAA’s Geophysical Fluid Dynamics Laboratory. Moreover, observations indicate that solar irradiance has actually decreased since the 1960s, which is in clear contrast to the increasing trend in global surface temperature, showing that the Sun could not have driven warming during this period (Figure 1). Figure 1 – Comparison of the global surface temperature time series (red) and the Sun’s energy that Earth receives (yellow) in watts per square meter since 1880. One can see that since the 1960s, the global temperature and solar activity have varied in opposite directions. Source: NASA/JPL-Caltech. Another reason why scientists know that the Sun is not responsible for modern warming can be found in atmospheric observations. Greenhouse gases absorb heat in the form of infrared radiation in the lower atmosphere (troposphere), resulting in warming of the planet’s surface and lower atmosphere. By contrast, greenhouse gases produce a cooling effect on the upper atmosphere (stratosphere), making the offset between the temperature in the troposphere and stratosphere a useful “fingerprint” of global warming caused by emissions[6-9]. Such a temperature offset between the lower and upper atmosphere is not expected from warming driven by solar irradiance, as this mechanism increases the temperature of the entire atmosphere. Atmospheric observations indicate that the troposphere has warmed while the stratosphere has cooled over the last several decades (Figure 2), in line with expectations of warming driven by greenhouse gases. Figure 2. Global temperature variations in the upper atmosphere (top graph) and in the lower atmosphere (bottom graph) since the 1960s. We observe a warming at the surface and a cooling above, which is consistent with the effect of added greenhouse gases in the atmosphere and inconsistent with the hypothesis of solar influence. Source: Met Office Hadley Centre. In addition to this atmospheric “fingerprint”, incoming and outgoing radiation measurements from satellite observations provide another line of direct evidence linking atmospheric greenhouse gas content to global warming[10,11]. Such studies invalidate May’s statement that “the human influence on climate has never been observed or measured”. When assessing the influence of all possible climate forcing mechanisms in a comprehensive literature review, the Fourth National Climate Assessment of the U.S.[12] identified CO2 and other well-mixed greenhouse gases as the dominant drivers of modern warming whereas the influence of solar activity was shown to be extremely minor (Figure 3), a finding also supported by the IPCC’s Fifth Assessment Report[1] and, more recently, the Sixth Assessment Report[13]. Figure 3. Time evolution in effective radiative forcings (ERFs) across the industrial era for anthropogenic and natural forcing mechanisms. The ERF measures the net heat gain or loss in the Earth’s climate system. Well-mixed greenhouse gases (WMGHG) are the long-lived gases that have a strong impact on climate and include carbon dioxide, methane, nitrous oxide, and different kinds of chlorofluorocarbons. Source: U.S. Fourth National Climate Assessment. May’s claim that climate models use “circular proof” in order to attribute warming to greenhouse gas emissions is rooted in the author’s misunderstanding of a value derived from climate models called transient climate response (TCR). TCR is the degree of model-simulated global warming associated with a 1% increase in CO2 per year compared to the preindustrial CO2 concentration[14]. Referencing Gillett et al., (2013)[14], May writes that previous IPCC models overestimated TCR and that the explicit assumption of the relationship between CO2 and warming in the definition of TCR is an example of “circular proof” when attributing the cause of warming to greenhouse gas emissions. However, TCR is not used in climate models to attribute warming to greenhouse gas emissions, but is rather a metric that scientists calculate to compare the performance of simulations from multiple climate models against each other and observations. Gillett et al. (2013) used more recent model simulations and observational temperature data not available to IPCC authors at the time in order to calculate a new range of estimates for the transient climate response to cumulative carbon emissions (TCRE). Related to TCR, TCRE is defined as “the ratio of global-mean warming to cumulative emissions at CO2 doubling in a 1% [per year] CO2 increase experiment”.[14] The new estimates were found to be between 0.7 and 2.0 K per EgC (exagrams, or 1015 kg, of carbon).[14] By contrast, previous estimates derived from models were reported to be between 0.8 and 2.4 K per EgC. This indicates that the level of simulated global-mean warming caused by greenhouse gas emissions is different for each model. The spread in TCR is due to different representations of the complex physical climate system and biogeochemical processes that models approximate. Thus, they shed light on the importance of accurately representing these processes in models. However, despite inter-model disagreements in TCR, the Climate Model Intercomparison Project 5 (CMIP5) models questioned by May were previously shown to reliably reproduce observational trends in surface land temperature, surface ocean temperature and ocean heat content around the world when using both natural (e.g., the Sun) and anthropogenic (e.g greenhouse gas emissions) forcings since the beginning of the twentieth century, but not natural forcings alone (Figure 4). The range of temperature and ocean heat content values simulated by the suite of CMIP5 models, of which observations generally fall close to the center, does not support May’s statement that models “clearly overestimate” warming. Similar claims about IPCC climate models have been previously reviewed by Climate Feedback and were found to be inaccurate. This is also consistent with more recent research that evaluated the performance of earlier CMIP models and found that “climate models published over the past five decades were skillful in predicting subsequent GMST [global mean surface temperature].”[15] Figure 4. CMIP5 model simulations of land and ocean surface temperatures in addition to ocean heat content since the beginning of the twentieth century using natural and anthropogenic (e.g., greenhouse gas emissions) climate forcings (red) and natural (e.g., solar irradiance) forcings alone (blue). Black lines denote observations. Source: Working Group I, IPCC AR5 Scientists’ Feedback: Henri Drake Postdoctoral research associate, Princeton University: “The author’s conclusion of circular logic is based on their misunderstanding of the TCRE [Transient climate response to cumulative carbon emissions, defined as ‘the ratio of global-mean warming to cumulative emissions at CO2 doubling in a 1% [per year] CO2 increase experiment’[14]]. The definition of the TCRE is not itself ‘proof’ that CO2 emissions drive climate change; it is just a simple metric to summarize Earth’s climate sensitivity to CO2 emissions and to facilitate comparisons between models and observations. The author is correct that detection and attribution methods, as used in the paper, indirectly use models to determine the spatial fingerprints of separate forcing components. It is ironic, however, that they consider these fairly rigorous and physical model-based methods to be disqualifying and yet in the next sentence celebrate Connolly et al’s (2021) ‘simple linear regression’ of surface temperature records against total solar irradiance [which is also a model] as ‘abundant evidence’ that the Sun drives climate change. Worst of all, the author completely ignores the fact that even putting General Circulation Models [the type of state-of-the-art models used by the IPCC] aside completely, there is ‘abundant evidence’ of greenhouse gas-induced climate changes, perhaps most notably the spectrally-resolved measurements of incoming/outgoing radiative fluxes which clearly show the net effects of absorption and re-emission in greenhouse gas bands.[12,13]” References: 1 – IPCC (2013) Working Group I, IPCC AR5. 2 – Oreskes (2004) The scientific consensus on climate change. Science. 3 – Anderegg et al. (2010)Expert credibility in climate change.Proceedings of the National Academy of Sciences. 4 – Cook et al. (2013) Quantifying the consensus on anthropogenic global warming in the scientific literature.Environmental Research Letters. 5 – Cook et al. (2016) Consensus on consensus: a synthesis of consensus estimates on human-caused global warming. Environmental Research Letters. 6 – Lockwood & Fröhlich (2007)Recent oppositely directed trends in solar climate forcings and the global mean surface air temperature. In Proceedings of the Royal Society of London A: Mathematical, Physical and Engineering Sciences. 7 – Lockwood (2008)Recent changes in solar outputs and the global mean surface temperature. III. Analysis of contributions to global mean air surface temperature rise. In Proceedings of the Royal Society of London A: Mathematical, Physical and Engineering Sciences. 8 – Santer et al. (2013)Human and natural influences on the changing thermal structure of the atmosphere.Proceedings of the National Academy of Sciences. 9 – Hegerl & Wallace (2002)Influence of patterns of climate variability on the difference between satellite and surface temperature trends. Journal of Climate. 10 – Raval & Ramanathan (1989). Observational determination of the greenhouse effect. Nature. 11 – Schmidt et al. (2010). Attribution of the present-day total greenhouse effect. Journal of Geophysical Research. 12 – U.S. Fourth National Climate Assessment, Climate Science Special Report. 13 – IPCC (2021). Working Group I, IPCC AR6 14 – Gillett et al. (2013). Constraining the ratio of global warming to cumulative CO2 emissions using CMIP5 simulations. Journal of Climate. 15 – Hausfather et al. (2019). Evaluating the performance of past climate model projects. Geophysical Research Letters.

https://science.feedback.org/review/more-than-75-percent-amazon-rainforest-losing-resilience-the-washington-post-sarah-kaplan/

Mostly accurate

The Washington Post, Sarah Kaplan, 2022-03-07

More than 75 percent of the rainforest is losing resilience; More than half of the rainforest could be converted into savanna in a matter of decades

Accurate: A recent study found that “more than three-quarters of the Amazon rainforest has been losing resilience since the early 2000s." Imprecise: Rather than turn into a savanna ecosystem, the Amazon rainforest would more likely transition into a “savanna-like” ecosystem. The difference would be that the degraded Amazon ecosystem would not contain as many tree species and would not store as much carbon as a savanna ecosystem.

The Amazon rainforest is the largest rainforest in the world, home to a vast array of biodiversity, including many species yet to be discovered by scientists. It faces significant risks from deforestation and climate change, and recent research shows that these threats are causing much of the forest to lose resilience – the ability to bounce back from disturbances such as logging, fire and drought.

Satellite images taken over the past several decades reveal that more than 75 percent of the rainforest is losing resilience...This widespread weakness offers an early warning sign that the Amazon is nearing its “tipping point”; The ecosystem could suffer sudden and irreversible dieback. More than half of the rainforest could be converted into savanna in a matter of decades

On March 7, the Washington Post published a story about the declining health of the Amazon. The story, based on a March study published in Nature Climate Change, reported that, according to satellite images, the Amazon rainforest is “nearing its tipping point,” with more than 75 percent of the rainforest losing resilience.[1] The Nature Climate Change study analyzed the Amazon’s resilience since the early 2000s and, consistent with the claim in the Washington Post, it found that “more than three-quarters of the Amazon rainforest has been losing resilience since the early 2000s.” The Washington Post’s claim “is 100% correct and it is the main result of the article on Nature Climate Change,” said Carlos Nobre, earth system scientist at the University of São Paulo, Brazil’s Institute of Advanced Studies. Research shows that the Amazon rainforest – the largest rainforest in the world – faces “dual threats” of climate change and deforestation.[2] A 2021 study estimated that, as a result of human activities, the Amazon has seen a “forest loss of around 17%, of which 14% has been converted mostly to agricultural land.”[3] Deforestation and climate change can lead to reduced dry season rainfall in the Amazon, and this lack of rain can lead to reduced forest resilience, making it more susceptible to future stressors, such as fire, drought and logging.[4] The image shows the decline of moisture in the air over the Amazon rainforest, particularly across the south and southeastern Amazon, during the dry season months – August through October – from 1987 to 2016. The measurements are shown in millibars. Credit: NASA/JPL-Caltech, NASA Earth Observatory “The twin pressures of deforestation and climate change on the Amazon rainforest remain a great concern,” Peter Cox, professor of climate system dynamics at the University of Exeter, wrote in Carbon Brief in 2020. “We are unlikely to know the vulnerability of the rainforest to climate change with any confidence until it is too late. However, we are sure that human-caused deforestation reduces the resilience of the forest to climate change and other stressors.” As reported by Carbon Brief, the Nature Climate Change study’s lead author Chris Boulton noted in a press conference that, although his study shows that the Amazon rainforest is “approaching a tipping point” – the point when changes in the forest become irreversible – it is unclear, based on research so far, when that tipping point will occur. The Washington Post also claims that “more than half of the rainforest could be converted into savanna in a matter of decades.” That claim “needs a few considerations,” Nobre said. “The conversion to tropical savanna natural ecosystem is more complicated and it would take many centuries,” Nobre said. “The likely conversion is towards open canopy degraded ecosystems. They may look like a tropical savanna, but not with all the tree species and also not storing as much carbon in the soil.” Scientists’ Feedback: Carlos Nobre Earth System Scientist, University of São Paulo, Brazil’s Institute of Advanced Studies: The first [claim – “satellite images taken over the past several decades reveal that more than 75 percent of the rainforest is losing resilience”] is 100% correct and it is the main result of the article on Nature Climate Change. The second [claim] needs a few considerations. Particularly, the sentence “more than half of the rainforest could be converted into savanna in a matter of decades”. The conversion to tropical savanna natural ecosystem is more complicated and it would take many centuries. The tropical savannas to the south and north of the Amazon rainforest are very rich in fire-resistant tree species. The likely conversion is towards open canopy degraded ecosystems. They may look like a tropical savanna, but not with all the tree species and also not storing as much carbon in the soil. Perhaps the sentence could be: “more than half of the rainforest could be converted into ‘savanna’-like open canopy degraded ecosystems in a matter of decades”. References: Boulton et. al (2022). Pronounced loss of Amazon rainforest resilience since the early 2000s. Nature Climate Change. Malhi et. al (2008). Climate Change, Deforestation, and the Fate of the Amazon. Science. Gatti et. al (2021). Amazonia as a carbon source linked to deforestation and climate change. Nature Climate Change. Zemp et. al (2017). Deforestation effects on Amazon forest resilience. Geophysical Research Letters.

https://science.feedback.org/review/wall-street-journal-steven-koonin-publishes-misleading-claims-climate-change-influences-greenland-ice-melt/

-1.75

The Wall Street Journal, by Steve Koonin, on 2022-02-17.

"Greenland’s Melting Ice Is No Cause for Climate-Change Panic"

[1] Briner et al. (2020). Rate of mass loss from the Greenland Ice Sheet will exceed Holocene values this century. Nature. [2] Trusel et al (2018) Nonlinear rise in Greenland runoff in response to post-industrial Arctic warming. Nature. [3] 1 – Kjeldsen et al. (2015) Spatial and temporal distribution of mass loss from the Greenland Ice Sheet since AD 1900. Nature. [4] The IMBIE Team (2019). Mass balance of the Greenland Ice Sheet from 1992 to 2018. Nature. [5] Kjeldsen et al. (2015). Spatial and temporal distribution of mass loss from the Greenland Ice Sheet since AD 1900. Nature. [6] Hugonnet et al (2021). Accelerated global glacier mass loss in the early twenty-first century. Nature. [7] Church et al. (2013). Sea Level Change. In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. [8] Aschwanden et al. (2019). Contribution of the Greenland Ice Sheet to sea level over the next millennium. Science advances. [9] Nerem et al. (2018) Climate-change–driven accelerated sea-level rise detected in the altimeter era. Proceedings of the National Academy of Sciences.

Reviewers’ Overall Feedback: Lauren Simkins Assistant Professor, University of Virginia: While the article uses real data on ice mass balance of the Greenland Ice Sheet, the message of slower rate of ice mass loss in the past 8-9 years does not mean that human-induced warming is not a concern, or less of a concern now. The slower rates of ice mass loss highlight the dynamic, non-linear, and often asynchronous response of the ice sheet to short (annual and sub-annual) changes in weather; yet the long-term, multi-decadal trends in climate and ice mass loss are where we should focus our attention. Overall, the article is, I believe, intentionally misleading and flawed, by presenting real data to support inaccurate interpretations and potential outcomes. Marco Tedesco Lamont Research Professor, Lamont-Doherty Earth Observatory of Columbia University: The article picks only the last 10 years, excluding the remaining time series for the context, hence “cherry-picking” that period and not considering many climatic factors when describing the downward trend. Eric Rignot Professor, University of California Irvine & Jet Propulsion Laboratory: The article does not quote clear sources and time periods for mass loss, which is increasing with time. Quoted numbers, 110gt/yr, is low and obscure. The article does not discuss the linkage between physical processes driving the mass loss and human activities, hence has little logic and physical basis for making claims. The article’s claims exaggerate the statements made by scientists about the urgency of the situation but the argument is vague, not quantitative and hand wavy. The old argument that the 30s were warmer than present is false. Anders Anker Bjork Assistant professor, University of Copenhagen: Science knows what caused the early 20th century warming and what is causing the current warming. The WSJ title could just as well have been: ‘Last decade showed highest mass loss from Greenland ever measured’. Annotations: “The average annual ice loss … would cause sea level to rise by 3 inches by the end of this century, Jason Briner Professor, Department of Geology, University at Buffalo: Of course keep this 3” in perspective. This does not include sea level coming from Antartica, from mountain glaciers, from thermal expansion of the oceans. It is a little narrow (and sure, maybe underwhelming for some) to consider just one of these sources in isolation. “and if losses were to continue at that rate, it would take about 10,000 years for all the ice to disappear, causing sea level to rise more than 20 feet” Jason Briner Professor, Department of Geology, University at Buffalo: This is only true if the rate of annual ice loss were to remain the same as today’s rate for a long time. That said, highly vetted and peer-reviewed climate and ice sheet models, which are very good at correctly modeling Earth’s past, suggest that the present rates of ice sheet mass loss will not stay the same, but will increase.[1] Lauren Simkins Assistant Professor, University of Virginia: Rather than extrapolating cumulative ice loss, a peer-reviewed study that uses fine-scale ice sheet model with uncertainty quantification indicates the Greenland Ice Sheet could disappear entirely in 1,000 years.[8] The “notion that humans are melting Greenland” is “simplistic”, “There are large swings in the annual ice loss and it is no larger today than it was in the 1930s, when human influences were much smaller”, “the annual loss of ice has been decreasing in the past decade even as the globe continues to warm.” Jason Briner Professor, Department of Geology, University at Buffalo: Of course such a statement is simplistic, yet still likely more or less true. And of course there are large swings in the annual ice loss rate – these swings have tracked well both Arctic climate (on decadal scales) and with modes of climate variability and weather patterns (on the sub-decadal scale). Annual loss has been decreasing in the past decade Lauren Simkins Assistant Professor, University of Virginia: The rate of ice mass loss has decreased since 2013, yet the annual loss of ice is still considerable and reflects the long-term impact of atmospheric warming and ice dynamic response to such.[4] [The WSJ article also criticizes the following statement made by, according to Koonin, “the media and politicians”:] “Greenland ice sheet on course to lose ice at fastest rate in 12,000 years.” Jason Briner Professor, Department of Geology, University at Buffalo: Of course this hits home, as the author of the paper with more or less that title. There’s nothing about this statement that is incorrect or exaggerated. It is important to know that it is based on a study that compiled and modeled rates of mass loss PER CENTURY and relies on the well-vetted models mentioned above to provide best estimates (with ranges given uncertainties) for this century (which isn’t over yet!). Our model, which performed well in simulating Greenland’s history, and stacks up well against other models that took part in a state-of-the-art model comparison effort, suggests that rates this century will, on average, have higher mass loss rates than at present as the Arctic is expected to heat up. It is all this information that goes into that quote. Its shrinking has been a major cause of recent sea-level rise, but as is often the case in climate science, the data tell quite a different story from the media coverage and the political laments Lauren Simkins Assistant Professor, University of Virginia: The data reflect major losses of ice, via ice thinning, ice mass loss, and accelerated ice discharge, despite a lower magnitude of overall ice mass loss since 2013; but the mass balance is still negative and on track (based on the multi-decadal trend) to continue to lose mass. Since human warming influences on the climate have grown steadily—they are now 10 times what they were in 1900— you might expect Greenland to lose more ice each year. Instead there are large swings in the annual ice loss and it is no larger today than it was in the 1930s, when human influences were much smaller. Lauren Simkins Assistant Professor, University of Virginia: This is a really simplistic interpretation that negates physics of glacial ice and its response to annual ocean and atmospheric temperatures. The non-linear response of the Greenland Ice Sheet to warming and the lag time between, for example, a warm month or couple of months and ice mass loss means that there are asynchronous changes in climate and ice mass balance.

https://science.feedback.org/review/prageru-video-on-climate-change-repeats-a-range-of-misleading-claims-by-steven-koonin/

-1.4

PragerU, by Steve Koonin, on 2024-10-25.

"Is There Really a Climate Emergency?"

Reviewers’ Overall Feedback: Mark Richardson Research Associate, Colorado State University/NASA JPL: The author of this video, Dr. Steven Koonin, says he is following the scientific reports published by the UN and US government, but by subtly changing wording and choosing not to mention important context this video is very likely to mislead readers. This style of selective wording and lack of context, an approach called “cherry picking”, applies to every one of Dr. Koonin’s scientific comments. Justin Schoof Professor and Chair, Southern Illinois University: Many statements are misleading and others are simply incorrect. Mark Zelinka Research Scientist, Lawrence Livermore National Laboratory: I believe most of Dr. Koonin’s talking points have been refuted in several other places, most notably here on climatefeedback.org. It appears as though most of the PragerU talking points are the same as those in his book and have not been updated to reflect being repeatedly corrected by the climate science community. Andrew King Research fellow, University of Melbourne: This video has many major errors and it is difficult to review the veracity of many claims due to the lack of referencing of sources. Ilissa Ocko Climate Scientist, Environmental Defense Fund: This piece is very misleading and uses borderline inaccurate/cherry-picked “facts” and flawed reasoning to make its case. For example, there is myriad evidence that many extreme weather events are intensifying and/or becoming more frequent in most parts of the world (see Intergovernmental Panel on Climate Change Sixth Assessment Report Working Group I Chapter 11, 2021); the extent depends on the region and the type of event, and therefore sweeping generalities (e.g. global flooding) or cherry-picked examples (e.g. heat waves in the U.S) do not adequately convey the severity of climate change in impacting communities and ecosystems worldwide.Annotations: The statements quoted below are from the video; comments are from the reviewers (and are lightly edited for clarity). Claim: “For example, government reports state clearly that heat waves in the US are now no more common than they were in 1900.” Justin Schoof Professor and Chair, Southern Illinois University: Many statements are misleading and others are simply incorrect. As a single example, there is a statement regarding heat waves in the U.S. being no worse than they were in 1900, according to government reports. Figure 1.2 of the 2018 U.S. National Climate Assessment clearly shows an increase in heat waves in recent decades. Heat waves are getting worse in the United States, especially in recent decades. Parts of the early 20th century, particularly the 1930s, were very warm in the United States. This was regional rather than global, but can be used to make recent changes in the US seem less relevant than they are. Lastly, we expect warming from greenhouse gases to impact minimum temperatures more than maximum temperatures and that’s exactly what’s happening. It makes for less dramatic warming in the maximums relative to the minimums. Daniel Swain Climate Scientist, University of California, Los Angeles: There is now extensive evidence that heatwaves are increasing due to global warming, both globally and also specifically in the United States–and recent government reports (in addition to peer-reviewed research in other venues) reflect this. For example: The EPA and the National Climate Assessment. It is true that heatwaves in the United States, although they are indeed increasing in aggregate, have increased at a slower rate than across much of the rest of the globe. But the reality is that the United States is indeed experiencing more extreme heat today than it was decades ago. Claim: “Hurricane activity is no different than it was a century ago.” Kevin Walsh Professor of Meteorology, University of Melbourne: The most recent authoritative assessment of this particular issue (Knutson et 2019), of which I was a co-author, concluded the following (among other conclusions): 1. There has been a poleward migration of tropical cyclone tracks in the western North Pacific region. 2. There has been an increase in the global proportion of very intense tropical cyclones in recent decades, as well as an overall increase in tropical cyclone intensity. 3. There has been an increased incidence of intense precipitation events associated with tropical cyclones in the Gulf of Mexico region. It was also concluded that these changes were likely due to anthropogenic climate change. So I’m not sure how this leads the author to state that there has been no change in hurricane activity in the last 100 years. Kerry Emanuel Professor of Atmospheric Science, MIT: [Comment from a previous evaluation of a similar claim.] This statement is flat out wrong. In the first place, the theoretically predicted trends would not have been detectable in the sparse and noisy hurricane record until recently, and in fact they HAVE recently been detected. The most up-to-date research published in the Proceedings of the National Academy of Sciences demonstrates an increase in the proportion of hurricanes that become major hurricanes (Category 3-5) globally, supporting theoretical predictions that date back to 1987 (see figure below). The proportion of major hurricane intensities to all hurricane intensities globally from 1979-2017. Data is binned into 3-year periods. The proportion of global major hurricanes increased by 25% over the 39-year time period analyzed. From Kossin et al. (2020).[20] Claim: “Floods have not increased across the globe over more than seventy years.” Mark Richardson Research Associate, Colorado State University/NASA JPL: Regarding floods, there are several types including flash, coastal and river flooding. The UN report [2] states that heavy rain events have gotten more extreme and more common “over a majority of land regions with good observational coverage since 1950”, and although some regions dried, the general tendency is therefore higher flash-flood risk (our recent work supports this[7]). Meanwhile, at tide gauges scattered around Earth’s coasts there has been a “median 165% increase in high-tide flooding over 1995—2014 relative to 1960—1980”. Changes in high river levels depend on the region, but the data are sparse so there is “low confidence” in global changes. Dr. Koonin chooses not to report the increased flash or coastal flooding risk, but instead states that global floods haven’t increased. This is not supported by the report he claims to be using. Claim: “Greenland’s ice sheet isn’t shrinking any more rapidly today than it was 80 years ago.” Daniel Swain Climate Scientist, University of California, Los Angeles: The Greenland Ice Sheet is currently melting at a rate comparable to (or greater than) any in the past 12,000 years, let alone 80 years ago. For more on this claim, see our article review from April 2021. Claim: “The media, the politicians, and a good portion of the climate science community attribute every terrible storm, every flood, every major fire to “climate change.” Daniel Swain Climate Scientist, University of California, Los Angeles: This statement is not a quantitative claim, but it appears to connote that scientists are systematically attributing extreme events to climate change without evidence. This is simply not correct. In fact, an entire sub-field of climate and atmospheric science has developed in recent years specifically aimed at developing and implementing scientifically valid methods of attributing specific extreme events to climate change (known as “extreme event attribution.”) It’s impossible to make a blanket statement about all kinds of extreme events (global warming is increasing the frequency and intensity of global heatwaves, for example, but decreasing the intensity of global cold snaps), but numerous scientists around the world now conduct research on this specific topic, and often find physically and statistically overwhelming evidence that climate change has increased the risk of specific events such as individual extreme heatwaves and extreme downpours (among other types of events). Some overviews of how “extreme event attribution” is conducted, as well as examples of applications to specific events, include: https://www.cell.com/one-earth/fulltext/S2590-3322(20)30247-5https://www.nap.edu/read/21852/chapter/5https://www.nature.com/articles/nclimate2657 Andrew King Research fellow, University of Melbourne: This video has many major errors and it is difficult to review the veracity of many claims due to the lack of referencing of sources. Here, I’ll just focus on the claim that scientists, the media and politicians attribute every extreme event to climate change. A community of climate scientists has worked to develop a robust and comprehensive methodology for thorough analysis of how human-caused climate change affects extreme weather events.[10,11] This approach has indeed been used to demonstrate that there are often very large effects of human-caused climate change on some events, such as the Siberian heat event of 2020.[16] It is incorrect to say that scientists link climate change to every single extreme event as some studies have not identified a clear link to some extreme events (a comprehensive set of the findings of these studies can be found here). It is the case that climate change is worsening many extreme weather events, particularly heatwaves, but this conclusion is founded on a large and growing number of peer-reviewed studies. Claim: “Natural fluctuations in the height and coverage of clouds have at least as much of an impact on the flows of sunlight and heat as do human influences. But how can we possibly know global cloud coverage say 10, let alone 50 years from now? Obviously, we can’t. But to create a climate model, we have to make assumptions. That’s a pretty shaky foundation on which to transform the world’s economy.” Timothy Myers Postdoctoral Researcher, Lawrence Livermore National Laboratory: These statements are very misleading and not logically coherent. While it is true that natural fluctuations in clouds can have impacts on the fluxes of heat and solar radiation as large or larger than those associated with climate change, this is neither a profound statement nor does it provide insight into how clouds will respond to planetary warming. To take another example, the natural fluctuations of Earth’s temperature in a given hemisphere from winter to summer are larger than the temperature rises due to human influences. But this tells us absolutely nothing about what the human influence on Earth’s temperature actually is. Moreover, there is indeed large climate model uncertainty with respect to how certain cloud types will respond to climate change[8]. But observations, theory, and high-resolution cloud models collectively provide evidence for how a variety of cloud types will change as unabated global warming continues[12-15]). In general, multiple lines of independent evidence inform our understanding of the human influence on climate – we do not rely on climate models alone[12]. This variety of evidence overwhelmingly suggests that the world’s economy must phase out the use of fossil fuels to ensure that the planet remains hospitable to organized human life. Mark Zelinka Research Scientist, Lawrence Livermore National Laboratory: Koonin is correct that subtle variations in cloud height, amount, and reflectivity can strongly modify Earth’s ability to absorb sunlight and emit heat to space. He is also correct that the need to model the entire planet’s climate for centuries precludes simulating the very small-scale processes that are involved in cloud formation, and this means that assumptions must be made around clouds in models. The upshot of this is that climate models disagree on how clouds will respond to warming[9]. This is why a grand challenge in climate research is to determine the extent to which clouds can act as a feedback on global warming [21]. If, say, low-level highly reflective clouds increase in coverage as the planet warms, this will decrease the amount of sunlight absorbed by the planet and put the brakes on warming. But if these clouds decrease in coverage with warming, this will allow more sunlight to be absorbed, thereby exacerbating warming relative to what it would be if clouds didn’t change – a positive feedback. There are, however, several key points left out of Koonin’s cloud argument. Koonin’s statements may lead you to believe that predictions of future warming are built on a house of cards, with everything resting on poorly-simulated clouds. The truth is that cloud changes can only modulate warming, not stop or reverse it[8]. There is no conceivable scenario in which cloud feedback prevents warming in the face of rising human emissions of greenhouse gases. In a world with rising CO2 emissions, how clouds respond determines whether the future is hotter or much hotter; steady or colder temperatures are simply off the table. Moreover, a plethora of evidence from detailed analyses of satellite cloud observations as well as very high resolution modeling (which do not require assumptions about key cloud processes) indicates that cloud changes provide an amplifying feedback[13][14[15][22][23]. This means that climate models, on average, predict the right sensitivity of climate to CO2 – around 3 C (5.4 F) for a doubling of CO2[12]. Moreover, satellite-based cloud records are now long enough that we can see trends that confirm many of the cloud responses that climate models predict to occur with warming [24][25]. Finally, climate scientists do not blindly follow climate model projections. We are well-aware that uncertainties surrounding clouds affects our ability to know precisely what future warming holds, and focus on predictions from models that better match observations. This means down-weighting models that are very insensitive to CO2 as well as those that are too sensitive to CO2. The latest IPCC report[2] in particular does this for most if not all projections. Summary: To correctly note that clouds lead to uncertainties in future climate prediction without simultaneously clarifying (1) that “no big deal” is not in the range of plausible futures (unless emissions are reduced), and (2) that a huge body of evidence now points to clouds providing an amplifying feedback on warming, is very misleading. To position oneself as a rogue truth-teller, bringing to light uncertainties that climate scientists are trying to bury or ignore despite abundant evidence to the contrary is, well, hubris. Claim: “Projecting future climate is excruciatingly difficult. Yes, there are human influences, but the climate is complex. Anyone who says that climate models are “just physics” either doesn’t understand them or is being deliberately misleading.” Mat Collins Professor, University of Exeter: This is a bit of a tricky one, I think. Much of what he says is at least partially true and the same points have been used to argue that we must urgently do something about climate change. It is really just the general dismissive tone and language of the piece. Deconstructing [this claim], for example, Yes making climate projections is complex He admits human influence Yes climate models do make approximations to the laws of physics For a general rebuttal, I think I would invoke the precautionary principle. Yes we don’t know everything we would like to about the complex details of climate change but we know enough that we should do something about it. Claim: “It takes centuries for the excess carbon dioxide to vanish from the atmosphere. So, any partial reductions in CO2 emissions would only slow the increase in human influences—not prevent it, let alone reverse it.” Ilissa Ocko Climate Scientist, Environmental Defense Fund: An example of flawed reasoning is that while the author is correct that CO2 can last for a long time in the atmosphere, and therefore partial reductions would only slow the increase in warming (and not prevent or reverse it), this does not mean that reductions in CO2 are not beneficial compared to what would happen otherwise. In fact, it is the opposite; every ton of CO2 we emit can commit us to warming for generations to come, meaning that every ton we reduce can help us avoid warming for centuries as well. Further, emissions goals are not just to reduce CO2 emissions, but to achieve “net zero” emissions by midcentury (a state in which we are not adding CO2 to the atmosphere beyond what can be removed) and then ultimately achieving negative CO2 emissions (more CO2 removed from the atmosphere than added); these actions *would* prevent additional warming and could even reverse warming.References: [1] Reidmiller et al. (2018) Chapter 1: Overview. In Impacts, Risks, and Adaptation in the United States, Fourth National Climate Assessment, Volume II. [2] IPCC (2021) Climate Change 2021: The Physical Science Basis. Contributions of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. [3] Knutson et al. (2019) Tropical cyclones and climate change assessment: Part I, Detection and attribution. Bulletin of the American Meteorological Society. [4] Knutson et al. (2021) Climate change is probably increasing the intensity of tropical cyclones. Science Brief. [5] Swain et al. (2020) Increased Flood Exposure Due to Climate Change and Population Growth in the United States. American Geophysical Union. [6] Sweet et al. (2018) Patterns and Projections of High Tide Flooding Along the U.S. Coastline Using a Common Impact Threshold. NOAA Technical Report NOS CO-OPS 086. [7] Chinita et al. (2021) Global mean frequency increases of daily and sub-daily heavy precipitation in ERA5. Environmental Research Letters. [8] Zelinka et al. (2017) Clearing clouds of uncertainty. Nature Climate Change. [9] Zelinka et al. (2020) Causes of Higher Climate Sensitivity in CMIP6 Models. Geophysical Research Letters. [10] Van Oldenborgh et al. (2021) Pathways and pitfalls in extreme event attribution. Climatic Change. [11] Philip et al. (2020) A protocol for probabilistic extreme event attribution analyses. Advances in Statistical Climatology, Meteorology and Oceanography. [12] Sherwood et al. (2020) An Assessment of Earth’s Climate Sensitivity Using Multiple Lines of Evidence. Reviews of Geophysics. [13] Myers et al. (2021) Observational constraints on low cloud feedback reduce uncertainty of climate sensitivity. Nature Climate Change. [14] Ceppi et al. (2021) Observational evidence that cloud feedback amplifies global warming. Proceedings of the National Academy of Sciences. [15] Cesana et al. (2021) Observational constraint on cloud feedbacks suggests moderate climate sensitivity. Nature Climate Change. [16] Ciavarella et al. (2021) Prolonged Siberian heat of 2020 almost impossible without human influence. Climatic Change. [17] Swain et al. (2020) Attributing Extreme Events to Climate Change: A New Frontier in a Warming World. One Earth. [18] Trenberth et al. (2015) Attribution of climate extreme events. Nature Climate Change. [19] Kjeldsen et al. (2015) Spatial and temporal distribution of mass loss from the Greenland Ice Sheet since AD 1900. Nature. [20] Kossin et al. (2020) Global Increase in Major Tropical Cyclone Exceedance Probability over the Past Four Decades. Proceedings of the National Academy of Sciences. [21] Bony et al. (2015) Clouds, circulation and climate sensitivity. Nature Geoscience. [22] Klein et al. (2017) Low-Cloud Feedbacks from Cloud-Controlling Factors: A Review. Surveys in Geophysics. [23] Bretherton (2015) Insights into low-latitude cloud feedbacks from high-resolution models. Philosophical Transactions of the Royal Society A. [24] Marvel et al. (2015) External Influences on Modeled and Observed Cloud Trends. Journal of Climate. [25] Norris et al. (2016) Evidence for climate change in the satellite cloud record. Nature.

https://science.feedback.org/review/coral-cover-great-barrier-reef-improved-2021-but-doesnt-mean-reef-growing-quickly-contrary-to-daily-wire/

Misleading

The Daily Wire, Ben Zeisloft, 2021-10-24

Study Shows The Great Barrier Reef Is Growing Quickly

Lack of context: Research shows that the Great Barrier Reef faces ongoing threats from climate change, including warmer ocean temperatures and more intense tropical cyclones. These threats pose long-term danger to coral reefs and can easily reverse short-term growth in coral cover. Misleading: The claim fails to note that the growth in coral cover is driven by Acropora, a genus of coral that’s particularly susceptible to stressors including coral bleaching, wave damage, and predators. Overstates the scientific impact of a finding: After being hit by multiple, widespread stressors between 2014 and 2020, 2021 was a relatively stressor-free year for the Great Barrier Reef, giving coral cover a chance to recover, according to an Australian Institute of Marine Science report. However, short-term recoveries in coral growth can be reversed quickly, and are not proof that the Great Barrier Reef as a whole is growing.

As the planet’s largest coral reef ecosystem, the Great Barrier Reef is home to thousands of marine species and is a major contributor to the Australian economy. However, its size and status cannot protect it from the impacts of climate change. The reef remains vulnerable to ocean warming, more intense storms, predator outbreaks, and other stressors caused by climate change. Warmer ocean temperatures can cause coral to “bleach”, a process in which they dispel symbiotic algae living within their tissue, which leaves them weaker and more susceptible to death. Under the right conditions, bleached coral can recover, but a single, low-disturbance year does not provide scientists enough data to make judgements on overall reef health, as short-term recovery can quickly be reversed.

Despite Climate Change Fearmongering, Study Shows The Great Barrier Reef Is Growing Quickly [...] The Australian government’s most recent official report on reef recovery indicates that coral cover at the Northern Great Barrier Reef “continued to increase to 27% from the most recent low point in 2017.” Meanwhile, the Central Great Barrier Reef saw a 26% increase in hard coral cover.

The Daily Wire published an article on 24 October, 2021 which claimed that a report from the Australian government found the Great Barrier Reef is “growing quickly”. The report the article references is the Australian Institute of Marine Science (AIMS) Long-Term Monitoring Program Annual Summary: Report of Coral Reef Condition 2020/2021[1], which summarizes the current health of the three regions of the Great Barrier Reef (Northern, Central, and Southern) based on scientific surveys conducted between August 2020 and April 2021. The Daily Wire’s claims misrepresent the findings of the AIMS report. The report stated that, after being hit by multiple, widespread stressors between 2014 and 2020, including “numerous severe tropical cyclones and three mass coral bleaching events in five years”, 2021 was a “low disturbance” year for the Great Barrier Reef. This lull in stressors allowed corals on the reef to begin recovering, and coral cover increased across all three Great Barrier Reef regions between 2020 and 2021. However, this increase in coral cover does not mean the reef is “growing quickly”, as claimed in the article. A single year is far too short a timeline to judge overall reef growth, explained Professor Terry Hughes, former director of the ARC Centre of Excellence for Coral Reef Studies. “The reefs are not growing or shrinking – that’s a geological process that occurs over centuries or more,” he said. “Growth rates of individual corals is not a conventional way to assess the condition of reefs.” A key point of context that was missing from the Daily Wire article is that the increase in coral cover described in the AIMS report is being driven by Acropora coral. This fast-growing genus tends to be more susceptible to wave damage, coral bleaching, and predation by the crown-of-thorns starfish. That means that, when faced with these stressors, any increase in Acropora coral cover that was previously documented can quickly be reversed. “The corals that grow back rapidly – Acropora ‘branching’ corals – are also very sensitive to human impacts, so this recovery will be temporary if climate change continues,” Chris Brown, a senior lecturer in the School of Environment and Science at Griffith University in Queensland, Australia, said. “A shift in the types of corals will have implications for the animals that use them as habitat, including the Great Barrier Reef’s valuable fisheries”. The AIMS report stated that the Great Barrier Reef continues “to be exposed to cumulative stressors, and the prognosis for the future disturbance regime is one of increased and longer lasting marine heatwaves and a greater proportion of severe tropical cyclones”. It also notes that the recovery outlined in the report “has been seen previously and can be reversed in a short amount of time”. This is important context that the Daily Wire article leaves out. Brown said in an email that some coral recovery was expected on the Great Barrier Reef after high-disturbance events. Brown referenced an “unprecedented” coral bleaching event in the Great Barrier Reef in 2016, which occurred as the result of record-high sea surface temperatures[2] and caused widespread bleaching and coral death. The bleaching event was the third global-scale coral bleaching event since the 1980s[3]. “Some types of coral will grow back rapidly after diebacks if they are left undisturbed,” Brown said in an email. “Unfortunately, the future prospects look dire, we expect heatwaves like that to occur 1 in every 3 years in the future due to climate change and greenhouse gas emissions.” Predictions like that are important for the long-term health of reefs, because frequent marine heat waves (along with other frequent disturbances) make it difficult for corals to make long-term recoveries, especially longer-lived species. As Hughes et al. noted in a 2017 study[3]: “The recovery time for coral species that are good colonizers and fast growers is 10–15 years, but when long-lived corals die from bleaching their replacement will necessarily take many decades. Recovery for long-lived species requires the sustained absence of another severe bleaching event (or other significant disturbance), which is no longer realistic while global temperatures continue to rise. Therefore, the assemblage structure of corals is now likely to be permanently shifted at severely bleached locations in the northern Great Barrier Reef.” Figure 1—The AIMS report visualized why August 2020 – April 2021 was a relatively good year for coral health in the Great Barrier Reef: low rates of bleaching and crown of thorns starfish (COTS) led to increases in coral cover across many of the reefs. The figure shows: a) The percentage of hard coral cover along the different segments of the reef. b) How different regions of the reef have changed in coral cover between 2021 and the previous survey (i.e. levels of increase or decrease in coral cover). c) The presence and severity of the COTS outbreak throughout the reef’s regions. d) The percentage of coral colonies affected by bleaching during the survey dates.Contrary to the Daily Wire’s claim, researchers found that coral growth rate on the Great Barrier Reef has declined in recent decades. In a 2012 study[4], for instance, De’ath et al. state that “coral cover depends not only on mortality from acute disturbances but on rates of growth. Rates of coral calcification on the GBR [Great Barrier Reef] and many other reef systems around the world have declined by 15–20% since ∼1990 due to increasing thermal stress”. Hughes et al. (2019)[5] also found that, in the Northern and Central Great Barrier Reef, corals’ rate of recruitment, which is the rate at which coral larvae attach themselves to a substrate and grow into adult coral, “has been substantially diminished” due to climate change and other stressors. Because of this diminished recruitment rate, the reef’s resilience to bleaching is “compromised”, the study stated. Lastly, a 2020 study by Dietzel et al.[6] documented “the systematic decline of absolute coral abundances across size classes, habitats, sectors and taxa on the GBR over the last two decades.” Along with thermal stress, more intense tropical cyclones are predicted to continue to threaten the Great Barrier Reef as climate change progresses: as Cheal et al. (2017)[7] note: “increases in cyclone intensity predicted for this century are sufficient to greatly accelerate coral reef degradation.” In addition to its misleading claim about reef growth, the Daily Wire article also makes a numerical error in its claim that “the Central Great Barrier Reef saw a 26% increase in hard coral cover”. The report stated that coral cover in the Central Great Barrier Reef “increased to 26% in 2021” while coral cover was at around 14% in years past—not that it increased by 26%. Since 2009, the Great Barrier Reef has faced three bleaching events, a wave of crown-of-thorn starfish outbreaks, and 17 cyclones. The coral growth seen during 2021 is encouraging, but as climate change continues, the reef risks having fewer and fewer low-disturbance years like this one to recover.UPDATE (2 Nov. 2021): The Daily Wire has issued a correction to its article, updating the headline to make clear the distinction between coral cover and reef size, and adding more context about Acropora coral. It also corrected the claim that coral cover in the Central Great Barrier Reef grew by 26% during the study period.Scientists’ Feedback: Chris Brown Research Fellow, Griffith University: Some types of coral will grow back rapidly after diebacks if they are left undisturbed. There was an unprecedented heatwave in 2016 that caused coral bleaching and death, so some regrowth since then is expected. Unfortunately, the future prospects look dire, we expect heatwaves like that to occur 1 in every 3 years in the future due to climate change and greenhouse gas emissions. Australia has some of the highest per-capita emissions of any nation globally, and fossil fuel extraction that contributes significantly to greenhouse gas emissions here and overseas. So it’s crucial for corals and all of Earth’s ecosystems that Australia urgently commit to substantial and rapid action to reduce fossil fuel extraction and emissions. With the COP upcoming in Glasgow now is the time to do that. Independent surveys of the Great Barrier Reef conducted by the Reef Life Survey confirm that the health of the reef’s corals is currently poor (you can view trends for habitat cover, ie corals, here). Recent and ongoing heatwaves are a major contributor to that, as are impacts from pollution and crown of thorns starfish predation. The report from AIMS also notes the types of corals growing on the reefs are changing. The corals that grow back rapidly – Acropora ‘branching’ corals, are also very sensitive to human impacts, so this recovery will be temporary if climate change continues. A shift in the types of corals will have implications for the animals that use them as habitat, including the Great Barrier Reef’s valuable fisheries. In 2016 we observed changes in the fish community in response to loss of corals and directly to the heatwave. The Reef Life Survey are conducting ongoing monitoring of the fish, which will help inform us about the impacts of these changes on valuable fisheries.Terry Hughes Professor, ARC Centre of Excellence for Coral Reef Studies, James Cook University: The report points out that where coral cover has increased (after bleaching in 2016 and 2017), the new corals are weedy species that are the most susceptible to the inevitable next heatwave. According to the report, one in six reefs surveyed in early 2021 has shown no increase in coral cover. None of the 20 reefs survey by AIMS in the southern region were affected by coral bleaching in 2016, 2017 or 2020. Many of these climate change denying blogs seem to confuse ups and downs in % coral cover with “reef growth” or “coral growth”. The reefs are not growing or shrinking – that’s a geological process that occurs over centuries or more. Growth rates of individual corals is not a conventional way to assess the condition of reefs. Another source of confusion in these blogs is relative versus absolute changes in coral cover. For example, an increase from 10 to 12% is often misrepresented as a 20% improvement, instead of a 2% gain (and an absolute change, up or down, of 2% is well within the measurement error).REFERENCES: [1] Annual Summary Report of Coral Reef Condition 2020/2021. (2021) Australian Institute for Marine Science. [2] Australia State of the Environment Report: Marine environment: 2011–16 in context. (2016) Commonwealth of Australia. [3] Hughes et al. (2017) Global warming and recurrent mass bleaching of corals. Nature. [4] De’ath et al. (2012) The 27–year decline of coral cover on the Great Barrier Reef and its causes. Proceedings of the National Academy of Sciences. [5] Hughes et al. (2019) Global warming impairs stock–recruitment dynamics of corals. Nature. [6] Dietzel et al. (2020) Long-term shifts in the colony size structure of coral populations along the Great Barrier Reef. Proceedings of the Royal Society B.[7] Cheal et. al. (2017) The threat to coral reefs from more intense cyclones under climate change. Global Change Biology.

https://science.feedback.org/review/rain-fell-on-greenland-summit-for-the-first-time-on-record-as-accurately-reported-by-cnn/

1.3

CNN, by Rachel Ramirez, on 2021-08-19.

"Rain fell at the normally snowy summit of Greenland for the first time on record"

Reviewers’ Overall Feedback: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Ted Scambos Senior Research Scientist, National Snow and Ice Data Center: It is typical for accuracy for the press – CNN and BBC and many others tend to write about climate such that the events sound more exciting, and less qualified or approximate. The main omission is that the rain event over the whole island was the largest for those days in August, and that the amount is an estimate from a model, based on weather re-analysis (which I think I explained to Rachel [Ramirez, the journalist who wrote the story on CNN]). That the overall ice sheet runoff was seven times higher than ’normal’ (1981-2010 average) is not hard to believe, because runoff tails off abruptly after the first week in August in most years. The event was a warm spike over about 50% of the island, and a lot of the southwestern slope was still in late summer mode. The statement about the crust at Summit Station forming a layer that would enhance run-off is a slight misquote: increased melting on the flanks of the ice sheet has led to thick ice layers that allow greater runoff. We should retain our stance that this was a major climate anomaly for Greenland and that the public was appropriately informed about the event — it is not an exaggeration to say it was an extreme event. The later Twitter reports of other melting events in the 1930s and 1950s do not include the Summit Station area, and that analysis of the GISP-2 and GRIP cores, and many others, show that melting (or rain, which would look like a melt event) is rare in the ‘dry snow zone’ of Greenland — hence the name. Kent Moore Professor, University of Toronto: The article is highly factual. One issue that we have is the lack of data over the Greenland Ice Sheet (both spatially and temporally). Thus some of the claims, although backed by the limited data, are valid; we can’t be sure that we may have missed similar outliers. For example, we can’t be sure that a rain event of the type described did not occur in the period before observations were made or may have occurred somewhere on the ice sheet before in a region without any observations. Xavier Fettweis Research scientist, University of Liege: The numbers and statistics given in the CNN article are based on a report from NSIDC which is: using outputs of the regional climate model MAR (from ULiège – Belgium) forced by the reanalysis ERA5 to give statistics at the scale of the whole ice sheet showing measurements (temperature and rainfall) at Summit. According to this paper, MAR is one of the internationally recognized models to quantify the surface mass balance of the Greenland ice sheet, and only outputs of models like this can give statistics such as the one listed in the CNN article.” Mira Berdahl Postdoctoral Scholar, University of Washington: This article is meant for a general audience and does well to emphasize the fairly drastic effects of climate change on the Greenland ice sheet. However, there are a few statements throughout, (e.g., global sea level rose permanently by 1.5 millimeters as a result), which I find slightly frustrating. I wouldn’t, for example, claim sea level rise is permanent (on what time scale?). Also, there should be more care taken to distinguish between rain events and melt events at the summit. I worry these could be confused if not explicitly explained. Also, I think the mention of polar bears, while interesting, is fairly tangential to this story. Overall, the story is worth getting out there, it is true that rain did fall for the first time in recorded history at the summit.

https://science.feedback.org/review/a-2014-study-showed-that-the-us-corn-belt-is-one-of-the-biggest-primary-producers-on-earth-in-july-but-didnt-show-that-it-produces-more-oxygen-than-the-amazon/

Inaccurate

Facebook, Facebook users, 2021-09-05

"the US corn crop, at its peak, produces 40% more oxygen than the Amazon rainforest."

Inaccurate: The 2014 paper “Global and time-resolved monitoring of crop photosynthesis with chlorophyll fluorescence” uses a new technique to study cropland productivity around the world, but it doesn’t examine oxygen emissions. The paper also doesn’t account for the productivity of natural ecosystems like rainforests. Therefore the paper cannot show that US Corn Belt produces more oxygen than the Amazon rainforest overall. Misleading: The 2014 paper shows that the maximum gross primary productivity (GPP) in the US Corn Belt achieved in July 2009 exceeded the GPP of any other region on Earth. The claim is misleading as it wrongly implies that the study concluded that the US Crop Belt was more productive year-round than the entire Amazon and that this productivity would result in the largest amount of oxygen emissions.

A remote sensing technique known as sun-induced chlorophyll fluorescence is used by scientists to measure gross primary productivity—the capacity of plants to absorb carbon dioxide through photosynthesis—over large regions. A 2014 study did show that, per unit area, the US Corn Belt is the most productive cropland on Earth during summer in the northern hemisphere. However, the study did not compare the productivity of natural ecosystems with that of croplands, nor did it measure the amount of oxygen produced by these environments.

"This satellite image shows the photosynthesis of America's 100 million acre Corn crop. Further research found the US corn crop, at its peak, produces 40% more oxygen than the Amazon rainforest. Thank you farmers."

Summary: A series of Facebook posts (such as this one) claiming that the United States Corn Belt produces 40% more oxygen than the Amazon rainforest went viral in September 2021. This claim is based on a 2014 study in Proceedings of the National Academy of Sciences that received wide attention at the time (see here, here, or here). The study attempted to understand how a new remote sensing technique could improve the knowledge we have of how croplands around the globe are growing and incorporating carbon from the air. This technology, called Sun-induced Chlorophyll Fluorescence, measures the emission of a small amount of near-infrared light by the chlorophyll molecule when it receives sunlight. This infrared radiation is emitted in all directions and can be detected from space by a satellite, giving the scientists an overview of how much photosynthesis is occurring on the ground at a given place and a given time. With this technique, scientists can estimate gross primary productivity, which is the amount of carbon that plants take from the atmosphere through photosynthesis to grow and develop. As the authors of the study wrote: “Here we demonstrate that new space-based observations of chlorophyll fluorescence, an emission intrinsically linked to plant biochemistry, enable an accurate, global, and time-resolved measurement of crop photosynthesis, which is not possible from any other remote vegetation measurement. Our results show that chlorophyll fluorescence data can be used as a unique benchmark to improve our global models, thus providing more reliable projections of agricultural productivity and climate impact on crop yields.” In addition to the main conclusion that this technique works well, the scientists noticed that the productivity of certain large cropland areas, such as the US Corn Belt or the Indo-Gangetic Plains in India, was underestimated in previous studies. In their study, the maximum value of sun-induced chlorophyll fluorescence worldwide is achieved in the US Corn Belt in July, at approximately 5 g CO2/m²/d. In contrast, South American croplands are estimated to produce a maximum of about 2.9 g CO2/m²/d in February (Southern hemisphere summer). Climate Feedback reached out to the first author of the study, Luis Guanter, who refuted the claim: “Our study had nothing to do with oxygen, but with plant gross primary production (GPP, amount of carbon absorbed by the plants through photosynthesis). During the June-July period the US Corn Belt shows in general higher rates of greenness (leaf chlorophyll content x plant biomass) and hence chlorophyll fluorescence (a proxy for photosynthesis) per unit surface than the Amazon forest, as it is shown in Figure 1. It is probably true that the US Corn Belt is fixing more carbon from the atmosphere in June-July than the entire Amazon forest for the same time period, since the US Corn Belt represents a large extension of high and dense plants growing at the same time.” Figure 1 – Global map of maximum monthly sun-induced chlorophyll fluorescence for 2009. From Guanter et al. (2014) The claim that the US Corn Belt is overall more productive than the Amazon is inaccurate and misleading as it wrongly implies that the study concluded that the US Crop Belt was more productive year-round than the entire Amazon and that this productivity would result in the largest amount of oxygen emissions. Conclusion: The paper determines whether the new Chlorophyll Fluorescence technique could be useful for remotely measuring cropland gross primary productivity. Using this technique, the authors observed that the US Crop Belt exhibited the highest level of productivity worldwide in July 2009. Based on this result, they concluded that the US Corn Belt holds the world record for gross primary productivity, specifically during that month. However, the paper did not study oxygen production, and there’s no evidence that these plants produce more oxygen throughout the entire year compared to other areas like the Amazon rainforest. For these reasons, the claim that the US Corn Belt is producing more oxygen than the Amazon is inaccurate and unsupported by the research it cites.Scientists’ Feedback: [Guanter is the first author of the scientific article on which the Facebook meme relied] “Our study had nothing to do with oxygen, but with plant gross primary production (GPP, amount of carbon absorbed by the plants through photosynthesis). Based on our analysis, the area-integrated GPP of the crops in the US Corn Belt is huge during their growing season (June-July), as a huge amount of highly productive plants are growing quickly and at the same time. During this June-July time, the GPP peak for the US Corn Belt seems to be higher than that of the Amazon for the same time period. Of course, this is not true anymore if we averaged for the whole year (not only June-July), and in any case, the atmospheric carbon absorbed by the crops in summer is returned to the atmosphere later through respiration.” “What we meant is that during that June-July period the US Corn Belt shows in general higher rates of greenness (leaf chlorophyll content x plant biomass) and hence chlorophyll fluorescence (a proxy for photosynthesis) per unit surface than the Amazon forest, as it is shown in this figure. It is probably true that the US Corn Belt is fixing more carbon from the atmosphere in June-July than the entire Amazon forest for the same time period since the US Corn Belt represents a large extension of high and dense plants growing at the same time. Apparently, the drop in atmospheric CO2 associated with this growth can also be seen in time series of CO2 data produced with satellites measuring concentrations of greenhouse gases. All this carbon is returned to the atmosphere after the summer. But again, there is no mention of the Amazon region in our article.”Reference Guanter et al. (2014). Global and time-resolved monitoring of crop photosynthesis with chlorophyll fluorescence. Proceedings of the National Academy of Sciences

https://science.feedback.org/review/sea-temperatures-around-the-great-barrier-reef-have-increased-over-the-last-150-years-contrary-to-claim-at-wattsupwiththat/

Inaccurate

Climate Change Dispatch, Climate Realism, Watts Up With That?, David Mason-Jones, 2021-08-28

"Great Barrier Reef Sea Surface Temperature: No Change In 150 Years"

Factually inaccurate: Over the past decades, many studies have shown that the global sea surface temperature has risen. In the Great Barrier Reef region, observations unambiguously show a warming over the past 150 years.Cherry-picking: The claim is based on a unique one-month dataset from the late 19th century. Comparing temperatures taken over the period of just one month then and now isn’t enough to conclude on an overall trend over a period of decades. In addition, measurement tools, techniques, and calibration methods have evolved since then and this needs to be taken into account.

Over the last 150 years, global sea surface temperature has been on the rise. Given that climate is defined by the weather conditions over a long period of time, one particular month or period of a given year can be warmer (or colder) than expected (outlier). Reliably determining a long-term trend in climate change across decades requires comparing temperature measurements across decades. Differences in calibration between modern-day temperature-measuring tools and those used centuries ago also mean that they cannot be compared without accounting for those differences.

"Great Barrier Reef Sea Surface Temperature: No Change In 150 Years. [...] If the sea surface temperature of the Great Barrier Reef has been trending upwards then a 150-year comparison should be sufficient to confirm it. When compared with today’s readings, it shows no upward trend."

Review: An article written by David Mason-Jones for Wattsupwiththat claims that sea temperatures around the Great Barrier Reef have not changed over the last 150 years. The claim was repeated in another article at ClimateRealism by Anthony Watts. Together, the articles received around 7,000 interactions on social media according to CrowdTangle, a social media analytics tool. In his article, Mason-Jones bases his claims on a post published by Dr. Bill Johnston in his blog. Johnston, a former research scientist at the New South Wales Department of Natural Resources, uncovered an old dataset from 1871 recorded by a marine expedition along the Australian coastline. This dataset, Johnston claims, exhibits the same temperature as measured in current times, which he thinks proves that the sea surface temperature did not change and therefore that global warming is not threatening the Great Barrier Reef. However, Johnston’s conclusion that sea surface temperatures haven’t changed is incorrect. Measurements by both the Australian Bureau of Meteorology and the Hadley Centre for Climate Prediction and Research[1] show that the sea surface temperatures are rising around the world, including around the Great Barrier Reef. The temperature anomalies averaged globally and in the Great Barrier Reef region are shown in figure 1 below.Figure 1 – Sea surface temperature anomalies over the last century in the Great Barrier Reef region (top) and globally (bottom). Anomaly values are defined with respect to the 1961-1990 temperature mean. (Source: Bureau of Meteorology) In addition to these direct temperature measurements, other observations confirm that the ocean has warmed[2]: geographical areas with a given temperature and precipitation type, or climate zones, are shifting towards the high latitudes (northward in the northern hemisphere, southward in the southern)[3], fish species distribution, seabirds migration patterns, or sea turtle breeding periods are changing, and more and more coral reefs are bleaching[4]. All these observations are consistent with a warming of the ocean and inconsistent with the claim that seawater temperature has not changed for 150 years. Thanks to this very large body of evidence, the IPCC was able to conclude in its latest assessment report that: “it is now very likely that global mean Sea Surface Temperature changed by 0.88°C from 1850-1900 to 2011-2020, and 0.60°C from 1980 to 2020. The tropical ocean has been warming faster than other regions since 1950, with the fastest warming in regions of the tropical Indian and western Pacific Oceans”[5]. Furthermore, the method used by Dr. Johnston to come to his conclusion is flawed. As Ken Caldeira, senior scientist at the Carnegie Institution for Science, explains: “One cannot establish trends in variable systems with single measurements, [especially when] somebody made measurements in 1871 with a thermometer that may or may not have been appropriately calibrated.” In other words, the measurements used by Dr. Johnston, which were taken 150 years ago, are likely to be affected by specific biases (for example, biases that arise due to the method of measurement[6]), and such biases aren’t accounted for in his comparisons with modern-day measurements. Furthermore, measurements that were taken over a period of one month wouldn’t reliably represent temperature changes over a period of several decades. Because outliers happen, certain periods in time may be warmer or cooler than expected. Temperature records from a single month that could have been particularly warm aren’t reliable evidence of any overall, long-term trend.Scientists’ Feedback: Ken Caldeira Senior Scientist, Carnegie Institution for Science: David Mason-Jones and Bill Johnston are apparently arguing that because somebody took a measurement in 1871 with a thermometer that may or may not have been appropriately calibrated, that decades of observations with carefully calibrated instruments should be ignored. Further, assuming the measurements of 150 years ago were done well, a warming trend over the past 150 years is entirely consistent with a warm month 150 years ago. One cannot establish trends in variable systems with single measurements. I do like to respect expertise. The temperature records developed by NOAA and other organizations were developed by teams of (mostly) Ph.D. scientists who publish their methods and results in peer-reviewed journals. If Bill Johnston wants his theories to be taken seriously, he should write them up and submit them to a high-quality peer-reviewed journal. It is typical of conspiracy theorists to say they can’t get their work published because there is a vast conspiracy trying to suppress the truth. On the other hand, it might just be the case that amateur conspiracy theorists are wrong.REFERENCES: 1 – Rayner (2003) Global analyses of sea surface temperature, sea ice, and night marine air temperature since the late nineteenth century. Journal of Geophysical Research 2 – Lough and Hobday (2011). Observed climate change in Australian marine and freshwater environments. Marine and Freshwater Research. 3 – Lough (2008). Shifting climate zones for Australia’s tropical marine ecosystems. Geophysical Research Letters 4 – Poloczanska et al. (2007). Climate change and Australian marine life. Oceanography and marine biology 5 – Fox-Kemper et al. (2021) Ocean, Cryosphere and Sea Level Change. In: Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press 6 – Smith and Reynolds (2002). Bias corrections for historical sea surface temperatures based on marine air temperatures. Journal of Climate

https://science.feedback.org/review/solar-forcing-is-not-the-main-cause-of-current-global-warming-contrary-to-claim-by-alex-newman-in-the-epoch-times/

Incorrect

Newsmax, The Epoch Times, The Western Journal, Alex Newman, 2021-08-16

The Sun and not human emissions of carbon dioxide may be the main cause of warmer temperatures in recent decades. There is a systemic bias in UN IPCC's data selection.

Incorrect: Solar irradiance variations have a very small impact on Earth’s current climate change. There is a very large consensus of scientific evidence showing that human emissions of greenhouse gases are the main cause of current climate change. The hypothesis that the Sun is responsible for climate change is inconsistent with real-world observations. Misleading: There’s no evidence that the IPCC’s conclusions are the result of bias. The scientific consensus about the cause of climate change is built on a significant number of publications (many thousands for the IPCC reports, for example), decades of studies, and methods that are shared and accepted by the scientific community.

Changes in solar irradiance have a very small influence on current climate compared to the effect induced by CO2 and other greenhouse gases. Ideas, methods and data sets used by scientists to study the various climate drivers are frequently discussed in the scientific literature and in the IPCC reports. Based on the body of evidence available, the scientific community concluded that solar variations don’t have any noticeable influence on the climate change observed in recent decades.

The change in the Sun’s irradiance are a plausible and important factor that can explain most of the observed changes in the thermometer data [and] depending on which published data and studies you use, you can show that all of the warming is caused by the sun. There is a systemic bias in UN IPCC's data selection.

1 – Lockwood & Fröhlich (2007). Recent oppositely directed trends in solar climate forcings and the global mean surface air temperature. In Proceedings of the Royal Society of London A: Mathematical, Physical and Engineering Sciences. 2 – Solanki et al. (2004). Unusual activity of the Sun during recent decades compared to the previous 11,000 years. Nature. 3 – Lean & Rind (1999). Evaluating sun–climate relationships since the Little Ice Age. Journal of Atmospheric and Solar-Terrestrial Physics. 4 – Lockwood (2008). Recent changes in solar outputs and the global mean surface temperature. III. Analysis of contributions to global mean air surface temperature rise. In Proceedings of the Royal Society of London A: Mathematical, Physical and Engineering Sciences. 5 – Santer et al. (2013). Human and natural influences on the changing thermal structure of the atmosphere. Proceedings of the National Academy of Sciences. 6 – Hegerl & Wallace (2002) Influence of patterns of climate variability on the difference between satellite and surface temperature trends. Journal of Climate. 7 – Bindoff, et al. (2013) Detection and attribution of climate change: From global to regional. Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change 8 – USGCRP, 2017: Climate Science Special Report: Fourth National Climate Assessment, Volume I [Wuebbles et al.]. U.S. Global Change Research Program. 9 – Doran & Zimmerman (2009) Examining the scientific consensus on climate change. Eos, Transactions American Geophysical Union. 10 – Anderegg et al. (2010) Expert credibility in climate change. Proceedings of the National Academy of Sciences. 11 – Cook et al. (2013) Quantifying the consensus on anthropogenic global warming in the scientific literature. Environmental research letters. 12 – Verheggen et al. (2014) Scientists’ views about attribution of global warming. Environmental science & technology. 13 – Cook et al. (2016) Consensus on consensus: a synthesis of consensus estimates on human-caused global warming. Environmental Research Letters. 14 – IPCC, 2013: Summary for Policymakers. In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Stocker et al. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. Figure SPM.5 15 – IPCC, 2021: Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [Masson-Delmotte et al.]. Cambridge University Press. In Press.

The claim that the Sun and not human emissions may be the main cause of warmer temperatures in recent decades has been made in a newspaper article written by Alex Newman and published in The Epoch Times on 16 August 2021. The article and its claims have been repeated in several articles including one at Newsmax. In the Epoch Times article, Newman additionally claimed that a new scientific paper proves a systematic bias in the International Panel on Climate Change (IPCC)’s workflow, accusing it of supporting an unscientific agenda and ignoring data that contradict a “chosen narrative”. But solar irradiance cycles and its influence on the climate are well-understood by scientists and the evidence shows clearly that solar variability cannot account for the recent climate change[1-3]. The Sun’s activity has been monitored since the beginning of the 20th century, and even if its irradiance (the amount of solar energy reaching the Earth) shows important yearly fluctuations, statistically it hasn’t shown an overall increase in the last decades (Figure 1 below). On the contrary, irradiance has decreased since the 60s (see the graph below) while global temperature increased, proving the lack of correlation between the two variables[4], and undermining the claim made in Newman’s article and the authors of the study he cited. Figure 1 – Comparison of the global surface temperature changes (red) and the Sun’s energy that Earth receives (yellow) in watts per square meter since 1880. One can see that since the 1960s, the global temperature and solar activity have varied in opposite directions. Source: NASA/JPL-Caltech Another line of evidence to consider is that if variations in the Sun’s irradiance were the cause of recent warming at the surface of the Earth, the entire atmosphere should see its temperature change accordingly, including the upper layers. But this is not what the scientific community observed. As the scientific literature[5-7] and satellite data show (see Figure 2), the temperature in the lower stratosphere (high altitude) falls while the temperature of the lower troposphere (low altitude) rises. This observation invalidates the hypothesis that the Sun is the driving factor of the global surface temperature increase we observe while it is consistent with the hypothesis that greenhouse gases are the cause. Figure 2 – Data from the Met Office Hadley Center showing global temperature variations in the upper atmosphere (top graph) and in the lower atmosphere (bottom graph) since the 1960s. We observe a warming at the surface and a cooling above, which is consistent with the effect of added greenhouse gases in the atmosphere and inconsistent with the hypothesis of a solar influence. Contrary to what is claimed by Newman and his guests about its supposed bias against the solar hypothesis, the IPCC is mandated to compile the knowledge produced by the entire scientific community and cautiously evaluate the scientific merit of any new contribution. Therefore contributing scientists consider every potential cause of climate change, including anthropogenic (human-caused) and natural causes. As mentioned in the U.S. Fourth National Climate Assessment[8], “between 93% to 123% of observed 1951-2010 warming was due to human activities” as shown in Figure 3 below. That anthropogenic factors can explain up to 123% of the warming observed is due to the fact that there are also cooling effects of some drivers, such as volcanic eruptions or changes in land use. The cooling effects compensate for some of the warming effects of increased atmospheric CO2 concentration by human emissions. This shows that natural forcings are accounted for in the IPCC’s or U.S. National Climate Assessment’s reports, solar forcings simply happen to be weaker. Figure 3 – Time evolution in effective radiative forcings (ERFs) across the industrial era for anthropogenic and natural forcing mechanisms. The ERF measures the net heat gain or loss in the Earth’s climate system. Well-mixed greenhouse gases (WMGHG) are the long-lived gases that have a strong impact on climate and include carbon dioxide, methane, nitrous oxide, and different kinds of chlorofluorocarbons. From the U.S. Fourth National Climate Assessment[8]. The same considerations are taken into account in the latest IPCC report, where all the forcing factors are compiled and their specific contributions assessed (see Figure 4). As mentioned in the sixth IPCC assessment report, compared to 1750, solar (-0.02 W/m²) driver is considered as very minor compared to carbon dioxide (+2.16 W/m²). Figure 4 – Observed warming contribution for each kind of driver. We can see that part of the global warming caused by human emission is masked by an aerosol effect. Details can be found in the last IPCC Summary: for Policymakers[15]. In the Epoch Times article, Newman also claims that “scientific views have been deliberately suppressed by the IPCC”, “that data sets are being selected that support the IPCC view while data contradicting it have been excluded”. A review of the literature shows that an overwhelming majority of scientists agree with the conclusions that the IPCC releases every five years in their Assessment Reports. This scientific consensus has been consistently measured for more than a decade[9-13]. The citation in the last IPCC report of a paper written by Connolly, who is attacking the IPCC for its supposed “confirmation bias” in Newman’s article, shows that relevant research papers are scientifically evaluated and duly considered. The ACRIM (Active Cavity Radiometer Irradiance Monitor) data sets that Newman and his guests claim were ignored by the IPCC appear in numerous studies cited in the report (the acronym itself is used 14 times in the fifth assessment report published in 2013[14]). It is notably written in this report that there is a reason why the signal produced by ACRIM exceeds the other sources for the Sun irradiance measurements, which may be a reason why it is no longer used as a reference: “The increase in excess of 0.04% over the 27-year period of the ACRIM irradiance composite, although incompletely understood, is thought to be more of instrumental rather than solar origin. The irradiance increase in the ACRIM composite is indicative of an episodic increase between 1989 and 1992 that is present in the Nimbus 7 data.”Scientists’ Feedback: Timothy Osborn Professor, University of East Anglia, and Director of Research, Climatic Research Unit: [This comment comes from a previous review of a similar claim.] There is strong evidence that solar forcing cannot explain much of the observed warming at all. The “fingerprint” of solar forcing does not match the observed changes at all, neither over time nor space. Solar forcing would warm both the stratosphere and the surface of the Earth, whereas CO2 warms the surface (and the troposphere) but cools the stratosphere. Using radiosondes and (more recently) satellites, we have observed a warming surface and troposphere together with a cooling stratosphere. See Santer et al (2013)[5] for one of many studies providing this evidence. Figure 5 – Zonal-mean atmospheric temperature trends in satellite observations from January 1979 to December 2012 showing warming of the lower atmosphere (troposphere) and cooling of the upper-atmosphere (stratosphere), from Santer et al (2013)[5] Britta Voss Postdoctoral Research fellow, U.S. Geological Survey: [This comment comes from a previous review of a similar claim.] Solar forcing is much smaller than CO2 forcing. As this figure from the latest IPCC report shows, CO2 radiative forcing (1.68 W/m2) dwarfs solar forcing (0.05 W/m2). Along with other greenhouse gases, CO2 dominates the total radiative forcing when all positive and negative factors are taken into account. Figure 6 – Radiative forcing estimates in 2011 relative to 1750. Values are global average radiative forcing, partitioned according to the emitted compounds or processes that result in a combination of drivers. Source IPCC AR5 Patrick Brown, Assistant Professor, San Jose State University: [This comment comes from a previous review of a similar claim.] Careful analysis that attempts to take into account all major factors and their evolution in time indicates that anthropogenic increases in greenhouse gasses account for more than 100% of the observed warming on the century timescale (requiring cancellation from cooling influences). See the summary graphic from Carbon Brief, below.

https://science.feedback.org/review/despite-2021-being-a-good-year-for-coral-health-coral-in-the-great-barrier-reef-has-declined-over-the-past-decade-and-is-threatened-by-climate-change-contrary-to-claims-by-peter-ridd/

Inaccurate

Climate Change Dispatch, The Australian, Watts Up With That?, Peter Ridd, 2021-07-21

“The amount of coral on the Great Barrier Reef is at record high levels”; those claiming the reef is threatened by climate change are alarmists

Inaccurate: Numerous scientific studies show a decrease, not an increase, in coral growth over the past decade. International scientific organizations are not ignoring the improvement in coral communities, and acknowledge the influence of periods with low disturbance on the ability of damaged reefs to recover. Misrepresents source: Peter Ridd misuses data from the Australian Institute of Marine Science in a graph showing how coral cover in the Great Barrier Reef has changed over time. Although the data show an improvement in the amount of coral covering the reef in 2021 compared to previous years, coral cover is not at a record high since 1985 for any region of the Great Barrier Reef.

Coral reefs comprise a small, but invaluable oceanic ecosystem, because they provide protection from storms and sturges, host wildlife, are a dense source of food and have a strong economic value for local communities. The growth rate and overall health of coral reefs are very sensitive to environmental conditions, including water temperature, pH, and extreme weather events. Warming water temperatures and increasing CO2 concentrations in the ocean often cause coral bleaching events, eventually resulting in the death of large fractions of numerous coral reefs around the world. However, some coral reefs can recover from these extreme events and adapt to changing conditions if they are given enough time and the appropriate conditions.

“The amount of coral on the Great Barrier Reef is at record high levels”; “Coral growth rates have, if anything, increased over the past 100 years”; those claiming the reef is threatened by climate change are alarmists

The claim that the amount of coral in the Great Barrier Reef has increased over the past century and reached a record high in 2021 was published on 23 July 2021 in an article published by Peter Ridd, a former physicist at James Cook University. The article was published on several websites, including Climate Change Dispatch, Watts Up With That, and The Australian, and together received more than 10,000 interactions on social media according to the social media analytics tool Crowdtangle. In the article, Ridd claims that the release of the latest annual report of the Australian Institute of Marine Sciences on the Great Barrier Reef shows a record high level of coral covering the reef. He uses this observation to claim that scientists who state that coral reefs are threatened by climate change are alarmists. These claims are not supported by scientific evidence and are based on misrepresentations of scientific data and a flawed understanding of coral reef science. For example, Ridd shows a figure allegedly from the latest Australian Institute of Marine Science (AIMS) report to support his claim that the amount of coral in the Great Barrier Reef reached a record high in 2021, but Ridd’s figure is neither consistent with the figures published in the AIMS report[1], nor with the scientific literature. Contrary to the claim, the recent AIMS report for the three regions of the Great Barrier Reef showed strong variation in coral cover across years, but no record high in 2021, as claimed in Ridd’s article (see Figure 1). Furthermore, scientific studies show a significant decrease in the amount of coral and coral growth rate since the 1980’s[2-5]. Moreover, scientific studies consistently show that the amount of coral cover and the growth rate of coral are negatively impacted by global warming. As stated in De’ath et al. (2012)[2], “over 1985-2012, […] we show a major decline in coral cover from 28% to 13.8% (0.53%/y), a loss of 50.7% of initial coral cover.” In addition, as described in van Woesik et al.[3], “Recent increases in temperatures appear to have caused the slowing of coral growth rates on the near shore Great Barrier Reef, from an average of 15.2 mm/yr in 1988 to 12.8 mm/yr in 2003, a decline of 1.02%/yr, which has been attributed to a corresponding increase in sea-surface temperature”. Figure 1 – Comparison between Ridd’s figure (top) and the data from the AIMS report (bottom) with data given for each of the three Great Barrier Reef regions showing no record high nor historic maximum in 2021. In his article, Ridd also claims that scientists “generally downplayed or ignored” the reefs capacity to recover from bleaching or extreme weather events, however, scientific studies on coral reefs acknowledge the capability for the reefs to recover and grow after such events[7-9]. Doing so, Ridd neglects to address the complexity of the coral reef diversity, species dynamics and differences around the globe, and misleads the reader into thinking scientists ignore these facts. As discussed in the AIMS report, the main hypothesis for the rapid recovery of the Great Barrier reefs during 2021 is that “2021 has been a low disturbance year”, and that a strong increase in fast growing Acropora corals created a shift in the population distribution of coral. These species easily colonize new territory and grow quickly, but they are also more susceptible to wave damage, coral bleaching, and predators, meaning that even if coral cover increases, the reef has not totally recovered from the last bleaching events. Peter Ridd also claims, “The science institutions have been claiming that there have been three disastrous bleaching events in the past five years, which does not accord with the latest statistics,” and, “while there have been three events, they occurred in largely different regions in each year. The reef has thus effectively had one major bleaching event in the past five years and the previous major event was in 2002.” Ridd’s statements are contradictory and misleading. Scientists identified five global coral bleaching events in the Great Barrier Reef over the last decade, which occurred in 2010, 2015, 2016, 2017 and 2020. Some scientists group the worldwide bleaching events from 2015 to 2017 into a single one, but others consider them to be independent events given the differences in intensity and geographic characteristics of events in 2016 and 2017 (see the figure below). These data confirm the occurrence of three distinct coral bleaching events in the Great Barrier Reef over the last five years[10]. One can see on the map that several reefs have been affected by two or even the three bleaching events. Figure 2 – Maps of the last three bleaching events that occured on the Great Barrier Reef. From ARC Centre for Excellence in Coral Reef Studies Finally, Ridd states that scientists use these bleaching events to spread a message of doom, hypothetically ignoring the “real” state of the Great Barrier and preparing headlines to deceive the public about the risks of climate change. Almost all coral reef scientists agree that climate change will affect coral reef health and resilience[11], it is wrong to claim that the messages scientists try to convey are of doom. As specified by the latest IPCC report about coral reefs, it is known with high confidence that ocean warming and acidification will “enhance the reef dissolution, affect the coral species distribution and lead to community change”[11]. The main message that the scientific community conveys is that coral reefs will continue to be endangered if environmental conditions keep changing in the shallow waters where most coral reefs live. As Box 5.5 in the latest IPCC report states: “Altogether, coral reefs of the future will not resemble those of today because of the projected decline and changes in the composition of corals and associated species in the remaining reefs (high confidence). The very high vulnerability of coral reefs to warming, ocean acidification, increasing storm intensity and Sea Level Rise under climate change (AR5 WG2), including enhanced bioerosion (high confidence) point to the importance of considering both mitigation and adaptation for coral reefs”[11]. For decades, scientists have highlighted the fact that coral reefs are very sensitive to their direct environmental conditions, and that if the water temperature increases and the pH of the sea water keeps changing due to global warming, corals will bleach and die faster than they can regenerate. According to two Australian coral reef specialists, coral reefs are capable of resilience, and they can recover from extreme events and bleaching if given enough time. Professor Terry Hughes, director of the Centre of Excellence for Coral Reef Studies at James Cook University, stated in a 2020 Guardian article, “It’s not too late to turn this around with rapid action on emissions…But business-as-usual emissions will make the Great Barrier Reef a pretty miserable place compared to today.” David Wachenfeld, chief scientist at the Great Barrier Reef Marine Park Authority added in the same article, “No one climate event will kill the Great Barrier Reef, but each successive event creates more damage. Its resilience is not limitless, and we need the strongest possible action on climate change.”LEARN MORE If you want to read more about coral reef recovery, bleaching events or other fact-checked claims made by Peter Ridd, you can follow these links : A fact-check article on a very similar claim made by Peter Ridd in 2019 The Australian Coral Reef Society’s statement regarding Ridd’s “questionable claims”REFERENCES: [1] Annual Summary: Report of Coral Reef Condition 2020/2021. (2021). Australian Institute for Marine Science. [2] De’ath et al. (2012). The 27–year decline of coral cover on the Great Barrier Reef and its causes. Proceedings of the National Academy of Sciences, 109(44), 17995-17999. [3] van Woesik et al. (2015) Keep up or drown: adjustment of western Pacific coral reefs to sea-level rise in the 21st century.Royal Society Open Science.2: 150181. [4] Anderson et al. (2017) Variation in growth rates of branching corals along Australia’s Great Barrier Reef. Scientific Reports 7, 2920. [5] Davis et al. (2021) Global coral reef ecosystems exhibit declining calcification and increasing primary productivity. Communications Earth & Environment 2, 105. [6] Cooper et al. (2008) Declining coral calcification in massive Porites in two nearshore regions of the northern Great Barrier Reef. Global Change Biology.14, 529–538. [7] Roth et al. (2018). Coral reef degradation affects the potential for reef recovery after disturbance. Marine Environmental Research, 142, 48-58. [8] Hoegh-Guldberg (2006). Complexities of coral reef recovery. Science, 311(5757), 42-43. [9] Gilmour et al. (2013). Recovery of an isolated coral reef system following severe disturbance. Science, 340(6128), 69-71. [10] Eakin et al. (2019) The 2014–2017 global-scale coral bleaching event: insights and impacts. Coral Reefs 38, 539–545. [11] IPCC Special Report Ocean & Cryosphere section 5.3.4 p 507 and box 5.5 p 539-540

https://science.feedback.org/review/youtube-video-falsely-claims-that-climate-models-systematically-over-estimated-warming-and-that-we-are-heading-towards-an-ice-age/

Inaccurate

Suspicious0bservers, Ben Davidson, 2021-05-05

"The official observed temperatures are coming consistently below the scary global warming numbers"; "Melting polar ice triggers ice age"

Inaccurate: The claim that climate models consistently overestimate global warming is inaccurate. Retrospective studies have found that climate models skillfully forecasted the evolution of global surface temperatures over the past few decades. Misrepresents sources: Ben Davidson quoted numerous studies to support his claim. However, he misrepresented these sources: the analyses did not conclude that models are inaccurate, nor that an ice age would be coming.

Climate scientists use models to simulate Earth's climate system and project the rate of global warming caused by human activities. State-of-the-art climate models have successfully forecasted global average surface temperatures over the past few decades.

"The official observed temperatures are coming consistently below the scary global warming numbers"; "Models fail to predict the future and the past due to bias, uncertainties, questionable data and unappreciated natural forcing"; "Melting polar ice triggers ice age"

The claim that climate models fail to predict the future or reproduce the past was published in a YouTube video by Ben Davidson on his channel, Suspicious0bservers, which has more than 500,000 subscribers. This video has been watched more than 57,000 times since it was published on May 5, 2021. In the video, Davidson makes numerous false claims about climate models as explained in this review. He shows screenshots of titles and abstracts from recent climate science publications, which he misinterpreted to support his conclusion. The core claim of the video is that “At no point have the climate models accurately predicted the future. The official observed temperatures are coming consistently below the scary global warming numbers”. However, this claim is contradicted by the fact that scientists found climate models skillfully forecast the evolution of global surface temperatures over the past few decades (see a previous Climate Feedback review here). For example, a 2019 study by Hausfather et al. found that climate models published between 1970 and 2007 “were generally quite accurate in predicting global warming in the years after publication, particularly when accounting for differences between modeled and actual changes in atmospheric CO2 and other climate drivers”[1] (read scientists’ comments belowfor further information). To support his claim that scientists overestimate global warming, Davidson argues that climate models are too sensitive to CO2, which means that the increase in global temperature forecasted for a given increase in atmospheric CO2 concentration is too high. Davidson refers to a 2020 study by Zhu et al. which shows that a recent climate model doesn’t accurately forecast past temperatures from the Eocene (50 millions years ago), predicting much warmer temperatures at the time than expected[2]. Scientists understand that some, but by no means all, of the most recent climate models show a high equilibrium climate sensitivity, which is defined as the long-term response of global mean surface temperature to a doubling of atmospheric CO2 concentrations[3]. This sensitivity to CO2 is poorly constrained, with a likely range of 1.5°C to 4.5°C, according to the IPCC Fifth Assessment Report. It’s a fact that some of the latest climate models have a sensitivity higher than 4.5°C, with values up to 5.6°C[3, 4].For example, the model tested in the Zhu et al. study has a sensitivity of 5.3°C. As a result, these models simulate stronger warming and have difficulties reproducing the observed warming trend. However, according to a 2020 study by Tokarska et al., this is the case for only a third of the models participating in the Sixth Coupled Model Intercomparison Project (CMIP6), which will form the basis for the upcoming Sixth Assessment Report of the IPCC[3]. Conversely, other CMIP6 models with climate sensitivity values that are within the IPCC likely range show global warming trends that are consistent with past global temperature observations. Moreover, as this study shows, “projected future warming is correlated with the simulated warming trend during recent decades, enabling us to constrain future warming based on consistency with the observed warming”. The study concludes that, taking this into account, “observationally constrained CMIP6 warming is consistent with previous assessments based on CMIP5 models”. Later on in the video, Davidson claims that, “recently half of Arctic warming was blamed on ozone loss… It told us that the heat that has been blamed on carbon all these years is a fantasy”. To support his claim that CO2 is actually not responsible for global warming, he displays a 2020 paper by Polvani et al. demonstrating that chemicals that destroy the ozone layer, such as chlorofluorocarbon (CFC’s), contributed to warming in the Arctic[5]. While it is true that these ozone depleting substances have the potential to warm the atmosphere, their effect on Arctic temperatures is weaker than the one induced by CO2 rising concentration, contrary to Davidson’s interpretation. As the authors of the study warn, “it is important to place ozone depleting substances in the context of the other anthropogenic forcings. The largest radiative forcing is associated with CO2, and it is three times larger than the radiative forcing from ozone depleting substances, over the 1955–2005 period” (see the figure below). Radiative forcing (RF) describes the net change in the energy balance of the Earth system in response to some imposed perturbation (for example, a change in CO2 concentration in the atmosphere). It is expressed in watts per square meter and averaged over a period of time, with positive RF leading to a warming and negative RF to a cooling. Radiative forcing is valuable for comparing the influence on global mean temperature of most individual agents affecting Earth’s radiation balance (e.g. specific greenhouse gases, aerosols, solar irradiance). Figure 1—Radiative forcing of greenhouse gases for 1955-2005. From Polvani et al. (2020)[5]Another misleading claim made by Davidson is that “the data itself has come under major questions by the world’s number one climate journal… The urban heat island effect adds on a major source of doubt…”. In this statement Davidson is suggesting that the rise in global temperature recorded is inaccurate and biased by the fact that temperatures are “naturally” getting higher in the cities due to urbanization. According to him, global warming is thus overestimated. He relies on a study by Zhang et al. published in March 2021 in Journal of Climate that quantifies the urbanization contribution on global land annual mean and extreme temperature records[6]. Cities do experience much warmer temperatures than nearby rural areas, especially at night or in winter, because urban building materials trap heat. This phenomenon is called Urban Heat Island (UHI). This urbanization effect influences temperature measurements locally, and scientists are well-aware that it needs to be properly identified and removed in temperature data series in order to ensure that global warming is accurately measured and not overestimated. According to the IPCC Fifth Assessment Report, “global adjusted data sets likely account for much of the UHI effect present in the raw data”[7]. Overall, adjustments to temperature data reduce the apparent global warming. At the global scale, the IPCC report argued that the uncorrected urbanization influences contribute no more than 10% to the centennial global land averaged temperature trends. As described in Zhang et al., “the urbanization effect on the trends of annual mean and extreme temperature indices series in East Asia is generally the strongest, which is consistent with the rapid urbanization process in the region over the past decades, but it is generally small in Europe during the recent decades”. After discrediting climate models predicting future global warming, Davidson claims that “the changes we are seeing are going to trigger an ice age. Melting the ice at the pole affects the heat transport in the ocean and triggers rapid cooling towards ice-age conditions”. He cites a study by Starr et al. published in January 2021 that links the melting of Antarctic icebergs and the onset of glacial periods[8]. This claim is inaccurate and misrepresents the results of the study it is based on. As discussed belowby Ian Hall, from Cardiff University, a co-author of the study, the study’s conclusion doesn’t apply in the warm conditions we are currently experiencing. On the contrary, the natural rhythm of ice age cycles may be disrupted as the Southern Ocean will likely become too warm for Antarctic icebergs to travel far enough to trigger the changes in ocean circulation required for an ice age to develop. This pattern is the exact opposite of the claim made by Davidson. The second part of the video is devoted to the claim that “climate has much more to do with sun, volcanoes and cosmic rays modulation than is allowed in the climate models”. This statement is inaccurate as there is strong evidence that solar forcing cannot explain much of the observed warming at all (see below , and previous Climate Feedback reviews here and here). Scientist’s Feedback: “At no point have the climate models accurately predicted the future” Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: [Comment from a previous evaluation of a similar claim] While models can never be a perfect representation of the Earth’s system, they do an excellent job of reproducing many aspects of the Earth’s climate, from rainfall and wind patterns to storm and hurricane formation and warming of the climate. In a 2019 paper we evaluated the performance of 17 historical climate model projections published between 1970 and 2001[1]. We found that 10 of those 17 projected a rate of future temperature change nearly identical to what actually happened in the real world in the years after they were published, while four of the models projected too much warming and three models too little warming[1]. This is particularly impressive for the 1970s-era models, which were published at a time when evidence of observed global warming was limited (and some even thought – based on limited observations – that the world was modestly cooling). Figure 2—Observed surface temperature change (HadCRUT5 – black line) compared to climate model projections from the years after the model was published (colored lines). Adapted from Hausfather et al. 2019 [1].“Oversensitivity to CO2” [Comment from a previous evaluation of a similar claim.] We and others have shown recently that almost all of the high climate sensitivity models in fact tend to overestimate recent warming[3], and taking that into account suggests that many of the new CMIP6 models are biased high, and that future warming is similar to what it was in earlier models. While it is correct that we are seeing models with high climate sensitivity, the evidence is growing that there are issues with at least some of these models. [Comment from a previous evaluation of a similar claim.] It is correct that the most recent versions of some climate models estimate more warming for a given increase in CO2 concentrations. It is also correct that how clouds are represented in these models is the likely reason for these higher estimates. However, it does not report all the science available on this topic and its claims are thus misleading. Available studies that have looked at what these new model projections mean have found that models with higher warming are worse in capturing global warming trends over the past decades, making their projections of very high warming less probable[9]. This is an important context that was omitted. [Comment from a previous evaluation of a similar claim.] The most advanced, state-of-the-art predictions of the sensitivity of Earth’s climate to increasing carbon dioxide are based on multiple lines of evidence: observations, the paleoclimate record, theory, and models of varying complexity[10]. Based on this evidence, climate scientists estimate a likely range of the planetary warming resulting from a doubling of atmospheric carbon dioxide: 2.6-3.9 C (or 4.7-7 F). Climate models produce a wider range of the severity of planetary warming in response to increasing carbon dioxide[11]. This is primarily because their simulation of cloud processes is highly variable, with some models performing better or worse than others. However, a variety of independent evidence taken together reveals how clouds throughout the planet will likely behave as the climate warms, allowing scientists to predict future temperature changes with more precision than climate models simulate[10].“Data itself has come under major questions” Jennifer Francis Senior Scientist, Woods Hole Research Center: [Comment from a previous evaluation of a similar claim] Adjustments are made for good reasons. One of the most common ones is toaccount for a station located in a growing city, where the urban heat island effect would add spurious warming. In most cases the adjustments reduce, not increase, the warming in the record. Victor Venema Scientist, University of Bonn, Germany: [Comment from a previous evaluation of a similar claim] The adjustments are scientifically important, but rather modest for the global mean temperature.The adjustments make the estimated warming smaller, not larger. Below are, for example, the raw and adjusted warming signals of the NASA GISS dataset. The how and why is discussed in this post. For example, if the surrounding of a station becomes more urban this often causes a warming that is local and needs to be removed to estimate the amount the world has truly warmed. Figure 3— Evolution of raw (red line) and adjusted (black line) temperatures. From Gavin Schmidt.“The changes we are seeing are going to trigger an ice age” Ian Hall Professor, Cardiff University: [Comment from a previous evaluation of a similar claim] Our paper is unambiguous and not relevant for modern/future climate change in this way, and reporting it as so is fundamentally misinterpreting our findings. In fact, in the press release for the study, we emphasise that our findings are specifically related to natural “Milankovitch” cycles in orbital forcing, however with current human greenhouse-gas emissions and increasing global temperatures, the Southern Ocean is likely too warm for icebergs to be transported as described in the paper and melt in the regions necessary for the chain of events we highlight to be triggered. Our study does not say or imply that an ice age is coming. It does emphasise the importance of understanding iceberg trajectories and melt patterns in developing the most robust predictions of their future impact on ocean circulation and climate. Moreover, it is well established that the onset of a glacial period has only ever, and can only ever, occur when atmospheric CO2 is below a certain threshold. When atmospheric CO2 concentration is too high, the orbital forcing which favours an ice age is simply not enough to cause an ice age. Under the current orbital configuration, a CO2 concentration of below pre-industrial levels would be required for an ice age to begin[12].“The climate has much more to do with sun, volcanoes and cosmic rays modulation” Peter Neff Assistant Research Professor, University of Minnesota: [Comment from a previous evaluation of a similar claim] This is easily disproven. Solar variability does not exert warming that matches observed temperature increases. See US National Climate Assessment 4, Figure 2.1 below. Figure 4— Human and natural influences on global temperatures. From US National Climate Assessment.REFERENCES: 1 – Hausfather et al. (2019) Evaluating the Performance of Past Climate Model Projections. Geophysical Research Letters. 2 – Zhu et al. (2020) High climate sensitivity in CMIP6 model not supported by paleoclimate models. Nature Climate Change 3 – Tokarska et al. (2020) Past warming trend constrains future warming in CMIP6 models. Science Advances. 4 – Meehl et al. (2020) Context for interpreting equilibrium climate sensitivity and transient climate response from the CMIP6 Earth system models. Science Advances. 5 – Polvani et al. (2020) Substantial twentieth-century Arctic warming caused by ozone-depleting substances. Nature Climate Change. 6 – Zhang et al. (2021) Urbanization Effects on Estimates of Global Trends in Mean and Extreme Air Temperature. Journal of Climate. 7 – IPCC Fifth Assessment report. Observations : Atmosphere and Surface. 8 – Starr et al. (2021) Antarctic icebergs reorganize ocean circulation during Pleistocene glacials. Nature. 9 – Andrews et al. (2020) Historical simulations with HadGEM3‐GC3.1 for CMIP6. Journal of Advances in Modeling Earth Systems. 10 – Sherwood et al. (2021) An Assessment of Earth’s Climate Sensitivity Using Multiple Lines of Evidence. Review: of Geophysics. 11 – Zelinka et al. (2020) Causes of Higher Climate Sensitivity in CMIP6 Models. Geophysical Research Letters. 12 – Tzedakis et al. (2012) Determining the natural length of the current interglacial. Nature Geoscience.

https://science.feedback.org/review/gregory-wrightstone-article-in-the-washington-times-presents-list-of-false-and-misleading-statements-about-the-impacts-of-co2-and-climate-change-co2-coalition/

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The Washington Times, CO2 Coalition, by Gregory Wrightstone, on 2021-04-21.

"There is no climate emergency"

1 – Hughes et al. (2017) Coral reefs in the Anthropocene. Nature. 2 – Hughes et al. (2017) Global warming and recurrent mass bleaching of corals. Nature. 3 – Brierley and Kingsford (2009) Impacts of Climate Change on Marine Organisms and Ecosystems. Current Biology. 4 – Handmer et al. (2012) Chapter 4 – Changes in Impacts of Climate Extremes: Human Systems and Ecosystems. Special Report of the IPCC. 5 – Gasparrini et al. (2015) Mortality risk attributable to high and low ambient temperature: a multicountry observational study. The Lancet. 6 – Gasparrini et al. (2017) Projections of temperature-related excess mortality under climate change scenarios. The Lancet Planetary Health. 7 – Franzke et al. (2020) Risk of extreme high fatalities due to weather and climate hazards and its connection to large-scale climate variability. Climatic Change. 8 – Haque et al. (2012) Reduced death rates from cyclones in Bangladesh: what more needs to be done? Bulletin of the World Health Organization 9 – Kaufman et al. (2020). A global database of Holocene paleoclimate records. Scientific Data. 10 – Burke et al. (2018) Pliocene and Eocene provide best analogs for near-future climates. PNAS. 11 – Schleussner et al. (2018). Crop productivity changes in 1.5 °C and 2 °C worlds under climate sensitivity uncertainty. Environmental Research Letters. 12 – Mbow et al. (2019) IP Food Security. In: Climate Change and Land: an IPCC special report on climate change, desertification, land degradation, sustainable land management, food security, and greenhouse gas fluxes in terrestrial ecosystems. IPCC report. 13 – Rosenzweig et al. (2014). Assessing agricultural risks of climate change in the 21st century in a global gridded crop model intercomparison. PNAS. 14 – Moore et al. (2017) New science of climate change impacts on agriculture implies higher social cost of carbon. Nature. 15 – Piao et al. (2020). Characteristics, drivers and feedbacks of global greening. Nature Reviews Earth & Environment, 1(1), 14-27. 16 – Peñuelas et al. (2017) Shifting from a fertilization-dominated to a warming-dominated period. Nature Ecology & Evolution. 17 – Marcott et al. (2013) A Reconstruction of Regional and Global Temperature for the Past 11,300 Years. Science. 18 – Kaufman et al. (2020) Holocene global mean surface temperature, a multi-method reconstruction approach. Scientific Data. 19 – Degroot et al. (2020) Towards a rigorous understanding of societal responses to climate change. Nature. 20 – Fischer and Knutti (2015) Anthropogenic contribution to global occurrence of heavy-precipitation and high-temperature extremes. Nature Climate Change. 21 – Zhang et al. (2014) Nitrogen and phosphorous limitations significantly reduce future allowable CO2 emissions, Geophysical Research Letters. 22 – De Graaff et al. (2006) Interactions between plant growth and soil nutrient cycling under elevated CO2: a meta-analysis. Global Change Biology. 23 – Lesk et al. (2016) Influence of extreme weather disasters on global crop production. Nature. 24 – Ray et al. (2019) Climate change has likely already affected global food production. Plos One. 25 – National Academies of Sciences, Engineering, and Medicine (2016) Attribution of extreme weather events in the context of climate change. The National Academies Press. 26 – Zhu et al. (2016) Greening of the Earth and its drivers. Nature Climate Change. 27 – Friedlingstein et al. (2020) Global carbon budget 2020. Earth Syst. Sci. Data. 28 – Humphrey et al. (2018) Sensitivity of atmospheric CO2 growth rate to observed changes in terrestrial water storage. Nature. 29 – Yuan et al. (2019) Increased atmospheric vapor pressure deficit reduces global vegetation growth. Science Advances. 30 – Büntgen et al. (2021) Recent European drought extremes beyond Common Era background variability. Nature Geoscience. 31 – Overpeck and Udall (2020) Climate change and the aridification of North America. PNAS. 32 – Abram et al. (2021) Connections of climate change and variability to large and extreme forest fires in southeast Australia. Communications Earth & Environment. 33 – Perkins et al. (2012) Increasing frequency, intensity and duration of observed global heatwaves and warm spells. Geophysical Research Letters. 34 – Perkins-Kirkpatrick (2020) Increasing trends in regional heatwaves. Nature Communications. 35 – Andela et al. (2017) A human-driven decline in global burned area. Science.

Reviewers’ Overall Feedback: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. This op-ed contains so many statements that give readers the wrong impression about the impacts of CO2 and global warming. For example, CO2 levels and temperatures were markedly higher than today’s levels during the part of Earth’s history for which we have geologic proxy measurements. However, it’s also true that during most of that 500 million years, mammals did not even exist, let alone humans. During some of that ancient history, continents near the equator were too hot to support life, while tropical vegetation flourished at what is now the poles. It is fallacious to suggest that a near-instant return to these conditions would be anything less than catastrophic for humanity. This article from NOAA summarizes Earth’s CO2 and climate history for a non-technical audience, and this article provides more detail. Although much of Wrightstone’s op-ed consists of statements presented in a misleading context (like above), some of it is downright false. For example, Wrightstone states that our current global average temperatures are remarkable “only if your record is limited to the last 150 years or so.” That is not correct. The prevailing understanding in paleoclimatology is that our current global average temperatures are some of the highest since before the last Ice Age more than 12,000 years ago[9]. If current warming trends continued under the RCP8.5 emission scenario, then by mid-next century we would likely achieve temperatures not seen since the early Eocene, more than 50 million years ago (Burke et al., 2018, see Figure 1)[10]. As described in Burke et al. (2018), “Under the Representative Concentration Pathway 8.5 (RCP8.5) emission scenario, by 2030 CE, future climates most closely resemble Mid-Pliocene climates, and by 2150 CE, they most closely resemble Eocene climates. Under RCP4.5, climate stabilizes at Pliocene-like conditions by 2040 CE. Pliocene-like and Eocene-like climates emerge first in continental interiors and then expand outward.”[10] Figure 1—Temperature trends from the past 65 million years before present and potential geohistorical analogs of the future climate system. From Burke et al. (2018)[10]. Wrightstone confuses correlation with causation when he discusses the fact that over the past century, global agricultural productivity has increased and weather-related deaths have decreased. We cannot thank anthropogenic climate change for this. Rather, better infrastructure and better health care have reduced the number of people who die from environmental factors such as weather. Progress in crop science and technology (as well as unsustainable depletion of the biosphere) have enabled a steady upward trend in crop production, outweighing any marginal effects of CO2 and warming. Higher CO2 and temperature can aid crop yields in temperate regions, but it comes at the expense of yields in more vulnerable developing tropical regions. It is ethically indefensible that Wrightstone celebrates potential gains for agriculture in the global North while ignoring the numerous studies that describe damages in the global South. For example, Schleussner et al. (2018) conclude that “Even when accounting for the full effects of CO2 fertilisation in crop models, median local tropical yields for wheat and maize are still found to be negatively affected”[11]. They predict that the magnitude of this negative effect will double between 1.5C warming and 2C warming. The other logical fallacies in Wrightstone’s article are too numerous to list here. Without wanting to resort to ad hominem arguments, I find it difficult to believe that Wrightstone (who works in the fossil fuel industry in the extraction of shale oil and gas) is making these arguments in good faith. Rather, this appears to be an intentionally misleading article assembled by someone who, as a geoscientist, understands the technical details but who is using them to distract and confuse rather than to educate the public. Alexis Berg Research Associate, Harvard University: This article recycles old tropes such as “it’s been warm before”, “CO2 levels have been higher in the past” (millions of years ago!), “CO2 is plant food”, “warming is good for ecosystems/humans”, “so far impacts are small, so they will remain small”, etc. All these pseudo-arguments have been addressed many times before (see examples here, here, and here). This article is clearly motivated, misleading and biased. It presents some facts that are technically true – e.g., in the context of Earth’s geological history, we are in a cold, low-CO2 period (at least for now!) – but that are irrelevant to the issue of global warming: we care about changes from current conditions, to which human civilization is adapted. The article also contains factually erroneous claims (see annotations below). Katrin Meissner Professor, University of New South Wales: This article is an aggregation of false statements. It also includes a few partially right statements, but these are taken out of context and presented in a misleading way. It is written in a provocative and arrogant tone, the argumentation is based on lies. Each paragraph contains at least a misleading statement. Although high CO2 concentration is beneficial to some plant growth, the impact of climate change on the growth is mostly detrimental[12-14]. The increase in crop production is mostly linked to fertilizer and agriculture practices, not to the growth in CO2. In fact, there is evidence that climate change has already had detrimental consequences on food production[14], and this may get worse in the future[12]. Yes, there have been higher CO2 levels in the atmosphere, but this was way before humans appeared on our planet. The current CO2 levels, and the rate of change, are way above what the human race has experienced. CO2 in the atmosphere is there for a very long time (not each molecule individually but the concentration perturbation). This is what generates an “emergency”, because there is no going back. Annotations: The statements quoted below are from the video; comments are from the reviewers (and are lightly edited for clarity). “The science and data strongly support that our planet’s ecosystems are thriving and that humanity is benefiting from modestly increasing temperature and an increase in carbon dioxide.” ; “Earth’s ecosystems and inhabitants are thriving because of increasing CO2 and rising temperatures not in spite of them.” There is no science nor is there any data that globally support the assertion that ecosystems are thriving or that humanity would benefit from increasing temperature or increasing carbon dioxide. There are literally tens of thousands scientific publications that indicate that ecosystems are increasingly being degraded due to climate change and other impacts[1-4]. Many people have lost their lives during heat waves or climate change caused natural disasters[5,6]. Alexis Berg Research Associate, Harvard University: It’s true that vegetation has been increasing globally in the last 40 years (since we have satellite measurements). Models suggest CO2 fertilization is the main contributor to the growth of forests and natural ecosystems[15]. Warming has beneficial effects in high-latitude, temperature-limited regions (e.g., Arctic greening), but opposite in the Tropics. Direct human management (agriculture, afforestation) also plays a role in some regions[15]. However, further warming could start having more negative effects on global vegetation, while the beneficial impacts of CO2 could run into some limitations (e.g., nitrogen limitation)[16]. Note as well that current warming levels already have very noticeable negative impacts on marine ecosystems (i.e., coral reefs)[1-3]. “These facts refute the claim that Earth is spiraling into one man-made climate catastrophe after another.” There is no claim of any “spiraling”, there is just a very robust assessment that greenhouse gas concentrations are rising, that they cause rapid climate change, and that the societal consequences of these changes (economy, health, etc.) will be disastrous for a large part of the world’s human population in the near future[4-7]. “Concentrations of this gas are slightly less than 420 parts-per-million (ppm), or one-sixth the average historic levels of 2,600 ppm for the last 600 million years” To compare with the last 600 million year average is irrelevant. Levels are unprecedented with respect to the time that humans have lived on Earth. Katrin Meissner Professor, University of New South Wales: This statement is partially correct. The average historic level was not 2600 ppm, but there were periods of times when CO2 was very high, likely as high as 1500-2000ppm. The ecosystems and biogeochemistry were adapted to these conditions, and they looked very different from today. There were no humans, many of the mammals around us did not exist. Not to mention that the sun’s energy output was slightly smaller during that time. Changing the present day world into a “dinosaur world” within a century would not be good news for the ecosystems we depend on, or for us. Alexis Berg Research Associate, Harvard University: This is a silly point. Yes it was hotter, with more CO2, hundreds of millions of years ago, but humans – mammals! – weren’t there. We care about change now. 420ppm is unprecedented in the last million years at least. By the same token one could say that during the last 600 million years the Earth was mostly ice-free (no ice caps) – so we shouldn’t care if the ice caps melt now (i.e., 70 m of sea-level rise). “Increases in carbon dioxide in the last 150 years, largely from the burning of fossil fuels, have reversed a dangerous downward trend in the gas’ concentration. During the last glacial period, concentrations nearly reached the “line of death” at 150 parts per million, below which plants die. Viewed in the long-term geologic context, we are actually CO2 impoverished.” Katrin Meissner Professor, University of New South Wales: Plants have adapted to lower CO2 concentrations, for example with the appearance of C4 plants. Also, the CO2 concentrations have varied between similar minima during glacials and maxima during interglacials over the past 800,000 years. All the minima are well above 150 ppm. Alexis Berg Research Associate, Harvard University: The last part is not untrue, but irrelevant. Pre-industrial (around 1800) CO2 was 280ppm. For the last 10,000 years (human civilization) it has been around that value, increasing slightly – not decreasing – until modern emissions began. Even without current CO2 emissions and associated warming, there would be no threat of imminent ice age or very low CO2 conditions. “The first 250 years of that warming preceded 20th century CO2 increases and were necessarily 100% naturally driven.” The author makes the frequent mistake of mixing natural variability (the slight warming after the Little Ice Age) and current warming, which is due to greenhouse gas forcing[17]. These processes are well understood by climate scientists. In fact there is no alternative explanation for the recent rapid warming, as described in this Climate Feedback review. “Longer-term data reveal multiple warming periods since the end of the last major ice age 10,000 years ago, each warmer than today.” Alexis Berg Research Associate, Harvard University: Following the last ice age (20 thousand years) and deglaciation, current (Holocene) global CO2 and climate conditions were reached around 10 thousand years ago. Global temperatures kept slightly increasing until the Holocene maximum, around 7 thousand years ago, and then slowly decreased, until the abrupt warming of the last 150 years. The recent reconstruction by Kaufman et al. (2020) indicates that “The warmest 200-year-long interval took place around 6500 years ago when global temperature was 0.7 °C (0.3, 1.8) warmer than the 19th Century (median, 5th, 95th percentiles).” Whether or not we are already there, the fact is that modern warming is going to lead to global climate conditions several times warmer than that (e.g., if we get to +3 or 4°C of global warming). Figure 1—Global mean temperature of the last 12,000 years using different methods to reconstruct past global mean surface temperature (colored lines). The black line indicates instrumental data from 1900-2010. From Kaufman et al (2020)[18]. “There is a strong correlation between the rise and fall of temperature and the ebb and flow of civilizations. During the last three warm periods dating back 6,000 years to the advent of the first great civilizations, humanity prospered and great empires arose. Intervening cold periods brought crop failure, famine, and mass depopulation. History advises us to welcome warmth and fear cold.” Katrin Kleemann Visiting Scholar, Ludwig Maximilian University of Munich: The examples mentioned here are vague, it is unclear which cold periods or which incidents of crop failure, famine, or population loss the author refers to. It is also unclear which “civilizations” the author is referring to. While it is true that past societies experienced natural climate change, these were regional and smaller in magnitude than present-day global warming. Nevertheless, the climate change during periods, such as the Late Antique Little Ice Age or the Little Ice Age, was profound enough to alter human life. It is, of course, deterministic to argue that the climate was the only factor that brought about crop failure, famine, or population loss. In reality, several factors come together that can then lead to crop failure or famine: for instance, inadequate planning, social upheaval, economic struggles, conflicts with other groups, etc.[19]. Past scholarship has focused a lot on the collapse of societies; however, recent scholarship has discovered that past societies and communities often were resilient in the face of modest climate change. Despite the climatic change, these societies or communities maintained their structure, function, and identity. Some societies adapted to the new, often colder, climatic regime and even managed to exploit the opportunities created by the shift in environmental circumstances[19]. The climate change faced by societies during the Late Antique Little Ice Age or the Little Ice Age was modest compared to the much greater magnitude of climate change that we are facing in the present and future due to the warming that our greenhouse gas emissions are causing. In the present, we are already experiencing what it looks like to live in a warming world – heat waves, rising temperatures on land and in the oceans, wildfires, to mention but a few, have devastating consequences for millions of people around the planet[19]. There is no such “strong correlation”. The rise and fall of social systems is affected by many factors and climate may be one of them. In most cases, there is insufficient evidence to explain the fall of past societies with a single factor. More importantly, none of the past “civilizations” had similarly large global populations and similarly high dependence on stable environmental conditions. Heat waves are becoming more frequent and more severe in many parts of the world. They even occur in the ocean and are one of the key drivers for the loss of tropical coral reefs. “Modestly warming temperature and increasing carbon dioxide lead to longer growing seasons and more productive harvests. The world’s remarkable ability to increase food production year after year is attributable to mechanization, agricultural innovation, CO2 fertilization, and warmer weather. Crop and food production has seen only positive effects from relatively small changes in the global climate.” Katrin Meissner Professor, University of New South Wales: Plants cannot live on CO2 alone. Those plants that profit from higher CO2 will need more water to maintain their larger growth and to compensate for larger evaporators-transpiration due to increased heat. They will therefore be more vulnerable to changes in precipitation patterns, and to aridification, which will be one of the consequences of higher CO2 levels in many regions[20]. They will also need more nutrients, which are not necessarily available[21,22]. Other plants do not profit from higher CO2, and their photosynthesis rates have been shown to decrease under higher CO2. More importantly, higher CO2 has been shown to reduce the nutritional quality of some plants we depend on, such as wheat[14]. Modestly warming temperature indeed leads to longer growing seasons and modest warming and increasing carbon dioxide can lead to more productive harvests (depending on the local conditions). However, with global warming, heatwaves and droughts are increasing in frequency and intensity[20]. Increases in extreme weather events can have strong negative effects on crop productivity and are expected to negatively impact food production[23]. Crop and food production as well as human settlements are also threatened by the increasing risk of wildfires due to global warming. Alexis Berg Research Associate, Harvard University: It is complicated to separate all factors contributing to crop yield changes, but there is evidence suggesting that global warming is already negatively impacting global food production, at least in some regions[24]. Note that crop yields respond not only to mean climate, but also to extreme events (e.g., heat waves, droughts) that get more intense and/or frequent with warming[23]. Of course, further warming makes it only more likely that negative impacts will start occurring. “Contrary to sensational media reports, extreme weather-related deaths in the U.S. have decreased more than 98% over the last 100 years. Twenty times as many people die from cold as from heat, according to a worldwide review of 74 million temperature-related deaths by Dr. Antonio Gasparrini and a team of physicians. Global warming saves lives.” Antonio Gasparrini Senior Lecturer, London School of Hygiene and Tropical Medicine: I think Mr. Wrightstone refers to an article I published some time ago, where we showed that indeed cold is currently associated with a much higher mortality[5]. However, this does not mean that the decrease in cold-related deaths expected with the warming of the planet will offset the heat-related increase in the future. Actually, from the evidence we have gathered so far by a follow-up study on an even larger dataset , it seems that this is not true unless in mild warming scenarios that require strict mitigation strategies[6]. Katrin Meissner Professor, University of New South Wales: This statement is false, based on fatality data from NOAA. Alexis Berg Research Associate, Harvard University: Moot point. The concern about global warming doesn’t stem from the direct impact of atmospheric conditions on human lives or deaths, but rather from its impact on the environmental factors that support society – water resources, natural and cultivated ecosystems, ecosystem services, etc. Note, however, that an increase in humid heat could lead to literally lethal atmospheric conditions during heatwaves in parts of the Tropics under a high-warming scenario. “During this period of increasing CO2 and slight warming, we have seen increasing food production, soil moisture, crop growth, and a “greening” of the Earth. All the while droughts, forest fires, heat waves, and temperature-related deaths have declined substantially.” Unfortunately, droughts, forest fires and heat waves are increasing world-wide, and so do temperature-related deaths[6,25]. The statements made here are invented by the author and entirely “at odds with reality”. The earth has indeed been greening in the past decades, and this has been attributed primarily to the increasing CO2 concentrations[26]. Terrestrial ecosystems have sequestered about 30% of anthropogenic CO2 emissions, and this land sink has retarded climate change[27]. However, as global warming progresses, negative impacts of especially heat and drought are increasing. In fact, we are already seeing the first signs of a decline in the land CO2 sink and increasing extreme heatwaves and droughts seem to be the most important reason[16,28,29]. Katrin Meissner Professor, University of New South Wales: Droughts and aridification have increased in many regions of the world. For example in Europe and North America[30,31]. Forest fires have increased and now show the fingerprint of global warming, e.g. in Australia[32] and the Arctic. Heat waves have increased in frequency, intensity and duration[33]. Alexis Berg Research Associate, Harvard University: I am not aware of any study showing an increase in soil moisture over the last decades (soil moisture is exceedingly difficult to measure globally). Heat waves have demonstrably increased[34]. Global burnt area has decreased globally over the last 20 years, yes (by 25%), but that signal is dominated by agricultural intensification and expansion, which replaces naturally-burning grasslands and savannah, in particular in the Tropics[35]. Some regions clearly show warming-influenced growth in wildfires in natural ecosystems (e.g., Western US, high latitudes). Changes in drought frequency/intensity are complex and hard to estimate – warming may not cause more droughts but may make existing ones worse. But in any case, the consensus is certainly not that there has been any “substantial decline” in droughts in recent decades. “Yes, there has been some warming, but it has been minuscule compared to the temperature change all of us experience in the course of a day.” Katrin Meissner Professor, University of New South Wales: The overall global warming that has been observed so far is small compared to the diurnal temperature difference we experience every day. But this is also a meaningless statement. We could take our daily food intake as an example. Most of the minutes of the day we eat nothing. During dinner, we might eat a pizza and drink a beer and therefore absorb 2000 calories within 20 minutes. Our intake throughout the day varies between 0 and 1000 calories per 10 minutes, assuming that our breakfast and lunch is a bit less calorific. Compared to a range between 0 and 1000, 10 calories is nothing – I therefore suggest we should all constantly eat 10 calories every 10 minutes throughout the day, on top of our normal intake, and let’s see what this will do to our health. UPDATES: 9 June 2021: Two of Amber Kerr’s statements were updated to explain that current global average temperatures are some of the highest since before the last Ice Age and to clarify the results discussed from Burke et al. (2018)[10].

https://science.feedback.org/review/wall-street-journal-article-repeats-multiple-incorrect-and-misleading-claims-made-in-steven-koonins-new-book-unsettled-steven-koonin/

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The Wall Street Journal, by Mark P. Mills, on 2021-04-25.

"‘Unsettled’ Review: The ‘Consensus’ On Climate"

1 – Kjeldsen et al. (2015) Spatial and temporal distribution of mass loss from the Greenland Ice Sheet since AD 1900. Nature. 2 – Frederikse et al. (2018) A Consistent Sea-Level Reconstruction and Its Budget on Basin and Global Scales over 1958–2014. Journal of Climate. 3 – Frederikse et al. (2020) The causes of sea-level rise since 1900. Nature. 4 – Dangendorf et al. (2019) Persistent acceleration in global sea-level rise since the 1960s. Nature Climate Change. 5 – Horton et al. (2018) Mapping Sea-Level Change in Time, Space, and Probability. Annual Review of Environment and Resources. 6 – IPCC (2014) Climate Change 2014: Summary: for Policymakers. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. 7 – Ortiz-Bobea, et al. (2021) Anthropogenic climate change has slowed global agricultural productivity growth. Nature Climate Change. 8 – Doerr and Santín (2016) Global trends in wildfire and its impacts: perceptions versus realities in a changing world. Philosophical Transactions of the Royal Society B. 9 – Bowman et al. (2020) Vegetation fires in the Anthropocene. Nature Reviews Earth & Environment. 10 – Gonzalez et al. (2018) Chapter 25: Southwest. In Impacts, Risks, and Adaptation in the United States: Fourth National Climate Assessment, Volume II. 11 – Hausfather et al. (2020). Evaluating the performance of past climate model projections. Geophysical Research Letters. 12 – Mouginot and Rignot (2019). Forty-six years of Greenland Ice Sheet mass balance from 1972 to 2018. PNAS. 13 – Church and White (2011) Sea-Level Rise from the Late 19th to the Early 21st Century. Surveys in Geophysics. 14 – Jevrejeva et al.(2014) Trends and acceleration in global and regional sea levels since 1807. Global and Planetary Change. 15 – Ray and Douglas (2011) Experiments in reconstructing twentieth-century sea levels. Progress in Oceanography. 16 – Hay et al. (2015) Probabilistic reanalysis of twentieth-century sea-level rise. Nature. 17 – Dangendorf et al. (2019), Persistent acceleration in global sea-level rise since the 1960s. Nature Climate Change. 18 – Blunden and Arndt (2019). State of the Climate in 2018. Bulletin of the American Meteorology Society. 19 – Nerem et al. (2018) Climate-change–driven accelerated sea-level rise detected in the altimeter era. PNAS. 20 – Kopp et al. (2016) Temperature-driven global sea-level variability in the Common Era. PNAS. 21 – Walker et al. (2021) Common Era sea-level budgets along the U.S. Atlantic coast. Nature. 22 – Bamber et al. (2019) Ice sheet contributions to future sea-level rise from structured expert judgment. PNAS. 23 – Yang et al. (2014) Spatial and temporal patterns of global burned area in response to anthropogenic and environmental factors: Reconstructing global fire history for the 20th and early 21st centuries. Journal of Geophysical Research: Biogeosciences. 24 – Williams et al. (2019) Observed Impacts of Anthropogenic Climate Change on Wildfire in California. Earth’s Future. 25 – Abatzoglou and Williams (2016) Impact of anthropogenic climate change on wildfire across western US forests. PNAS. 26 – Goss et al. (2020) Climate change is increasing the likelihood of extreme autumn wildfire conditions across California. Environmental Research Letters. 27 – Abram et al. (2021) Connections of climate change and variability to large and extreme forest fires in southeast Australia. Communications Earth & Environment. 28 – Feurdean et al. (2020) Recent fire regime in the southern boreal forests of western Siberia is unprecedented in the last five millennia. Quaternary Science Reviews. 29 – Jones et al. (2020) Climate Change Increases the Risk of Wildfires. ScienceBrief Review. 30 – Gensini and Brooks (2018) Spatial trends in United States tornado frequency. npj Climate and Atmospheric Science. 31 – Elsner et al. (2018) Increasingly Powerful Tornadoes in the United States. Geophysical Research Letters. 32 – Diffenbaugh et al. (2013) Robust increases in severe thunderstorm environments in response to greenhouse forcing. PNAS. 33 – Hoogewind et al. (2017) The Impact of Climate Change on Hazardous Convective Weather in the United States: Insight from High-Resolution Dynamical Downscaling. Journal of Climate. 34- Brooks et al. (2014) Increased variability of tornado occurrence in the United States, Science. 35 – Marvel et al. (2019) Twentieth-century hydroclimate changes consistent with human influence. Nature. 36– Diffenbaugh et al. (2015) Anthropogenic warming has increased drought risk in California. PNAS. 37 – Williams et al. (2020) Large contribution from anthropogenic warming to an emerging North American megadrought. Science. 38 – Kossin et al. (2020) Global Increase in Major Tropical Cyclone Exceedance Probability over the Past Four Decades. Proceedings of the National Academy of Sciences. 39 – Liu et al. (2019) Causes of large projected increases in hurricane precipitation rates with global warming. npj Climate and Atmospheric Science. 40 – Knutson et al. (2020)Tropical Cyclones and Climate Change Assessment: Part II: Projected Response to Anthropogenic Warming. Bulletin of the American Meteorological Society. 41 – Hsiang et al. (2017) Estimating economic damage from climate change in the United States. Science. 42 – Lüthi et al. (2008). High-resolution carbon dioxide concentration record 650,000–800,000 years before present. Nature. 43 – Foster et al. (2017). Future climate forcing potentially without precedent in the last 420 million years. Nature Communications. 44 – Mills et al. (2019) Modelling the long-term carbon cycle, atmospheric CO2, and Earth surface temperature from late Neoproterozoic to present day. Gondwana Research. 45 – Siegert et al. (2020) What ancient climates tell us about high carbon dioxide concentrations in Earth’s atmosphere. Grantham Institute Briefing Note 13, Imperial College London.

Reviewers’ Overall Feedback: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: The Wall Street Journal article reviewing Dr. Steven Koonin’s new book is a mix of factually correct, correct but misleading, and inaccurate statements. It seems to be cherry-picking different datasets and factoids to downplay the severity of future climate impacts. For example, while Koonin mentions that global area burned by fires is decreasing, he is conflating purposefully set agricultural fires (which are decreasing) with wildfires that are increasing in many regions due to climate change. Similarly, he highlights one dataset that suggests some ambiguity about whether the rate of sea level rise today exceeds that of the 1940s, while ignoring four other datasets that show clear modern acceleration (see below). Finally, his criticism that climate models have poor skill in “retroactive prediction” ignores the fact that climate models published since the 1970s were quite accurate in projecting the warming that actually occurred in the years after they were published, as we discuss in our recent paper[11]. This book review uncritically regurgitates an assortment of misleading and/or outright false claims that presumably appear in the underlying volume. As has been thoroughly emphasized by scientists here and elsewhere, climate change is clearly increasing the frequency and/or severity of different kinds of extreme weather events in the United States and elsewhere (including heat waves), has indeed resulted in an accelerating rate of sea level rise, and has very large societal and economic implications. Twila Moon Research Scientist, University of Colorado, Boulder: Many conclusions highlighted in this article are examples of cherry-picking information and failing to provide the context of change. In other instances, statements are fully wrong and unsupported by scientific research. Kerry Emanuel Professor of Atmospheric Science, MIT: Early in the review, the novelist Michael Chrichton is quoted as saying “If it’s consensus, it isn’t science. If it’s science, it isn’t consensus. Period.” But those making policy would be foolish not to go with a scientific consensus; anything else would almost by definition be subjective. What is the point of quoting Chrichton if not to cast doubt on the value of scientific consensus? The existence of a consensus is not at all tantamount to the idea that the “science is settled”. Annotations: The statements quoted below are from the article; comments are from the reviewers (and are lightly edited for clarity). ”Greenland’s ice sheet isn’t shrinking any more rapidly today than it was eighty years ago.” Twila Moon Research Scientist, University of Colorado, Boulder: This statement is untrue. The per year average ice loss during 2003-2010 is roughly 2.5 times higher than during 1900-2003. This is evident in the following figure from Kjeldsen et al.[1] Figure 3 — Surface elevation change rates in Greenland during 1900-1983 (a), 1983-2003 (b), and 2003-2010 (c). The numbers listed below each panel are the integrated Greenland-wide mass balance estimates expressed as gigatonnes per year and as millimetre per year GMSL (global mean sea level) equivalents. From Kjeldsen et al. 2015[1]. If we look in more detail at changes over 1972-2018, we can further see that the ice sheet was mostly in balance (gain about the same amount of snow/ice in winter as is lost in summer) during the 1970s and 1980s[12]. It was only in the mid-1990s that Greenland ice loss began to increase more substantially. Over the last 20 years, ice loss has been rapid and large, creating measurable sea level rise, which we experience as increases in coastal erosion, flooding, problems with water and sewer systems at the coasts, and saltwater inundation of freshwater sources. ”The rate of sea-level rise has not accelerated.” Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: This statement is inaccurate; all observational sea level rise (SLR) datasets show rapid acceleration in recent years, and most now show sea levels rising faster than at any point since records began in the early 1900s. Reconstructing past changes in global sea levels is far from a simple task. While high-quality satellite measurements with global coverage have been available since the early 1990s, prior to that researchers had to rely on tide gauges scattered around the world. These tide gauges primarily cover coastal regions, leaving it up to researchers to figure out how best to fill the gaps. Tide gauges are also subject to factors that can complicate the interpretation of local sea level changes, namely subsidence (sinking land) or isostatic rebound (rising land due to melting glaciers). The IPCC 5th Assessment Report featured three estimates of global sea level rise[6]: from Church and White[13], Jevrejeva[14], and Ray and Douglas[15]. Two additional SLR datasets – Hay et al.[16] and Dangendorf et al.[17] – have been published in recent years. All five of these datasets are shown in the figure 5 below (coloured lines), along with satellite altimeter measurements (in black) after 1993. Figure 4— Estimates of global mean sea level from 1992-2006 (in millimetres), and 20-year average rate of global sea level rise (mm/year) from various references. From Carbon Brief. Recently, there has been some debate around whether the current rate of SLR exceeds that experienced back in the 1940s. Three of the five datasets (Dangendorf, Hay, and Church and White) suggest that the current rate of sea level rise – as measured by accurate satellite altimeters – is around 50% faster than was experienced in the 1940s. The Ray and Douglas dataset suggests that current rates of SLR measured by satellite altimeters are modestly above the 1940s peak, while one of the five – Jevrejeva – suggests that the current rate of SLR is below that of the 1940s. However, even the authors of the Jevrejeva dataset suggest in their accompanying paper that a longer view of sea level – from 1800 to present – still suggests that “the rate of sea level rise is increasing with time”[14]. There is also evidence of accelerating SLR over the post-1993 period when high-quality satellite altimetry data is available. According to the 2018 State of the Climate report[18], acceleration in SLR during the post-1993 period is around 0.1mm each year; this means that the rate of SLR is increasing by 1mm per year each decade. For more details, see my discussion of sea level rise acceleration at Carbon Brief. Thomas Frederikse Postdoctoral researcher, Jet Propulsion Laboratory/California Institute of Technology: Satellite measurements, which started in 1993, show a clear acceleration in sea level [19]. Also, if we go further back in time, tide-gauge observations show that sea levels are persistently accelerating since the 1960s[4], and overall, the observed sea-level rise during the 20th century is higher than during any other century over the last 3000 years[20,21]. [Comment from a previous evaluation of a similar claim] This is literally the opposite of what a growing body of recent evidence has shown. Research actually shows that rates of global sea level rise have accelerated in recent years[19], and estimates regarding the upper end of plausible further sea level rise over the coming century have actually increased considerably as the non-linear contribution by continental ice sheets comes into clearer focus[22]. So, if anything, sea level rise is becoming more of a problem than previously thought. ”The extent of global fires has been trending significantly downward.” Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: This statement is accurate but misleading. The vast majority of fires globally are purposefully set for agricultural clearing, and these have declined in recent years. Conflating all fires with forest and wildfires is not helpful in understanding changing drivers of fire risk. A 2014 study suggests that in the tropics climate change may have also reduced the area burned over the past 50 years, due, in part, to wetter conditions[23]. However, they find that climate change has likely increased fire risk in the high latitudes and mid-latitudes over recent decades. Figure 5 —Contribution of different factors in changes since 1900 in forest-fire area globally (a) and for different regions : (b) northern high latitudes (>55°N), (c) northern extratropics (55°N to 30°N), (d) tropics (30°N to 20°S), and (e) southern extratropics (>20°S). Effects of climate change (including changes in temperatures and precipitation) are shown by the vertical stripes. Human land management activity is shown by the diagonal stripes, while the effect of CO2 fertilization and nitrogen deposition is shown by the dots. From Yang et al. (2014)[23]. Hotter and drier conditions have been a major factor in the increase in areas burned by wildfires in many regions – such as the western US – in recent years. For example Williams et al. (2019) found that in California, “nearly all of the increase in summer forest‐fire area during 1972–2018 was driven by increased VPD [vapor pressure deficit]” driven by climate change[24]. Earlier work by Abatzoglou and Williams (2016) found that fuel aridity – driven by observed warming and drying – was the major driver of enhanced fire activity in the Western US[25]. For more details, see my Carbon Brief analysis of the role of climate change in US wildfires. [Comment from a previous evaluation of a similar claim] Overall trends in area burned globally are strongly driven by decreases in intentional agricultural burning in tropical areas, which is not related to climate change. In regions where non-agricultural fires occur naturally (including the western United States[24-26], eastern Australia[27], and the Siberian Arctic[28], there is strong evidence that climate change has already increased the severity and extent of wildfire[29]. [Comment from a previous evaluation of a similar claim] The observed decline in global average area burned has been misused numerous times to support false claims about the role of climate change in wildfire trends. Climate change as well as human activities affect global fire activity (see here for a summary and update on Doerr and Santin, 2016[8]). The overall global decrease is mostly driven by less fire in what used to be more extensive savannahs and grasslands and is largely due to the human driven removal of flammable vegetation. In quantitative terms, fire in those grassy ecosystems account for around 70% of the total global area burnt, so the reduction in fire activity here outweighs the increase in burned area that we are seeing in other parts of the world over the last two decades where fires have greater impacts such as Canada, parts of the USA or Siberia. In other words, where humans have not converted flammable landscapes to less or-non flammable landscapes by removing or changing the vegetation, warming temperatures are, overall, associated with an increase in fire activity. A very thorough global analysis of trends and fire knowledge overall has been made by Bowman et al. in 2020[9]. Gary Yohe Professor of Economics and Environmental Studies, Wesleyan University: Fires are local events whose regional patterns of intensity and frequency fit well into risk-based calibrations. They can also be perfect examples of a new troubling tendency in which several types of impacts attributed to climate change show up at the same place at the same time, feeding on each other combining forces to produce still greater extremes – something that long-term trends of one type of climate change impact simply cannot explain. Take, for example, the 2020 California fire experience. Only three of the state’s largest 20 fires (in terms of acres burned) had burned prior to 2000, but nine of the biggest 10 have occurred since 2012. That is, moving toward the next decade, extreme fires were becoming more likely and more intense. In 2017, 9,270 fires burned a record 1.5 million acres. The Mendocino Complex fire the next year became the “largest wildfire in California history.” And then came 2020. A new largest fire in California history, the Complex fire, started in August of 2020. Soon after came the 3rd, 4th, 5th, and 6th largest in history. By October 3, these five conflagrations had combined with nearly 8,000 other more “ordinary” fires to kill 31 people and burn more than four-million acres; and, on that day, all five were still burning at the same time. Why is this happening? It is becoming clear that nature can produce combinations of influences on local environmental conditions. Many of the 2020 fires in California were caused by literally thousands of dry lightning strikes that fed into a witches’ brew of simultaneous conditions that have all been linked to global warming: the end of a multi-year record drought all-time record heat punctuated July, August, and much of September widespread tinderbox stands of dead trees from multi-year and growing infestations of bark beetles decades of normal warming that had extended the western fire season by some 75 days ”tornado frequency and severity are also not trending up; nor are the number and severity of droughts.” Kerry Emanuel Professor of Atmospheric Science, MIT: Koonin sets up a strawman in claiming that tornado frequency and severity are not trending up. The scientific consensus on this is that we simply do not have the data to determine trends in tornadoes, and what little theoretical work has been done on this suggests that severity might go up and frequency might go down, but again there is no real consensus. [Comment from a previous evaluation of a similar claim] There is relatively little evidence in either direction at this point in time regarding global or even regional trends in tornado frequency/intensity. This is largely due to sparse and temporally inhomogeneous historical records in the United States, and virtually non-existent records in other regions. There is some evidence of regional shifts in tornado frequency[30], and perhaps an increase in overall tornado “power” in the United States[31], but in general there is an absence of strong evidence regarding this claim. Future projections regarding climate change and tornado risk are of somewhat low confidence, but there is evidence that atmospheric environments favorable for severe convective storms (which are the types of storms capable of producing tornadoes) may increase in the future due to climate warming[32,33]. Andreas Prein Project Scientist, National Center for Atmospheric Research: [Comment from a previous evaluation of a similar claim] It is not clear if climate change will make U.S. tornadoes worse or more frequent. The observational record does not show any significant change in the frequency of U.S. tornadoes in the last 60 years but there is a tendency that more tornadoes occur during big outbreak days[34] and there are spatial shifts in the occurrence of tornadoes[30]. Whether these changes are related to climate change is, however, unclear. ” the number and severity of droughts are also not trending up.” [Comment from a previous evaluation of a similar claim] Observed spatial trends in global hydroclimate over the past century have been consistent with those expected from human influence in the climate system[35]. In many mid-latitude and subtropical regions, this has indeed included an increase in the frequency/intensity of drought[36,37]–but in other regions (such as the Northern Hemisphere high latitudes), this includes an increase in moisture availability and decrease in drought (as expected from climate model simulations). Therefore, it doesn’t really make sense to make blanket statements regarding overall global drought trends, since only some places are expected to get drier (and others wetter) in a warming climate.“Humans have had no detectable impact on hurricanes over the past century” Kerry Emanuel Professor of Atmospheric Science, MIT: This statement is flat out wrong. In the first place, the theoretically predicted trends would not have been detectable in the sparse and noisy hurricane record until recently, and in fact they HAVE recently been detected. The most up-to-date research published in the Proceedings of the National Academy of Sciences demonstrates an increase in the proportion of hurricanes that become major hurricanes (Category 3-5) globally, supporting theoretical predictions that date back to 1987 (see figure below)[38]. Figure 6—The proportion of major hurricane intensities to all hurricane intensities globally from 1979-2017. Data is binned into 3-year periods. The proportion of global major hurricanes increased by 25% over the 39-year time period analyzed. From Kossin et al. (2020)[38]. Furthermore, the phrase “in the past century” is telling nothing since no one familiar with the global record of tropical cyclones would look at data prior to 1980; it is just way too poor to be able to detect trends. [Comment from a previous evaluation of a similar claim] While there remains no strong evidence for an increase in tropical cyclone (hurricane) frequency on a global basis, there is evidence that the most intense tropical cyclones are indeed becoming stronger in terms of maximum wind speeds and minimum central pressure[38] and are producing more extreme rainfall[39]. In fact, these trends are consistent with predictions regarding tropical cyclone behavior due to global warming: there is a strong expectation that the maximum potential intensity of hurricanes will increase due to rising ocean temperatures, even as the overall frequency of such storms does not change greatly or perhaps even decreases[40]. ”Global crop yields are rising, not falling.” Frances Moore Assistant Professor, University of California Davis: While global crop yields are rising, this does not constitute evidence that climate change is not adversely affecting agriculture. IPCC estimates are that increased heat and drought resulting from anthropogenic warming will slow the rate of yield growth, not reverse it[6]. Given a growing population and rising incomes, this will place increasing strain on the global food supply. A recent paper by Ortiz-Bobea et al. (2021) found that anthropogenic warming since 1961 removed the equivalent of 7 years of productivity growth[7]. The effect is substantially more severe in warmer regions such as Africa and Latin America and the Caribbean. Moreover, the authors concluded that “Global agriculture has grown more vulnerable to ongoing climate change”. David Lobell Associate Professor, Stanford University: This statement implies that people are claiming global crop yields are falling, which is false. it also is a logical fallacy to say that if things aren’t causing a net decrease then it isn’t a concern. One could say the economy is larger than it was 30 years ago, so nothing hurting the economy is a concern. Or global health is better, so a pandemic is no big deal. ”The net economic impact of human-induced climate change will be minimal through at least the end of this century.” Gary Yohe Professor of Economics and Environmental Studies, Wesleyan University: It is impossible to support a statement like this because economic damages are very dependent on unpredictable investments in adaptation and because sectoral coverage of the aggregate economy is woefully incomplete. A much more honest statement should read something like this from the IPCC Fifth Assessment: “there is low to medium confidence in attribution of climate change influence on a few sectors… Risks of global aggregate impacts are moderate for additional warming between 1°C to 2°C compared to 1986–2005… Aggregate economic damages accelerate with increasing temperature (limited evidence, high agreement) but few quantitative estimates have been completed for additional warming around 3°C.” Since 2014, more comprehensive studies have offered still incomplete portraits of the correlations between distributions of net economic damage (not just fitted values) along alternative global development pathways and increases in global mean temperature[41]. See figure below : Figure 7 — Estimates of total direct damages across all sectors from climate change on the U.S. economy. The x-axis refers to temperature change (°C) for 2080-2099 relative to 1980-2010. From Hsiang et al. 2017[41]. ”while global atmospheric CO2 levels are obviously higher now than two centuries ago, they’re not at any record planetary high—they’re at a low that has only been seen once before in the past 500 million years.” Scott Wing Curator and Research Scientist, Department of Paleobiology, Smithsonian Institution: This statement is incorrect. CO2 levels were lower than today’s at every glacial maximum for the last 800,000 years[42], as revealed by ice core records (see Figure 8 below). Figure 8 — Past CO2 concentration obtained from air trapped in ice cores from Antarctica. From https://keelingcurve.ucsd.edu For times before ice cores (>800,000 years) CO2 levels have to be inferred less directly from geochemical or biological proxies. These proxies have larger uncertainties associated with them than direct measurements or ice cores. Still, today’s levels are thought to be similar to those for the Pliocene and late Miocene, 2-10 million years ago. Of course polar ice caps were much smaller and sea levels much higher when CO2 was as high as it is now. Going farther back atmospheric CO2 concentrations becomes less certain, but probably it was higher than present during much of the long warm period prior to Antarctic glaciation beginning 34 million years ago and going back to the last major ice age in the Carboniferous, about 300 million years ago[43]. Lee Kump Professor, PennState University: This statement is misleading. Yes, atmospheric CO2 levels have been much higher than they are now in the VERY DISTANT geological past. But 500 million years ago the sun was dimmer than today, and high CO2 levels compensated for low irradiance. As the sun has become brighter over the history of our planet, CO2 levels in general have fallen, keeping our planet habitable[44]. So statements like “record planetary high” are meaningless. What’s meaningful is that at over 400 parts per million, the atmosphere today has a carbon dioxide level that Earth hasn’t seen in the last 2-5 million years, and climates at that time were warmer than today, ice sheets were smaller, and sea level was higher. Various scenarios for fossil-fuel burning take us above 1000 ppm in the next several decades, a level not seen for over 50 million years and at a time without ANY significant ice sheets on the planet and a much warmer climate (at least 10°F warmer on a global average). Figure 9— Estimates for atmospheric CO2 concentration (colored lines) during the last 420 millions years, based on different proxies. Average error shown as light grey bands. From Mills et al.[44] Dana Royer Professor, Wesleyan University: The fact that CO2 levels have been higher in the past[45] should not be used as evidence that humans are not changing the climate or that we should not be concerned about our near future. Statements like the one above are common for climate skeptics, but they widely miss the mark for two main reasons: If we continue on our current trajectory, global temperatures will soon reach levels not experienced since the time when ice sheets (like on Antarctica and Greenland) were absent. This was a “very” different Earth, and one humans have no experience living in. The “rate” of climate change is faster than all documented climate change events in the geologic record. The fastest rates of change that we know about (in thousands of years) are associated with mass extinctions. Our current rate of change is hundreds of years. This is scary and does not bode well.CORRECTION (2 JUNE 2021) This review was updated in order to correct an error made in interpreting the Greenland Ice Sheet mass balance figure from Kjeldsen et al[1]. The Greenland Ice Sheet didn’t lose more mass during 2003-2010 than during all of 1900-2003 combined as previously written. Rather, the figure shows that the per year average ice loss during 2003-2010 is roughly 2.5 times higher than during 1900-2003.

https://science.feedback.org/review/bidens-climate-plan-doesnt-say-anything-about-limiting-meat-consumption-contrary-to-daily-mail-fox-news-claim/

Inaccurate

Daily Mail, Emily Crane, 2021-04-22

Biden’s climate plan limits meat consumption by 90%; “Biden's climate plan could limit you to eat just one burger a MONTH”

Inaccurate: President Joe Biden’s climate plan to reduce greenhouse gas emissions in half by 2030 doesn’t include any statements about limiting meat consumption.

In April 2020, President Joe Biden announced a climate plan to halve greenhouse gas emissions in the US by 2030. The plan doesn’t include any statements about limiting red meat consumption. The climate plan primarily focuses on investing in carbon pollution-free energy sources, reducing carbon pollution in transportation, and enhancing carbon sinks, such as forests and agricultural soils.

Biden’s climate plan limits meat consumption by 90%; “Biden's climate plan could limit you to eat just one burger a MONTH”

Review: The claim that President Joe Biden’s climate plan could limit meat consumption appeared in an article published by the Daily Mail in April 2021 and was repeated in numerous Twitter and Facebook posts. A version of this claim also appeared on Fox News, but the outlet recently apologized for airing misinformation. These claims received hundreds of thousands of interactions on Facebook and other social networks. Although few specifics have been announced, Biden’s climate plan aims to cut US greenhouse gas emissions in half by 2030. The plan doesn’t include any statements about limiting meat consumption, contrary to implications made in the Daily Mail article. For example, the article includes a graphic stating “What will be required to meet Joe’s green targets: cut 90% of red meat out diet, only eat 4lbs a year”. However, the speculative claims made in the Daily Mail article aren’t based on Biden’s climate plan, but rather on an unrelated 2020 study from the University of Michigan on meat consumption. As stated in a 22 April 2021 White House Fact Sheet, the climate plan aims to reduce greenhouse gas emissions in half by 2030 through investments in carbon pollution-free energy sources, reducing carbon pollution in transportation, and investing in carbon sinks, such as forests and agricultural soils. The plan also aims to cut emissions and reduce costs for families by upgrading the efficiency and electrification of buildings through heat pumps, induction stoves, and following modern energy codes. According to an AP fact-check, “Martin Heller, one of the authors of the University of Michigan study, confirmed in an email to The Associated Press that there was no connection between the research and Biden’s climate plan”. On April 26, 2020, the United States Department of Agriculture spokesperson said that there is no truth to the claim that Biden’s climate plan limits red meat consumption, in an article published by The Hill. “This is a fabrication. There is no such effort or policy that exists by this Administration. It’s not a part of the climate plan nor the emissions targets. It is not real” As reported in a Politico article, Agriculture Secretary Tom Vilsack stated during a virtual briefing hosted by the North American Agricultural Journalists, “There is no effort designed to limit people’s intake of beef coming out of President Biden’s White House or USDA”. UPDATE 30 April 2021: This post was updated to state that the Daily Mail article claimed that Biden’s climate plan could limit meat consumption.

https://science.feedback.org/review/video-promoted-by-john-stossel-for-earth-day-relies-on-incorrect-and-misleading-claims-about-climate-change/

-1.8

Stossel TV, by David Legates, Patrick Michaels, John Stossel, on 2021-04-17.

"Are we doomed?"

Reviewers’ Overall Feedback: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Andrew King Research fellow, University of Melbourne: This video is misleading in so many ways it’s hard to know where to begin. For a start there’s a repeated assertion that climate “alarmists” won’t enter debate on climate change, but there are many examples of renowned climate scientists such as Gavin Schmidt, Michael Mann and David Karoly entering into debates with climate change denialists. Many scientists have found such debates to be unhelpful as they give the false impression of balance despite there being broad consensus among climate scientists that human greenhouse gas emissions have caused at least 1°C of global warming to date. In these debates, climate denialists recycle the same flawed arguments even though they have been debunked many times (see here). On the issue of being able to adapt to 5°C of global warming, while humans are resilient to some change, we know that, especially in the developing world, capacity to adapt to climate change is limited. A slew of recent studies has demonstrated that even at 2°C of global warming the impacts of climate change would be pervasive and devastating. Many studies show that severe heatwaves, which already kill many thousands of people in the current climate, would become much more deadly even with relatively little additional global warming, let alone 5°C of warming (for example, Saeed et al. (2021)[9]. In order to adapt to global warming humans require that the planet’s ecosystems also survive, but with only another 1°C of global warming the vast majority of the world’s coral reefs would be damaged beyond recognition[10]. Severe heat-induced bleaching and ocean acidification, both of which are linked to human-induced climate change, are damaging the world’s reefs already[11]. Hundreds of millions of people globally rely on there being healthy coral reefs[12], but even beyond 1.5°C global warming the survival of the world’s reefs is at threat. There are many, many other ways in which going beyond another 1°C of global warming would be extremely damaging, including extreme and continued sea level rise[13], and the increased possibility of triggering major disruptions to the Earth system with irreversible consequences (for example, this Nature article). The notion that society could adapt to, or even thrive, at 5°C of global warming is fanciful. Misinformation that masks the threats that global climate change poses has the potential to slow down our efforts to tackle this problem. It is vital that society is guided by the science and acts to reduce greenhouse gas emissions so future generations don’t pay the price.Timothy Osborn Professor, University of East Anglia, and Director of Research, Climatic Research Unit: This video has little scientific credibility. It builds up false strawmen about climate change and then pretends to demolish them with flawed reasoning and cherry-picked statements. Here are some examples: 1. The suggestion that the evidence for climate change is not being debated is false — evidence is continually being weighed up during the research process and in scientific publications and then in scientific assessment processes such as the IPCC. 2. The claim that sea levels have been rising for 20,000 years is false. It is likely that sea levels fell slightly over the last 2,000 years until the last century when they began rising and have recently accelerated. See Barnett et al. (2019)[14]. 3. The claim that because Netherlands have reduced coastal flooding means that the world could simply adapt to a global temperature rise of 5 degrees Celsius has no support at all. There is ample evidence for the colossal impacts that such an unprecedented rate of climate change would have and the evidence is that it would be overwhelmingly damaging. The evidence is summarised in the IPCC’s ‘reasons for concern’[15].Victor Venema Scientist, University of Bonn, Germany: The video is mostly innuendo, tossed together with incorrect and misleading claims and impossible expectations. A clear example of a misleading statement is describing the figure below as “the water has been rising for approximately 20,000 years”, while until recently the sea level in the age we built our infrastructure was remarkably stable (see figure 2). Figure 2—Created by Robert A. Rohde from published data and incorporated into the Global Warming Art project. Annotations: The statements quoted below are from the video; comments are from the reviewers (and are lightly edited for clarity). Claim: “Even if the planet warmed by 5 degrees, humans can adjust. People in Holland did… Are you telling me that people in Miami are so dumb that they are just going to sit there and drown?” … “the water has been rising for approximately 20,000 years and probably will continue” “but we can adapt, like Holland has.” Benjamin Horton Professor, Earth Observatory of Singapore: [Comment from a previous evaluation of a similar claim] False. Comparison of long tide gauge records and multi-centennial to millennial scale sea-level reconstructions from the same region indicates that the rate of rise during the instrumental period (since ~1850 CE) was significantly faster than it was during the late Holocene (the 4000–2000 years prior to ~1850 CE). The data demonstrate that an acceleration in the rate of sea-level rise occurred[16]. Patrick Brown Assistant Professor, San Jose State University: From approximately 20,000 years ago to approximately 4,000 years ago, there was a very large rise in sea level (approximately 125 meters or 410 feet) that occurred as the Earth emerged from the last glacial maximum (due to orbital changes). The fact that this occurred is largely irrelevant to the question of how much disruption multi-meter sea level rise (See figure below from Oppenheimer et al., 2019)[17] over the next several centuries will inflict on our current society. It is of course the case that various adaptation options are on the table (see figure below from Oppenheimer et al., 2019)[17]. The appropriate question is whether it costs more (in the broadest sense of the word cost) to reduce CO2 emissions or by continuing to emit indefinitely and choosing only adaptation. There are sufficient fossil fuels available to completely melt the Greenland and Antarctica ice sheets and raise global sea levels approximately 60 meters or 200 feet[18]. This would represent an astronomical cost much larger than the cost to transition to a near-zero emissions energy system[19]. Thus, relying 100% on adaptation fails the cost-benefit test in the long term. Claim: “the alarmists say hurricanes and other storms are getting worse. No they aren’t. You can take a look at all the hurricanes around the planet, we can see them since 1970 thanks to global satellite coverage and we can measure their power and we can add up their power. And there is no significant increase whatsoever. There is no relationship between hurricane activity and the surface temperature of the planet.” Kerry Emanuel Professor of Atmospheric Science, MIT: The most up-to-date research published in the Proceedings of the National Academy of Sciences demonstrates an increase in the proportion of hurricanes that become major hurricanes (Category 3-5) globally, supporting theoretical predictions that date back to 1987 (see figure below)[3]. As explained in a previous review, the latest consensus papers published in 2019 by Knutson et al. show a strong consensus that tropical cyclones will become more intense (but not necessarily more frequent) as the climate warms[2]. There is also a unanimous consensus that tropical cyclones will produce more rain, and in places with sufficient rain measurements, there is strong evidence for heavier rain events[2]. Figure 3—The proportion of major hurricane intensities to all hurricane intensities globally from 1979-2017. Data is binned into 3-year periods. The proportion of global major hurricanes increased by 25% over the 39-year time period analyzed. From Kossin et al. (2020)[4]. Patrick Brown Assistant Professor, San Jose State University: While there are no substantial trends in the global frequency of total hurricanes, major hurricanes or accumulated cyclone energy over the past few decades[20], it would be premature to say that there is no relationship between global mean surface temperature and global hurricane activity (broadly defined). For instance, know that there is a stronger relationship between surface temperature and hurricane rain rates than there is between surface temperature and hurricane wind speeds. The IPCC 2019 summarizes hurricane (or tropical cyclone, TC) projections going forward in the following paragraph: “Tropical cyclones (TCs) projections for the late 21st century are summarised as follows: 1) there is medium confidence that the proportion of TCs that reach Category 4-5 levels will increase, that the average intensity of TCs will increase (by roughly 1-10%, assuming a 2°C global temperature rise), and that average TCs precipitation rates (for a given storm) will increase by at least 7% per degree Celsius of sea surface temperature warming, owing to higher atmospheric water vapour content, 2) there is low confidence in how global TC frequency will change, although most modelling studies project some decrease in global TC frequency and 3) sea level rise will lead to higher storm surge levels for the TCs that do occur, assuming all other factors are unchanged (very high confidence).”[21] Claim: ”The Obama administration’s model projects that the amount of global warming that would be saved if we were going to go to zero emissions tomorrow (which would put us back to the stone age) would be 0.14°C. So no real effect on the climate.” Patrick Brown Assistant Professor, San Jose State University: This is a number corresponding to the United States acting in isolation. The United States currently represents about 14% of annual new CO2 emissions. So of course, eliminating only that portion of emissions will not solve the problem. However, if all the governments in the world were to act in coordination to bring emissions down to near zero, then global temperatures will stop increasing. The amount of global warming avoided from going to zero emissions globally (compared to burning all fossil fuels) is closer to 8 degrees Celsius which equates to approximately 22 degrees Fahrenheit over land. So global programs to limit emissions make an enormous difference. This is exactly why this process is mediated through entities like the United Nations – because it is a collective action problem that requires international cooperation. Claim: “The idea of carbon dioxide being pollution that just does harm and threatens the food supply is a myth. If you are really concerned about the plants, more carbon dioxide makes them not just grow faster but also makes them more water efficient. CO2 is a greenhouse gas but it also helps feed the world.” Sara Vicca Postdoctoral research fellow, University of Antwerp: The claim is misleading. Plants need CO2 to grow and they often grow better when the CO2 concentration increases. However, this fact is often abused to claim that increasing CO2 concentrations is mainly positive, while it also has several adverse effects. Increasing CO2 causes ocean acidification, which negatively affects marine life and threatens to disrupt the marine food web. And of course elevated CO2 warms the planet, thereby generating a cascade of effects from melting of glaciers and sea level rise to altered precipitation patterns and increasing frequency and intensity of extreme weather events such as heatwaves and droughts. These in turn threaten water and food supplies, and as climate change progresses, this is also likely to undo much of the beneficial effect that CO2 has on plant growth[5-8]. Patrick Brown Assistant Professor, San Jose State University: It is true that increases in atmospheric CO2 make photosynthesis more efficient and have resulted in ‘greening’ trends observable from space. See, for example, the IPCC statement below[7]. “Globally, greening trends have increased over the last 2-3 decades by 22-33%, particularly over China, India, many parts of Europe, central North America, southeast Brazil and southeast Australia (high confidence). This results from a combination of direct and indirect factors (i.e. CO2, fertilisation, extended growing season, nitrogen deposition […])” However, this CO2 fertilization effect is just one of a myriad of influences on crop productivity and quality. Global crop models take into account many potential changes (including the fertilization effect from CO2) and tend to indicate that the net effect of increased CO2 (including its climate affects) will cause yields to decrease[5]: “At the global scale, Iizumi et al. (2018) used a counterfactual analysis and found that climate change between 1981 and 2010 has decreased global mean yields of maize, wheat, and soybeans by 4.1, 1.8 and 4.5%, respectively, relative to preindustrial climate, even when CO2 fertilisation and agronomix adjustments are considered.”[22] Also, increased atmospheric CO2 tends to decrease the nutritional quality of crops[5,22]. Kristie Ebi Professor, University of Washington: Higher CO2 concentrations reduce the nutrient density of major cereal crops, including wheat and rice. At CO2 concentrations expected later this century, protein declines about 10%, micronutrients about 5%, and B-vitamins about 30%[23]. This matters because there are more than 2 billion people worldwide with micronutrient deficiencies (Micronutrient Deficiency – Our World in Data). This is significantly higher than the numbers of people who are food insecure. Estimates of the numbers of people potentially affected are in the hundreds of millions. [The idea that increased CO2 so far is helping feed the world is an exaggeration as explained by Professor Philip Robertson in a previous review:] G Philip Robertson Professor, Michigan State University: In general, CO2 has had a positive effect on crop growth, but it’s impossible to separate historical effects from the greater effects of genetics and nitrogen and other inputs. However, it’s generally considered to be a fraction of those. We know better future effects because we have CO2 fertilization experiments in the field comparing present to future CO2 levels. Those experiments suggest that corn may have about a 1% gain [because of increased CO2] and soybeans 3-4 times that. However, these gains will almost certainly be offset by yield declines associated with the temperature increases caused by elevated CO2, which are well known. Historically, it’s worth noting that we had elevated CO2 long before we had the green revolution, and crop yields didn’t increase much until the green revolution. You can see this in graphs of average US corn yields from 1900. Source: University of Nebraska-Lincoln Claim: “It is not the case that we “have twelve years to act” Patrick Brown Assistant Professor, San Jose State University: I agree with the sentiment that there is very weak evidence that crossing 1.5°C represents some unique tipping point into catastrophe. This claim is made in regards to a 2018 Intergovernmental Panel on Climate Change report[24]. That report was on the impacts associated with global warming of 1.5°C (2.7°F) above preindustrial levels as well as the technical feasibility of limiting global warming to such a level. In 2018, the year 2030 was 12 years away and 2030 was deemed the earliest year in which the 1.5°C threshold could be crossed. The media coverage of the report did often portray it as saying we have 12 years (until 2030) to act on climate else catastrophe would ensue but the report did not actually make such claims. The report was not tasked with defining a level of global warming which might be considered to be catastrophic (or any other alarming adjective). Rather, the report was tasked with evaluating the impacts of global warming of 1.5°C (2.7°F) above preindustrial levels, and comparing these to the impacts associated with 2.0°C (3.6°F) above preindustrial levels as well as evaluating the changes to global energy systems that would be necessary in order to limit global warming to 1.5°C. To summarize, the IPCC’s literature review found that impacts of global warming at 2.0°C are worse than at 1.5°C[24]. There was no claim by the IPCC that we have 12 years to avoid catastrophe. Therefore, I do not take issue with the Facebook video portraying this framing as a myth.REFERENCES: 1 – Lambeck et al. (2014) Sea level and global ice volumes from the Last Glacial Maximum to the Holocene. PNAS. 2 – Knutson et al. (2020) Tropical Cyclones and Climate Change Assessment: Part II: Projected Response to Anthropogenic Warming. Bulletin of the American Meteorological Society. 3 – Kossin et al. (2020) Global increase in major tropical cyclone exceedance probability over the past four decades. PNAS. 4 – Liu et al. (2019) Causes of large projected increases in hurricane precipitation rates with global warming. npj Climate and Atmospheric Science. 5 – Moore et al. (2017) New science of climate change impacts on agriculture implies higher social cost of carbon. Nature. 6 – Terrier et al. (2019) Nitrogen and phosphorus constrain the CO2 fertilization of global plant biomass. Nature Climate Change. 7 – Shukla et al. (2019) Technical Summary:, 2019. In: Climate Change and Land: an IPCC special report on climate change, desertification, land degradation, sustainable land management, food security, and greenhouse gas fluxes in terrestrial ecosystems. IPCC report. 8 – Mbow et al. (2019) IP Food Security. In: Climate Change and Land: an IPCC special report on climate change, desertification, land degradation, sustainable land management, food security, and greenhouse gas fluxes in terrestrial ecosystems. IPCC report. 9 – Saheed et al. (2021) Deadly Heat Stress to Become Commonplace Across South Asia Already at 1.5°C of Global Warming. Geophysical Research Letters. 10 – Hughes et al. (2017) Coral reefs in the Anthropocene. Nature. 11 – Hughes et al. (2017) Global warming and recurrent mass bleaching of corals. Nature. 12 – Pendleton et al. (2016) Coral Reefs and People in a High-CO2 World: Where Can Science Make a Difference to People? Plos One. 13 – Nauels et al. (2019) Attributing long-term sea-level rise to Paris Agreement emission pledges. PNAS. 14 – Barnett et al. Late Holocene sea level. Past Global Changes. 15 – O’Neill et al. (2017) IPCC reasons for concern regarding climate change risks. Nature Climate Change. 16 – Kopp et al (2016) Temperature-driven global sea-level variability in the Common Era. PNAS. 17 – Oppenheimer et al. (2019) Sea Level Rise and Implications for Low-Lying Islands, Coasts and Communities. In: IPCC Special Report on the Ocean and Cryosphere in a Changing Climate. 18 – Winkelmann et al. (2015) Combustion of available fossil fuel resources sufficient to eliminate the Antarctic Ice Sheet. Science Advances. 19 – Brown et al. (2020) Break-even year: a concept for understanding intergenerational trade-offs in climate change mitigation policy. Environmental Research Communications. 20 – Blunden and Arndt (2020) State of the Climate in 2019. Bulletin of the American Meteorological Society. 21 – IPCC (2019) Technical Summary. In: IPCC Special Report on the Ocean and Cryosphere in a Changing Climate. 22 – Iizumi et al. (2018) Crop production losses associated with anthropogenic climate change for 1981–2010 compared with preindustrial levels. International Journal of Climatology. 23 – Zhu et al. (2018) Carbon dioxide (CO2) levels this century will alter the protein, micronutrients, and vitamin content of rice grains with potential health consequences for the poorest rice-dependent countries. Science Advances. 24 – IPCC (2018) Summary for Policymakers. In: Global Warming of 1.5°C. An IPCC Special Report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate poverty. World Meteorological Organization.

https://science.feedback.org/review/a-third-of-antarctic-ice-shelf-risks-collapse-at-4c-above-pre-industrial-levels-as-accurately-described-in-cnn-article/

Accurate

CNN, Amy Woodyatt, 2021-04-09

"A third of Antarctic ice shelf risks collapse as our planet warms"

Accurate: A recent study found that 34% of the Antarctic ice shelf was at risk of collapse at 4°C above pre-industrial levels. Lacks context: The claim doesn’t provide a timescale for when this collapse might occur or mention that not all ice shelves are susceptible to collapse.

Ice shelves are floating sheets of ice that are connected to land masses. They gain and lose surface ice over time depending on snowfall and atmospheric and ocean temperatures. A recent study found that 34% of the Antarctic ice shelf is vulnerable to collapse under a future climate scenario that is 4°C above pre-industrial levels.

"A third of Antarctic ice shelf risks collapse as our planet warms"

1 – Gilbert and Kittel (2021) Surface melt and runoff on Antarctic ice shelves at 1.5°C, 2°C and 4°C of future warming. Geophysical Research Letters.

Review: The claim that “A third of Antarctic ice shelf risks collapse as our planet warms” appeared in a CNN article and CNN Climate Instagram post published in April 2021, receiving more than 22,000 interactions on Facebook and Instagram, according to the social media analytics tool CrowdTangle. The claim is based on a study recently published in Geophysical Research Letters that estimated surface melt and runoff on Antarctic ice shelves under three future global warming scenarios[1]. Ice shelves are floating sheets of ice that are connected to land masses. They gain and lose ice at their surface over time depending on a variety of factors, including snowfall and the temperature of the atmosphere and the ocean. Ice shelves grow when snowfall accumulates on their surface and shrink when surface ice melts during the summer. This balance between ice gain and loss is referred to as the surface mass balance. While ice shelves don’t directly contribute to sea level rise, they play a critical role in holding back glaciers. If ice shelves collapse, glacial ice can flow more easily into the ocean, contributing to sea level rise. One way ice shelves can collapse is through a process called hydrofracture. This occurs when surface melt runs into gaps in the ice shelf during warmer months. When this water freezes, it expands, causing fractures and potentially the disintegration of the ice shelf. In the recent study, scientists modeled ice melt, runoff, and the surface mass balance of Antarctic ice under three global warming scenarios: 1.5°C, 2°C, and 4°C above pre-industrial levels. As Dr. Ella Gilbert, the lead author of the study describes below, 34% of the area of the Antarctic ice shelf is vulnerable to collapse under the 4°C scenario, consistent with the claim (see figure 1). Figure 1—Average ice shelf runoff for the entire Antarctic ice shelf (Antarctica) and three regions of the ice shelf (Antarctic Peninsula, East Antarctica, and West Antarctica) from 1980 to 2100. Colors represent different model simulations and the black line shows the mean of all models. Ice shelf runoff was modeled for three future climate scenarios (1.5°C, 2°C, and 4°C above pre-industrial levels) and the time periods of these are indicated in Antarctica panel. From Gilbert and Kittel (2021)[1]. While the article and Instagram post accurately described results of the study, scientists who reviewed this claim thought it could benefit from a bit more detail. Specifically, they note that not all ice shelves are susceptible to collapse and that the article didn’t specify a timeline for when collapse of the Antarctic ice shelf might occur. Scientists’ Feedback: Ella Gilbert Research Scientist, British Antarctic Survey: Overall I think the Instagram post isn’t inaccurate, maybe just omits some of the details. CNN did actually write a pretty good article about the paper, I guess the nuances just got a bit lost in the Instagram post. One of the main conclusions of the study is that 34% of ice shelf area​ is susceptible to hydro-fracturing driven collapse at 4 degrees above pre-industrial temperatures. This value increases from 9% in the historical period to 14% and 18% at 1.5 and 2 degrees, respectively. That means that keeping warming to 2 degrees results in a halving of the ice shelf area at risk. The caveats are that many ice shelves are dynamically stable and therefore unlikely to collapse unless their dynamical regime is altered (e.g. by very large calving events), which is virtually impossible for some ice shelves (for example the George VI ice shelf is surrounded on three sides by rock, making it extremely resilient to change despite high melt rates. We identify 4 ice shelves – the Larsen C, Wilkins, Pine Island and Shackleton ice shelves to be most vulnerable at 4 degrees. Twila Moon Research Scientist, University of Colorado, Boulder: The statement in the Instagram post and article headline is accurate but incomplete. The research looked at ice shelf stability under a range of future warming scenarios, finding more vulnerability at higher temps (future increase of 4C especially). So one point of the paper is the importance of limiting Earth warming. Other details that aren’t reflected with the short published statement is the timescale of collapse. So much about ice loss on Earth is about how quickly ice is lost. Not including this information can leave the audience to make any number of assumptions. I found that the article itself was good at providing accurate information. There is still a missing time elements in some cases, but the article has much more detail on both the research article and how that connects with other science findings, such as the urgent need for action to limit future warming. I didn’t note anything that I think requires specific clarification, as I felt the article overall was appropriate. READ MORE: The first author of the paper, Dr. Ella Gilbert, wrote several articles summarizing the study’s findings for Carbon Brief and The Conversation.

https://science.feedback.org/review/in-viral-turning-point-usa-video-candace-owens-and-charlie-kirk-falsely-claim-there-is-no-evidence-of-global-warming-and-scientists-dont-know-the-cause/

Inaccurate

Turning Point USA, Candace Owens, Charlie Kirk, 2021-04-11

There is no factual data to back up global warming; real scientists don’t know whether CO₂, solar sunspots or natural activity cause global warming

Factually inaccurate: It is a measured fact that Earth has warmed over the past century, as shown by atmospheric and oceanic temperature records. Incorrect: : Anthropogenic emissions of CO2 and other greenhouse gases are the leading cause of global mean temperature rise in the industrial era. Solar activity plays only a minor role in current climate changes, and is not a major contributor to the global warming trend observed over the past decades.

Scientists have unequivocally demonstrated increases in the temperature of the Earth’s atmosphere and oceans over the past century. The rate of global warming has been accelerating since the 1980s, and the last decade was the warmest on record. Global warming also affects the melting of sea and land ice, and induces changes in ecosystems, such as species migration to higher latitudes or higher elevations. Numerous scientific studies established a clear link between human-caused increases in greenhouse gases and global warming.

They changed it from global warming to climate change. Do you know why ? Because, when scientists are looking into global warming, there was no factual data to back up their argument. Real scientists are still debating whether CO₂ or solar sunspots or natural variability cause global warming

Review: The claim appeared in a video posted on Facebook and Instagram by Turning Point USA, a partisan organization that advocates for conservative policies on high school, college, and university campuses The video, featuring Charlie Kirk, founder of Turning Point USA, and Candace Owens, received more than 640,000 views on Facebook alone since it was published on 11 April 2021. First, there is no evidence to support the claim that “they changed from global warming to climate change”. Climate scientists use both terms in the scientific literature, as they refer to two distinct, but causally-related phenomena. Global warming describes the long-term trend of increasing average global temperature, whereas climate change refers to changes in the various measures of climate. These measures include temperature, as well as precipitation, wind patterns, drought prevalence, and the occurrence of other extreme events. In 2005, the National Academy of Sciences stated that “the phrase ‘climate change’ is growing in preferred use to ‘global warming’ because it helps convey that there are changes in addition to rising temperatures”[1]. There’s no evidence that a complete shift in terminology took place, and there’s no reason to do so, contrary to the video’s claim. Second, many lines of scientific evidence unambiguously demonstrate that the Earth’s surface is experiencing rapid global warming. The first line of evidence is the continuous record of surface temperatures recorded at thousands of weather stations worldwide. Some records date back to the early eighteenth century. When averaged together, these data indicate a clear increasing trend in the Earth’s surface temperature. According to the 2018 IPCC report, “Human activities are estimated to have caused approximately 1.0°C of global warming above pre-industrial levels, with a likely range of 0.8°C to 1.2°C”[2]. And the rate of global warming is accelerating, as stated in NOAA’s latest report, “the global annual temperature has increased at an average rate of 0.08°C (0.14°F) per decade since 1880 and over twice that rate (+0.18°C / +0.32°F) since 1981”. Furthermore, some of the warmest years in the 141-year record occurred in the last decade, with 2016 being the warmest and 2020 being the second warmest (see figure below). Figure—Global temperature anomaly data relative to the 20th century average temperature from the Global Historical Climatology Network-Monthly data set and International Comprehensive Ocean-Atmosphere Data Set. These data sets show consistent global warming trends. From NOAA. Another line of evidence of global warming is the increase in ocean heat content observed by scientists over the past decades. The increased concentration of heat-trapping greenhouse gases in the atmosphere generated an energy imbalance in the Earth’s climate system of almost 1 W m−2 [3]. This means that Earth radiates less energy to space than it receives from the Sun, essentially less heat is going out, than is going in. Over 90% of this excess heat accumulates in the ocean because of its large heat capacity compared to the atmosphere. Over the past decades, scientists have observed an increase in ocean heat content. Specifically, each decade has been warmer than the preceding decade in terms of ocean heat content, and 2020 hit a record high (see figure below). Figure—Global upper 2000 m ocean heat content (OHC) from 1958 through 2020. The histogram presents annual anomalies relative to a 1981-2010 baseline, with positive anomalies shown as red bars and negative anomalies as blue. Units : Zetta Joules (ZJ, equals to 1021 Joules). From Advances in Atmospheric Science. According to Cheng et al. (2021), “the most recent data indicate that the ocean heat content in the upper 2000 m layer of the world’s oceans has increased with a mean rate of 5.7 ± 1.0 ZJ yr−1 for the 1958−2020 period”[4]. (The unit is in ZettaJoules, which is equivalent to 1021 Joules, that is millions of millions of billions). The authors also found that there is a more rapid increase that began in the 1980s. The average annual increase from 1986 to 2020, is almost eight times larger than the linear rate from 1958~1985. Sea level rise, which scientists have observed since 1900, is another line of evidence that global warming is occuring[5]. Sea level rise is caused, in part, by the thermal expansion of the oceans and, in part, by the melting of glaciers on land. In addition to rising temperatures of Earth’s atmosphere and oceans, global warming has caused land and sea ice to melt. “Over the last decades, global warming has led to widespread shrinking of the cryosphere”, as stated in a special report on the ocean and cryosphere released by the IPCC[6]. “Most glaciers are shrinking (high confidence), the Greenland and Antarctic ice sheets are losing mass (high confidence), sea ice extent in the Arctic is decreasing (very high confidence), Northern Hemisphere snow cover is decreasing (very high confidence), and permafrost temperatures are increasing (high confidence).” Multiple studies demonstrated that ecosystems are also responding to global warming in numerous ways[7]. For example, many ecosystems experience earlier springs and later falls compared to the 20th-century averages. Global warming is also driving large-scale shifts in species distributions, as many animals and plants are moving higher in elevation and latitude to find suitable habitats[8]. Finally, the claim that real scientists don’t know whether CO2 or solar sunspots or natural variability causes global warming is incorrect. According to the IPCC, the current scientific consensus is that variations in solar activity only play a very small role in Earth’s recent climate[9]. Human-produced greenhouse gases are the primary cause of global warming trends and their effects are much stronger than those due to recent variations in solar activity. The human-caused drivers of global warming and climate change are well understood and reflect decades of research on the topic[10]. For example, an analysis of the major factors that influence global surface temperatures, and how their effects change over time, found that human-caused increases in greenhouse gas emissions account for 100% of the warming trends observed over the past century, given that humans also cause cooling effects such as the emissions of particles (aerosols) (see figure below). Figure—The estimated role of different factors influencing global surface temperatures from 1850 to 2017. Observed temperatures are shown in black dots. Global warming over the past 150 years was primarily driven by greenhouse gas emissions (red). Solar activity (yellow) is a minor contributor and follows the Sun’s natural 11-year cycle. From Carbon Brief. The role of human activity in the increase in global CO2 concentration is also unquestionable. Scientists are now able to track fossil fuel emissions by measuring the level of radioisotope carbon-14 (14C) in the air[11]. This natural isotope has a half-life of 5,700 years and is widely used in archeological studies for dating. Fossil fuels are completely devoid of 14C, because they have been buried for millions of years, and have lost all of it through radioactive decay. Therefore, the degree of 14C-depletion of the CO2 in air samples reflects the contribution from fossil fuel combustion. Kirk dismisses the significance of the scientific consensus on the subject of human-caused global warming, but scientific consensus is important insofar as it reflects the consensus of evidence that supports or refutes competing hypotheses, and scientists with expertise on the subject are able to assess the evidence. In the case of climate change, the evidence accumulated over the past few decades is consistent with the explanation that human activities are the cause of the observed increases in global temperature. Kirk says that “we don’t vote on gravity, we don’t vote on Newton’s second law, we prove it”. But this is also a misunderstanding of how science works. Scientists do not “prove” that a hypothesis is valid in the mathematical sense of the term, instead they propose all the hypotheses that could explain a given phenomenon (here the increase in global temperature) and then they collect data to evaluate whether the data is consistent or inconsistent with each hypothesis. For instance, the hypothesis that solar activity explains current global warming trends was ruled out since, among other pieces of evidence, the entire atmosphere hasn’t warmed[12], which would be the case if that hypothesis was true. The hypothesis that natural variation within the climate system explains global warming was also ruled out, as no natural mechanism has been found that could explain the trends observed over the past century. In addition, a natural cycle coming from the ocean for instance would redistribute heat in the ocean and not simply increase the amount of heat in the oceans as observed. Contrary to Kirk’s assertion, it is the failure to disprove the theory of gravity that led scientists to accept its validity. The same is true for global warming: hypotheses stating that “there is no warming” or that “warming is caused by something else other than human activity” fail to propose a verifiably valid explanation for the warming trends observed, making the human-influence explanation the only valid one. Scientists’ Feedback: Baird Langenbrunner Associate Editor, Nature Climate Change: There has been very clear and measurable warming since this time period [industrial revolution]—this has been confirmed time and time again using station data and satellite measurements and it matches well with predictions based on increases in greenhouse gas concentrations. Even in the brief periods when the surface temperature warms less quickly, the oceans continue to warm, which together with the atmosphere accounts for all the extra heat predicted by increased greenhouse gas concentrations. Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: This claim is not accurate. Global temperature datasets, developed by a number of independent research groups, show robust warming in the troposphere and at the Earth’s surface. The radiative effect of carbon dioxide has also been observed[13]. Considering multiple lines of evidence, the IPCC concluded that it is “extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century.” More recent analysis of satellite data shows that tropospheric warming from the satellite record is pronounced and cannot be explained by natural climate variability alone[14]. Gavin Schmidt Director, NASA Goddard Institute for Space Studies: There is indeed overwhelming evidence for warming in the last century. [The] claim that no one knows the attribution of this to human impacts is not a valid description of the state of knowledge. There are indeed plenty of studies that use statistical or model-based fingerprints to assess this and they overwhelmingly find a dominance of human activities over natural forcings or internal variability. For the more recent period (1950 onwards) the claims are even stronger—that effectively all the warming is caused by human activity with only a ~10% uncertainty due to internal variability.UPDATE 20 May 2021: Charlie Kirk has issued a correction saying that their claims were false (see the screenshot below). The video has now been deleted.REFERENCES: 1 – The National Academy of Sciences (2005) Understanding and responding to climate change. 2 – IPCC (2018) Summary: for Policymakers. IPCC Special Report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways. 3 – Trenberth et al. (2014) Earth’s energy imbalance. Journal of Climate. 4 – Cheng et al. (2021) Upper Ocean Temperatures Hit Record High in 2020. Advances in Atmospheric Science. 5 – Frederikse et al. (2020) The causes of sea-level rise since 1900. Nature. 6 – IPCC (2019) Framing and context of the report. IPCC Special Report on the Ocean and Cryosphere in a Changing Climate. 7 – Weiskopf et al. (2020) Climate change effects on biodiversity, ecosystems, ecosystem services, and natural resource management in the United States. Science of the Total Environment. 8 – Burrows et al. (2011) The Pace of Shifting Climate in Marine and Terrestrial Ecosystems. Science. 9 – IPCC (2013) Anthropogenic and natural radiative forcing. Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. 10 – Hegerl and Zwiers (2011) Use of models in detection and attribution of climate change, Wires Climate Change. 11 – Basu et al. (2020) Estimating US fossil fuel CO2 emissions from measurements of 14C in atmospheric CO2, PNAS. 12 – Ogawa et al. (2014) Upper atmosphere cooling over the past 33 years, Geophysical Research Letters. 13 – Feldman et al (2015) Observational determination of surface radiative forcing by CO2 from 2000 to 2010, Nature. 14 – Santer et al. (2017) Tropospheric Warming Over The Past Two Decades, Scientific Reports.

https://science.feedback.org/review/deserts-cool-the-planet-by-reflecting-solar-radiation-to-space-vegetated-areas-have-an-overall-warming-effect-so-planting-trees-in-deserts-doesnt-necessarily-cool-the-planet-the-guardian/

Inaccurate

The Guardian, Steve Rose, Ties Van der Hoeven, 2021-03-20

"Deserts are heat producers, reflecting around 60% to 70% of the solar energy that falls on them straight back into the atmosphere."; "If we want to do something about global warming, we have to do something about deserts."

Inaccurate: Deserts reflect solar radiation to space through the atmosphere, cooling the planet. Vegetated areas have an overall warming effect on the planet because they absorb sunlight and increase atmospheric water vapor. Claim in The Guardian article that we need to plant forests in the desert to combat climate change isn’t accurate.

Deserts reflect solar radiation to space through the atmosphere. Because solar radiation isn’t absorbed by the atmosphere, deserts have a cooling effect on the planet. While vegetated areas can reduce temperatures at the ground level locally due to evapotranspiration, they have an overall warming effect on the planet because they absorb more sunlight and heat than deserts. That being said, preventing forests from being cut is an effective way to limit global warming via another mechanism: preventing the carbon stored in trees from being released into the atmosphere.

"Deserts are heat producers, reflecting around 60% to 70% of the solar energy that falls on them straight back into the atmosphere." ; "In addition to sequestering carbon, green areas also help cool the planet" ; Vegetation reduces temperature and solar reflection, creating a stable climate; "If we want to do something about global warming, we have to do something about deserts."

1 – Pierrehumbert (1995) Thermostats, Radiator Fins, and the Local Runaway Greenhouse. Journal of the Atmospheric Sciences. 2 – Goffner et al. (2019) The Great Green Wall for the Sahara and the Sahel Initiative as an opportunity to enhance resilience in Sahelian landscapes and livelihoods. Regional Environmental Change. 3 – Charney (1975) Dynamics of deserts and drought in the Sahel. Quarterly Journal of the Royal Meteorological Society. 4 – Yosef et al. (2018) Large-scale semi-arid afforestation can enhance precipitation and carbon sequestration potential. Scientific reports. 5 – Kemena et al. (2018) Atmospheric feedbacks in North Africa from an irrigated, afforested Sahara. Climate Dynamics. 6 – Pausata et al. (2016) Impacts of dust reduction on the northward expansion of the African monsoon during the Green Sahara period. Earth and Planetary Science Letters. 7 – Muschitiello et al. (2015) Arctic climate response to the termination of the African Humid Period. Quaternary Science Reviews. 8 – Davies et al. (2015) The impact of Sahara desertification on Arctic cooling during the Holocene. Climate of the Past.9 – Keller et al. (2014) Potential climate engineering effectiveness and side effects during a high carbon dioxide-emission scenario. Nature Communications.

Review: The claim that deserts warm the planet was published in an article by The Guardian in March 2021, which received more than 30,000 interactions on Facebook according to the social media analytics tool CrowdTangle. The article makes several inaccurate or misleading claims about the role deserts play in global warming and climate change. Specifically, the article makes the inaccurate claim that “Deserts are heat producers, reflecting around 60% to 70% of the solar energy that falls on them straight back into the atmosphere”. As the reviewers describe below, deserts cool rather than warm the planet[1]. Deserts reflect solar radiation to space, meaning it isn’t absorbed by the atmosphere. The article also claims that areas covered by vegetation cool the planet, however, these dark areas can have a warming effect on the planet because of their albedo effect, which describes how much sunlight is absorbed versus reflected. While vegetated areas can have a cooling effect at the ground level in local regions due to evaporation, they have a warming effect in terms of the global energy balance by increasing atmospheric water vapor, as the reviewers describe below. Furthermore, planting trees has an indirect cooling effect as the trees absorb CO2 while they grow, however, if these habitats are lost through harvesting, natural disasters, or other events, this CO2 will be released. The effects of vegetated areas on temperature are complex and vary between regions. Scientists’ Feedback: “Deserts are heat producers, reflecting around 60% to 70% of the solar energy that falls on them straight back into the atmosphere.” Matthew Huber Professor, Purdue University: Deserts reflect sunlight through the atmosphere TO SPACE, where it is lost from the atmosphere. Thus deserts cool the planet. Sunlight is transmitted through the atmosphere, not absorbed. Raymond Pierrehumbert Professor, University of Oxford: The statement that “Deserts are heat producers” is absolutely wrong. It is true that they reflect back 60-70% of the sunlight but the reflected light absolutely does not get absorbed by the atmosphere. It just goes right back to space where it came from, and this happens efficiently over deserts since the skies tend to be clear and cloud free. Further, when the surface of the desert heats up, the infrared it radiates gets out to space easily, because the air is very dry and cloud free. Taken together, deserts cool the planet, they don’t warm it. The claim in the Guardian article that, “Deserts are heat producers, reflecting around 60% to 70% of the solar energy that falls on them straight back into the atmosphere,” misunderstands the impact of reflection on the planetary energy balance, as well as the role of deserts in global climate. Reflection (or albedo) is a cooling mechanism, not a warming one. Deserts would be even hotter if the sand were black. Because solar radiation that reaches the surface cannot be transmitted through the solid earth, it can only be absorbed at the surface (where the energy is used to evaporate water or raise the temperature of the ground), or the light can be reflected away. Of the light that is reflected upward, most of it passes through the atmosphere and is lost to space, as if it never existed. This is for the same reason light from the Sun coming “downward” reached the surface in the first place– Earth’s atmosphere, especially in the dry subtropics–is rather transparent to solar radiation. If instead a small amount of solar radiation is absorbed by the atmosphere on its passage upward (or downward), this is still not much different than if it had been absorbed directly at the surface anyway. That absorbed energy is still in the coupled surface-atmosphere system. Reflection does not create a source of “new” energy, which of course must be conserved. Although tropical deserts are hot locally, they are unique regions for the energy balance of the planet. Not only does desert sand have a high albedo, but the hot surface also emits infrared radiation strongly to space through a relatively dry and cloud-free atmosphere. This lack of greenhouse trapping also helps deserts get cold at night. In fact, because the Saharan and Arabian desert regions are bright and effectively lose infrared energy (both cooling mechanisms), the annual mean top-of-atmosphere net radiation is negative over those regions (see figure below), which is unusual for a land region near the equator. Over the Amazon in South America, for example, the outgoing thermal radiation is instead relatively low due to the high moisture content and energy emanating from cold cloud tops. Figure 1—Annual-mean planetary albedo, outgoing thermal (longwave) radiation, and net top-of-atmosphere radiation from CERES EBAF averaged from 2005-2015. Net radiation is incoming solar minus outgoing solar (reflection) minus outgoing thermal (emission) radiation. Radiative heating/cooling in the tropics is tightly coupled to vertical motion. The net radiative loss over the large deserts is balanced largely by atmospheric heat transport in the form of air with a high potential temperature flowing in at high altitudes, and descending while being heated adiabatically. This branch of the Hadley circulation continuously provides warm air to the lower atmosphere through subsidence and carries moisture out of the region in near-surface equatorward outflow. The desert surface also has limited evaporation, and so these regions get quite hot, yet are so-called “radiator fins”for the low latitudes that cool the planet[1]. Indeed, the moist part of the deep tropics would be close to a runaway greenhouse state, in isolation, if not for heat transport to the extra-tropics and emission to space from the dry zones in between. “In addition to sequestering carbon, green areas also help cool the planet.” Matthew Huber Professor, Purdue University: Green areas have lower albedo than shiny, high albedo deserts, thus their impact on the solar part of the energy budget is warming. Raymond Pierrehumbert Professor, University of Oxford: Greening would take up some carbon, but “sequestering” is the wrong word since the carbon isn’t very securely stored. It is right near the surface where it can easily oxidise back to CO2. The ability of land practices to cause more carbon uptake is real, but the effect is exaggerated in terms of the proportion of the climate problem it can deal with. But green areas do not cool the planet. By absorbing more sunlight, they actually warm the planet. The statement confuses the local surface energy balance with the global balance. By providing a moist and shaded surface, the evaporation helps cool the ground locally. However, the evaporation just moves heat to another part of the atmosphere. Further, a sufficiently green moist area can cause warming by increasing atmospheric water vapour, though the amount of warming depends on what kind of clouds form, and where. (Clouds reflect sunlight, but both water vapour and clouds add to the greenhouse effect). “In areas covered by vegetation, much of that solar energy is instead used in evapotranspiration: the process of condensation and evaporation by which water moves between plants and the atmosphere.” Matthew Huber Professor, Purdue University: It is true that locally most sunlight in these regions drives evaporation, not local sensible heating. But this latent heat gain is transferred into latent heat release and warming in convergence (raining) regions, it is not lost to the energy budget of the tropics. Raymond Pierrehumbert Professor, University of Oxford: Yes, evapotranspiration increases, but this only causes local cooling, which is made up for where the energy of the water vapour is released, when it condenses back into the ocean. On the balance, evaporation does not cause a cooling of the planet. Evapotranspiration can move energy away from the local surface, but it cannot move energy into outer space! Only infrared radiation or reflection of sunlight can do that. “ ‘If vegetation comes back, you increase cover, you reduce temperature, you reduce solar reflection, you start creating a stable climate,’ says Van der Hoeven. ‘If we want to do something about global warming, we have to do something about deserts.’ ” Matthew Huber Professor, Purdue University: Since deserts reflect back solar radiation and are associated with dryer upper atmosphere (and hence a reduced water vapor greenhouse effect) deserts are a vital part of maintaining a relatively cool tropical mean temperature. Raymond Pierrehumbert Professor, University of Oxford: It is absolute rubbish to say that “If we want to do something about global warming, we have to do something about deserts.” There may be local benefits to greening a desert, in terms of the local environment or food production, but deserts cool the planet as a whole, they don’t warm them. Whether human interventions can produce a “stable” greened climate is controversial. The great greening of the Sahara that happened some thousands of years ago was driven by changes in the Earth’s orbital characteristics, which the proposed human interventions don’t duplicate. Coming back to local afforestation/reforestation and greening efforts in arid places such as Africa or Australia, which have either been proposed or are currently being implemented [e.g., Green the Sinai in the Guardian article, The Great Green Wall (see e.g., Goffner et al., 2019[2])], the goal is usually to geoengineer regional climate toward wetter conditions, which may come with many benefits for local populations. It is also reasonable to expect that in some areas there will be local cooling due to enhanced evapotranspiration and cloud cover, despite the reduced surface albedo due to the darker (vegetated) surface. The reduction in surface albedo could shift the tropical rainbelt known as the Inter Tropical Convergence Zone northward, bringing rainfall to the desert, a biogeophysical feedback recognized by Charney in the 1970s[3]. However, the broader climate effects and sustainability of such efforts, even if scaled up beyond the Sinai domain, are complicated. Modeled climate impacts of such proposals even locally are complex, with Sahara greening altering local atmospheric circulation, such as the African easterly jet and the intensity of the monsoon winds in the Sahel (e.g., Yosef et al. 2018; Kemena et al. 2018[4,5]), or changing dust fluxes (as is important during past “Green Sahara” episodes)[6]; that dust also contain iron and other nutrients that fertilize the ocean, which could affect productivity in other regions. The self-sustainability of this geoengineering is also in question, since much of the evapo-transpired water is precipitated in areas removed from the greening project (e.g., Kemena et al. 2018[5]). Because the desertification/greening in Africa can have impacts globally, even in the polar regions[7,8], more comprehensive assessments with Earth system models are needed before deployment, in addition to discussions of ethics and geopolitics. For example, in Keller et al. (2014), afforestation experiments actually increase global temperature due to albedo reductions (see figure below) highlighting potential far-field side effects of such proposals[9]. Figure 2—Plots taken from Keller et al. (2014), showing changes in surface air temperature, carbon inventories, primary productivity, and surface albedo, in climate engineering experiments using the University of Victoria Earth system model (UVic) of intermediate complexity[9].

https://science.feedback.org/review/solar-geoengineering-isnt-happening-or-damaging-the-planet-aircraft-contrails-are-formed-by-water-vapor-not-chemicals/

Incorrect

Geoengineering Watch, Dane Wigington, 2021-03-10

"The intentional dimming of direct sunlight by aircraft dispersed particles, a form of global warming mitigation known as “Solar Radiation Management”, has and is causing catastrophic damage to the planet’s life support systems."

Incorrect: Aircrafts produce contrails when water vapor from jet exhaust condenses at high altitudes. Scientists agree that there is no evidence of chemtrails or solar geoengineering.

Solar geoengineering describes hypothetical strategies to combat global warming by reflecting sunlight away from the Earth. There is no scientific evidence that solar geoengineering is happening or having catastrophic effects on the planet or human health. There is also no scientific evidence of aircraft chemtrails. Instead, aircrafts produce contrails when water vapor from jet exhaust mixes with the atmosphere and condenses at high altitudes.

"Global climate engineering operations are a reality. Atmospheric particle testing conducted by GeoengineeringWatch.org has now proven that the lingering, spreading jet aircraft trails, so commonly visible in our skies, are not just condensation as we have officially been told. ... The intentional dimming of direct sunlight by aircraft dispersed particles, a form of global warming mitigation known as “Solar Radiation Management”, has and is causing catastrophic damage to the planet’s life support systems. The highly toxic fallout from the ongoing geoengineering operations is also inflicting unquantifiable damage to human health."

1 – Shearer et al. (2016) Quantifying expert consensus against the existence of a secret, large-scale atmospheric spraying program. Environmental Research Letters. 2 – Kärcher (2018) Formation and radiative forcing of contrail cirrus. Nature. 3 – Trisos et al. (2018) Potentially dangerous consequences for biodiversity of solar geoengineering implementation and termination. Nature Ecology & Evolution.4 – Parker and Irvine (2018) The Risk of Termination Shock From Solar Geoengineering. Earth’s Future.

Review: The claims that climate engineering is happening and causing catastrophic damage to the planet’s life support systems was published in a YouTube video by Dane Wigington of Geoengineering Watch. The video received more than 155,000 views, as of 24 March 2021. These claims were also repeated in an article published by Health Impact News. The video incorrectly claims that climate engineering is happening and that jet aircraft trails are not condensation, but dispersed particles that dim direct sunlight to mitigate the effects of global warming. Claims such as these are often referred to as “chemtrails”. Contrary to these claims, atmospheric chemists and geochemists agree that there is no scientific evidence of “chemtrails”, “covert geoengineering”, or a secret large-scale atmospheric program to mitigate climate change[1]. Aircraft engines produce condensation trails, or contrails, as hot, humid exhaust mixes with the atmosphere at altitudes of 8 – 13 km. Specifically, water vapor from the jet exhaust condenses and may freeze at high altitudes, where there is a lower vapor pressure and temperature than the exhaust. As described in a Scientific American article, “this mixing process forms a cloud very similar to the one your hot breath makes on a cold day”. A 2018 study provides additional details about the process of contrail formation, “Depending on surrounding atmospheric conditions, contrails can be short- or long-lived. Long-lived contrails are those that remain for at least 10 min—defined by the World Meteorological Organization as Cirrus homogenitus—and are the only man-made type of ice clouds”.[2] As Doug MacMartin notes below, contrails are essentially artificial cirrus clouds, which are wispy, hair-like clouds found at high altitudes. The video also claims that Solar Radiation Management (SRM) “has and is causing catastrophic damage to the planet’s life support systems”. SRM, or solar geoengineering, describes hypothetical strategies to combat global warming by reflecting sunlight away from the Earth. “Possible methods include reducing heat-trapping clouds, sending a giant sunshade up into orbit or releasing aerosols into the stratosphere,” according to a Carbon Brief article. While some studies suggest that SRM could negatively impact biodiversity, which subsequently affects human health, others find that some of the risks of solar geoengineering can be minimized[3,4]. Currently, conversations about SRM strategies, or albedo modification, are purely theoretical. “We are confident that there is no currently active program to actually test or implement albedo modification outdoors,” wrote David Keath. Therefore, the video’s claims that SRM is happening and causing catastrophic damage are also incorrect. Scientists’ Feedback: Douglas MacMartin Senior Research Associate, Cornell University: All of these claims are pure fantasy. The alternative hypothesis to their supposed conspiracy (which would require cooperation from hundreds of thousands of people in every single country on the planet) is the rather mundane belief that clouds are made of water, and since jet fuel is hydrocarbon, burning it produces water vapour as well as cloud condensation nuclei, and thus produces contrails; basically an artificial cirrus. The SRM for global warming mitigation would involve putting things like sulfate (which wouldn’t leave trails) much higher into the atmosphere than any current aircraft can fly. If that was being done, it would be trivially detectable from satellite observations. We also know with 100% certainty that (a) the aircraft contrails they see aren’t geoengineering, and (b) no-one is doing geoengineering.

https://science.feedback.org/review/destruction-of-the-amazon-forest-very-likely-contributes-to-global-warming-as-accurately-described-in-the-national-geographic-article/

1

National Geographic, by Craig Welch, on 2021-03-11.

"First study of all Amazon greenhouse gases suggests the damaged forest is now worsening climate change"

1 – Covey et al. (2021). Carbon and Beyond: The Biogeochemistry of Climate in a Rapidly Changing Amazon. Frontiers in Forests and Global Change. 2 – Baccini et al. (2017). Tropical forests are a net carbon source based on aboveground measurement of gain and loss. Science. 3 – Zemp et al. (2017). Self-amplified Amazon forest loss due to vegetation-atmosphere feedbacks. Nature Communications. 4 – Scott et al. (2018). Impact on short-lived climate forcers increases projected warming due to deforestation. Nature Communications. 5 – Hubau et al. (2020). Asynchronous carbon sink saturation in African and Amazonian tropical forests. Nature. 6 – Nobre et al. (2016). Land-use and climate change risks in the Amazon and the need of a novel sustainable development paradigm. PNAS. 7- Lovejoy and Nobre (2018). Amazon tipping point. Science Advances.

Reviewers’ Overall Feedback: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. The article is good overall, although there are two small issues. First, the title seems to overestimate the results. The scientific study the National Geographic article is based on cannot account for all of the climate forcers, as there are no Amazon basin wide estimates (as clearly stated in the study). This drawback could potentially change the overall warming effect, and therefore the title seems to exaggerate. However, it is true that to look at the climatic effect of the Amazonian rain forest, one should not only look at CO2. Second, when the article says the moisture respired by plants falls as rain again, one should say only 50% falls as rain again, according to Zemp et al. (2017)[3]. When the article says: “But until recently, no one had attempted to understand that balance”, I’m not sure if the author is claiming that the study authors are the only ones who assessed this balance, as Scott et al., 2018 conducted the first global approach taking into account Amazonia[4]. Richard Houghton Senior Scientist Emeritus, Woodwell Climate Research Center: Even considering CO2 alone, the Amazon basin is likely a carbon source rather than a sink, according to Baccini et al. (2017)[2]. Based on satellite-measurement of carbon stocks, we could already conclude that the forests of Brazil and Latin America were losing more carbon than they were accumulating. However, the Baccini et al. study did not specifically quantify Amazonian forests, and did not consider other greenhouse gases. The main contribution of this new study is that the forests of the Amazon basin are adding to climate change, not helping to slow it. And the conclusion is based on a comprehensive analysis of several greenhouse gases. Overall this is an informative article, for the most part accurately reporting the findings of a recent review[1]. However, the original headline and photo caption (since updated) suggested that the Amazon is “no longer storing carbon for our planet” – which is inaccurate given the 150-200 billion tonnes of carbon the rainforest is still estimated to store and recent observations showing that in most years carbon storage in undisturbed areas is for the moment still growing (Hubau et al., 2020)[5]. The headline and caption also didn’t initially make it clear enough that the higher emissions are primarily driven by human disturbance rather than natural feedbacks to climate change. The difference between disturbance-driven emissions and natural feedbacks is an important point to be clear on because several steadily worse milestones – a net warming feedback from across the whole Amazon due to direct human disturbances, undisturbed areas transitioning from carbon sinks to sources due to climate change, and a deforestation or warming-induced ‘tipping point’ beyond which a large-scale regime shift to savannah becomes inevitable – are often conflated in popular discussion of climate change and the Amazon rainforest. While this review suggests the former may be close or passed, undisturbed rainforest may take another couple of decades to become a persistent carbon source[5] and the ‘dieback’ tipping point could occur beyond 20-40% deforestation (vs. ~17% now) or ~4°C of global warming[6,7]. If the Amazon had become a net warming forcing, but this was still human-driven, then this means this may still be reversible by mitigating disturbance, whereas a transition to net positive feedbacks from undisturbed rainforest would not be easily reversible. Although the increased focus on non-carbon dioxide forcings in the Amazon is welcome, it is also not mentioned in this article that part of the reason for the mainstream focus on carbon is that other forcing agents, such as methane, tend to be quite short-lived, reducing their long-term effect and making carbon storage the dominant factor for long-term climate change. There is some debate too over the ideal timescale and accounting method for comparing the contribution of short-lived climate forcers to carbon dioxide, but in contrast to the study, the article does not get into the issue of timescales and how it could affect the study’s conclusion. As a result, the article still lacks some extra context on forcing timescales and why some other climate scientists might disagree with the overall conclusion on this basis. The updated article does a good job overall though at conveying the uncertainties discussed in the review, making it clear that net warming due to the Amazon is not yet confirmed, and also illustrates the Amazon’s biogeochemical complexity and the many ways it can interact with climate change.

https://science.feedback.org/review/atlantic-ocean-circulation-system-is-slowing-down-as-accurately-described-in-the-new-york-times-article/

1.5

The New York Times, by Jeremy White, Moises Velasquez-Manoff, on 2021-03-02.

"In the Atlantic Ocean, Subtle Shifts Hint at Dramatic Dangers"

1 – Caesar et al. (2021) Current Atlantic Meridional Overturning Circulation weakest in last millennium. Nature Geoscience. 2 – Duchez et al. (2016) Drivers of exceptionally cold North Atlantic Ocean temperatures and their link to the 2015 European heat wave. Environmental Research Letters. 3 – Josey et al. (2017) The Recent Atlantic Cold Anomaly: Causes, Consequences, and Related Phenomena. Annual Review of Marine Science. 4 – Rahmstorf et al. (2015) Exceptional twentieth-century slowdown in Atlantic Ocean overturning circulation. Nature Climate Change. 5 – Caesar et al. (2018) Observed fingerprint of a weakening Atlantic Ocean overturning circulation. Nature. 6 – Collins et al. (2019) Extremes, Abrupt Changes and Managing Risk. In: IPCC Special Report on the Ocean and Cryosphere in a Changing Climate.

Reviewers’ Overall Feedback: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. This article is well-written, and the visuals are outstanding. It is a very strong piece of science communication. That being said, there is at least one error. The author mistakenly conflates the long-term warming hole with the shorter-term North Atlantic cold anomaly. The two phenomena have very different timescales and are likely driven by different mechanisms. The long-term warming hole that is the focus of the NYT article may have been driven by the Atlantic Meridional Overturning Circulation (AMOC) slowdown as discussed, but the 2015 cold anomaly that was linked to European heat waves was a shorter-term phenomena that was likely caused by successive winters with extreme heat loss, as opposed to an AMOC slowdown. Indeed, in the study by Duchez et al. that was linked to in the NYT article, the authors state “It is important to distinguish between this long-term warming hole and the short term 2015 cold anomaly that is the focus of our study.”[2] Unfortunately, the authors of the NYT article missed this distinction and conflated the two phenomena. To be fair, this is an easy mistake to make! Many of our own colleagues have confused the two phenomena at first glance. For more information on the causes of the recent, short-term North Atlantic cold anomaly, see this review article[3]. Marcos Fontela Postdoctoral researcher, Institute of Marine Research (IIM-CSIC): It is a very powerful and insightful article. The article has awesome graphics and good selection of quotes, although it would be very nice to have the comments from the lead author of the article (L. Caesar). The article has very good, up-to-date references. Some minor comments: 1) As was already pointed by Dan Jones on twitter, they mixed the decadal-scale cold blob and the short-term subpolar North Atlantic 2015 cold anomaly. 2) In the article sometimes the distinction between the Gulf Stream and AMOC is not very clear. It’s true that sometimes the AMOC is called the Gulf Stream System, but because the AMOC is a network of currents, we should keep in mind that Gulf Stream and AMOC are not synonyms. There are more currents in the AMOC and they are not only in the surface-subsurface layer. Stefan Rahmstorf Professor, Potsdam University: The article provides a very good and credible overview of recent scientific findings regarding the Atlantic Meridional Overturning Circulation (AMOC) and nicely covers science history all the way back to discoveries in the 16th Century. It properly describes the relationship between Gulf Stream and AMOC, and it uses beautiful visualisations. One minor comment, it describes our recent study as providing “reconstructions of sea temperature around the North Atlantic, some going back 1,600 years”, whilst what we mostly provided are proxy data series for AMOC strength from the sediments at the bottom of the Atlantic, most of which are unrelated to temperature. But that is just one sentence in an otherwise great article. Generally speaking, the article is sound and has numerous sources of scientists to equilibrate the debate. There are only a few things that are maybe exaggerated and not clearly explained in my opinion, e.g.: The estimate that the AMOC has weakened by 15% is not in Rahmstorf et al. (2015)[4], but in Caesar et al. (2018)[5]. Also, the sentence “Hurricanes derive their energy from heat in the water” is a bit misleading when referring to mid-latitude storms. The fact that a weakening AMOC might enhance their probability is mainly due to strengthening of equator-pole temperature gradient. Consensus is low on the paper cited in the article. Why not refer to the IPCC chapter 6.7 special report on extremes, abrupt changes, and managing risks in the ocean and cryosphere in a changing climate instead to find consensus on potential climatic impacts?[6] Annotations: The statements quoted below are from the article; comments are from the reviewers (and are lightly edited for clarity). “Scientists at the U.K.’s National Oceanography Centre have somewhat counterintuitively linked the cold blob in the North Atlantic with summer heat waves in Europe. In 2015 and 2018, the jet stream, a river of wind that moves from west to east over temperate latitudes in the northern hemisphere, made an unusual detour to the south around the cold blob. The wrinkle in atmospheric flow brought hotter-than-usual air into Europe, they contend, breaking temperature records.” Here, the decadal-scale warming hole that is possibly linked to AMOC slowdown has been conflated with the shorter-term cold anomaly that featured record low North Atlantic sea surface temperatures in 2015. The authors of the U.K.’s National Oceanography Centre study are careful to make this distinction in their article: “It is important to distinguish between this long-term warming hole and the short-term 2015 cold anomaly that is the focus of our study.”[2] The long-term warming hole that is the focus of this New York Times article is not the same thing as the short-term 2015 cold anomaly. The two phenomena have very different timescales and different causes. Current understanding suggests that the short-term 2015 cold anomaly was caused by successive winters with extreme heat loss, i.e. it was largely driven by changes in air-sea heat exchange. The longer-term warming hole may have been caused by the AMOC slowdown, as discussed in this article. For more information on the 2015 cold anomaly and its causes, see this review article led by Simon Josey[3]. ““That was not predicted,” said Joel Hirschi, principal scientist at the centre and senior author of the research. It highlights how current seasonal forecasting models are unable to predict these warm summers. And it underscores the paradox that, far from ushering in a frigid future for, say, Paris, a cooler North Atlantic might actually make France’s summers more like Morocco’s.” As in the paragraph above, here the long-term warming hole has been conflated with the short-term North Atlantic cold anomaly, which are phenomena with very different timescales and causes. Predicting future short-term North Atlantic cold anomalies and subsequent possible heat waves would be done using seasonal forecasting models. Predicting the longer-term impacts of an AMOC slowdown would be done using climate models run under different emissions scenarios. Conflating the two mechanisms and timescales has resulted in some confusion in this part of the article.

https://science.feedback.org/review/scientists-didnt-announce-impending-environmental-catastrophes-every-decade-since-the-1970s/

Inaccurate

Facebook, Facebook users, 2021-02-20

Science said in the: 70s, another ice age in 10 years; 80s, acid rain will destroy all crops in 10 years; 90s: the ozone layer will be destroyed in 10 years; 2000’s the ice caps will be gone on 10 years

Factually inaccurate: Over the past few decades, scientists have studied and discussed major environmental concerns, such as acid rain, ozone layer destruction, and melting ice caps. However, the majority of scientists didn’t claim that these environmental issues would cause drastic, short-term catastrophes, such as the destruction of all crops in ten years. Misrepresent sources: The claim misrepresents the perspective of most scientists on these environmental issues. Specifically, a few of the alleged consequences of these environmental issues stemmed from a small number of scientists, or would take far longer than a decade to occur.

Over the past century, scientists have studied climate change, acid rain, ozone layer depletion, and melting ice caps, as well as other environmental issues. Scientific understanding of the mechanism behind these events and their potential consequences has increased significantly through observational studies, experiments, and model simulations. Early warnings related to these environmental issues led to national and international regulations aimed at mitigating them, such as acid rain, ozone depletion, and climate warming.

”Government funded science: 70’s: another ice age in 10 years; 80’s: acid rain will destroy all crops in 10 years; 90’s: the ozone layer will be destroyed in 10 years; 2000’s the ice caps will be gone on 10 years”

1 – Peterson et al. (2012). The myth of the 1970s global cooling scientific consensus. Bulletin of the American Meteorology Society. 2 – Rasool and Schneider (1971). Atmospheric Carbon Dioxide and Aerosols: Effects of Large Increases on Global Climate. Science. 3 – Charney et al. (1979). Carbon dioxide and climate : a scientific assessment. National Academy of Science. 4 – Sherwood et al. (2020). An Assessment of Earth’s Climate Sensitivity Using Multiple Lines of Evidence. Reviews of Geophysics. 5 – O’Neill (1988) Acid Rain: A Selective Bibliography. California Polytechnic State University. 6 – Irving (1990) NAPAP Acid Rain Conference improves scientific consensus, discounts extremes. EOS. 7 – National Acid Precipitation Assessment Program (1991) Acidic deposition: state of science an technology. 8 – Irving (1983) Acidic Precipitation Effects on Crops: A Review and Analysis of Research. Journal of environmental quality. 9 – Barse et al. (1985) Effect of air pollution and acid rain on agriculture: an annotated bibliography. United State Department of Agriculture. 10 – United State Environmental Protection Agency (2020) The Legacy of EPA’s Acid Rain Research. 11 – WMO/UNEP (1994) Scientific Assessment of Ozone Depletion. 12 – Prather et al. (1990) Global impact of the Antarctic ozone hole: Dynamical dilution with a three‐dimensional chemical transport model. Journal of Geophysical Research – Atmospheres. 13 – Prather et al. (1996) The ozone layer: The road not taken. Nature. 14 – Newman et al. (2009). What would have happened to the ozone layer if chlorofluorocarbons (CFCs) had not been regulated? Atmospheric Chemistry and Physics. 15 – IPCC (2001) Climate Change 2001: Synthesis Report. 16 – IPCC (2007) Climate Change 2007: Synthesis Report. 17 – Velicogna (2009) Increasing rates of ice mass loss from the Greenland and Antarctic ice sheets revealed by GRACE. Geophysical Research Letters – The Cryosphere.

Review: The claim that government funded scientists have announced catastrophic short-term environmental effects every decade since the 1970s have been repeated in hundreds of Facebook posts such as this one. In the 1970s, the majority of climate studies projected global warming The claim that scientists announced a forthcoming ice age in the 1970s is a popular myth frequently used by those who want to cast doubt on what climate scientists say today about global warming. However, as stated in Peterson et al. (2008), “a review of the climate science literature from 1965 to 1979 shows this myth to be false. The myth’s basis lies in a selective reading of the texts both by members of the media at the time and by some observers today. In fact, emphasis on greenhouse warming dominated the scientific literature even then”.[1] Only a few scientific studies predicted global cooling. For instance, in the often-cited Rasool and Schneider (1971) paper, the authors simulated the cooling effect of aerosols (suspended particles in the air) if their concentration were to increase significantly in the future[2]. However, it’s incorrect to claim there was a scientific consensus predicting global cooling and an imminent ice age. On the contrary, by the end of the 1970s scientists agreed that greenhouse gases were the dominant forcing of the global climate changes happening currently[1]. The few ice-age predictions were abandoned shortly thereafter. Furthermore, actions taken since the 1970s to reduce aerosol emissions resulting from industrial activity have strongly limited the cooling effect of aerosols on the climate. Contrary to the claim’s suggestions, observed global warming patterns are well-aligned with most of the predictions made by scientists in the 1970s. In its 1979 report, the U.S. National Academy of Sciences concluded, “when it is assumed that the CO2 content of the atmosphere is doubled and statistical thermal equilibrium is achieved, the more realistic of the modeling efforts predict a global surface warming of between 2°C and 3.5°C, with greater increases at high latitudes”.[3] This is in close agreement with the latest estimation of Earth’s climate sensitivity, ranging 2.6-3.9°C[4]. In conclusion, the claim emphasizes a prediction from a minority of studies and neglects the scientific consensus that emerged in the 1970s on the role of greenhouse gasses as a major driver of global warming. In the 1980s, scientists thought acid rain contributed to lake acidification and forest dieback The claim that scientists projected the destruction of all crops within ten years due to acid rain is a misinterpretation of the scientific debate that occurred in the early 1980s. At the time, acid rain caused by nitrogen dioxide (NO2) and sulfur dioxide (SO2) emissions from coal power electricity plants and other sources was a major environmental concern. Scientists hypothesized that these emissions were responsible for lake acidification and the dying of forests in Europe and North America, resulting in numerous studies on the topic[5]. The U.S. National Acid Precipitation Assessment Program (NAPAP) was launched in 1980 to guide national debate on clean-air legislation. Researchers spent a decade studying atmospheric deposition and its effects on aquatic and terrestrial ecosystems. Irving (1990) explained, “when NAPAP was initiated in 1981, scientific opinion on acid rain was divided. The issue was viewed by some as a rapidly intensifying disaster requiring immediate remediation, and by others as a speculative hypothesis without sufficient substantiation. Most scientific opinion now lies well inside both of these two positions”[6]. The first NAPAP report concluded that acid rain damaged certain lakes and streams in the eastern United States and Canada, and contributed to the decline of high-elevation red-spruce forests[7]. Contrary to the claim, scientists didn’t project that all crops would be destroyed by acid rain within ten years. In a paper published in 1983, Irving indicated that an “analysis of the current literature concludes that the effects of acidic precipitation on crops appear to be minimal and that when responses are observed, they may be positive or negative”[8]. A couple of years later, a report from the U.S. Department of Agriculture reached the same conclusion, “acid rain seems to be far less damaging to agriculture (if damaging at all) than the gaseous pollutants”[9]. Gaseous pollutants, such as SO2 and NO2, and acid rain originate from similar sources: man’s pollutant emissions into the atmosphere. Adoption of policies like the Clean Air Act in the U.S., and the Geneva Convention on Long-Range Transboundary Air Pollution in Europe led to a drastic reduction of industrial SO2 and NO2 emissions, mitigating the effects of acid rain. For example, average annual ambient concentrations of SO2 decreased 93% between 1980 and 2018 in the U.S.[10]. In conclusion, the claim is misleading and doesn’t reflect the research and scientific discussions about acid rain that occurred in the 1980s. In the 1990s, the ozone layer over the Antarctic was thinning dramatically in spring The claim that scientists said the ozone layer would be destroyed in ten years is an exaggeration related to the discovery of the ozone hole. In the early 1980s, ground-based and satellite measurements revealed that the stratospheric ozone layer was thinning over the South Pole every spring. The reduction in ozone concentration was coined “ozone hole” metaphorically. The hole refers to the area in which ozone concentrations drop below the historical threshold of 220 Dobson Units. This observation raised concerns because stratospheric ozone protects Earth’s surface from the Sun’s harmful ultraviolet radiation. From 1980 through the early 1990s, the ozone hole rapidly grew in area and depth, with ozone depletion of up to 60%. Contrary to the claim, the ozone hole is essentially a seasonal, regional-scale phenomenon in the Antarctic, although anomalous ozone decreases of about 4 – 5% per decade were also observed in the midlatitudes of both hemispheres[11]. In 1990, a simulation study showed that “as the vortex breaks down and the ozone hole is dispersed, significant depletions to column ozone, of order 10 Dobson units (3%) occur as far north as 40°S during austral summer”[12] . This study also concluded that 70% of the initially prescribed ozone deficit is replenished through stratospheric chemistry by the end of the year. A global and abrupt destruction of the ozone layer was, however, not projected in ten years. During the 1980s, scientists discovered that human-made chemicals, such as chlorofluorocarbons (CFCs, used in refrigerators and aerosol spray), facilitated the destruction of the ozone layer. The global recognition of the destructive potential of CFCs led to the 1987 Montreal Protocol, a treaty that phased out the production of ozone-depleting chemicals. As a result, annual ozone holes roughly stabilized in the early 21st century. A lack of action would have led to severe ozone depletion, with increased levels of solar UV radiation levels at the Earth’s surface. Prather et al. (1996) modeled the ozone response to continued growth of the ozone-depleting substances without the Montreal Protocol, and calculated a globally-averaged total ozone depletion of 10% by 1999[13]. A more complex simulation estimates that in the absence of regulation, 17% of the globally-averaged column ozone would have been destroyed by 2020, and 67% by 2065, in comparison to 1980[14]. Also, “large ozone depletions in the polar region become year round rather than just seasonal as is currently observed in the Antarctic ozone hole”. When taking into account the impact of the Montreal Protocol, the authors predicted that the ozone layer would recover by 2050-2060[14]. In conclusion, the claim is incorrect based on observations of the ozone hole and the projections made about ozone depletion in the 1990s. In the 2000s, studies projected that polar ice caps could melt over millennia The claim that scientists projected the imminent melting of ice caps is an overstatement that does not reflect current research or scientific understanding. The fate of the Arctic and Antarctic ice sheets is the subject of numerous observational studies and simulation research because of their contributions to sea-level rise. Unlike ice caps, sea ice does not raise sea-level when it melts, but has declined dramatically in the Arctic. In addition, the poles are warming at a rate nearly three times faster than the global average. Due to different geographical settings, the Arctic and Antarctic ice sheets respond differently to the rise in global temperatures. In 2001, the Intergovernmental Panel on Climate Change (IPCC) third assessment report concluded, “The Antarctic ice sheet as a whole is likely to increase in mass during the 21st century. However, the West Antarctic ice sheet could lose mass over the next 1,000 years with an associated sea-level rise of several meters”[15]. In contrast, the report stated, the Greenland ice sheet is likely to lose mass during the 21st century and contribute a few centimeters to sea-level rise. Scientists projected more significant losses in ice sheet mass over millennial time scales, as the ice sheets continue reacting in response to climate warming. As stated in the IPCC report, “Ice sheet models project that a local warming of larger than 3°C, if sustained for millennia, would lead to virtually a complete melting of the Greenland ice sheet with a resulting sea-level rise of about 7 meters”. Authors of the IPCC report acknowledged an incomplete understanding of some of the underlying processes. Based on more recent observations, the 2007 IPCC report concluded that the risk of additional contributions to sea-level rise from both the Greenland and possibly Antarctic ice sheets “may be larger than projected by ice sheet models and could occur on century time scales”[16]. At the time, polar ice sheets were shown to be losing mass at an accelerating rate by the end of the 2000s[17]. In conclusion, the claim is incorrect, as the possibility of an abrupt melting of ice caps wasn’t considered in the 2000s.

https://science.feedback.org/review/the-scientific-research-facility-haarp-cannot-create-natural-disasters-or-influence-human-thoughts-and-movements-contrary-to-online-claims/

Incorrect

Gaia, Anonymous, 2020-12-11

HAARP may deliberately create destruction on a global scale, causing earthquakes, cyclones, flooding, snowstorms, around the world; HAARP may be attacking the citizens of the world telepathically, influencing thoughts with low frequency vibrations

Incorrect: The Gaia article leaves the reader with an extremely poor understanding of how the High-frequency Active Auroral Research Program (HAARP) works. The facility is a high-frequency (shortwave radio) transmitter and doesn’t transmit low-frequency vibrations, as stated in the Gaia article. HAARP analyzes physics phenomena in the uppermost part of the atmosphere (known as the ionosphere) by studying the small heating effects the transmitter creates there that last for only a few seconds. Thus, it cannot affect human thought processes or movements in any way. Inadequate support: There is no scientific evidence provided to support the claims made in the Gaia article about HAARP’s ability to cause natural disasters or control human behaviors. The Gaia article cited an article by the U.K. tabloid The Express and another Gaia article as supporting evidence for the natural disasters claim, but these are not scientific or peer-reviewed sources. The claim that HAARP can control minds is purportedly supported by a “leaked classified government file”, but the article provided no direct link or reference to this file.

The High-frequency Active Auroral Research Program (HAARP) is a research facility that uses a high-power, high-frequency transmitter to study the physical properties and behaviour of the highest point of the atmosphere, the ionosphere. One example of natural phenomena that HAARP studies is the aurora borealis, also known as the northern lights. Radio transmissions from HAARP only cause small effects in the ionosphere that last for a brief span of a few seconds. There is no evidence that HAARP can cause natural disasters or influence with human movements and thoughts.

The HAARP organization may deliberately create destruction on a global scale, causing earthquakes, cyclones, flooding, snowstorms, and other disasters, around the world; The HAARP facility may be attacking the citizens of the world telepathically, influencing thoughts with low frequency vibrations; "it is possible to control human movements, glandular functions, and specific mental manifestations using electromagnetic stimulation."

1 – McCoy et al. (2018) Haarp, a Powerful Active Ionospheric Laboratory Open for International Research. 42nd COSPAR Scientific Assembly. 14-22 July 2018, Pasadena, California, USA 2 – Todd Pedersen (2015) HAARP, the most powerful ionosphere heater on Earth. Physics Today. 3 – Inan et al. (2004) Multi‐hop whistler‐mode ELF/VLF signals and triggered emissions excited by the HAARP HF heater. Geophysical Research Letters. 4 – Piddyachiy et al. (2011) DEMETER observations of the ionospheric trough over HAARP in relation to HF heating experiments. Journal of Geophysical Research: Space Physics

Review: The claim appeared in an article published by Gaia in mid-December 2020, receiving more than 16,000 interactions on Facebook according to the social media analytics tool Crowdtangle. The High-frequency Active Auroral Research Program (HAARP) is a research facility operated by the University of Alaska Fairbanks[1]. It transmits high-frequency radio signals into the highest point of the atmosphere, the ionosphere, using 360 radio transmitters and 180 antennas. The facility covers about 14 hectares (0.14 kilometers squared) near the town of Gakona, Alaska, which is about 250 kilometers northeast of Anchorage, Alaska’s largest city. The radio signals are partially absorbed between 100 kilometers and 350 kilometers in altitude, accelerating electrons in the ionosphere and briefly “heating” it up[2]. By analyzing how radio waves interact with electrons in the ionosphere[3,4], researchers at HAARP are able to study phenomena, such as the effects of the aurora borealis, or northern lights, on radio systems and aircraft communications at high altitudes. HAARP has previously been the subject of conspiracy theories, but “claims in the Gaia article about HAARP’s ability to cause natural disasters or control human behaviors are false,” said Robert McCoy, director of the Geophysical Institution at the University of Alaska Fairbanks. “HAARP is a high-frequency transmitter (basically a shortwave radio),” he explained. “It is used to conduct experiments on a 100 x 100 kilometer patch of the overhead ionosphere. Transmissions from HAARP only cause small effects in the ionosphere that last a few seconds. In addition, the facility is operated only a few hours each year. The amount of high-frequency energy coming from amateur radio operators around the world almost certainly exceeds transmissions from HAARP. HAARP cannot affect any of the natural phenomena mentioned in the article, such as earthquakes and snowstorms, and there is no way it can interact with humans or influence them.” HAARP produces only small heating effects in the ionosphere. It therefore cannot influence natural phenomena like cyclones or hurricanes, which occur in the much lower-altitude (7 kilometer) troposphere and generate orders of magnitude more energy. In a 2018 U.S. News article, McCoy said that HAARP is “not a weapon, and it couldn’t be”. “The way high-frequency radios work is that the atmosphere is transparent to those signals. If we made this (facility) 10 times bigger and tried, we still couldn’t affect the weather. Minds? Electrical signals in the mind are very low-frequency. HAARP is very large-frequency; the waves are meters-long. So there’s no way they could control minds,” he explained. Former HAARP Chief Scientist Chris Fallen said in a 2017 news article published on the University of Alaska Fairbanks website that HAARP attracts more attention than the average scientific research facility, likely because of its focus on an obscure area of the atmosphere called the ionosphere. This has led to misunderstandings about the purpose of the HAARP facility, he explained. “HAARP cannot control the weather, contrary to one conspiracy theory. It has too little power and affects a different part of the atmosphere. Neither can it manipulate our brains, as alleged by another theory. Generally, space physicists focus on regions more than 60 miles (nearly 97 kilometers) above our heads, where HAARP’s radio waves are 100 times weaker than those from mobile phones.” Scientists’ Feedback: Robert McCoy Director, Geophysical Institute, University of Alaska:HAARP has previously been the subject of conspiracy theories, but claims in the Gaia article about HAARP’s ability to cause natural disasters or control human behaviors are false. HAARP is a high-frequency transmitter (basically a shortwave radio). It is used to conduct experiments on a 100 x 100 kilometer patch of the overhead ionosphere. Transmissions from HAARP only cause small effects in the ionosphere that last a few seconds. In addition, the facility is operated only a few hours each year. The amount of high-frequency energy coming from amateur radio operators around the world almost certainly exceeds transmissions from HAARP. HAARP cannot affect any of the natural phenomena mentioned in the article, such as earthquakes and snowstorms, and there is no way it can interact with humans or influence them. READ MORE Learn more about this topic by reading this post by the University of Alaska Fairbanks

https://science.feedback.org/review/breitbart-article-makes-numerous-false-claims-about-the-impacts-of-climate-change-based-on-global-warming-policy-foundation-post-delingpole-goklany/

-2

Breitbart, by James Delingpole, Indur Goklany, on 2021-02-07.

"Study Disputes That Earth Is in a ‘Climate Emergency’"

1 – IPCC (2014) Climate Change 2014: Summary: for Policymakers. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. 2 – National Academies of Sciences, Engineering, and Medicine (2016) Attribution of extreme weather events in the context of climate change. The National Academies Press. 3 – Swain et al. (2020) Attributing extreme events to climate change: A new frontier in a warming world. One Earth. 4 – Knutson et al. (2020) Tropical Cyclones and Climate Change Assessment: Part II: Projected Response to Anthropogenic Warming. Bulletin of the American Meteorological Society. 5 – Liu et al. (2019) Causes of large projected increases in hurricane precipitation rates with global warming. npj Climate and Atmospheric Science. 6 – Allamano et al. (2009) Global warming increases flood risk in mountainous areas. Hydrology and Land Surface Studies. 7 – Franzke et al. (2020) Risk of extreme high fatalities due to weather and climate hazards and its connection to large-scale climate variability. Climatic Change. 8 – Gonzalez et al. (2018) Chapter 25: Southwest. In Impacts, Risks, and Adaptation in the United States: Fourth National Climate Assessment, Volume II. 9 – Nabuurs et al. (2013) First signs of carbon sink saturation in European forest biomass. Nature Climate Change. 10 – De Graaff et al. (2006) Interactions between plant growth and soil nutrient cycling under elevated CO2: a meta-analysis. Global Change Biology. 11 – Mbow et al. (2019) IP Food Security. In: Climate Change and Land: an IPCC special report on climate change, desertification, land degradation, sustainable land management, food security, and greenhouse gas fluxes in terrestrial ecosystems. IPCC report. 12 – Moore et al. (2017) New science of climate change impacts on agriculture implies higher social cost of carbon. Nature. 13 – Moore and Lobell (2015) The fingerprint of climate trends on European crop yields. PNAS. 14 – Diffenbaugh (2020) Verification of extreme event attribution: Using out-of-sample observations to assess changes in probabilities of unprecedented events. Science Advances. 15 – Swain et al. (2020) Attributing Extreme Events to Climate Change: A New Frontier in a Warming World. One Earth. 16 – Haque et al. (2012) Reduced death rates from cyclones in Bangladesh: what more needs to be done? Bulletin of the World Health Organization 17 – Kossin et al. (2020) Global increase in major tropical cyclone exceedance probability over the past four decades. PNAS. 18 – Vohra et al. (2011) Global mortality from outdoor fine particle pollution generated by fossil fuel combustion: Results from GEOS-Chem. Environmental Research. 19 – Zhang et al. (2019) Ozone Pollution: A Major Health Hazard Worldwide. Frontiers in Immunology. 20 – Patz et al. (2005) Impact of regional climate change on human health. Nature. 21 – Mitchell et al. (2016) Attributing human mortality during extreme heat waves to anthropogenic climate change. Environmental Research Letters. 22 – Gensini & Brooks (2018) Spatial trends in United States tornado frequency. npj Climate and Atmospheric Science. 23 – Elsner et al. (2018) Increasingly Powerful Tornadoes in the United States. Geophysical Research Letters. 24 – Diffenbaugh et al. (2013) Robust increases in severe thunderstorm environments in response to greenhouse forcing. PNAS. 25 – Hoogewind et al. (2017) The Impact of Climate Change on Hazardous Convective Weather in the United States: Insight from High-Resolution Dynamical Downscaling. Journal of Climate. 26 – Marvel et al. (2019) Twentieth-century hydroclimate changes consistent with human influence. Nature. 27 – Diffenbaugh et al. (2015) Anthropogenic warming has increased drought risk in California. PNAS. 28 – Williams et al. (2020) Large contribution from anthropogenic warming to an emerging North American megadrought. Science. 29 – Abatzoglou and Williams (2016) Impact of anthropogenic climate change on wildfire across western US forests. PNAS. 30 – Williams et al. (2019) Observed Impacts of Anthropogenic Climate Change on Wildfire in California. Earth’s Future. 31 – Goss et al. (2020) Climate change is increasing the likelihood of extreme autumn wildfire conditions across California. Environmental Research Letters. 32 – Abram et al. (2021) Connections of climate change and variability to large and extreme forest fires in southeast Australia. Communications Earth & Environment. 33 – Feurdean et al. (2020) Recent fire regime in the southern boreal forests of western Siberia is unprecedented in the last five millennia. Quaternary Science Reviews. 34 – Jones et al. (2020) Climate Change Increases the Risk of Wildfires. ScienceBrief Review. 35 – Bowman et al. (2020) Vegetation fires in the Anthropocene. Nature Reviews Earth & Environment. 36 – Doerr and Santín (2016) Global trends in wildfire and its impacts: perceptions versus realities in a changing world. Philosophical Transactions of the Royal Society B. 37 – Beillouin et al. (2020) Impact of extreme weather conditions on European crop production in 2018. Philosophical Transactions of the Royal Society B. 38 – Tigchelaar et al. (2018) Future warming increases probability of globally synchronized maize production shocks. PNAS. 39 – Mehrabi and Ramankutty (2019) Synchronized failure of global crop production. Nature Ecology & Evolution. 40 – Chatzopoulos et al. (2020) Climate extremes and agricultural commodity markets: A global economic analysis of regionally simulated events. Weather and Climate Extremes. 41 – Hall et al. (2014) Understanding flood regime changes in Europe: a state-of-the-art assessment. Hydrol. Earth Syst. Sci. 42 – Murphy et al. (2013) Climate-driven trends in mean and high flows from a network of reference stations in Ireland. Hydrological Sciences Journal. 43 – Birsan et al. (2005) Streamflow trends in Switzerland. Journal of Hydrology. 44 – Solin (2008) Analysis of floods occurrence in Slovakia in the period 1996–2006. J. Hydrol. Hydromech. 45 – Vormoor et al. (2015) Climate change impacts on the seasonality and generation processes of floods – projections and uncertainties for catchments with mixed snowmelt/rainfall regimes. Hydrol. Earth Syst. Sci. 46 – Lawrence and Hisdal (2011) Hydrological projections for floods in Norway under a future climate. 47 – Pall et al. (2019) A Climatology of Rain-on-Snow Events for Norway. Journal of Climate. 48 – Madsen et al. (2014) Review of trend analysis and climate change projections of extreme precipitation and floods in Europe. Journal of Hydrology. 49 – Nerem et al. (2018) Climate-change–driven accelerated sea-level rise detected in the altimeter era. PNAS. 50 – Bamber et al. (2019) Ice sheet contributions to future sea-level rise from structured expert judgment. PNAS.

Reviewers’ Overall Feedback: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. This article uses a single poorly-sourced, non-peer reviewed report as a basis for making numerous misleading and in multiple instances demonstrably false claims regarding climate change and its global implications. Kerry Emanuel Professor of Atmospheric Science, MIT: The article is mostly inaccurate and uniformly misleading. For example, in declaring that hurricane frequency is not increasing, it neglects to mention that there was never a consensus prediction that the frequency of all hurricanes would increase, or in stating that weather-related deaths are decreasing fails to mention that the reasons for that have nothing to do with climate change but rather with rapidly improving warnings and preparedness. This is a biased and purposely misleading article that contradicts evidence-based scientific literature. The authors did not care to cross-check the claims made by Mr. Goklany nor to set them in the broader context of the scientific evidence about climate change and impacts (e.g. IPCC reports)[1]. The article’s scientific credibility is very low. The author cherry-picks data, makes broad generalizations and characterizations based on incomplete or flimsy reasoning, and repeatedly misinterprets technological and economic progress in justifying false claims and misinformation minimizing global warming impacts. Annotations: The statements quoted below are from the article; comments are from the reviewers (and are lightly edited for clarity). “according to a study for the Global Warming Policy Foundation” It is important to note that the purported “study” that is the subject of this article is not actually a study in any meaningful sense of the word. It is written by a single author who is not a physical or climate scientist, contains no previously unpublished data, and has not been peer-reviewed. This is not a “study”. It is a single-author, non-peer reviewed opinion piece that cherry-picks, misinterprets and conflates previous findings. “Most extreme weather phenomena have not become more extreme, more deadly, or more destructive.” There is an extensive and growing body of evidence showing that many kinds of extreme weather have increased in magnitude and/or frequency as the climate has warmed. Evidence is strongest regarding increases in extreme heatwaves and extreme precipitation events[14], but there is also extensive evidence regarding increasing intensity of other physical event types such as droughts, wildfires, and hurricanes (especially in specific regions). Indeed, there is now an entire sub-field of climate science, known as “extreme event attribution,” devoted to understanding how climate change is affecting the occurrence and intensity of extreme weather-related events[15]. Kerry Emanuel Professor of Atmospheric Science, MIT: Globally, the leading causes of mortality from weather phenomena during the period 1981-2020, in order, are drought, tropical cyclones, heat waves, floods, and convective storms. For most of these, when normalized by population, there are either no significant trends or downward trends[7]. In most, if not all, cases, this is attributable to improved emergency management. For example, there have been large decreases in tropical cyclone fatality thanks to far better warning, more and better evacuations, and in some places like Bangladesh, the massive construction of evacuation shelters[16]. Weather is taking fewer lives, but when one looks at damage the story is quite different. Since the early 1970s there has been a 380% increase in global weather-related damage normalized each year by world domestic product. Some of this is demographic; for example, there has been a 200% increase in coastal population, but much of the rest is owing to worse weather disasters, as measured by damage. From a strictly meteorological perspective, the latest consensus papers published in 2019 by Knutson et al. show a strong consensus that tropical cyclones will become more intense (but not necessarily more frequent) as the climate warms[4], and a paper published by Kossin in 2020 shows that the fraction of high intensity tropical cyclone observations has been increasing (see figure below)[17]. Figure 2—The proportion of major hurricane intensities to all hurricane intensities globally from 1979-2017. Data is binned into 3-year periods. The proportion of global major hurricanes increased by 25% over the 39-year time period analyzed. From Kossin et al. (2020)[17]. There is also a unanimous consensus that tropical cyclones will produce more rain, and in places with sufficient rain measurements, there is strong evidence for heavier rain events[4]. There is also strong evidence for an increase in the incidence of drought in some regions[1]. In a nutshell, deaths from extreme weather events are indeed decreasing but this is because of improving warnings, evacuations, and shelters, mostly in the developing world. There is strong evidence that weather events globally are becoming more destructive and more extreme[1]. “Empirical evidence directly contradicts claims that increased carbon dioxide has reduced human wellbeing. In fact, human wellbeing has never been higher” Jennifer Francis Senior Scientist, Woods Hole Research Center: The increase in atmospheric carbon dioxide does not directly affect human health, but it does directly cause increased global temperature and ocean acidification, and both of these are having major detrimental effects on human and ecosystem wellbeing. Carbon dioxide increase does not directly affect human well being, but the main process responsible for increasing CO2 is also responsible for air pollution that does directly affect human health[18,19]. In addition, many environmental consequences from anthropogenic greenhouse gas emissions and global warming have heavy costs in terms of human lives and life quality, for example heatwaves, famines due to drought, increase/expansion in infectious diseases[20,21]. There are “More hot days and fewer cold days” This is essentially the only scientifically accurate claim I can discern in the entire article. ”Cyclones/hurricanes [are not] more intense or frequent” While it is true that there remains no strong evidence for an increase in tropical cyclone (hurricane) frequency on a global basis, there is evidence that the most intense tropical cyclones are indeed becoming stronger (in terms of maximum wind speeds and minimum central pressure[17] and are producing more extreme rainfall[5]. In fact, these trends are consistent with predictions regarding tropical cyclone behavior due to global warming: there is a strong expectation that the maximum potential intensity of hurricanes will increase due to rising ocean temperatures, even as the overall frequency of such storms does not change greatly or perhaps even decreases[4]. “Tornadoes [are not] increas[ing] and becom[ing] more intense” There is relatively little evidence in either direction at this point in time regarding global or even regional trends in tornado frequency/intensity. This is largely due to sparse and temporally inhomogeneous historical records in the United States, and virtually non-existent records in other regions. There is some evidence of regional shifts in tornado frequency[22], and perhaps an increase in overall tornado “power” in the United States[23], but in general there is an absence of strong evidence regarding this claim. Future projections regarding climate change and tornado risk are of somewhat low confidence, but there is evidence that atmospheric environments favorable for severe convective storms (which are the types of storms capable of producing tornadoes) may increase in the future due to climate warming[24,25]. ”Droughts [are not] more frequent and intense” Observed spatial trends in global hydroclimate over the past century have been consistent with those expected from human influence in the climate system[26]. In many mid-latitude and subtropical regions, this has indeed included an increase in the frequency/intensity of drought[27,28]–but in other regions (such as the Northern Hemisphere high latitudes), this includes an increase in moisture availability and decrease in drought (as expected from climate model simulations). Therefore, it doesn’t really make sense to make blanket statements regarding overall global drought trends, since only some places are expected to get drier (and others wetter) in a warming climate.There has been no increase in the area burned by wildfire; the area peaked in the mid-19th century This is highly misleading, as it conflates different types of fire (many of which are not wildfires to begin with). Overall trends in area burned globally are strongly driven by decreases in intentional agricultural burning in tropical areas, which is not related to climate change. In regions where non-agricultural fires occur naturally (including the western United States[e.g., 29-31], eastern Australia[32], and the Siberian Arctic[33], for example) there is strong evidence that climate change has already increased the severity and extent of wildfire[34]. The statement that “Area burned by wildfire increasing — No (area peaked in mid-19th century)” is misleading in its implication that climate change is not making wildfires worse or more extreme and deadly. The overall global decrease is mostly driven by less fire in what used to be more extensive savannahs and grasslands and is largely due to the human driven removal of flammable vegetation. In quantitative terms, fire in those grassy ecosystems account for around 70% of the total global area burnt, so the reduction in fire activity here outweighs the increase in burned area that we are seeing in other parts of the world over the last two decades where fires have greater impacts such as Canada, parts of the USA or Siberia. In other words, where humans have not converted flammable landscapes to less or-non flammable landscapes by removing or changing the vegetation, warming temperatures are, overall, associated with an increase in fire activity. A very thorough recent global analysis of trends and fire knowledge overall is here[35]. And very importantly, associated with these regional increases, we have also seen a rise in fire impacts, for example in the number of fatalities. As reported in our wildfire trend analysis, in the period 1994-2014, an average of 71 deaths per year had been recorded in wildfire disasters recorded in the International Disaster Database[36]. Since 2015 this has risen to 122 deaths per year. The observed decline in global average area burned has been misused numerous times to support false claims about the role of climate change in wildfire trends. Climate change as well as human activities affect global fire activity (see here for a summary and update on Doerr and Santin, 2016[36]. “Cereal yields [are not] decreasing”; “they have tripled since 1961”; “Food supplies per capita [are not] decreasing” — they “increased 31 per cent since 1961” This is also misleading because crop yield increase since the 1960s is related to the massive increase in nitrogen fertilization and agricultural industrialization. However, studies have shown that extreme events made more likely by global warming are associated with losses in crop yields[37-39] and peaks in crop prices[40]. There are no “Land area and beaches shrinking, coral islands submerged”, instead there has been “marginal expansion” Ryan Sriver Associate Professor, University of Illinois: Observed expansion of beach areas is mainly due to human intervention and coastal management, not climate change. ”mortality from ‘Extreme Weather Events’ has declined by 99 per cent since the 1920s” No reference to this claim. On the contrary, scientific attribution studies such as Mitchell et al. 2016 show clear impacts of extreme events on excessive mortality[21]. ”fewer people are dying from heat; death rates from climate-sensitive diseases like malaria and diarrhoea have decreased (since 1900 malaria death rates have declined 96 per cent); hunger rates have declined; poverty has declined (GDP per capita has quadrupled since 1950 even as CO2 levels have sextupled); life expectancy has more than doubled since the start of industrialisation; health adjusted life expectancy has increased” All of these have multiple confounding factors (e.g. technological, health and economical development) so that these changes cannot be directly linked to CO2, but also do not invalidate negative effects of climate change. As such, this statement is simply misleading. [You can read this review to learn more about climate change impacts on health.] “Almost everywhere you look, climate change is having only small, and often benign, impacts. The impact of extreme weather events ― hurricanes, tornadoes, floods and droughts ― are, if anything, declining.” This contradicts the evidence presented in dozens of scientific contributions, and summarized in IPCC reports[1]. Jennifer Francis Senior Scientist, Woods Hole Research Center: This statement can be characterized as wishful thinking — contradicts all science-based evidence. It is misleading to state that flood magnitudes do not increase. Trend analyses of flood magnitudes in Europe have shown increases, decreases and no change depending on the location[41]. For example, increases have been observed in Ireland (during 1976–2009), Switzerland, Slovakia (for small catchments of 5–150 km2) and Norway (for rainfall-dominated catchments)[6,42-45]. Snowmelt floods, on the other hand, have been observed to decline in flood magnitude for Norway[45,46]. Rain-on-snow events (including floods caused by rain-on-snow) have been observed to increase at high elevations and decrease at low elevations, for Norway[47]. Future projections of flood magnitudes also show increases, decreases and no trends, depending on the location, catchment properties and flood-generating process. It is therefore misleading to state that flood magnitudes do not increase in the future. Madsen et al. (2014) write: “With respect to hydrological projections of changes in flood frequency at the catchment scale, both positive and negative changes in extreme discharge are projected. Increases in peak discharges are projected for sub-basins in the Scheldt and Meuse in Flanders (Boukhris and Willems, 2008, Willems et al., 2010), for catchments in Denmark (Sunyer et al., 2010, Madsen et al., 2013), for Bavaria and Baden-Württemberg (Hennegriff et al., 2006) and Saxony-Anhalt (Hattermann et al., 2011) in Germany, for western, mid-northern and all of coastal Norway (Lawrence and Hisdal, 2011), for the Hron catchment in Slovakia (Hlavcová et al., 2007), in coastal, southern areas in Sweden (Bergström et al., 2012), and in many catchments within the UK (Reynard et al., 2001, Reynard et al., 2010, Prudhomme et al., 2003, Kay et al., 2006, Kay and Jones, 2012).”[48] “Death rates from such events have declined by 99% since the 1920s.” So mortality rates from hurricanes and tornadoes have decreased since the 1920s until now. Is this because these storms are more “benign” now than they were in the past as the author suggests, or is it because we are now much better at forecasting and preparing for them now than we were 100 years ago (before the invention of computers)? “Even sea-level rise — predicted to be the most damaging impact of global warming — seems to be much less of a problem than thought, according to to the study’s findings.” This is literally the opposite of what a growing body of recent evidence has shown. Research actually shows that rates of global sea level rise have accelerated in recent years[49], and estimates regarding the upper end of plausible further SLR over the coming century have actually increased considerably as the non-linear contribution by continental ice sheets comes into clearer focus[50]. So, if anything, sea level rise is becoming more of a problem than previously thought. “A recent study showed that the Earth has actually gained more land in coastal areas in the last 30 years than it has lost through sea-level rise.” Jennifer Francis Senior Scientist, Woods Hole Research Center: Please provide this peer-reviewed study by a legitimate practicing environmental scientist to support this counterintuitive statement. This statement is false. The Earth has perhaps gained more “sandy beaches” along coastal areas according to the study cited. However, this is primarily due to coastal management, not sea-level rise. In fact, the authors of that study find large beach erosion in protected coastal areas (ie. regions without human intervention)[51]. “Nitrogen fertilisers and carbon dioxide fertilisation have together increased global food production by 111 per cent.” These are cherry-picked and highly misleading. The article cites increasing cereal yields as a reason why climate change is not a problem, but ignores the large evidence base showing that rising temperatures are damaging crop yields and slowing yield growth[11-13]. Moreover, benefits from CO2 fertilization saturate whereas damages from warming accelerate over time[9], meaning extrapolation from the historical record is not meaningful. To claim that nitrogen fertilizers are a benefit of fossil fuels is an extremely tortured logic and misleading in the extreme – synthetic fertilizers have very little to do with the question of how much to reduce energy generation from fossil fuels.

https://science.feedback.org/review/noaa-shows-clear-global-warming-trends-over-the-past-58-years-based-on-radiosonde-data/

Inaccurate

Facebook, Facebook users, 2021-01-29

“The 58 year net gain of global temperature is zero. We are simply in a cyclical, normal ebb and flow of temperature.”

Inaccurate: Clear global warming trends of Earth’s ocean, land, lower and atmosphere have been observed over the past 58 years as well as over longer time periods. Radiosonde data collected from 1958 to 2019 also shows a pattern of warming in the lower atmosphere (troposphere).

Clear global warming trends of Earth’s ocean, land, lower and atmosphere have been observed over the past 58 years as well as over longer time periods. Radiosondes are used to collect upper air measurements from the troposphere and stratosphere. Most data comes from weather services that launch radiosondes at the same time all over the world to generate standardized observations that can be used to evaluate global trends in weather and climate. Radiosonde and satellite data from 1958 to 2019 demonstrate global warming.

NOAA graph doesn’t show a full record of radiosonde temperature data; "the warming that has taken place in the last 37 years was preceded by a 21 year "cooling" period. The 58 year net gain of global temperature is zero. We are simply in a cyclical, normal ebb and flow of temperature."

Review: The claim that there has been no increase in global temperature over the past 58 years was published by numerous users on Facebook in late January and early February 2021 (see example here), receiving thousands of interactions on the platform. This claim is incorrect, as data from NOAA has clearly demonstrated strong global warming trends over the past 58 years, as well as over longer timescales (see figure below)[1-3]. Figure 1—Global temperature anomaly data of Earth’s ocean and land surface relative to the 20th century average temperature from the Global Historical Climatology Network-Monthly data set and International Comprehensive Ocean-Atmosphere Data Set. These data sets show consistent global warming trends. From NOAA. The posts also make the incorrect claim that “we are simply in a cyclical, normal ebb and flow of temperature”. As stated in the IPCC 2014 report, “Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia.”[1] The Fourth National Climate Assessment also states, “Global annually averaged surface air temperature has increased by about 1.8°F (1.0°C) over the last 115 years (1901–2016). This period is now the warmest in the history of modern civilization. The last few years have also seen record-breaking, climate-related weather extremes, and the last three years have been the warmest years on record for the globe.”[2] The posts imply that NOAA is hiding radiosonde data because they released a graph from the past 37 years even though they had 58 years of data. However, the posts don’t show the graph or provide any references to support this claim. Although it is unclear from the posts, this claim may have originated from a 2016 blog post that claimed, “NOAA Radiosonde Data Shows No Warming For 58 Years”. This claim is false, as radiosonde data from 1958 to 2019 show a clear trend of global warming[4]. A radiosonde is a small instrument suspended from a large balloon that transmits data on pressure, temperature, and relative humidity. NOAA uses radiosondes to assess long-term temperature trends in some regions of the Earth’s atmosphere, including the troposphere and lower-stratosphere. Radiosonde data from 1958 to 2019 shows that the global warming rate of the troposphere is 0.18°C per decade[4]. These warming trends are also evident from satellite data (see figure below)[4,5]. Figure 2—Global annual temperature anomalies for the lower troposphere from radiosondes (top) and satellites (bottom) from 1958 to 2019. Adapted from Ades et al. (2020)[4]. Human-caused greenhouse gas emissions are expected to warm the lower troposphere while cooling the upper layers of the atmosphere[6]. This is because the lower troposphere acts as an insulating blanket that traps and re-emits infra-red radiations near the Earth’s surface. As more greenhouse gases are emitted into the atmosphere, more heat is trapped in the lower troposphere, resulting in a cooling effect in the upper layers of the atmosphere. Scientists’ Feedback: Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: This claim is false. Full time series of radiosonde (balloon-borne) temperature measurements (since 1958) are not new and are frequently depicted in routine climate reports. For example, in the State of the Climate in 2019 Report (on NOAA’s website), Figure 2.7 (in Global Climate, Figure reproduced above as Figure 2) shows the data since 1958 in a NOAA dataset (RATPAC vA2). The rate of warming over both the full period (1958 – 2019) and the satellite era (1979 – 2019) are noted in Table 2.3 (see table below). Both time periods show rapid warming of the Earth’s lower atmosphere (the troposphere). Similar data was shown in the report a decade ago (here)[7]. It is true that global atmospheric and surface warming is not perfectly linear and global temperature was relatively flat over 1958 – 1980. This feature is reproduced by climate models and is driven by human and volcanic emissions of aerosols (which tend to cool the planet). This is demonstrated, for example, in the Fourth National Climate Assessment (see interactive Figure 2.1). Global warming is not a myth and is evident in a wide variety of geophysical measurements of the Earth’s atmosphere, oceans, and cryosphere. “Radiosonde temperature data” are taken by weather balloons and NOAA’s “RATPAC” temperature record, which began in 1958, was published in 2005[8] and is currently on the NOAA website. Since “global warming” usually means near the surface where we live, here are NOAA weather balloon temperatures from the surface up to about 5.5 km (18,000’). Temperatures at the NOAA weather balloon stations have increased by about 1 °C (1.8 °F) since 1958 (see figure below).This Facebook post is misleading to say that NOAA “just released that they have 58 years” of this data, because it has been public for at least 15 years. That data shows about 1 °C (1.8 °F) warming since 1958, so the Facebook post is wrong to say “the 58 year gain of global temperature is zero”. It misleads readers by making up things that aren’t true. Unfortunately, there aren’t many weather-balloon stations and they usually launch from land, missing the ~70 % of Earth’s surface is ocean. Weather balloons are useful, but don’t give the most complete picture of global warming. That comes from weather stations, ships and buoys combined. Here is the 1880—2020 NOAA temperature record that shows the clear warming pattern since 1958 and before. Victor Venema Scientist, University of Bonn, Germany: The claim seems to be about NOAA’s radiosonde temperature dataset RATPAC, which includes data from 1958 to the present. That dataset currently spans 62 years, suggesting that the meme is 4-5 years old. NOAA’s RATPAC homepage gives four publications from 2003 and 2005 that showed data starting in 1958. In this case, the 37-year period would end in 2016, and the 37 years could correspond to a graph comparing radiosondes to the satellite retrievals, which start in 1979. Another reason the author of the claim may have seen data plotted starting in 1979 is that the more recent data is more reliable. The claim does not accurately describe the warming of the Earth. The land warming estimate of NOAA’s Global Historical Climate Network version 4 can be found below[9]. Clearly there was warming over the full period and the variations are not cyclical. The period 1958 to 1979, where the author of the claims that there is as much cooling as there is warming in the latter period is not warming. The reason for this is well understood: a fast increase in air pollution from a rapid expansion of fossil fuel use[10]. The above graph shows the temperature over land at the surface. The claim does not specify which temperature dataset they are referring to. It could describe the upper air temperature at the 850 mbar pressure level of RATCAP shown below[9]. Even at the 200 mbar level there is no warming and at the 50 mbar level the atmosphere is cooling. The warming at the surface and the cooling higher up are one of the predicted signatures of global warming due to an increase in greenhouse gases. Global warming refers to the warming at surface level. The station dataset is a much better way to estimate this. Not only are station observations made with better instruments of a higher quality than the one-use radiosonde data, but we also have many more stations, which gives a better estimate of the average warming, especially in the Southern Hemisphere. The longer period for which we have station data helps see that cycles the claim talks about are not an accurate description of global warming.REFERENCES: 1 – IPCC (2014) Climate Change 2014: Summary: for Policymakers. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. 2 – Wuebbles et al. (2017) Executive summary. In: Climate Science Special Report: Fourth National Climate Assessment, Volume I. 3 – Neukom et al. (2019) No evidence for globally coherent warm and cold periods over the preindustrial Common Era. Nature. 4 – Ades et al. (2020) Global Climate. Bulletin of the American Meteorological Society. 5 – Santer et al. (2017) Tropospheric Warming Over The Past Two Decades. Scientific Reports. 6 – Santer et al. (2013) Human and natural influences on the changing thermal structure of the atmosphere. PNAS. 7 – Blunden et al. (2011) State of the Climate in 2010. Bulletin of the American Meteorological Society. 8 – Free et al. (2005) Radiosonde Atmospheric Temperature Products for Assessing Climate (RATPAC): A new data set of large‐area anomaly time series. Journal of Geophysical Research. 9 – Menne et al. (2018) The Global Historical Climatology Network Monthly Temperature Dataset, Version 4. Journal of Climate. 10 – Haustein et al. (2019) A Limited Role for Unforced Internal Variability in Twentieth-Century Warming. Journal of Climate. UPDATES: 8 February 2021: This post was updated to include comments from Mark Richardson and Victor Venema.

https://science.feedback.org/review/prageru-post-by-william-happer-uses-flawed-reasoning-to-claim-that-climate-models-always-fail/

Incorrect

PragerU, William Happer, 2021-01-24

"climate models that attempt to predict the future temperature of the planet...don’t work. They haven’t worked in the past. They don’t work now."; "the number of factors that influence climate—the sun, the earth’s orbital properties, oceans, clouds, and, yes, industrial man—is huge and enormously variable"; "CO2 is a minor contributor to the warming of the earth"

Incorrect: Climate models can account for a variety of factors that influence Earth’s climate, including land, atmosphere, ice, and human activities. The effects of these factors can vary depending on the climatic pattern being evaluated. For instance, greenhouse gas emissions have a strong effect on global warming, whereas the Sun and the Earth’s orbital properties do not influence the global temperature over the timescales relevant to current warming trends. Climate models don’t need to perfectly capture every parameter to accurately model the average global temperature. State-of-the-art climate models have accurately reproduced past climatic patterns and forecasted future global warming trends. Human caused emissions of CO2 are a significant driver of global warming.

A variety of factors influence Earth’s climate, such as land, atmosphere, and ice, but not all aspects need to be perfectly modeled to produce useful forecasts of global temperature in climate models. State-of-the-art climate models have successfully forecasted global average surface temperatures over the past few decades.

"climate models that attempt to predict the future temperature of the planet...don’t work. They haven’t worked in the past. They don’t work now."; "the number of factors that influence climate—the sun, the earth’s orbital properties, oceans, clouds, and, yes, industrial man—is huge and enormously variable"; "We can’t predict what effect the atmosphere is going to have on future temperatures because we can’t predict cloud formations"; "Compared to water—H20, carbon dioxide—CO2—is a minor contributor to the warming of the earth"

1 – Hausfather et al. (2019) Evaluating the Performance of Past Climate Model Projections. Geophysical Research Letters. 2 – Shakun et al. (2012) Global warming preceded by increasing carbon dioxide concentrations during the last deglaciation. Nature. 3 – Feldman et al. (2015) Observational determination of surface radiative forcing by CO2 from 2000 to 2010. Nature. 4 – Santer et al. (2013) Human and natural influences on the changing thermal structure of the atmosphere. PNAS. 5 – IPCC (2014) Climate Change 2014: Summary: for Policymakers. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. 6 – Hayhoe et al. (2017) Climate models, scenarios, and projections. In: Climate Science Special Report: Fourth National Climate Assessment, Volume I. 7 – Gillet et al. (2021) Constraining human contributions to observed warming since the pre-industrial period. Nature Climate Change. 8 – Held and Soden (2000) Water Vapor Feedback and Global Warming. Annual Review of Energy and the Environment. 9 – Sherwood et al. (2021) An Assessment of Earth’s Climate Sensitivity Using Multiple Lines of Evidence. Review of Geophysics. 10 – Zelinka et al. (2020) Causes of Higher Climate Sensitivity in CMIP6 Models. Geophysical Research Letters. 11 – Chen et al. (2019) Advancements in Hurricane Prediction With NOAA’s Next‐Generation Forecast System. Geophysical Research Letters. 12 – Rappaport et al. (2009) Advances and Challenges at the National Hurricane Center. Weather and Forecasting. 13 – Cangialosi (2019) National Hurricane Center Forecast Verification Report. 14 – Rosenblum and Eisenman (2017) Sea Ice Trends in Climate Models Only Accurate in Runs with Biased Global Warming. Journal of Climate. READ MORE Carbon Brief published an in-depth article about how climate models work. UPDATES: 28 January 2021: This post was updated to clarify two sentences. 1 February 2021: This post was updated to include comments from Timothy Myers.

Review: The claim that climate models don’t work was published by William Happer in a post by PragerU, a group that has published misinformation in the past on a series of topics and boasts more than 4.5 billions views for the content it disseminates. The core claim of the post is that “the climate models that attempt to predict the future temperature of the planet … don’t work” and “over the last 30 years, one climate prediction after another – based on computer models – has been wrong”. However, this claim is contradicted by the fact that climate models have been found to skillfully forecast the evolution of global surface temperatures over the past few decades. In addition, the post doesn’t provide any evidence to support its claims. A 2019 study found that climate models published between 1970 and 2007 “were generally quite accurate in predicting global warming in the years after publication, particularly when accounting for differences between modeled and actual changes in atmospheric CO2 and other climate drivers”[1] (see figures 1, 2 and 3 below). These observations directly contradict the claim in the PragerU post. Read scientists’ comments below for further information. Figure 1 —A comparison of climate projections (black) from a model published in 1988 to observed differences in temperature relative to a 1958-1987 baseline (temperature anomaly). The black lines represent high (A), moderate (B), and low (C) emissions scenarios. From Hausfather et al. (2019)[1]. In support of this claim, Happer’s post provides several arguments. CO2 concentration changes are driving current climate warming, not H2O One argument is that “compared to water (H2O), carbon dioxide (CO2) is a minor contributor to the warming of the earth”. In reality, CO2 is a key driver of the current warming of global temperature due to its direct greenhouse effect (absorbing infra-red radiations) and its indirect effect called the water-vapour feedback. Both CO2 concentrations and water vapour feedback are already taken into account in state-of-the-art climate model simulations. Numerous scientific studies demonstrated that human-caused emissions of CO2 are the key driver of global warming over the past century[2,3,4]. As stated in a 2014 IPCC report, “Anthropogenic greenhouse gas emissions have…led to atmospheric concentrations of carbon dioxide, methane and nitrous oxide that are unprecedented in at least the last 800,000 years. Their effects…are extremely likely to have been the dominant cause of the observed warming since the mid-20th century.”[5] While natural factors, such as water vapor, do affect Earth’s climate, “Human emissions of carbon dioxide (CO2), methane (CH4), and other greenhouse gases now overwhelm the influence of natural drivers on the external forcing of Earth’s climate,” as stated in the 4th National Climate Assessment[6]. As described by Dr. Mark Zelinka below, “CO2 causes warming, and the warmer atmosphere contains more moisture, further enhancing Earth’s greenhouse effect”. The post is incorrect in stating that CO2 is a “minor contributor” to global warming and misleads readers by ignoring the fact that water vapour concentrations do not control variations in temperature but act as a feedback instead. The climate is a complex system, but not all aspects need to be perfectly modeled to produce useful forecasts of global temperature Another argument implies that Earth’s climate is too complex to be accurately modelled: “the number of factors that influence climate—the sun, the earth’s orbital properties, oceans, clouds, and, yes, industrial man—is huge and enormously variable”. While the earth’s orbital properties are important to explain past climate variations over timescales ranging from thousands to hundreds of thousands of years, they do not vary fast enough to have had any influence on the past hundred years of climate change. Dr Michael Wehner explains: “The number of factors influencing the climate is large, but they do not all affect the climate in equal ways. Climate models routinely include solar luminosity variations and orbital properties as external drivers. Human influences including atmospheric composition and land usage changes are similarly included as external drivers.” The post also uses flawed reasoning to conclude that climate models are wrong in general based on cherry-picking one example of a weather model that didn’t accurately capture the path of a single hurricane. In addition to being logically flawed, this argument confuses weather and climate. This is the same issue with the post’s claim that “Trying to figure out what two fluids will do in interaction with each other on a planetary scale over long periods of time is close to impossible”. However, forecasting the evolution of global temperatures does not require to perfectly model the behaviour of every water and air particle. Instead, it requires a proper understanding of forcings (change in solar radiations, greenhouse gases) and internal feedbacks (like the water vapour feedback and others). These feedback modulate the magnitude of the expected warming, but will not lead to a cooling for instance. This is akin to the “impossible expectations” argument, a technique used to deny climate change as explained in the book chapter The Five Types of Climate Change Denial Argument by Haydn Washington. Background on the author of the claim: William Happer is a retired physicist who did not lead scientific research on climate change. He co-founded the political advocacy organization CO2 coalition, and has previously made misleading statements about climate models and the impact of rising CO2. Scientists’ Feedback: The statements quoted below are from the post; comments are from the reviewers (and are lightly edited for clarity). “[Climate models] don’t work”; “the number of factors that influence climate—the sun, the earth’s orbital properties, oceans, clouds, and, yes, industrial man—is huge and enormously variable.” Mark Zelinka Research Scientist, Lawrence Livermore National Laboratory: All of these processes (and many others) are included in models, allowing them to simulate the climate. This assertion is simply wrong. Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: This is not accurate; while models can never be a perfect representation of the Earth’s system, they do an excellent job of reproducing many aspects of the Earth’s climate, from rainfall and wind patterns to storm and hurricane formation and warming of the climate. In a 2019 paper we evaluated the performance of 17 historical climate model projections published between 1970 and 2001[1]. We found that 10 of those 17 projected a rate of future temperate change nearly identical to what actually happened in the real world in the years after they were published, while four of the models projected too much warming and three models too little warming[1]. This is particularly impressive for the 1970s-era models, which were published at a time when evidence of observed global warming was limited (and some even thought – based on limited observations – that the world was modestly cooling). Figure 2—Observed surface temperature change (HadCRUT5 – black line) compared to climate model projections from the years after the model was published (colored lines). Adapted from Hausfather et al. 2019[1]. Walter Hannah Climate Model Developer, Lawrence Livermore National Lab: While modelling the climate system involves dealing with a lot of uncertainty, solar activity and Earth’s orbit do not contribute much uncertainty. Making climate projections often revolves around a set of assumptions about anthropogenic emissions. These are often idealized, like a 1% increase in CO2 per year, but that does not make the results invalid. We can still learn a lot about the response of clouds and ocean circulation from studying these idealized experiments that can inform our response to the changing climate. Michael Wehner Senior Scientist, Lawrence Berkeley National Laboratory: The number of factors influencing the climate is large, but they do not all affect the climate in equal ways. Climate models routinely include solar luminosity variations and orbital properties as external drivers. Human influences including atmospheric composition and land usage changes are similarly included as external drivers. Ocean models are part of coupled climate models such as in the publicly available CMIP global climate models. Clouds are also part of the atmospheric components in these climate models. While clouds are the largest source of uncertainty, they are simulated well enough that this statement has no merit in my opinion. Timothy Myers Postdoctoral Researcher, Lawrence Livermore National Laboratory: The overall claim that “[climate models] don’t work” is illogical, vague, and seems to imply, hyperbolically, that the models have no use whatsoever. Climate models are imperfect representations of nature that represent just one tool scientists use to understand how and why Earth’s climate varies. Climate models are good at simulating some physical processes and deficient in their simulation of other processes. Simply because the climate is complex does not mean we cannot reasonably model or understand it. “Compared to water—H20, carbon dioxide—CO2—is a minor contributor to the warming of the earth.” Mark Zelinka Research Scientist, Lawrence Livermore National Laboratory: This is a well-worn trope that Dr. Happer unfortunately uses to mislead. Water vapor acts as a strong amplifier of warming initiated by CO2. I think of water vapor molecules as soldiers and CO2 as the commander. The commander decides to invade and the soldiers do most of the work. The soldiers do not randomly decide to invade. Similarly, water vapor cannot randomly decide to increase in the atmosphere. Rather, CO2 causes warming, and the warmer atmosphere contains more moisture, further enhancing Earth’s greenhouse effect – a textbook amplifying feedback. Michael Wehner Senior Scientist, Lawrence Berkeley National Laboratory: This statement is incorrect. This misses the point. Increases in CO2 affect the energy balance leading to more atmospheric moisture. Climate models incorporate the radiative properties of both compounds. This statement is incorrect. Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: This is an incredibly misleading – and incorrect – statement. Water vapor is a powerful greenhouse gas, but it’s also one that is temperature limited. Water vapor has a very short lifetime in the atmosphere, so adding more water vapor by itself cannot effectively cause long-term climate warming. CO2, on the other hand, lasts for centuries to millennia in the atmosphere, and accumulates. Our best estimate is that around 100% of observed warming since the late 1800s is attributable to human emissions of CO2 and other greenhouse gases[7]. However, water vapor does have a role in that warming, but as a feedback rather than a forcing[8]. Higher temperatures caused by rising atmospheric CO2 increase the amount of water vapor in the atmosphere by increasing evaporation and by higher air temperatures allowing more water vapor to be present. This additional atmospheric water vapor enhances the warming from CO2 (and other greenhouse gases), but would not be in the atmosphere without their warming effects[8]. Walter Hannah Climate Model Developer, Lawrence Livermore National Lab: Water is more abundant and a more powerful greenhouse gas. However, the residence time of water vapor in the atmosphere is very short compared to CO2, and the spatial distribution of water is much less homogenous than atmospheric CO2. If humans were to emit a lot of water instead of CO2 it would be rained out rather quickly. With large and constant water vapor emissions we probably would see a change in the localized climate. None of this contradicts the fact that CO2 can also have an impact on the climate. Our CO2 emissions will elevate the atmospheric concentration for hundreds of years and contribute a small, but persistent, downward radiative flux over the whole planet. That small contribution is enough to be concerned about even if you can find other things that make it seem “too small”. Timothy Myers Postdoctoral Researcher, Lawrence Livermore National Laboratory: This is misleading and excessively vague. Water vapor is the primary and most abundant greenhouse gas in the atmosphere, and water in its liquid form in the oceans has an enormous capacity to retain and redistribute heat. Without water vapor, the planet would be much colder. But the increase of CO2 and other greenhouse gases due to human activity is the primary reason why the planet has warmed since the middle of the 20th century. “We can’t predict what effect the atmosphere is going to have on future temperatures because we can’t predict cloud formations.” Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: Clouds are one of the big areas of uncertainty in projecting future climate change, as they form on scales too small to directly simulate in climate models. Uncertainties in how clouds will change in a warming world is one of the main reasons why we are uncertain if doubling CO2 concentrations will warm the world by 2C or as much as 4.5C at equilibrium. However, suggesting that these cloud uncertainties mean that we can’t predict future changes is quite misleading. As discussed earlier, it’s clear that our climate models have performed quite skillfully in predicting the changes we’ve actually seen in the real world after they were published. A somewhat cloudy crystal ball is, after all, much better than no crystal ball at all. Walter Hannah Climate Model Developer, Lawrence Livermore National Lab: The biggest source of error in climate projections is how certain cloud types will react. This is a very active area of research right now, and probably will be for the next decade. However, I do not know of any credible climate scientist that feels that clouds could reverse the warming trend we expect from CO2. It’s possible that clouds will make the climate less sensitive than we thought, but that should not alleviate our concerns about the impact of global warming. For example, even a strong negative cloud feedback will not remedy the problem of ocean acidification from CO2, which is likely to be a very serious problem in the future. Mark Zelinka Research Scientist, Lawrence Livermore National Laboratory: Dr. Happer has correctly identified a key uncertainty in models’ predictions of future temperature – how clouds will respond to warming. This is a big reason why the scientific community tries to constrain models’ predictions using observations of how clouds respond to warming. We do not blindly accept model results as truth – we constantly evaluate them against observations, allowing us to hone our estimates of future warming. That said, we do not know *nothing* about future temperature — instead we have a range of plausible outcomes, all of which suggest a warmer future. Michael Wehner Senior Scientist, Lawrence Berkeley National Laboratory: Recent state of the art cloud system resolving models do very well in simulating intense storms and the cloud formations associated with them. Timothy Myers Postdoctoral Researcher, Lawrence Livermore National Laboratory: This is false. We know that Earth’s temperature will continue to rise as greenhouse gas emissions increase unabated. The most advanced, state-of-the-art predictions of the sensitivity of Earth’s climate to increasing carbon dioxide are based on multiple lines of evidence: observations, the paleoclimate record, theory, and models of varying complexity[9]. Based on this evidence, climate scientists estimate a likely range of the planetary warming resulting from a doubling of atmospheric carbon dioxide: 2.6-3.9 C (or 4.7-7 F). Climate models produce a wider range of the severity of planetary warming in response to increasing carbon dioxide[10]. This is primarily because their simulation of cloud processes is highly variable, with some models performing better or worse than others. However, a variety of independent evidence taken together reveals how clouds throughout the planet will likely behave as the climate warms, allowing scientists to predict future temperature changes with more precision than climate models simulate[9]. “A major aspect of climate involves the complicated interaction between two very turbulent fluids: the atmosphere, which holds large amounts of water (think rain and snow), and the oceans, which cover fully 70% of the earth’s surface…We can’t predict either side of the atmosphere/ocean equation.” Walter Hannah Climate Model Developer, Lawrence Livermore National Lab: We can (and we do) predict both of these systems reasonably well. Coupled models often produce strong regional errors, but this does not invalidate the basic conclusion about the concerning amount of warming we expect from elevated CO2. Michael Wehner Senior Scientist, Lawrence Berkeley National Laboratory: This statement is misleading. Climate science is a statistical one and we can simulate the statistical behavior of the relevant aspects of the climate quite well. In fact, simulations of future climate made in the 1990s have been shown to predict the present day warming very well. Furthermore, climate models are extensively independently evaluated by analysts not involved in model development. Clearly some aspects of climate model simulations can be improved, but the global energy budget is well simulated by nearly all models. Timothy Myers Postdoctoral Researcher, Lawrence Livermore National Laboratory: This is false. Many aspects of both the atmosphere and ocean are predictable, though the degree of predictability varies depending on the process in question. A recent study finds that “climate models published over the past five decades were generally quite accurate in predicting global warming in the years after publication”[1]. If models can’t predict the path of a hurricane, they can’t predict climate over the last 30 years, “one climate prediction after another – based on computer models – has been wrong.” Mark Zelinka Research Scientist, Lawrence Livermore National Laboratory: This is another well-worn trope. Dr. Happer has unfortunately confused weather and climate in this statement. The accuracy of weather forecasts – and in particular extreme events like hurricanes – can be degraded by poor data about the current state of the atmosphere that gets fed into the models. These issues are very different from those that affect climate model predictions – namely, how clouds and humans will respond in the future. Secondly, the nature of weather forecasts (“what is the probability of rain in my city tomorrow afternoon?”) are very different from climate projections (“how much warmer on average will the 2050s be in California?”). It is also worth mentioning that hurricane track forecasting is becoming extremely skillful, in contrast to Dr. Happer’s assertion. Cherry picking a bad hurricane track forecast to throw shade on climate model projections is like claiming Tom Brady isn’t going to the Hall of Fame because he burned his breakfast yesterday. Michael Wehner Senior Scientist, Lawrence Berkeley National Laboratory: I think that the National Hurricane Center would beg to differ. Hurricane track forecasting has improved dramatically over the past few decades and has led to substantially reduced fatalities[11,12]. The statement is a (false) assertion, without any evidence. Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: Modern weather models – which share many parts of their code with our long-term climate models – are actually quite good at predicting hurricane tracks[13]. Moreover, the fact that our prior model projections have proven quite accurate at estimating how much warming actually occurred gives us confidence that our models – while imperfect – are accurate enough to get a good sense of how much warming to expect in the future if we keep emitting CO2 and other greenhouse gases. Figure 3—Historical temperatures (colored lines) and the last generation of climate models (black line shows the model average, with the grey shaded area representing the range across all the models). From: https://www.carbonbrief.org/state-of-the-climate-2020-ties-as-warmest-year-on-record Walter Hannah Climate Model Developer, Lawrence Livermore National Lab: Let’s think about this idea that “computer models are always wrong”. Computer models do amazingly well at a lot of things, but it is also very easy to find little things that they do not do well at. It is not fair to judge all weather and climate models based on only the things they do wrong. One model might not rain enough in one area of the globe, but even if it gets it mostly correct everywhere else people will criticize the model for being “wrong”, which is completely unfair. Hurricane forecasts are another good example where they can be right most of the time, only to then be harshly judged when they get the hurricane track wrong. We care about these small errors because they can potentially mean an unexpected loss of life or property, but to use blanket statements about all computer models being wrong is simply dishonest or naïve. Timothy Myers Postdoctoral Researcher, Lawrence Livermore National Laboratory: This is an illogical statement and misleading. The author is conflating weather forecasting of a hurricane with long-term climate prediction, and more fundamentally, he is conflating weather with climate. As the American Meteorological Society states, climate is defined as “The slowly varying aspects of the atmosphere–hydrosphere–land surface system. As distinguished from climate, weather consists of the short-term (minutes to days) variations in the atmosphere.” Simply because some weather forecasts are inaccurate does not imply that changes in climate are unpredictable. Climate model projections are not intended to forecast changes in the atmosphere as precisely as the particular path of a single hurricane. Some of the main elements of the climate that models are used to predict are changes in large-scale patterns of temperature, humidity, precipitation, and wind. It’s false to say that “Over the last 30 years, one climate prediction after another — based on computer models — has been wrong”. Models accurately predict some climate changes and imprecisely predict others, with some overpredictions and some underpredictions. For example, a recent study finds that “climate models published over the past five decades were generally quite accurate in predicting global warming in the years after publication”[1]. To take another example, climate models tend to underestimate the rapid Arctic sea ice decline observed in recent decades[14].

https://science.feedback.org/review/video-interview-of-ian-plimer-at-sky-news-falsely-claims-that-a-new-study-announces-an-incoming-ice-age-partly-based-on-an-incorrect-daily-mail-headline/

-2

Sky News Australia, Daily Mail, by Ian Plimer, on 2021-01-13.

"“Earth's climate is 'cyclical' as new study claims an ice age is coming”"

1 – Starr et al. (2021) Antarctic icebergs reorganize ocean circulation during Pleistocene glacials. Nature. 2 – Keeling (1979). The Suess effect: 13Carbon-14Carbon interrelations. Environment International. 3 – Eide et al. (2017). A global estimate of the full oceanic 13C Suess effect since the preindustrial. Global Biogeochemical Cycles. 4 – Meehl et al. (2020). Context for interpreting equilibrium climate sensitivity and transient climate response from the CMIP6 Earth system models. Science Advances. 5 – Shakun et al. (2012). Global warming preceded by increasing carbon dioxide concentrations during the last deglaciation. Nature. 6 – (2011) Climate past and future. Nature Geosciences. 7 – Feldman et al. (2015). Observational determination of surface radiative forcing by CO2 from 2000 to 2010. Nature. 8 – IPCC (2014) Climate Change 2014: Summary: for Policymakers. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. 9 – Caeser et al. Observed fingerprint of a weakening Atlantic Ocean overturning circulation. Nature. 10 – Peterson et al. (2008) The myth of the 1970s global cooling scientific consensus. Bulletin of the American Meteorological Society. 11 – Keigwin et al. (2018) Deglacial floods in the Beaufort Sea preceded Younger Dryas cooling. Nature Geoscience. 12 – Broecker et al. (2010) Putting the Younger Dryas cold event into context. Quaternary Science Reviews. 13 – Huybers et al. (2006) Links between annual, Milankovitch and continuum temperature variability. Nature. 14 – Markonis et al. (2013) Climatic Variability Over Time Scales Spanning Nine Orders of Magnitude: Connecting Milankovitch Cycles with Hurst–Kolmogorov Dynamics. Surveys in Geophysics. 15 – Sigman et al. (2000) Glacial/interglacial variations in atmospheric carbon dioxide. Nature. 16 – Archer et al. (2005). A movable trigger: Fossil fuel CO2 and the onset of the next glaciation. Geochemistry, Geophysics, Geosystems. 17 – Tzedakis et al. (2012). Determining the natural length of the current interglacial. Nature Geoscience. 18 – Bader et al. (2020). Global temperature modes shed light on the Holocene temperature conundrum. Nature Communications. 19 – Kaufman et al. (2020). Holocene global mean surface temperature, a multi-method reconstruction approach. Scientific Data. 20 – Ganopolski et al. (2016). Critical insolation–CO 2 relation for diagnosing past and future glacial inception. Nature. 21 – Lisiecki et al. (2005). A Pliocene‐Pleistocene stack of 57 globally distributed benthic δ18O records. Paleoceanography. 22 – Petit et al. (1999). Climate and atmospheric history of the past 420,000 years from the Vostok ice core, Antarctica. Nature. 23 – Hönisch et al. (2009). Atmospheric carbon dioxide concentration across the mid-Pleistocene transition. Science. 24 – Cui et al. (2020). A 23 m.y. record of low atmospheric CO2. Geology. 25 – Rubino et al. (2013) A revised 1000 year atmospheric δ13C‐CO2 record from Law Dome and South Pole, Antarctica. Journal of Geophysical Research: Atmospheres.

Reviewers’ Overall Feedback: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Twila Moon Research Scientist, University of Colorado, Boulder: This video is chock full of false and misleading information, and presented in a way to make the correct scientific information seem like a farce. For example, the direct link between human emissions of carbon dioxide and global warming is very well established[8]. The physics and chemistry of this link has been understood for well over 100 years, and science continues to affirm it. In another example, projections of the Earth’s future temperature – created through the efforts of thousands of scientists across the globe – show that the planet will continue to warm under all scenarios of continued emissions of heat-trapping gases. There will NOT be a sudden natural cooling over the coming centuries. Humans are warming the planet, and human actions will continue to be the primary control on future temperature trends for the Earth. Peter Neff Assistant Research Professor, University of Minnesota: This fawning, biased interview with Sky’s favorite denier missed the point of the new paper about Antarctic iceberg and freshwater forcing on ocean circulation[1]. If they’d only read the Daily Mail article about this work, they’d see this statement: “Over the past three million years the Earth has regularly plunged into ice age conditions, but at present is currently situated within an interglacial period where temperatures are warmer. However, it may not happen again in the same way, due to the impact of human-created CO2 emissions warming the world.” For Plimer to think that human activities don’t affect planetary energy balance means he possesses arrogance that far eclipses his understanding of Earth’s climate system. Alexis Berg Research Associate, Harvard University: The starting point of the segment is an article in the Daily Mail, which mistakenly claims scientists are now warning of an incoming ice age, in a new study[1]. The study in question does no such thing, of course (which is actually clear if you read, not even the study, but the Daily Mail article itself), but the host and his guest, Ian Plimer, are not ones to care for such details and are all too happy to seize on this misleading, sensationalist headline to then deliver the usual mix of cherry-picked, out-of-context, and flatly wrong elements that have been addressed many times before, such as “climate has varied before”, “not unprecedented”, and “it’s the sun”. Willem Huiskamp Postdoctoral research fellow, Potsdam Institute for Climate Impact Research: In this video Cory Bernardi and well known climate science denier Ian Plimer deliberately misrepresent the findings of a recent article published by Starr et al. in Nature[1]. They imply that the mechanism proposed in the paper, ie., a reorganisation of the Atlantic Overturning cell due to changes in Antarctic iceberg-derived freshwater fluxes during glacial periods can somehow be applied to the present day and as a result, that a glacial period is imminent. This is patently absurd – the described mechanism is one feedback in a series that are required for a glacial inception and cannot simply be applied in isolation to the present day climate in which we have dramatically increased concentrations of atmospheric CO2, a potent greenhouse gas. Ian Plimer of course ignores this – claiming that climate is cyclical and that no one has ever proven anthropogenic CO2 to have driven global warming. Both claims have been extensively debunked here at Climate Feedback on previous occasions (see reviews here, here, and here), but to offer a brief refutation of the first point: The Earth’s climate is indeed cyclical over time-periods of multiple millennia and are driven primarily by the Earth’s orbital cycles. It is true that we are currently in a warm interglacial period and that up until the late 19th and early 20th Centuries, the world was gradually cooling again (see this figure by Ed Hawkins). However, the magnitude of greenhouse gases we have emitted into the atmosphere and the rate at which we have done so has been sufficient to overpower this natural cycle and warm the Earth considerably. Even with a slow down (which we have observed and even expect in a warming world)[9], or even shutdown of the Atlantic overturning circulation, this warming will continue as long as concentrations of greenhouse gases increase. Dan Jones Physical Oceanographer, British Antarctic Survey: This video features a large number of incorrect statements. Many of these statements are myths that have been debunked again and again. In the video, Plimer and the anchor suggest that climate scientists in the 1970s predicted an ice age. This is not an accurate summary of scientific thinking in the 1970s. Peterson et al. (2008) showed that global warming was a prominent hypothesis in that decade[10]. They claim that “We are getting towards the end of a warm period. The peak of the warmth was about 5,000 years ago and we are heading to the next inevitable ice age.” There is no evidence for this claim. Plimer is essentially stating, without evidence, that the climate system will continue operating just as it has for hundreds of thousands of years. This statement ignores the fact that the climate system changes that we have already observed have the fingerprints of human activity all over it (e.g., the stratosphere is cooling, which is a characteristic pattern of global warming). You cannot explain recent warming since the 1850s without including human-driven carbon dioxide emissions. They claim, “No one has ever shown that human emissions of carbon dioxide drive global warming.” This is a misleading statement that ignores the entire history of climate science. We have known since the time of the US Civil War (the UK Victorian Era) that carbon dioxide acts as a greenhouse gas. If more carbon dioxide is added to the atmosphere, then more energy will arrive at Earth’s surface. Adding energy to the climate system will change it; that extra energy does not simply vanish. Notably, we cannot explain warming since the 1970s using natural factors alone; we have to consider anthropogenic greenhouse gas emissions to explain this decadal scale warming. Ian Plimer has strong connections to the Australian mining industry, which has a personal stake in preserving our current fossil-fuel heavy energy system. This was not disclosed during the interview, as Plimer was simply presented as a geologist. In the interview, Plimer suggests that the Australian Bureau of Meteorology is only using relatively short records of the past few decades to understand climate change. This statement ignores how climate science operates. The scientists working at the bureau will also be familiar with the literature on long-term climate change; it is disingenuous to suggest that they somehow don’t have access to or an understanding of the data and literature on long-term climate cycles. Plimer goes on an irrelevant rant about the education system, suggesting that anyone who disagrees with him is somehow poorly educated. This is an example of the “No true Scotsman” logical fallacy and is incorrect reasoning. David Battisti Professor of Atmospheric Sciences, University of Washington: It is old news (50+ years) that glacial cycles are due to changes in insolation (not CO2) that are due to variations in the orbit of the Earth around the Sun, and that these glacial cycles have time scales of 40,000 -100,000 years. Many of the statements in this video make it clear that the commentator (Plimer) does not understand the scientific article, which relates to a potential feedback that may operate in glacial cycles. But the main thrust of the comments made in the interview concern whether changes in CO2 impact climate, whether humans are responsible for the increases in CO2, and the impacts of the increased CO2 on climate. The reviewer asks for 5 papers that show these links. I will simply note that the all 5 IPCC Assessment reports document the overwhelming evidence (thousands of peer reviewed papers) that: (i) CO2 is increasing due to burning of fossil fuels, that (ii) the warming of the planet seen since 1850 is much greater than can be explained by solar forcing, but it is entirely consistent with the warming expected due to the observed increase in CO2 and changes in atmospheric aerosols (also due to human activity). Michael Lockwood Professor of Space Environment Physics, University of Reading: The idea of an ice age being triggered by global warming appears to be an extrapolation of what happened at the end of the last ice age in an interval called the Younger Dryas. As the world emerged from the last ice age it was pitched back into this further cold interval (named after a flower that thrived in the cold throughout Europe at the time). There have been a number of theories of its origin, of which some are now generally discounted, such as a comet impact. It is known that as the world warmed, a huge meltwater lake (Lake Agassiz) formed on the north American continent, the remnants of which today are the Great Lakes. A disruption of the Atlantic MOC (i.e. the Gulf stream) by the escaping cold, salt-free meltwater may have caused a temporary reverse in the global warming and a temporary return to ice age conditions[11]. Whatever the mechanism, it is thought such an event is likely to have been an inevitable consequence of the end of the glaciation[13]. As an analogy and predictor for what might happen because of present global warming, it is of no relevance whatsoever: the global warming involved in causing the Younger Dryas was that at the end of an ice age – the ice sheets that melted were vast and reached down to temperate latitudes (in the UK it reached Oxford!). The video invokes solar changes as a cause of ice ages. This is wrong. They are intimately connected by changes in Earth’s orbit around the Sun – the so called “Milankovich cycles”[13,14]. These are indeed cycles and it is certainly true that Earth will return to another ice age. It is also true that another ice age is “due” in the sense that the present interglacial (warm period), the holocene, has been unusually long. The quip about it happening on a Tuesday hides the central fallacy here. The Milankovich cycles are extremely long and what is “due” on their timescales is far, far into the future even on the timescale of anthropogenic global climate change which has been centuries (but is now rapidly turning to decades). The video says carbon dioxide rose at the start of ice ages. This is not true. We know well how the abundances of all atmospheric gases, including CO2, changed during ice ages from analysis of air bubbles in ice sheets and dating when that ice formed[15]. Carbon dioxide fell during the ice ages – not because it had any causative role in forming the ice age (as explained, above they are caused by changes in Earth’s orbital characteristics), rather, because colder water can store more carbon dioxide and because much carbon dioxide became locked into the ice and no longer took part in the carbon cycle exchanges between the atmosphere and the oceans and biosphere. We know this was a response and not a cause because the CO2 changes lag, not precede, the temperature changes. Lastly, asking for 5 papers that show that anthropogenic carbon dioxide is causing global warming reveals a complete failure of understanding of the science – indeed of science in general. It is like asking for 5 papers that prove that a pain in your stomach, head or chest is due to cells on your body in which the cell division (which is part of the normal replacement and replication procedure in growth and repair) has gone into overdrive: in other words, what we refer to in a shorthand as a cancer. Our knowledge of cancer and its causes does not rest on 5 papers, nor can it be summed up in 5 papers. It rests on thousands and thousands of papers which cancer experts knit together into a coherent understanding. It is exactly the same with climate change science. Annotations: The statements quoted below are from the article; comments are from the reviewers (and are lightly edited for clarity). “Cardiff University has released a study on the ice ages, It claims that icebergs melting in the Antarctic may actually trigger a reaction that plunges Earth into an ice age.” Ian Hall Professor, Cardiff University: This statement ignores the key finding from our study – we find that the climate systems response to Antarctic icebergs is highly sensitive to where they melt. We specifically describe the sequence of events which occurred during past interglacial to glacial conditions over the last 1.5 million years. Alexis Berg Research Associate, Harvard University: The authors of the study did not say that – as the Daily Mail notes itself. Paleoclimate scientists understand that the cyclical ice ages of the last million years or so are linked to small, cyclical changes in the Earth’s orbit, but the exact mechanistic details are not fully understood: the new Nature paper that the Daily Mail reports on, suggests a role for changes in the spatial patterns of iceberg melt in the inception of past ice ages. It doesn’t say current melt is going to trigger a new ice age: as the Daily Mail itself writes, “The impact of human-created CO2 emissions could make the Southern Ocean too warm for Antarctic icebergs to reach, bringing an end to this 1.6 million year cycle of ice ages starting with melting icebergs, study authors warned.” So, kind of the opposite actually. So the article headline is plain wrong, and so is the premise of the Sky News segment. “But I thought alarmists were telling us that our approach to climate was leading us into believing that we’re the direct cause of global warming and we’re all going to boil and now we’re saying the ice age is coming again.” Ian Hall Professor, Cardiff University: Our paper is unambiguous and not relevant for modern/future climate change in this way, and reporting it as so is fundamentally misinterpreting our findings. In fact, in the press release for the study, we emphasise that our findings are specifically related to natural “Milankovitch” cycles in orbital forcing, however with current human greenhouse-gas emissions and increasing global temperatures, the Southern Ocean is likely too warm for icebergs to be transported as described in the paper and melt in the regions necessary for the chain of events we highlight to be triggered. Our study does not say or imply that an ice age is coming. It does emphasise the importance of understanding iceberg trajectories and melt patterns in developing the most robust predictions of their future impact on ocean circulation and climate. “What’s going on is cycles – we’re getting towards the end of a warm period, the peak of the warmth was about 5000 years ago, and we are heading for the next inevitable ice age.” Ian Hall Professor, Cardiff University: “What’s going on is cycles” is at least a reference to our paper. However, the paper does not deal with modern (post-industrial) climate timescales. The statement by Ian Plimer is not supported by the majority of scientific evidence regarding the duration of the ‘present interglacial’. Plimer here is lacking an understanding of the concept of thresholds. It is well established that the onset of a glacial period has only ever, and can only ever, occur when atmospheric CO2 is below a certain threshold. When atmospheric CO2 concentration is too high, the orbital forcing which favours an ice age is simply not enough to cause an ice age. For example, a study by Archer and Ganapolski (2005) found that no glacial inception will occur with atmospheric CO2 concentrations above 400 ppm[16]. Tzedakis et al. (2012) go on to show that under the current orbital configuration, a CO2 concentration of below pre-industrial levels would be required for an ice age to begin[17]. Hypothetically, if atmospheric CO2 was lower than around 240 ppm, we might have seen the inception of an ice age develop at some point over the coming several millennia. However, as we approach atmospheric CO2 concentrations of double this, caused by human greenhouse-gas emissions, the scientific consensus is clear: we are not currently heading for an ice age. Regarding the “5000 year cooling trend” alluded to by Plimer, it is important to recognise that this is still an active area of research. Whether the Holocene was characterised by a long-term cooling or warming trend is a more complex question than this comment suggests. It is in fact likely that different temperature trends prevailed over different regions[18]. Whilst Holocene climate variability is an interesting exercise in our understanding of the climate system, it is important to remember that regardless of whether there was a long-term cooling or warming trend over the Holocene, the warming we have experienced since the industrial era is unprecedented in its rate – this is not part of some long-term trend, it is very clearly an anthropogenic perturbation of the climate system. Alexis Berg Research Associate, Harvard University: It’s true that we are in an interglacial period, the Holocene, which, prior to the abrupt warming of the past century, had been warmest around 6000 years ago, as far as paleo-climate scientists can reconstruct. However, owing to recent man-made warming, there’s every indication that current temperatures are now on par with the warmest temperatures of even that period[19], and they will continue to increase because of greenhouse gas emissions, to a level (for instance, +3 degrees compared to pre-industrial temperatures) probably not seen in the last couple million years. So we are not headed into an ice age any time soon. In fact, a study in Nature showed that, even without man-made CO2 emissions and warming, the next orbitally-driven ice age would probably not have happened before another 50,000 years (which is a bit unusually long)[20]; and given current man-made warming, now it won’t happen for another 100,000 years[19,20]. “We’ve had 6 major ice ages, during which we’ve had glaciations and warmer periods – all of that happened before humans were on planet earth.” Ian Hall Professor, Cardiff University: It is not clear where Plimer got the number 6 from here. Using a conservative definition of an ice age, there have been at least 10 in the last 1 million years, with over 50 since the development of a substantial northern hemisphere ice sheet[21]. Peter Neff Assistant Research Professor, University of Minnesota: Causes of past climate fluctuations are relatively well understood, paced by slight changes in Earth’s orbit around the sun (Milankovitch cycles). That human emissions of greenhouse gases are currently trapping heat and warming the planet is accepted fact. Our activities now exert more control on Earth’s climate than orbital variations, and will override any coming ice age based on orbitally-induced decreases in the amount of incoming solar radiation. “Every single major ice age started when we had more CO2 in the atmosphere than now.” Ian Hall Professor, Cardiff University: Again, it is not clear where this claim comes from, it is simply not supported by any existing records of atmospheric CO2 over the Pleistocene[22,23]. The highest CO2 concentration recorded in ice core records (0 – 800 thousand years ago) is around 300 ppm[22]; the highest Pleistocene CO2 reconstructed using geochemical proxies (boron isotopes) is similar, around 300ppm[23]. Indeed, over the past 23 million years, CO2 has never reached atmospheric concentrations as high as today, maxing out at around 350 ppm during the mid-Miocene[24]. “No-one has ever shown that human emissions of carbon dioxide drive global warming. If you think it has been shown, please give me the 5 scientific papers that show this.” Ian Hall Professor, Cardiff University: Among the vast scientific literature on this topic, the following 5 papers are a good starting point: How do we know that the increased atmospheric CO2 concentrations are from humans burning fossil fuels? The Suess effect[2,3]. How do we know that this CO2 drives global warming? Our understanding of the physics of radiative forcing date back at least to the work of Svente Arrhenius (1859 – 1927). This is not a contentious topic in the modelling of Earth’s climate system. From the simple to the sophisticated, our models of the climate system are unequivocal[4], as are the geological data[5,6]. Alexis Berg Research Associate, Harvard University: This rhetorical and, frankly, absurd point by Ian Plimer (and others) has been addressed before in other reviews. Yes, there is no one silver bullet argument, but multiple lines of evidence. In a way it’s a akin to a murder trial: sure, there is no one videotape absolutely “proving” that CO2 killed the victim, but we know CO2 was there, had the means and the motive (it’s a greenhouse gas), there’s even partial eye witness account (showing the increase in greenhouse effect in observations)[7], there is DNA evidence (~climate modeling shows CO2 explains the warming well) and all the other possible suspects (sun, volcanoes, etc) have solid alibis. So the case has been solved for a while now[7]. Peter Neff Assistant Research Professor, University of Minnesota: This is an easily verified falsehood. Plimer should be aware of work by Australian colleagues at the Commonwealth Science and Industrial and Research Organization (CSIRO) that shows how carbon dioxide emissions have rapidly increased in the last 150 years, using Antarctic ice and bubbles of old air trapped inside (locked in as snowflakes trap air between their fingers and are buried). The Law Dome research site in Antarctica is a keystone in our understanding of the atmospheric carbon budget going back the last 2000 years. I was a leader of the most recent scientific expedition to this important location, and can verify that the work of Plimer’s fellow Australian’s at this site is world class (see here). Not only is a ~40% increase in carbon dioxide observed in the last 150 years, but the stable isotope of carbon, 13-C has declined over that period. That definitively indicates that the carbon dioxide being emitted comes from a source depleted in 13-C, which provides clear evidence for attribution of industrial period carbon dioxide variations to human activity (fossil fuel hydrocarbons are depleted in 13-C). See figure 6 of Rubino et al., 2013 below[25]. “People have very little outdoor experience…We have a city-based population that doesn’t read the scientific literature, that has had no life experience.” Peter Neff Assistant Research Professor, University of Minnesota: Plimer goes on to make absurd arguments based on common cultural tropes and lines of division, suggesting that those living in cities and having “very little outdoor experience.” This has nothing to do with one’s understanding and experience of climate and has no relevance to the science of climate change and the unprecedented warmth that Australia’s Bureau of Meteorology reports year after year. Given our understanding of the factors at play, it is clear that human emissions of greenhouse gases is trapping excess heat in the atmosphere, causing warming that is particularly impacting Australia by way of extreme drought and severe fires. Australia’s temperature has been rapidly rising since this new anthropogenic warming emerged in the last ~century. The climate of the deep past is immaterial here, as this time is not analogous to the working of Earth’s climate system today, as any geologist would know if they were properly educated at a modern, degree-granting institution of higher education. From the Australian Government Bureau of Meteorology.“Most of [the cycles in climate] are driven by… the sun.” Peter Neff Assistant Research Professor, University of Minnesota: This is again, easily disproven. Solar variability does not exert warming that matches observed temperature increases. See US National Climate Assessment 4, Figure 2.1 below.

https://science.feedback.org/review/rates-of-global-sea-level-rise-have-accelerated-since-1900-contrary-to-bloggers-claims/

Inaccurate

NoTricksZone, Watts Up With That?, Kenneth Richard, Pierre L. Gosselin, 2021-01-11

“there has not been a long-term distinctive change in sea level rise rates in the last 120 years”

Factually inaccurate: Global sea level has risen at an increased pace since industrialization, with the fastest rates of sea level rise occurring in the late 20th century. Cherry-picking: The article only reports average rates of global sea level rise from two time periods and two studies, while ignoring all the other available data demonstrating that rates of sea level rise have accelerated since the 1990s.

The rate of global sea level rise has changed over the past 120 years and accelerated since the early 1990s, based on tide gauge and satellite data. Current sea level rise primarily results from glacial ice melting and the expansion of seawater as it warms due to human-caused global warming.

“A new analysis of global sea level rise rates concludes the rising trend was 1.56 mm/yr−¹ from 1900-2018. This is the same rate as for 1958-2014 (1.5 mm/yr−¹), indicating there has not been a long-term distinctive change in sea level rise rates in the last 120 years. Neither of these trends would appear to correlate well with the linearly accelerated rise in CO2 emissions since the 1940s.”

1 – Frederikse et al. (2018) A Consistent Sea-Level Reconstruction and Its Budget on Basin and Global Scales over 1958–2014. Journal of Climate. 2 – Frederikse et al. (2020) The causes of sea-level rise since 1900. Nature. 3 – Dangendorf et al. (2019) Persistent acceleration in global sea-level rise since the 1960s. Nature Climate Change. 4 – Horton et al. (2018) Mapping Sea-Level Change in Time, Space, and Probability. Annual Review of Environment and Resources. 5 – Slangen et al. (2016) Anthropogenic forcing dominates global mean sea-level rise since 1970. Nature Climate Change 6 – Church and White (2011). Sea-Level Rise from the Late 19th to the Early 21st Century. Surveys in Geophysics.

Review: The claim that rates of sea level rise haven’t significantly changed in the past 120 years appeared in blog posts published by NoTricksZone and ‘Watts Up With That?’ in January 2021. Contrary to the claim, scientific studies show that rates of global sea level rise have changed over time and accelerated, notably since the 1990s, primarily due to glacial ice melting and the expansion of seawater as it warms[1-4]. To evaluate how the rate of sea level rise has changed over time, scientists evaluate long-term trends in mean sea level, primarily based on data from tide gauges and satellites. They can then use these observations to calculate whether this rate has increased, decreased, or remained the same over time. These studies consistently show a distinct pattern of accelerated rates of global mean sea level (GMSL) rise since the 1990s (see figure 1)[2,3]. Figure 1—Global mean sea level (GMSL) trend in mm per year from 1900 to 2015, based on data from tide gauges and satellites. From Dangendorf et al. (2019)[3]. Instead of evaluating all available scientific studies exploring rates of global sea level rise, the bloggers only present data from two time periods and two papers, ignoring everything else and drawing a misleading conclusion. Furthermore, the bloggers do not calculate the rate of acceleration in GMSL. Doing so would indicate that GMSL has accelerated at a rate of about 0.012 mm yr-2 from 1900 to 2018, as Frederikse, the author of the study on which the bloggers rely, describes below. Therefore, the bloggers’ claims are inaccurate and based on cherry-picked data. While the overall rate of GMSL has accelerated since 1900, the rate of change also varies over time. Specifically, there were higher rates of sea level rise during the 1940s and since the 1990s and lower rates of sea level rise in the 1920s and 1970s(see figure 1)[2,3]. One study demonstrates that the rate of GMSL has accelerated over the past two decades, estimating that from 1993 to 2018 GMSL rose 3.35 mm per year, more than double the average rate from 1900-2018[2]. These estimates of accelerated rates of sea level rise are supported by additional scientific studies. For instance, Dangendorf et al. (2019) describes, “the pace of GMSL has been accelerating since 1993, which is consistent with independent estimates of increasing mass contributions from Greenland and Antarctica over the last two decades.”[3] An analysis from 14 studies that estimates rates of GMSL using satellite and tide gauge data also show clear patterns of accelerated rates since 1993 (see figure 2)[4]. Figure 2 – Rates of sea level rise over the 20th century (green) and since 1992 (blue). The time windows for each paper cited are as follows: (a) 1993–2014; (b) 1993–2014; (c) 1993–2010; (d) 1993–2009; (e) 1901–1990 (green), 1993–2012 (blue); ( f ) 1901–1990; (g) 1901–1990 (green), 1993–2010 (blue); (h) 1900–1999 (green), 1993–2009 (blue); (i) 1900–2009; ( j) 1901–1990 (green), 1993–2009 (blue); (k) 1992–2010; (l) 1993–2010; (m) 1904–2003; (n) 1880–1990. From Horton et al. (2018)[4]. While rates of GMSL have changed over time, there has been an unambiguous rise in sea level over time, as measured by tide gauges and satellites (see figure 3). Figure 3 – Changes in global mean sea level from 1880 – 2014. Sea level variations are caused by a variety of natural and human-caused factors. While land mass movements and ocean circulation patterns influence sea levels, human-induced climate change is accelerating the rate of sea level rise[5]. Specifically, greenhouse gas emissions have increased global temperatures, causing ice sheets to melt and oceans to thermally expand. For example, one study found that the rate of sea level rise since 2000 resulting from the expansion of seawater as it warms “is significantly greater than at any moment in the twentieth century.”[2] Scientists’ Feedback: Thomas Frederikse Postdoctoral researcher, Jet Propulsion Laboratory/California Institute of Technology: This text cherry-picks two trend estimates of global sea levels (one number from 1900-2018 and one number from 1958-2014) to ‘show’ there’s no acceleration in global sea level since 1900. That is false. Global sea levels have accelerated since 1900, something that the authors could have calculated themselves by fitting a second-order polynomial through the time series of global sea level, which are publicly available. That simple calculation gives a significant and positive acceleration in global sea level of 0.012 +/- 0.004 mm yr-2 over 1900-2018. Instead, the article just takes two numbers and draws conclusions without looking into the actual numbers. The article also discusses the lack of direct correlation between CO2 emissions and global sea levels, due to the above-average rates of sea level and glacier mass loss in the 1930s. This is an oversimplification of the physics behind global sea levels, since many more processes than just CO2 affect global sea levels. As a result, such a clear correlation is not expected. For example, the above-average rate around ~1930 can be traced down to regional heatwaves in the Arctic region, causing a lot of ice melt[3], while a large part of the slowdown in the rate of global sea-level rise can be tracked down to retention of water behind newly-constructed dams[6]. In conclusion, this article cherry-picks numbers to claim there’s no acceleration in global sea level. Benjamin Horton Professor, Earth Observatory of Singapore: A review paper I wrote shows that for every paper that calculated present day sea level rise there is a clear increase in rate[4].

https://science.feedback.org/review/scientific-studies-established-clear-links-between-human-caused-increased-in-atmospheric-co2-and-global-warming-patrick-moore/

Incorrect

Instagram, Patrick Moore, 2020-12-16

“It’s a good thing that we are putting some more carbon dioxide in the atmosphere. The scientific method has not been applied in such a way as to prove that carbon dioxide is causing the Earth to warm.”

Incorrect: Scientific studies find that human-caused increases in atmospheric CO2 levels and other greenhouse gases are the primary driver of global warming. Flawed reasoning: Increased atmospheric CO2 levels increased plant growth in some regions of the world, but the argument that CO2 is not harmful to the planet because it facilitates plant growth is flawed. Human-caused increases in atmospheric CO2 can negatively affect natural ecosystems and human society by causing global warming, ocean acidification, and sea level rise.

Atmospheric CO2 levels have increased by 47% since 1850, due to agricultural development, the burning of fossil fuels, and other human activities. Since 1950, approximately 100% of the global warming trend is attributed to increased CO2 emissions. Although CO2 has increased plant growth in some regions of the world, it can also negatively impact natural ecosystems and human societies.

“It’s a good thing that we are putting some more carbon dioxide in the atmosphere. If we bring it up to a higher level than it is today, we will get, immediately, an increase in the growth of crops and trees, which is not a bad thing. The scientific method has not been applied in such a way as to prove that carbon dioxide is causing the Earth to warm.”

1 – IPCC (2014) Climate Change 2014: Summary: for Policymakers. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. 2 – Shakun et al. (2012) Global warming preceded by increasing carbon dioxide concentrations during the last deglaciation. Nature. 3 – Feldman et a. (2015) Observational determination of surface radiative forcing by CO2 from 2000 to 2010. Nature. 4 – Friedlingstein et al (2019) Global carbon budget 2019. Earth System Science Data. 5- Zhu et al. (2016) Greening of the Earth and its drivers. Nature Climate Change. 6 – Wuebbles et al. (2017) Executive summary. In: Climate Science Special Report: Fourth National Climate Assessment, Volume I. 7- Moore et al. (2017) New science of climate change impacts on agriculture implies higher social cost of carbon. Nature. 8- De Graaff et al. (2006) Interactions between plant growth and soil nutrient cycling under elevated CO2: a meta-analysis. Global Change Biology. 9 – Doney et al (2009) Ocean acidification: The other CO2> problem. Annual Review of Marine Science. 10 – Mbow et al. (2019) IP Food Security. In: Climate Change and Land: an IPCC special report on climate change, desertification, land degradation, sustainable land management, food security, and greenhouse gas fluxes in terrestrial ecosystems. IPCC report. 11 – Harries et al. (2001) Increases in greenhouse forcing inferred from the outgoing longwave radiation spectra of the Earth in 1970 and 1997. Nature.

Review: These claims appeared in a video featuring Patrick Moore, an industry consultant, which has received more than 13,000 views since it was published on Instagram in December 2020. Contrary to what is claimed, the scientific evidence clearly demonstrates a causal link between atmospheric CO2 concentrations and global warming[1-4]. Furthermore, although carbon dioxide can increase plant growth in some environments, it can also negatively impact natural ecosystems and human societies by causing global warming, imbalancing the carbon cycle, and driving weather extremes[1,4,5]. Pre-industrialization atmospheric CO2 levels were around 280 parts per million (ppm)[1]. Since 1950, the burning of fossil fuels, agricultural development, and other human-caused land-use changes have led to steady increases in atmospheric CO2. Today, atmospheric CO2 exceeds 400 ppm (see figure below). Figure—The Keeling Curve, a daily record of global atmospheric CO2, shows relatively stable CO2 concentrations from 1700 to 1950, as measured by ice-cores. After 1950, CO2 concentrations rose rapidly from 300 to over 400 ppm, as measured at the Mauna Loa Observatory. From Scripps Institute of Oceanography. Alongside these increases in atmospheric CO2, global land and ocean temperatures have steadily increased (see figure below). Figure—Global temperature anomaly data relative to the 20th century average temperature from the Global Historical Climatology Network-Monthly data set and International Comprehensive Ocean-Atmosphere Data Set. These data sets show consistent global warming trends. From NOAA. As stated in a 2014 IPCC report, “Anthropogenic greenhouse gas emissions have increased since the pre-industrial era, driven largely by economic and population growth, and are now higher than ever. This has led to atmospheric concentrations of carbon dioxide, methane and nitrous oxide that are unprecedented in at least the last 800,000 years. Their effects, together with those of other anthropogenic drivers, have been detected throughout the climate system and are extremely likely to have been the dominant cause of the observed warming since the mid-20th century.”[1] And the 2017 US National Climate Assessment states, “This assessment concludes, based on extensive evidence, that it is extremely likely that human activities, especially emissions of greenhouse gases, are the dominant cause of the observed warming since the mid-20th century. For the warming over the last century, there is no convincing alternative explanation supported by the extent of the observational evidence.”[6] An analysis of the factors that influence global surface temperatures found that anthropogenic increases in greenhouse gas emissions account for more than 100% of the warming trends observed since 1850 (see figure below). Figure—The estimated role of different factors influencing global surface temperatures from 1850 to 2017. Observed temperatures are shown in black dots. Global warming over the past 150 years was primarily driven by greenhouse gas emissions (red). From Carbon Brief. While increased levels of CO2 have increased plant growth in some regions of the world, these effects also decrease with increasing CO2 concentrations[7]. In addition to CO2, plants require water and other nutrients to grow. Scientific studies show the effects of CO2 on plant growth depend on the availability of other nutrients, such as phosphorus and nitrogen[8]. The plant growth benefits of CO2 can also be outweighed by negative climate impacts, such as increasing water stress, heat stress, and ocean acidification[9,10]. In order to assess the overall impact of CO2 on the planet, all known effects of CO2 on land ecosystems and human societies should be evaluated together. Scientists’ Feedback: [Comment from a previous evaluation of a similar claim.] First, greenhouse gases are well studied, and their properties are nonnegotiable: They absorb and re-emit longwave radiation, whether they’re in a laboratory setting or in the real atmosphere. To back this up with historical evidence, scientists have known since the 1860s that CO2 is a greenhouse gas and since the 1890s that this will affect the heat budget of the Earth through warming. Even then, these claims were based on empirical evidence, and they’re supported by decades of laboratory research. Second, the link between increased greenhouse gas concentrations and warming continues to be supported by research in the last two decades. One study from 2001 used satellites to measure the type of energy entering and exiting Earth’s atmosphere and concluded that increases in greenhouse gases were responsible for extra heat measured between 1970 and 1997[11]. The authors state that their results “provide direct experimental evidence for a significant increase in the Earth’s greenhouse effect that is consistent with concerns over radiative forcing of climate.” (Here, the term “radiative forcing” refers to the extra energy trapped in the atmosphere by greenhouse gases, cause warming.) A more recent study arrived at similar conclusions, confirming predictions of the greenhouse effect in Earth’s atmosphere and providing “empirical evidence of how rising CO2 levels … are affecting the surface energy balance.”[3] In other words, rising CO2 was linked directly to warming, even when things like plant uptake of CO2 were considered. [Comment from a previous evaluation of a similar claim.] The primary empirical evidence that greenhouse gasses cause global warming is the absorption (as a function of wavelength of radiation) of gasses like CO2, CH4 and N2O. This was discovered in 1859 by John Tyndall and has become a part of fundamental physics. Anyone can check this empirical relationship at any time with an absorption spectroscopy device. The empirical evidence that increases in greenhouse gas concentrations (from fossil fuel burning) are the primary cause of century-scale warming is that observed global temperatures have risen in line with what would be expected from the observed increase in greenhouse gas concentrations and observations of natural drivers of climate change (e.g. solar output and volcanic eruptions) indicate that natural drivers are not causing warming. [Comment from a previous evaluation of a similar claim.] This is the usual misleading argument that if CO2 is good for plants, it cannot be bad for the climate. CO2 is needed for plant growth (along with water, nutrients, and energy from the sun)—but it does not change the fact that CO2 is a greenhouse gas. It increases the radiative forcing of the planet and leads to warming, as observed over the last century[5]. [Comment from a previous evaluation of a similar claim.] CO2 is indeed fundamental for most life on Earth. Plants need CO2 to grow and they are at the base of the food chain. However, this fact is often abused to claim that increasing CO2 concentrations is mainly a good thing. Although plant growth is often stimulated by increasing CO2 concentrations, CO2 also causes ocean acidification and warms the planet, thereby generating a cascade of effects from melting of glaciers and sea level rise to altered precipitation patterns and increasing frequency and intensity of extreme weather events such as heatwaves and droughts[1,9,10]. These in turn threaten water and food supplies, and as climate change progresses, this is also likely to undo much of the beneficial effect that CO2 has on plant growth[10].

https://science.feedback.org/review/the-clothing-industry-produces-3-to-10-of-global-greenhouse-gas-emissions-as-accurately-claimed-in-patagonia-post/

Accurate

Instagram, Patagonia, 2020-11-30

“The clothing industry contributes up to 10% of the pollution driving the climate crisis.”

Accurate: Scientific studies and analytical reports from the United Nations and charitable organizations estimate that the fashion industry contributes 3 to 10% of global greenhouse gas emissions. Lacks specifics: The claim does not specify the type of pollution the fashion industry is contributing to nor the source of this information. However, it likely refers to greenhouse gas emissions, primarily CO2, that drive climate change.

Globally, the fashion industry is estimated to contribute 3 - 10% of the greenhouse gas emissions that are causing climate change, based on scientific studies and reports from the United Nations and charities. The clothing industry has a variety of other environmental impacts, including intensive water use, water pollution through dying and textile production, and pesticide and herbicide pollution through the agricultural production of cotton. Microplastics, which are shed primarily from synthetic textiles during washing, are also polluting the oceans, potentially negatively impacting human health and natural ecosystems.

“The clothing industry contributes up to 10% of the pollution driving the climate crisis.”

1 – Hertwich and Peters (2009) Carbon Footprint of Nations: A Global, Trade-Linked Analysis. Environ. Sci. Technol. 2 – Ivanova et al. (2015) Environmental Impact Assessment of Household Consumption. Journal of Industrial Ecology. 3 – Chen and Burns (2006) Environmental Analysis of Textile Products. Clothing and Textiles Research Journal. 4 – De Falco et al. (2019) The contribution of washing processes of synthetic clothes to microplastic pollution. Scientific Reports. 5 – Ivar do Sul and Costa (2013). The present and future of microplastic pollution in the marine environment. Environmental Pollution. 6 – Fischedick et al. (2014) Industry. In: Climate Change 2014: Mitigation of Climate Change. Contribution of Working Group III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. 7 – Huang et al. (2016) Energy-related GHG emissions of the textile industry in China. Resources, Conservation and Recycling. 8 – Boucher and Friot (2017) Primary Microplastics in the Oceans: A Global Evaluation of Sources. IUCN. 9 – Mair et al. (2016) Global inequities and emissions in Western European textiles and clothing consumption. Journal of Cleaner Production. 10 – Ivanova et al. (2017) Mapping the carbon footprint of EU regions. Environmental Research Letters.

Review: The claim appeared in an Instagram post published by the clothing company Patagonia in late November 2020, and has received more than 502,000 views. Although the post does not indicate the source of the claim, scientific studies estimate that clothing contributes 3 to 10% of greenhouse gas emissions that drive climate change[1,2]. In addition, clothing production and use causes water pollution, pesticide pollution, and the release of microplastics into the ocean that can negatively impact human health and natural ecosystems[3-5]. The environmental impact of clothing has increased since 2000, primarily due to the rise of “fast fashion,” which refers to the production of inexpensive, rapidly produced clothing that follows the latest fashion trends. As described in a 2014 IPCC report, “during the period 2000–2005, the advent of ‘fast fashion’ in the UK led to a drop in prices, but an increase in sales equivalent to one third more garments per year per person with consequent increases in material production and hence industrial emissions.”[6] In 2017, the Ellen MacArthur Foundation, a charitable organization in the UK, published a report exploring the environmental impact of the fashion industry based on analyses from McKinsey & Company and contributions from more than 100 experts at academic institutions and in the fashion industry. While not a peer-reviewed publication, the report found that clothing sales doubled from 2000 to 2015, whereas the average number of times a garment is worn decreased by 36% (see figure below). Figure—Global clothing sales and utilization from 2000 to 2015. From the Ellen MacArthur Foundation A new textiles economy: Redesigning fashion’s future (2017). Numerous scientific studies have estimated the greenhouse gas emissions (GHG) attributed to clothing and the fashion industry. For example, a study evaluating the carbon footprint of individuals in various nations found that clothing contributed 1 to 6% to the per capita GHG footprint in 70 countries in 2001[1]. In Hong Kong, clothing contributed 28% to per capita GHG[1]. A 2015 study found that clothing consumption in European households contributed 3.5% of the carbon footprint, 4.3% of the land footprint, 4.7% of the material footprint, and 5% of the water footprint in 2007 (see figure below)[2]. Figure—Contribution of clothing and other factors to the carbon (orange), land (green), material (yellow), and water (blue) footprint of EU households. Contributions to the environmental footprint, the quality of products bought (expenditure per capita), and the footprint intensity. From Ivanova et al. 2015[2]. Another study that analyzed the environmental impact of the textile industry in China found that it contributed 4 to 8 billion tons of GHG from 200 to 2011 (see figure below), and estimated a contribution of 18.5 billion tons of GHG emissions in 2020[7]. Figure—Textile production and GHG emissions from various energy sources for the textile industry in China. From Huang et al. (2016)[7]. Some sources, including the Ellen MacArthur Foundation report and the United Nations Environment Programme (UNEP), estimate the global fashion industry contributes 1.2 billion tonnes of CO2 equivalent or 8 to 10 percent of global carbon emissions. In addition to GHG emissions, the fashion industry has been linked to a variety of other environmental impacts, including intensive water and pesticide use as well as pollution to water, air, and soil[3-6]. As described in a report from the UNEP, “The fashion industry is the second-biggest consumer of water and produces 20 per cent of global wastewater.” For instance, a single pair of jeans consumes 3,781 liters of water, according to a Levi Strauss & Co. life cycle assessment. Clothing also contributes to global microplastic pollution in the ocean, primarily through the washing process. One study estimates that synthetic clothing contributes 35% of microplastic pollution in oceans, with approximately 124 to 308 mg released for each kg of washed fabric[4]. An IUCN report, estimates that synthetic textiles consume 42,534 kilotons of plastic each year, a portion of which end up in the ocean[8]. Additional waste from the fashion industry occurs when clothes are discarded or incinerated. According to the Ellen MacArthur report, only 13% of clothes are recycled and less than 1 percent are recycled into new clothing. In contrast, the report estimates that 73% of clothing goes to landfills or is incinerated (see figure below). Figure—The global material flow of clothing in 2015. From the Ellen MacArthur Foundation A new textiles economy: Redesigning fashion’s future (2017). In addition to environmental impacts, the fashion industry also impacts human health and wellbeing. For example, a 2016 study found the demand for clothing and textiles often depends on low-cost labor, primarily in Brazil, Russia, India, and China[9]. Overall the claim, “the clothing industry contributes up to 10% of the pollution driving the climate crisis” is accurate, as it falls within 1 to 10% range of estimates for GHG emissions in scientific studies and organization reports. In addition, clothing production and consumption can be an energy- and water-intensive process that causes water pollution, microplastic release, and human health impacts. Scientists’ Feedback: Simon Mair Lecturer, University of Bradford: I’d say this is accurate. Typically studies put clothing between 3-10% of greenhouse gas emissions. There’s a brief write up of this in my thesis (section 2.3.3 page 42-43). This is aging now, but I see no reason the core estimates would have changed. This slightly more recent paper also puts clothing in the same range[9]. Ten percent is probably at the higher end of estimates, but still has a solid basis in the science. The issue with carbon footprint estimates is that they are very sensitive to different assumptions, methods, and/or data, so a 10% range is probably within an acceptable margin of error. Chris K. Y. Lo Associate Professor, The Hong Kong Polytechnic University: The claim [that the fashion contributes] up to 10% [of pollution driving the climate crisis] is not very far from the United Nations’ research estimate, which is 8%. Elisa Tonda, Head of the Consumption and Production Unit at the UN Environment Programme (UNEP), one of the 10 UN bodies involved in the Alliance, explained the urgency behind its formation in a UN News article: “The global production of clothing and footwear generates 8% of the world’s greenhouse gas emissions and, with manufacturing concentrated in Asia, the industry is mainly reliant on hard coal and natural gas to generate electricity and heat. If we carry on with a business-as-usual approach, the greenhouse gas emissions from the industry are expected to rise by almost 50% by 2030.” However, I have no access to the UN environment programme original report to confirm how this number was calculated. There is a more recent claim from our field that was published in a report authored by McKinsey & Company and Global Fashion Agenda, which estimates the fashion industry contributes roughly about 4% of the global emission. From a study that investigated the total emission of fashion and textiles production in China, the figure is even higher, assuming that China is responsible for 40 to 50% of global fashion and textiles production over the past 10 years[7]. This study projected the GHG emissions based on China’s government electricity, and combustion data using different energy sources. The China textile industry (50% of global production) is at 18.486 billion CO2 tons in 2020. This figure is surprisingly high. If it’s true, the global fashion and textiles GHG emission would be around 18.46 billion tons doubled, which is 36.9 billion tons in the best case scenario, which is close to 10 times higher than the 2nd source stated. Based on the energy consumption of textiles and fashion production in China, the pollution is very serious. The annual GHG pollution composition is just the tip of an iceberg. The microplastic problem causing water pollution is accumulating, and the negative effects to our ecosystem and human health is long lasting. It is far more devastating than GHG emission in a particular year.

https://science.feedback.org/review/brush-rake-attachments-are-primarily-used-to-pile-up-heavy-forest-debris-as-part-of-active-thinning-harvesting-and-removal-projects/

Misleading

Facebook, Facebook users, 2018-11-21

“this is [...] a brush rake. It's used for clearing underbrush and debris from the forest floor that builds up and creates fuel for wild fires. Now you can stop looking stupid trying to make fun of Trump telling California to rake the forest.”

Misleading: Brush rakes mount to the front of machines and are used to pile up heavy woody debris that accumulates after blow down events or as part of active timber harvesting or thinning projects. They are not used throughout forests across the U.S. to broadly perform fuel removal.

Brush rakes are attachments for the front of a wheeled or tracked machines that are used to push woody debris and large vegetation into piles. They are typically used as part of active, labor-intensive thinning, harvesting, removal, and restoration projects—not to rake large areas or clear live brush.

“this is what the United States Department of Agriculture Forestry Service calls a brush rake. It's used for clearing underbrush and debris from the forest floor that builds up and creates fuel for wild fires. Now you can stop looking stupid trying to make fun of Trump telling California to rake the forest.”

Review: The claim appeared alongside the photo below in a Facebook post that was published in November 2018 and recently shared widely on the platform. To date, the post was shared 84,000 times, according to the social media analytics tool CrowdTangle. The post states, “this is what a United States Department of Agriculture Forestry Service calls a brush rake. It’s used for clearing underbrush and debris from the forest floor that builds up and creates fuel for wild fires.” A brush rake is an attachment for the front of a wheeled or tracked machine that is used to push woody debris and large vegetation into piles. According to the USDA Forest Service, raking is “the process of pushing slash or residues into piles, generally windrows, with a brush rake or a towed rake implement.” In forestry, slash and residues refer to woody debris that are left in the forest after a logging or timber harvesting event. Brush rakes are typically used in active thinning, harvesting, and reforestation projects, as the USDA Forest Service described in an email to Climate Feedback: “Brush rakes are attachments, usually on bulldozers but can also be attached to smaller skid-steers or even rubber tired tractors. In Hazardous Fuels work they are typically used to create machine piles when there is very heavy fuel loading such as after a blow down event or after timber harvest or thinning where there is a lot of large, woody material on the ground; they can move the material into piles or windrows so they can be disposed of later, usually by burning the piles. Unlike a standard blade that would also move the soil, the brush rake mostly just moves the vegetation and while the machinery does disturb the soil, it does a better job of not removing the soil than using a conventional blade. Leaving the soil on site is critical for replanting or reseeding in areas where reforestation is desired.” While the post might imply that brush rakes are used throughout forests across the country to clear woody debris, their use is limited depending on the terrain and vegetation type. As the reviewer describes below, brush rakes are often used in the southeastern U.S. to clear rapidly growing hardwood trees. In contrast, it is difficult to use brush rakes to manage fuel loads in some regions of the western U.S. where the topography is steep and the vegetation differs. As Christine McMorrow, Resource Management Communications for CALFIRE stated in an email to Climate Feedback, “Brush rakes are used to remove brush to both prepare for reforestation, but also to reduce fuels. They aren’t used much on the fireline, but I’ve seen them around. They have a role and can be useful in very brushy areas. CAL FIRE has a few that are used in the Southern Region.” Overall, the post accurately refers to the attachment as a brush rake, but misrepresents the contexts in which it is most often used and incorrectly implies that it could be used to significantly reduce fuel loading across California. Scientists’ Feedback: Malcolm North Research Ecologist, US Forest Service: The picture is of a brush rake attachment on the front of a D4 Caterpillar tractor, which is used to reduce fuels in the SE US (the reason why it’s pictured amongst longleaf pine). It doesn’t get much use in the western U.S., including California, because the topography is generally steeper (limiting where it can operate) and fuels are different in the SE where rapid regrowth, particularly of hardwoods, means you need something that can comb and rip the regrowth out. In the western U.S., brush rakes are a tool commonly used in the construction of fire lines, where the litter and duff are raked away to expose mineral earth. It’s called a McLeod rake. In sum, the mental picture and definition of a brush rake differs between the southeastern and western US, in part because fuels are different and because of operational constraints.

https://science.feedback.org/review/guardian-article-on-arctic-methane-emissions-lacks-important-context-jonathan-watts/

-1

The Guardian, by Jonathan Watts, on 2020-10-27.

"'Sleeping giant' Arctic methane deposits starting to release, scientists find"

1-McGinnis et al. (2006) Fate of rising methane bubbles in stratified waters: How much methane reaches the atmosphere?, Journal of Geophysical Research: Oceans 2-Wallmann et al. (2018) Gas hydrate dissociation off Svalbard induced by isostatic rebound rather than global warming, Nature Communications 3-Saunois et al. (2020) The Global Methane Budget 2000–2017, Earth System Science Data 4-Jackson et al. (2020) Increasing anthropogenic methane emissions arise equally from agricultural and fossil fuel sources, Environmental Research Letters 5-Westbrook et al. (2009) Escape of methane gas from the seabed along the West Spitsbergen continental margin, Geophysical Research Letters 6-Berndt et al. (2014) Temporal Constraints on Hydrate-Controlled Methane Seepage off Svalbard, Science 7-Kretschmer, et al. (2015) Modeling the fate of methane hydrates under global warming, Global Biogeochemical Cycles 8-Archer (2015) A model of the methane cycle, permafrost, and hydrology of the Siberian continental margin, Biogeosciences 9-Steinle et al. (2015) Water column methanotrophy controlled by a rapid oceanographic switch, Nature Geoscience 10-Mau et al. (2017) Widespread methane seepage along the continental margin off Svalbard – from Bjørnøya to Kongsfjorden, Scientific Reports 11-Lund Myhre et al. (2016) Extensive release of methane from Arctic seabed west of Svalbard during summer 2014 does not influence the atmosphere, Geophysical Research Letters 12-Pohlman et al. (2017) Enhanced CO2 uptake at a shallow Arctic Ocean seep field overwhelms the positive warming potential of emitted methane, PNAS 13-Shakhova et al. (2014) Ebullition and storm-induced methane release from the East Siberian Arctic Shelf, Nature Geoscience 14-Thornton et al. (2020) Shipborne eddy covariance observations of methane fluxes constrain Arctic sea emissions, Science Advances 15-Berchet et al. (2016) Atmospheric constraints on the methane emissions from the East Siberian Shelf, Atmospheric Chemistry and Physics 16-Tohjima et al. (2020) Estimation of CH4 emissions from the East Siberian Arctic Shelf based on atmospheric observations aboard the R/V Mirai during fall cruises from 2012 to 2017, Polar Science 17-Thornton, et al. (2016) Methane fluxes from the sea to the atmosphere across the Siberian shelf seas, Geophysical Research Letters 18-Christensen et al. (2019) Tracing the climate signal: mitigation of anthropogenic methane emissions can outweigh a large Arctic natural emission increase, Scientific Reports

Reviewers’ Overall Feedback: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Frans-Jan W. Parmentier Associate Professor, Lund University & University of Oslo:This article’s claim that methane deposits in the Arctic Ocean are starting to be released, awakening a “sleeping giant”, cannot be supported by the limited observational data. Besides, even if these newly found seeps are increasing, they are located too deep in the ocean to have a significant impact on the concentration of methane in the atmosphere. First of all, a newly discovered source is not the same as a changing source. Second, these findings are not unexpected nor the first of their kind in the Arctic. Gas hydrates are commonly found along continental slopes at depths where high pressures and low temperatures allow for their existence. The presence of hydrates to the west of high-arctic Svalbard is well-known[5]. These hydrates have been studied extensively and occur at a similar depth as the recent findings reported by the Guardian. This makes for an ideal comparison to understand what’s going on in the Laptev Sea. The gas hydrates near Svalbard have been venting methane for at least 3,000 years, induced by geological processes rather than global warming[2], while methane release varies with the seasons[6]. Similar processes may be at play for the gas hydrate deposits found in the Laptev Sea. This underlines the need to monitor methane seeps over a long time period before rushing to the conclusion that they are increasing due to recent climate change. Model studies show that the impact of climate change on gas hydrates will be a slow process, over timescales from centuries up to a millennium[7,8]. Most importantly, the ocean is an efficient filter for methane when the water is more than 100 m deep[1]. When bubbles rise up towards the surface, methane quickly dissolves into the ocean water and is removed through oxidation[1,9]. Since the hydrates near Svalbard and in the Laptev Sea are located below a depth of 300 m, they are unlikely to influence atmospheric concentrations—even when they start to destabilize. Although the article in the Guardian acknowledges that most methane dissolved into the ocean water, the researchers also report that “methane levels at the surface were four to eight times what would normally be expected and this was venting into the atmosphere”. Elevated methane levels are not uncommon in the ocean, also near Svalbard[9]. More than a thousand gas seeps have been documented along the coast of Svalbard[10] (just six were reported by the recent expedition in the Laptev Sea). Despite the widespread release of methane into the ocean off the coast of Svalbard and extensive monitoring with land-based, ship-based and airborne methods, no significant impact on the atmosphere has been found[11]. In fact, the small amount of methane that is released at hotspots is offset by an enhanced uptake of CO2 in the same area[12]. It should be noted that the researchers interviewed by the Guardian have previously suggested very high emissions from the shallower parts of the Laptev Sea and nearby seas[13], where methane can escape to the atmosphere in larger quantities. However, three independent studies that tried to confirm those results showed that those estimates were overestimated by about a factor of five[14,15,16]. While high methane concentrations have been detected near seeps in the Laptev Sea[17], these elevated concentrations are highly localized, which makes them less important at the regional scale[14]. The article in the Guardian grossly exaggerates a small source that is unlikely to increase, while using frightening metaphors of the awakening of a “sleeping giant”. This draws attention away from genuine feedbacks in the Earth system such as the release of carbon from permafrost thaw, the deterioration of global ecosystems, and the rapid loss of sea ice. Anthropogenic methane emissions are roughly 50 to 70 times larger than emissions from the Arctic Ocean, and we can compensate for Arctic methane release by reducing anthropogenic emissions with present-day technology[18]. That’s the real giant that we can and should tackle, rather than hypothetical sea monsters. Ben Poulter Research Scientist, NASA:The article claims that frozen methane, stored in ocean sediments in the Arctic, has become destabilized and is being emitted to the atmosphere. The article generally overlooks the fact that 1) the methane emitted from the sediments does not escape to the atmosphere because it is oxidized in the water column, 2) the methane fluxes the research crew are measuring have been detected in previous cruises and are not an indicator of a rapid change, and 3) this work has been disputed previously through independent studies using atmospheric, or top-down, constraints to measure the Arctic methane budget. Paul Overduin Senior Scientist, Alfred Wegener Institute:The words “starting” and “triggering” tacitly assume that the beginning of a process was observed (i.e., that has not taken place until now). The article provides no evidence to support this assumption. “Triggering” connotes a small impulse leading to an explosive result—this word choice is not neutral, but highly suggestive. The article then softens the claim of a new release/source relevant to climate: “…most of the bubbles were currently dissolving…”, “…findings were preliminary” and “…will not be confirmed until they return”. The article then goes on to contradict the assumption of “starting”: methane emissions have been observed before (“the third source of methane emissions from the region”, “previously reported the gas is being released”, “second year in a row”). No differentiation is provided between previous and current observations. Important context is omitted: such methane emissions are observed at many locations on Arctic slopes and could be expected at this location. Currently, Arctic methane sources are a small contribution to atmospheric methane. The source of the methane observed in this story is of central importance in judging whether it is sensitive to climate change or likely to be large enough to affect climate. Only one mention of the source is made: “gas hydrate”, without any background. This is a very understudied part of a region that is most strongly affected by climate change. It is tremendously challenging for science to fund research and every new observation is of value and should be analyzed thoroughly and soberly, in context. David Archer Professor, University of Chicago:Putting these new methane emissions into a global context, they are much smaller than emissions fluxes from tropical wetlands, the main natural source. This means that unless Arctic methane fluxes blow up by a factor of 100 or more, they won’t play a huge role in global warming. I was relieved by the first quote in the article, beginning “At this moment, there is unlikely to be any major impact on global warming…,” but I was less happy with a later quote, “Potentially they can have serious climate consequences, but we need more study before we can confirm that.”

https://science.feedback.org/review/sea-ice-loss-due-to-climate-change-is-the-biggest-threat-to-polar-bear-survival-and-has-already-led-to-declines-in-some-polar-bear-subpopulations-contrary-to-climate-realism-video-m/

Misleading

Climate Realism, Heartland Institute, Andy Singer, 2020-10-23

“In 1950, there were around 10,000 polar bears globally. Today, polar bear populations are near 39,000. Polar bear populations are increasing dramatically as the planet has warmed.”

Factually inaccurate: The current global polar bear population is estimated to be 20,000 to 26,000 bears distributed among 19 subpopulations, not 39,000 as claimed. Fails to grasp significance of observation: Polar bears were heavily harvested in the 1950s and 1960s. An increase in polar bear population size since the 1950s does not demonstrate that polar bears are not affected by climate change, but rather that an agreement was signed in 1973 stating that harvesting should be done at sustainable levels. Inadequate support: There is no scientific evidence provided to support the claims made in the video or the figure showing increases in the global polar bear population size over time.

Loss of sea ice habitat caused by climate change is the most important threat to the long term survival of polar bears. Of the 19 subpopulations of polar bears, two have already experienced declines due to losses in sea ice. It is difficult to estimate trends in the global polar bear population; however, trends at the subpopulation level from 2019 show that four subpopulations declined, five were stable, and only two increased.

“In 1950, there were around 10,000 polar bears globally. Today, polar bear populations are near 39,000. That alone pokes a hole in the whole plight of the polar bears story. Polar bear populations are increasing dramatically as the planet has warmed.”

1 – Stirling et al (2012) Effects of climate warming on polar bears: a review of the evidence. Global Change Biology. 2 – Stern et al (2016) Sea-ice indicators of polar bear habitat. The Cryosphere. 3 – Regehr et al (2016) Conservation status of polar bears (Ursus maritimus) in relation to projected sea-ice declines. Biology Letters. 4 – Bromaghin et al (2015) Polar bear population dynamics in the southern Beaufort Sea during a period of sea ice decline. Ecological Applications. 5 – Lunn et al (2016) Demography of an apex predator at the edge of its range: impacts of changing sea ice on polar bears in Hudson Bay. Ecological Applications. 6 – Wiig et al (2015) Ursus maritimus. The IUCN Red List of Threatened Species. 7 – Derocher et al (2013) Rapid ecosystem change and polar bear conservation. Conservation Letters. 8- Harvey et al. (2017) Internet blogs, polar bears, and climate-change denial by proxy. BioScience. 9 – Hunter et al (2010) Climate change threatens polar bear populations: a stochastic demographic analysis. Ecology. 10 – Molnar et al. (2020) Fasting season length sets temporal limits for global polar bear persistence. Nature Climate Change. UPDATES: 30 October 2020: This post was updated to include additional comments from Ian Stirling.

Review: The claims appeared in a Facebook video published in October 2020 by “Climate Realism”, a project run by the Heartland Institute, which has a history of publishing climate information inconsistent with findings from the scientific community. The video suggests that global warming is not a threat to polar bears because the global polar bear population increased in size since 1950. Contrary to this claim, scientific evidence demonstrates that sea ice loss induced by climate change is currently the greatest threat to the long-term survival of polar bears[1-3]. Polar bears rely on sea ice to hunt seals (their primary prey), mate, establish dens, and move to new regions seasonally[2]. Loss of sea ice is occurring in almost all polar bear subpopulations. Scientists can evaluate the effects of climate change on polar bears by correlating local losses in sea ice habitat with polar bear subpopulation size. Several studies using this approach found that loss of sea ice has already negatively affected some subpopulations, including Western Hudson Bay and Southern Beaufort Sea (see figure below)[4,5].Figure—Estimated size of the Western Hudson Bay polar bear subpopulation using data from capture-recapture models from 1984-2011. From Lunn et al. 2016[5]. In addition to declines in population size, loss of sea ice also affects polar bear body condition and survival rates. “Long-term monitoring studies in Canada suggest that polar bear body condition, survival and population growth rates are all negatively impacted by declines in the availability of sea ice habitat and there are no data to suggest that polar bears are thriving in areas where sea ice has significantly declined,” said Gabrielle Lamontagne, a communication advisor for Environment and Climate Change Canada. The trend of the global polar bear population is unknown, according to the IUCN Red List[6], however trends can be observed at the subpopulation scale. The current global polar bear population is estimated to be 20,000 to 26,000 bears, which are distributed among 19 subpopulations[6,7]. Of the 19 subpopulations measured by the IUCN Polar Bear Specialist Group, only two increased, four declined, and five were stable in 2019. The other subpopulations did not have enough data to demonstrate short or long-term trends (see figure below). Figure—Geographic distribution, size, and trends of 19 polar bear subpopulations measured by the IUCN Polar Bear Specialist Group. Colors reflect subpopulation trends in 2019. Shape and size represent subpopulation size, measured in the number of bears. Adapted from the IUCN Polar Bear Specialist Group. These data directly contradict the video’s estimate that the global polar bear population is 39,000 bears. Although there is no scientific source cited in the video, the inaccurate number was most likely drawn from a blog published by Susan Crockford in March 2019. As stated in Harvey et al. (2018), “as of this writing, Crockford has neither conducted any original research nor published any articles in the peer-reviewed literature on the effects of sea ice on the population dynamics of polar bears.”[8] While the global polar bear population may have increased from 1950 to today, data on polar bear populations was limited or non-existent prior to the late 1970s, as described by the reviewers below. During this time, hunting, killing, and capturing polar bears were the biggest threats to their survival. In 1973, the Agreement on the Conservation of Polar Bears was signed to address these practices[7]. Specifically, Article II of the agreement states, “Each Contracting Party shall take appropriate action to protect the ecosystems of which polar bears are a part, with special attention to habitat components such as denning and feeding sites and migration patterns, and shall manage polar bear populations in accordance with sound conservation practices based on the best available scientific data.” This agreement likely led to an increase in the global polar bear population in the 1970s[9]. But as stated in Hunter et al. (2015), “there is no evidence that these increases continued, and such recoveries, where they occurred, are irrelevant to the effects of recent changes in the availability of sea ice”[9]. Overall, the claims made in the video are not consistent with scientific evidence demonstrating that loss of sea ice habitat due to climate change is the biggest threat to the long-term survival of polar bears[10]. Some subpopulations of polar bears have already declined due to losses in sea ice. The claim that the global polar bear population is 39,000 bears is unsupported and inconsistent with current evidence. Scientists’ Feedback: Andrew Derocher Professor, University of Alberta: [comment from a previous evaluation of a similar claim] There are 19 subpopulations of polar bears across the Arctic. Four are likely decreasing (according to the IUCN/SSC Polar Bear Specialist Group – of which I am a member). Five are likely stable and two are likely increasing. The remainder are unknown. If one considers the “global” population as if there is 1 population in the Arctic, the claim of “growing” cannot be supported. While we have zero data on polar bear abundance until the late 1970s, polar bears were commercially harvested until ca. 1973 when the Agreement on the Conservation of Polar Bears was signed that introduced harvest controls. Polar bears, while based on poor or no data, were heavily depleted in the 1950s-1960s. So, from 1970 to 2020, polar bear populations overall increased. This of course ignores areas that have now declined (Western Hudson Bay, Southern Hudson Bay, Southern Beaufort Sea) and M’Clintock Channel that was severely overharvested post-1973. It’s a word game. Past increases were due to harvest controls. Current declines are due to climate change associated loss of sea ice[1,2,3]. Ian Stirling Adjunct Professor, University of Alberta: First, and most importantly, there never was a factual basis for the “estimate” in 1950 as no population studies of polar bears had been done anywhere in the Arctic at that time. The number was a genuine “guestimate”, i.e., simply a guess based on what little was known before there had been any population surveys or research on the relationship between the polar bears and seals. Another important additional ecological aspect was that in 1950, no one realized how enormous the populations of ringed and bearded seals were around the circumpolar Arctic or, consequently, what their potential might be for supporting much larger populations of polar bears than were normally seen not too far offshore where some humans traveled regularly. As serious quantitative population-level surveys began in the late 1960s and early 1970s, in response to the heavy overharvesting that had taken place in several populations, mainly through the 1960s and into the early 70s. Much of this new research was facilitated by increased research budgets and the development of more effective and safer immobilization drugs which, together, made the first quantitative studies of a few populations possible. So, although no one has any factual idea about the size of the circumpolar population of polar bears in 1950, it seems pretty clear that the total guestimate of 10,000 was likely low, even in the face of heavy overharvest of some populations. However, given that there were simply no quantitative data with which to estimate population size in 1950, the only accurate statement that can be made is that we simply don’t know. [the following comment is from a previous evaluation of a similar claim] As for real numerical information on polar bears, if anyone wants to know how much can be said with as much reliability as is possible, they should go to the web site for the IUCN Polar Bear Specialists Group (which I am also a member of). Note on the left hand side there are headings that give estimates and summaries (with references) of knowledge for all the 19 populations. The estimates for some populations are labelled as current, outdated, and nonexistent for others, particularly in Russia, so it is not technically possible to have a “total estimate”. In reality, it is the status and trends of the 19 individual populations that count. Several populations, such as those in western and southern Hudson Bay, and the southern Beaufort Sea are confirmed unequivocally, from long-term data, to have declined significantly as a direct result of climate warming causing steady loss of sea ice[4,5]. Some other populations are likely also declining, just judging from the extent of the steady loss of ice but we lack long-term data with which to make that assessment, and a couple are doing OK, such as Foxe Basin and Davis Straight, and one seems to be increasing (M’Clintock Channel). However, unless we are able to stop global warming and maybe even start to cool the planet, all populations will decline severely and some will be lost forever[9,10]. The steady loss of sea ice in all subpopulation regions is well summarized by Stern and Laidre[2]. Dr. Derocher and I also published a review a few years ago that gives the state of knowledge about the effects of climate warming on polar bears[1].

https://science.feedback.org/review/climate-change-can-make-it-harder-for-the-amazon-rainforest-to-grow-back-from-deforestation-but-that-does-not-mean-40-of-it-will-now-turn-into-a-savanna/

Imprecise

The Guardian, Fiona Harvey, 2020-10-05

“Amazon near tipping point of switching from rainforest to savannah”

Misrepresents a complex reality: Some Amazon forests exist in climates that can support both savannas and rainforests. While it is possible that some Amazon forests may recover as savanna instead of rainforest after deforestation, this is a natural phenomenon that is not new. Lacks specifics: The claim is supported by the study it is based on, but may be misunderstood by readers without sufficient context. The study describes whether a deforested area might recover as savanna rather than rainforest as climate changes. However, the study authors note in their paper that they overlook other components that may impact how a forest responds to climate change, such as the ability for trees to cope with water stress.

Some Amazon forests occur in climates that can also support savannas, and this natural phenomenon is not recent. The stability of rainforests can be influenced, in part, by the ability of trees to regulate rainfall on a regional scale. If disturbed on a large scale, then, some rainforests might regrow as savannas. Severe climate change may result in some regions in the Amazon becoming increasingly unsuitable for rainforests, while other regions are predicted to become more suitable.

“Amazon near tipping point of switching from rainforest to savannah. As much as 40% of the existing Amazon rainforest is now at a point where it could exist as a savannah instead of as rainforest. Any shift from rainforest to savannah would still take decades to take full effect, but once under way the process is hard to reverse. Rainforests are highly sensitive to changes in rainfall and moisture levels, and fires and prolonged droughts can result in areas losing trees and shifting to a savannah-like mix of woodland and grassland.”

1 – Staal et al. (2020) Hysteresis of tropical forests in the 21st century. Nature Communications. 2 – Nepstad et al. (1994) The role of deep roots in the hydrological and carbon cycles of Amazonian forests and pastures. Nature.3 – Nepstad et al. (2007) Mortality of large trees and lianas following experimental droughts in an Amazon forest. Ecology. 4 – Balch et al. (2015) The susceptibility of Southeastern Amazon Forests to fire: Insights from a large-scale burn experiment. BioScience. 5 – Segovia et al. (2020) Freezing and water availability structure the evolutionary diversity of trees across the Americas. Science Advances. 6 – Dexter et al. (2018) Inserting tropical dry forests into the discussion on biome transitions in the tropics. Frontiers in Ecology and Evolution.

Review: The claims appeared in an article published by The Guardian on 5 October 2020, which has received more than 65,000 interactions on Facebook according to the social media analytics tool CrowdTangle. These claims are based on a study recently published in Nature Communications, which maps potential distributions of tropical forests based on recent and severe climate change models[1]. Specifically, the Guardian article claims, “As much as 40% of the existing Amazon rainforest is now at a point where it could exist as a savannah instead of as rainforest,” which can be misleading to readers without additional context as it might imply that 40% of the Amazon rainforest is currently at a tipping point. This statement does not appear in the study the article is based on[1]. Instead, the study examines how resilient forests are to deforestation in current and future climates. In addition, this claim might incorrectly suggest that the Amazon rainforest did not have the possibility of existing as a savanna before. As described in the study, some forests in the Amazon occur in climates that can also host savannas[1]. The stability of forests is influenced by rainfall levels and the ability of forests to regulate rainfall at a regional scale through forest-rainfall feedback (see figure below). This feedback describes the process of trees extracting water from the soil and releasing it into the air through photosynthesis. When a forest is lost, the feedback is also lost, reducing rainfall. As a result, the vegetation that grows back can be different than what was present previously. Figure—The forest-rainfall feedback affects the stability of forest distributions. Under high rainfall conditions, forests are stable (green). Under intermediate rainfall, land can exist as bistable forest, where it is either forest (yellow, bottom) or non-forest (grassland or savanna; yellow, top). Under low rainfall conditions, only non-forest exists (red). At a regional scale, the forest-rainfall feedback can impact the minimal (top) and maximal (bottom) extent of the forest. From Staal et al. (2020)[1]. The study explored how rainfall and rainfall-forest feedback affect forest resilience to recent climate (2003-2014) and late 21st century climate (2071-2100) under a severe climate change scenario (SSP5-8.5). Under severe climate change, the authors found, “an area of 1.91 million km2 changes from unsuitable to suitable (i.e. either stable or bistable) for forest, whereas an area of 2.37 million km2 changes from suitable to unsuitable,” (see figure below)[1]. This means that some current forests could convert to savanna after deforestation, particularly under future climate change. The article in The Guardian notes this when it says, “They also looked at what was likely to happen if greenhouse gas emissions kept rising, and found that the ability of forests to grow back once trees were lost would be much reduced.” But other statements in the article fail to make it clear that this is contingent on a deforestation event. Figure—(a) Minimal (green) and maximal (beige) forest distributions under recent climate (2003-2014). (b) Minimal (green) and maximal (beige) forest distributions under severe climate in the late 21st century (2071-2100). (c) Changes in forest distribution between current and late 21st century climate. Red areas are suitable for stable forests under recent climate, but become unsuitable for forests in the late 21st century due to low rainfall levels. Blue areas are unsuitable for forests under recent climate, but become suitable for forests in the late 21st century due to higher rainfall levels. From Staal et al. (2020)[1]. While the Staal et al. (2020) study predicts potential changes in forest distribution in South America based on projected rainfall levels as well as rainfall-forest feedback, it also acknowledges limitations of their approach. For instance, the study does not account for other factors that might affect forest resilience to climate change, such as the ability of trees to cope with water stress, as the reviewers describe below[2-5]. The article in The Guardian also claims, “Any shift from rainforest to savannah would still take decades to take full effect, but once under way the process is hard to reverse,” and “Rainforests are highly sensitive to changes in rainfall and moisture levels, and fires and prolonged droughts can result in areas losing trees and shifting to a savannah-like mix of woodland and grassland.” While these statements might be correct, they were not explicitly explored in the study the article was based on[1]. As noted by the reviewers below, long-term experiments are needed to evaluate how the Amazon forest responds to environmental disturbances, such as low rainfall. Scientists’ Feedback: Arie Staal Researcher, Utrecht University: As much as 40% of the existing Amazon rainforest is now at a point where it could exist as a savannah instead of as rainforest. This statement is supported by our study, but it may cause misunderstanding[1]. The phrasing “is now at a point” might cause people to believe that part of the Amazon possibly existing as savanna was not the case before, and something has changed so that a transition could be imminent. That is not what we state in our study. The fact that some forests exist in a climate that can also support savanna is a natural phenomenon; while it does create the potential for large-scale switches to savanna, we don’t mean to say that 40% of the Amazon rainforest is on the brink of collapse. But again, the above statement in itself is not a false representation of our work. Any shift from rainforest to savannah would still take decades to take full effect, but once under way the process is hard to reverse. This is based on a statement that I gave to the Guardian in which I meant that in case a shift would occur at a particular location, the process would probably take a few decades. The words “full effect” might be understood as if the statement applies to large scales (such as 40% of the Amazon), which is stretching my original intention, although it could still be true. Here I should add that this statement goes beyond our present study – we did not investigate such time scales or trajectories. It is context that is based on existing (but uncertain) evidence in the literature. The second part of the sentence is fine. In summary, I would say that this statement is not false, but rather speculative. Rainforests are highly sensitive to changes in rainfall and moisture levels, and fires and prolonged droughts can result in areas losing trees and shifting to a savannah-like mix of woodland and grassland. A better phrasing would have been “Rainforests can be [highly] sensitive to…” or “Some rainforests are [highly] sensitive to…”. Other than that nuance, I consider the statement to be correct and consistent with our results. The resulting ecosystem will be distinct from natural savannas regarding biodiversity, but resemble them in structure. In short, the devil is in the detail. These claims made in the Guardian are not false, but without proper context they can be prone to misunderstanding. Daniel Nepstad Executive Director and President, Earth Innovation Institute: The statement “As much as 40% of the existing Amazon rainforest is now at a point where it could exist as a savannah instead of as rainforest” is very misleading. It implies that something has changed—that rainfall is declining across the entire Amazon—when it has not. Dry season length and air temps have increased in parts of the eastern and SE Amazon, where deforestation is concentrated. We are not seeing big reductions in rainfall over the largely forested center and west of the Amazon. The Staal et al. (2020) paper is simply pointing out something we have known for a long time. We find natural savannas (cerrados) and closed canopy forest across a large range of annual rainfall. The savannas of Alter do Chão, near Santarem (that captured international media attention last year when they caught fire) are there because of the sandy soil of that region. They are surrounded by tall, dense forests—with annual rainfall of about 2000 mm. The Staal et al. (2020) paper has left land-use and fire outside of the study and is basically saying that climate-change-driven shifts in the boundaries between savanna and closed canopy forests move slowly and are shaped by the influence of the forest itself on evapotranspiration and rainfall patterns. My own experiments have demonstrated that the Amazon forest is remarkably tolerant of drought and fire, partly because it is deeply-rooting and hard to burn[2,3,4]. Amazon forests can tap soil moisture stored to at least 12 meters depth. That is how they get through dry years. See this blog I wrote about these experiments. Luciana Alves Assistant Researcher, University of California, Los Angeles: First, I would like to say that the paper’s authors (Staal et al.) were very careful with the interpretation of their findings, always highlighting throughout the paper that the projections are a “first-order approach to provide useful insights”, and that they did not take into account other important factors affecting the distribution of tropical forests, specifically the ability of trees to cope with water stress by changing carbon allocation patterns and making adjustments to water-use efficiency due to increased CO2 and temperature. To run their models, the authors assumed all tropical forests are similar, i.e., their level of resilience to disturbance is the same, independent of distinct evolutionary histories[5], composition, and distribution of tree traits conferring resilience or resistance to strong disturbance events. Specifically, about the claim published in The Guardian piece that “As much as 40% of the existing Amazon rainforest is now at a point where it could exist as a savannah instead of as rainforest“, I believe it is an oversimplification. To be fair, I did not find that statement in the paper. Although the climatic conditions may not be stable to support rainforests, drier areas within tropical America are currently covered by tropical dry and transitional forests; most importantly, tropical dry forests actually occur in drier areas than savannas in South America[5,6]. The other claims: “Any shift from rainforest to savannah would still take decades to take full effect, but once under way the process is hard to reverse,” and “Rainforests are highly sensitive to changes in rainfall and moisture levels, and fires and prolonged droughts can result in areas losing trees and shifting to a savannah-like mix of woodland and grassland.” Yes, any shift will take decades to take effect, but it is not really clear for me why bi-stable states are not possible to be maintained in the paper’s modelling approach if one takes into account the other important factors mentioned above shaping the resilience of tropical forests. There are still open questions on the mechanisms driving changes in tropical forests in response to multiple stressors (such as climate change, fire and deforestation). Adam Pellegrini University Lecturer, University of Cambridge: The Staal et al. article raises interesting questions about the resilience (i.e., ability to recover from a disturbance) of tropical rainforests. Ultimately, however, we need experimental tests of the ability of forests to recover from extreme perturbations by drought and fire, which can take years to produce meaningful results. Consequently, we are left with much uncertainty about how tree communities may respond to a changing climate: species better equipped to tolerate drought and fire may colonize, and physiological adaptations like resprouting could assist in tree recovery (to just name a few factors). Undoubtedly trees will die in the future, and tropical forests are especially vulnerable to drought and fire; however, we know from fire experiments in savannas that when fire is excluded, forests can regrow, and they do so on the order of decades. Whether the ability of forests to regrow after fire will be hampered by climate change remains the golden question. UPDATES: 16 Oct. 2020: The details of this post were updated to clarify that the article is not misleading, but some statements could be misinterpreted by readers without additional context.

https://science.feedback.org/review/article-by-the-daily-caller-oversimplifies-drivers-of-wildfires-and-downplays-role-of-climate-change-chris-white/

-1

The Daily Caller, by Chris White, on 2020-09-13.

"Wildfires Will Become Worse Thanks To Decades-Old Liberal Policies, Says Fire Expert Who Predicted Uptick In Blazes"

1 – Stephens et al. (2005) Federal forest-fire policy in the United States. Ecological Applications. 2 – Gonzalez et al. (2018) Chapter 25: Southwest. In Impacts, Risks, and Adaptation in the United States: Fourth National Climate Assessment, Volume II. 3 – Steel et al. (2015) The fire frequency‐severity relationship and the legacy of fire suppression in California forests. Ecosphere. 4 – Donato et al. (2006) Post-wildfire logging hinders regeneration and increases fire risk. Science. 5 – Abatzoglou and Williams (2016) Impact of anthropogenic climate change on wildfire across western US forests. PNAS. 6 – Williams et al. (2019) Observed impacts of anthropogenic climate change on wildfire in California. Earth’s Future. 7 – Williams et al. (2014) Correlations between components of the water balance and burned area reveal new insights for predicting forest fire area in the southwest United States. International Journal of Wildland Fire. 8 – Anderson (2006) Chapter 17: The use of fire by Native Americans in California. Fire in California’s Ecosystems. 9 – Weber et al. (2020) Spatiotemporal trends in wildfires across the western United States. Remote Sensing. 10 – Littell et al. (2018) Climate change and future wildfire in the western United States: An ecological approach to nonstationarity. Earth’s Future.11 – Turner et al. (2011) Decadal trends in net ecosystem production and net ecosystem carbon balance for a regional socioecological system. Forest Ecology and Management.

Reviewers’ Overall Feedback: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: The causes of the increase in burned area in the western US in recent decades – and the record-setting fires of 2020 – are complex, driven by a mix of a changing climate, a 100-year legacy of overzealous fire suppression in forests adapted for frequent low-level fires, more people living in highly flammable wildland urban interface areas, and at times a counterproductive role of some environmental regulations. However, this article glosses over much of this complexity, presenting a simple but misleading narrative that land management rules enacted by the Clinton administration set the stage for the destructive fires we are experiencing today. In reality, the large fuel build up we have seen in some western forests dates from well before the Clinton administration. Restrictions on logging only play a minor role, as most forests were not regularly logged and traditional logging is not a particularly effective form of fuel management. Large, mature trees are at relatively low fire risk; the problem is smaller pre-commercial trees and undergrowth that can allow fires to burn hotter and reach into the canopy of larger trees. Cutting down mature trees in many cases exacerbates the growth of denser and less fire-resistant replacement vegetation. Thinning of smaller trees, brush removal, and controlled burns are the most effective means of fuel reduction, and historically the timber industry has had little involvement in these activities. At the same time, it is quite clear that a changing climate has played a large role in increasing fuel aridity and making conditions ripe for the severe fires we are experiencing today. The recent Fourth National Climate Assessment suggested that up to half the increase in burned area since the 1980s can be attributed to changing climate conditions, and recent work finds a clear link between climate change and increased burned area in the California Sierras[2,5,6]. While some uncertainties remain, this article highlights voices that are unrepresentative of the growing consensus among both climate and wildfire scientists on the role of climate in recent wildfire activity. It is clear that we need improved forest management – more thinning of pre-commercial trees, brush removal, and controlled burns – to reduce fuel loading in western US forests and make up for the US Forest Service’s misguided legacy of fire suppression. And there are certainly cases where environmental rules have gotten in the way of effective forest management and need to be streamlined. But blaming the increase in fire activity solely on environmental regulation is a misrepresentation that minimizes other important factors and ignores the complex history of forest management in the western US. The article paints recent fires in the western US as stemming from “Liberal” legislative efforts during the 1990s to protect old forests from unsustainable logging rather than from climate change. A large body of scientific research shows that year to year variability in regional burned area is strongly affected by summer air temperatures (see figure below). Figure—Correlation between annual forest burned area and maximum daily temperature anomalies during the summer months (June, July, and August) in the southwest US from 1984-2013. Adapted from Williams et al. (2014)[7]. Rising regional temperatures exponentially increase the atmospheric vapor pressure deficit (VDP), which causes forests to become drier and more flammable, contributing to the conflagrations currently observed in the region[5]. Other factors also contribute to this current problem, such as more people living and playing in urban-proximate forests, as well as a century of fire suppression leading to fuel accumulation in dry forests with historically frequent fire[1,2]. Nevertheless, climate change is a key driver of recent increases in fire activity across the western USA[2,5,6]. This article’s focus on criticizing liberal policies in general and President Clinton in particular does not do justice to this highly complex issue. Fire suppression in western forests has been pursued in earnest for roughly a century, long predating Clinton’s terms as president. Likewise, the 1973 Endangered Species Act (protecting the spotted owl and other forest-dwelling species) was signed by a Republican president. Policymakers of all affiliations have worsened (or failed to solve) the West’s difficult wildfire problems. The article does make some valid points, such as the fact that decades of fire suppression has created a dangerous disequilibrium in western forests with massive fuel loads of crowded trees and dense brush. The article is also on the right track in mentioning that logging could have (and may yet still) play a role in reducing this fuel load. But, like most of the article, this argument is oversimplified. Logging strategies differ depending on whether the goal is profit, fire prevention, wildlife habitat, or some combination thereof. Furthermore, many of the fire-prone areas in question are too rugged and remote for any commercially viable logging operation. The article’s statements about prescribed burns are generally correct but incomplete. Prescribed burning is now (belatedly) recognized as a crucial management tool that has been underutilized due to bureaucratic obstacles and lack of incentives. Unfortunately, it is not possible to fix the problem by immediately and drastically increasing annual prescribed burn acreage. Many forests are now too dense; prescribed burns would become infernos that destroy human life and property, leaving a charred wasteland instead of a clean forest floor. Although there is no clear way out of this conundrum, fire experts are actively working on it. Native American controlled burning techniques are receiving an overdue resurgence of interest[8]. The most problematic part of the article is the climate change section. It misleadingly says that “climate change has almost nothing to do with fire kindling gathering across the forest floors.” True, but that is not the point. Climate change dries out the fuel and increases air temperatures, making fires more likely to start, more likely to spread, and more likely to reach catastrophic intensities. This seems to be what happened when the Creek Fire in Fresno County suddenly exploded into a conflagration during the record-breaking heat wave of 6 Sep. 2020. Climate change may also gradually kill trees via direct effects (temperature, drought) or indirect effects (pests, pathogens), creating an even more flammable landscape. Experts do debate the relative contribution of poor forest management vs. climate change in creating the significant positive trend in acreage burned and numbers of large fires in recent decades in the West[9]. It’s not a simple or homogenous question, because fires in some forest types are more “fuel-limited” while fires in other forest types are more “climate-limited”[3]. But most peer-reviewed studies on this topic have identified climate change as an important factor over broad swaths of Western land area and vegetation types. For example, Abatzoglou and Williams (2016) estimated that climate change has already roughly doubled the acreage of forest fires in the Western US (comparing 1984-2015 to historical background levels)[5]. This trend is expected to accelerate: Littell et al. found that by 2040, “statistical climate‐fire models project large increases in area burned,” ranging from 43% to 240%, for the large majority of Western vegetation types. (Fuel-limited vegetation types, a minority of the total, were not expected to burn more)[10]. In conclusion, this Daily Caller article addresses an important topic in a superficial way, making some reasonable arguments but glossing over important details. The dismissal of climate change as a contributing factor to Western wildfires contradicts the best available evidence and appears to be politically rather than scientifically motivated. 1) The article neglects the voluminous literature that connects increased frequency of large fires, increased area burned, and increased fire severity to climate. 2) The article focuses on one ecosystem type (seasonally dry mixed conifer forests with mixed severity fire regimes) where the impact of climate change has been exacerbated by fuel accumulation due to fire suppression, and misleadingly conflates this one factor with the increase in large fire frequency, size and severity across the region in a diverse array of ecosystems that are not affected by fire suppression in the same way. It ignores that fire is increasing throughout the region, regardless of whether it is burning in ecosystems that have been changed by fire suppression or not. Many of the largest fires that are directly impacting communities in California and around the West are not burning in these seasonally dry forests. 3) The article conflates the effects of prescribed fire with the effects of logging on fuels. It ignores the fact that past logging focused on larger diameter trees, which are more profitable, rather than the removal of small diameter trees. Removing small diameter trees while leaving large diameter mature trees can enhance seasonally dry forests’ resilience to fire and other climate change impacts, and result in greater stability of their stored carbon, but is not usually profitable without significant public subsidies. Logging that maximizes removal of the most profitable timber can increase long term fire risk[4]. 4) The article ignores the fact that spotted owls became endangered because most of their old growth habitat had already been logged over. Today, the challenge is to get mechanical fuels treatments and prescribed fire onto the landscape at scale in ways that can enhance the resilience of owls and other species’ habitat to climate change. Annotations: The statements quoted below are from the article; comments are from the reviewers (and are lightly edited for clarity). Bob Zybach Bob Zybach works at the Heartland Institute, a conservative think-tank. According to PBS Frontline, “Few entities have worked harder to instill doubt in American minds about the science of climate change than the Heartland Institute.” Those numbers dropped between 1991 and 2000 and continued dropping The drop really began around 1988 (see figure below)[11]. Figure—Annual harvest removals in the Pacific Northwest region of the US from 1985 to 2007. From Turner et al. (2011)[11].They’ve gone and left hundreds of thousands of acres of burnt timber, a fire bomb waiting to happen, standing in place The suggestion here seems to be that burned areas should have been salvage logged to reduce the risk of future fire. A seminal study from southern Oregon found that salvage logging not only reduced seedling establishment, but importantly increased fine and coarse fuels on the ground, likely increasing fire risk[4]. Zybach is not convinced. “The lack of active land management is almost 100 percent the cause,” he told the DCNF, noting that climate change has almost nothing to do with fire kindling gathering across the forest floors. Other researchers share his skepticism. This statement is misleading. While climate change might not strongly affect the accumulation of “fire kindling,” it plays a huge role in how dry and flammable forests become during summer. A recent study published in the prestigious Proceeding of the National Academy of Sciences found: “Although numerous factors aided the recent rise in fire activity, observed warming and drying have significantly increased fire-season fuel aridity, fostering a more favorable fire environment across forested systems. We demonstrate that human-caused climate change caused over half of the documented increases in fuel aridity since the 1970s and doubled the cumulative forest fire area since 1984.” Also see this for further discussion on the topic: https://www.pnas.org/content/113/42/11649. Global warming may contribute slightly Again, Abatzoglou and Williams (2016) show that “Although numerous factors aided the recent rise in fire activity, observed warming and drying have significantly increased fire-season fuel aridity, fostering a more favorable fire environment across forested systems. We demonstrate that human-caused climate change caused over half of the documented increases in fuel aridity since the 1970s and doubled the cumulative forest fire area since 1984.”[5] Fuel aridity alone can explain about 75% of the year to year variability in burned area across the West and climate change is causing large parts of the region to become more arid.

https://science.feedback.org/review/climate-change-forest-management-and-several-other-causes-contribute-to-wildfire-severity-and-total-area-burned-in-the-western-united-states/

Misleading

Facebook, Facebook users, 2020-09-09

“Forest fires are caused by poor management. Not by climate change.”

Misrepresents a complex reality: The causes and behaviors of wildfires in the western US are influenced by a variety of factors, including weather conditions, climate change, past fire suppression practices, and an increase in the number of people living near wildlands. Incorrect: Scientific studies demonstrate clear links between climate change, hotter and drier conditions, and an increase in dry vegetative fuel load, drastically increasing the amount of forest fire area in the western US.

In addition to land management practices, the severity of wildfires in the western US is influenced by extreme heat, drought, and the amount of dry vegetative fuel, which are all linked to human-caused climate change. Climate change is not the only factor that affects fire behavior, but it is an important one. Since 1984, the forest fire area in the western US likely doubled due to climate change.

“Forest fires are caused by poor management. Not by climate change. While fire behavior is affected by weather and climate...fires around the state of California do not happen because of climate change; they are caused because of an unsustainable fuel load and failed environmental practices.”

1 – Abatzoglou et al. (2016) Impact of anthropogenic climate change on wildfire across western US forests. PNAS. 2 – IPCC (2014) Climate Change 2014: Summary: for Policymakers. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. 3 – National Academies of Sciences, Engineering, and Medicine (2016) Attribution of extreme weather events in the context of climate change. The National Academies Press. 4 – Diffenbaugh (2020). Verification of extreme event attribution: using out of-sample observations to assess changes in probabilities of unprecedented events. Science Advances. 5 – Swain et al. (2020) Attributing extreme events to climate change: A new frontier in a warming world. One Earth. 6 – Swain et al. (2018) Increasing precipitation volatility in twenty-first-century California. Nature Climate Change. 7 – Dong et al. (2019) Mechanisms for an amplified precipitation seasonal cycle in the U.S. west coast under global warming. Journal of Climate. 8 – Westerling. (2016) Increasing western US forest wildfire activity: sensitivity to changes in the timing of spring. Philosophical Transactions of the Royal Society B. 9 – Jolly et al. (2015) Climate-induced variations in global wildfire danger from 1979 to 2013. Nature Communications. 10 – Goss et al. (2020) Climate change is increasing the risk of extreme autumn wildfire conditions across California. Environmental Research Letters. NOTES This fact check is available at IFCN’s 2020 US Elections FactChat #Chatbot on WhatsApp. Clickhere, for more.

Review: The claim that the forest fires currently burning in the western United States are caused by poor forest management and not climate change appeared in multiple Facebook posts published in September 2020. While forest management practices, specifically fire suppression, have increased the fuel load, scientific evidence also links climate change to hotter and drier conditions, which increase the amount of dry vegetative fuel and the total area burned in the western US[1]. Forest management efforts like thinning and prescribed burns are important to restore forests to the lighter fuel loads that existed before the fire suppression policies of the 20th century, says Valerie Trouet, an associate professor at the University of Arizona. But climate change is also a key contributor to fire severity today. As described in Abatzoglou and Williams (2016), “human-caused climate change caused over half of the documented increases in fuel aridity since the 1970s and doubled the cumulative forest fire area since 1984” (see figure below)[1]. Figure—Western US forest fire area on a logarithmic scale compared to standardised fuel aridity, with data points during the 1984-1999 (blue dots) and 2000-2017 (red dots) periods highlighted. Map insert shows the western US forest areas. From Abatzoglou et al. (2016)[1]. Several states in the western US, including California, Oregon, and Washington, are currently experiencing extreme drought (see figure below). August was also the hottest month on record for California. These conditions, combined with strong winds, increased the severity of the current wildfires. In addition to climate and weather, factors such as past fire suppression (causing fuel accumulation over time) and people living in closer proximity to wildlands also influence wildfire behavior, as described by the reviewers below. For a more in-depth discussion of how climate change influences wildfires in California, see our 2018 post: A discussion with experts on California wildfire links to climate change. UPDATE (8 October 2020): Stossel TV claimed this review was inappropriately used to apply a “Missing Context” flag to their video on Facebook. This claim is based on a misrepresentation of our process, and of the assessments of the scientists who contributed to this review. For an explanation of how we rated their video, read our post published here. Scientists’ Feedback: Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: [Comment from a previous evaluation of a similar claim] The claims that climate plays no role in natural disasters and wildfires fly in the face of a large peer-reviewed scientific literature showing clear links between climate change and extreme heat events, drought, and extreme rainfall as well as links between hotter and drier conditions and wildfire areas burned in many regions of the world[2-5]. All three factors – buildup of vegetation due to fire suppression, more people living in the wildland-urban interface, and hotter and drier conditions have contributed to severe wildfires in regions like the western US in recent years. A 2016 study showed that climate change is responsible for over half the increase in fuel aridity (drier fuel load), and has doubled the cumulative forest area burned[1]. Rising average global temperatures have led to higher spring and summer temperatures, which in turn have led to earlier spring snowmelt. Further, there is evidence that climate change is causing winter rains to come later in autumn, and stop earlier in spring[6,7]. This is extending the area and time periods in which forests become combustible, and in parts of California, fire season is now 50 days longer than in 1979[8,9]. Stefan Doerr Professor, Swansea University: [Comment from a previous evaluation of a similar claim] Several global climate trends promote fire: increased temperature, frequency, intensity and/or extent of heatwaves, droughts and extreme winds. This is very well established and summarised in the IPCC (2014) report[2,3].Climate change has led to an increase in area burned in regions where fires burn more intensely and have a greater impact (e.g. western USA and Canada)[1,10]. Daniel Swain Climate Scientist, University of California, Los Angeles: [Comment from a previous evaluation of a similar claim] This is misleading and incorrect as stated. While the legacy of 20th century forest management policies, as well as urban incursion into the wildlands, are indeed relevant in some areas, research has shown that such non-climate factors cannot account for the enormous increase in area burned by wildfire both in the broader American West and California specifically. In fact, drying of vegetation due to climate change is responsible for about half of the observed increase in western U.S. forest fire area burned over the past several decades[1]. More specifically in California, observed warming and drying more than doubled the occurrence of extreme fire weather conditions between 1979 and 2018—a trend that is attributable to human-caused climate change[10].

https://science.feedback.org/review/western-us-wildfires-are-not-the-result-of-widespread-arson/

Inaccurate

We The Governed, Glen Morgan, 2020-09-10

a distressing number of the [West coast] fires are not accidents, and willful arson is the cause.

Factually Inaccurate: Rumors that the widespread wildfires burning in California, Oregon, and Washington were started by arsonists are unfounded and contradicted by documentation of other causes of ignition.

Recent wildfires on the West Coast have been ignited by a number of sources, including lightning, power lines, and even a smoke machine at a party. Their severity is the result of strong winds and intense drought driven by a dry summer and record warmth, which is part of an ongoing human-caused warming trend.

it appears that a distressing number of these fires are not accidents, and willful arson is the cause.

Rumors like this one have spread widely, accusing extremists and protestors of starting the fires that are currently burning across California, Oregon, and Washington. Some of these rumors cite isolated incidents like the arrest of a Washington man at a fire in the median of a divided highway, which was quickly contained. However, multiple authorities responding to fires have stated that reports of widespread arson are false rumors. In Oregon, the Portland office of the FBI posted a statement asking the public to “help us stop the spread of misinformation”. Reports that extremists are setting wildfires in Oregon are untrue. Help us stop the spread of misinformation by only sharing information from trusted, official sources. Reports that extremists are setting wildfires in Oregon are untrue. Help us stop the spread of misinformation by only sharing information from trusted, official sources. pic.twitter.com/ENc4c3kjep — FBI Portland (@FBIPortland) September 11, 2020 — FBI Portland (@FBIPortland) September 11, 2020 The Douglas County Sheriff’s Office similarly posted to its Facebook page: “Rumors spread just like wildfire and now our 9-1-1 dispatchers and professional staff are being overrun with requests for information and inquiries on an untrue rumor that 6 Antifa members have been arrested for setting fires in Douglas County, Oregon. This is not true! Unfortunately, people are spreading this rumor and it is causing problems.” The Jackson County Sheriff’s Office posted: “We are inundated with questions about things that are fake stories. One example is a story circulating that varies about what group is involved as to setting fires and arrests being made. This is not true! When official information about the investigation is available it will be on reputable government, fire and law enforcement internet sites and social media pages.” The Oregonian has reported that an arson investigation is underway for the Almeda fire in Oregon, but quotes the Ashland police chief as saying, “One thing I can say is that the rumor it was set by Antifa is 100% false information. We have some leads, and none of it points in that direction.” At a 15 September news conference, Clackamas County Sheriff Craig Roberts said,“I want the public to completely understand that our office has no intelligence or information about any group committing any crimes. No arrests have been made associated with any group.” Asked about rumors of people planting gas cans or cutting down power poles that had been confirmed to be false, Sheriff Roberts said, “Let me give you an example of how things get spun out of control: We had some good Samaritans that actually saw a gas can in a suspicious place that just happened to be left behind. Just on their own, they said, ‘You know what, I’m going to take this and put it in a place so nobody has access to it.’ They hid it, next thing you know, somebody saw them doing that, the thing became suspicious, I called in our terrorism task force folks, they tracked it down, and they’re actually good Samaritans that are delivering water to the fire folks to help, and they were trying to do just a good deed.” Another set of claims focuses on a 14 September arrest in Portland of a man suspected of using Molotov cocktails to start several brush fires along the freeway. All of these fires were quickly extinguished, and are unrelated to wildfires in the state. According to the Portland Police Bureau: “East Precinct officers were dispatched with Portland Fire and Rescue to a report of multiple fires burning along the west side of the I-205 freeway. Portland Fire and Rescue extinguished three of them while passing community members put out the other three. All were caught early. No one was injured and no structures were burnt.” Oregon’s Riverside Fire is currently listed on InciWeb as human-caused, but Portland’s KOIN news reported that the Clackamas County Sheriff stated, “There’s a lot of concern that different organized groups might be involved in setting these fires. I can tell you that we have no evidence of that and that’s why we want to make perfectly clear that we’re looking at each and every tip that comes in. At this point, we have nothing to substantiate that there’s any group that is out there setting fires.” Human ignitions include accidents related to abandoned campfires or sparks from vehicles or other machinery. The Whitney Fire in Oregon was started by a downed powerline. Causes of other major fires in Oregon and Washington have not been determined. In California, meanwhile, the largest fires started during dry lightning storms in mid-August. California’s Dolan Fire, which has burned over 120,000 acres, is an exception. The Monterey County Sheriff’s Office arrested a man near the location of that fire’s origin and he has been charged with arson on forest land, battery, and cultivating marijuana, although the cause of the fire has not yet been officially determined. While steps to prevent ignitions are important when wildfire risk is high, it’s the dry conditions that make fires possible and determine their potential intensity, with subsequent weather conditions (such as winds) also playing an important role in wildfire behavior. Just as attempted arson would be unsuccessful in a wet forest, any type of ignition can lead to a large wildfire when fuels are extremely dry. Wildfire outbreaks don’t typically correlate with a specific ignition type (excepting lightning storms) but rather with weather conditions amidst drought. Much of Northern California, Oregon, and Washington are currently in severe to extreme drought after a dry and warm summer. August, for example, was the warmest on record for California and the tenth warmest for Oregon. August in both states was among the 30 driest on record. Combined with recent unfavorable winds, these conditions are responsible for the severity of the current fires. Across the American West, fuel aridity—the measure of how dry vegetation is on the landscape—has been increasing over time due to warming temperatures.[1] To learn more about the relationship between climate change and fire behavior in California, specifically, read our 2018 post on this topic: A discussion with experts on California wildfire links to climate change. Additionally, some rumors have used US-only maps to argue that fires suspiciously stop at the US-Canada border or at the US-Mexico border. This is false, and satellite data show (see below) that there are several fires in southern British Columbia, as well. Additional information on active fires can be found on British Columbia’s wildfire dashboard. A much smaller area of Canada is currently experiencing drought conditions, limiting fire risk. 1- Abatzaglou and Williams (2016) Impact of anthropogenic climate change on wildfire across western US forests, PNAS UPDATES: 16 September 2020: This post was updated with additional details. 18 September 2020: This post was updated with additional details. NOTES This fact check is available at IFCN’s 2020 US Elections FactChat #Chatbot on WhatsApp. Clickhere, for more.

https://science.feedback.org/review/planting-trees-can-help-mitigate-some-aspects-of-climate-change-but-it-cannot-solve-all-environmental-crises/

Lacks context

8 Billion Trees, Pamela Anderson, 2020-08-23

“Trees provide a solution to almost all environmental crises we're facing. Trees reverse climate change by cleaning carbon from the air.”

Lack of context: Trees can absorb and store carbon, thus mitigating some effects of climate change, but tree planting alone cannot solve climate change because the amount of CO2 absorbed by forests is far less than the amount humans emit. As a result, tree planting needs to be complemented with other more effective solutions such as reducing fossil fuel emissions and avoiding deforestation. Misrepresents a complex reality: The effects of tree plantings as a climate solution vary depending on tree species, tree age, geographic location, and how efforts are implemented.

Trees provide a variety of ecosystem services, such as absorbing and storing carbon, that can help mitigate environmental crises and climate change. However, that alone is not sufficient to halt climate change. Reducing fossil fuel emissions and avoiding deforestation are necessary climate solutions, to which planting trees could provide additional benefits.

“Trees provide a solution to almost all environmental crises we're facing. Trees reverse climate change by cleaning carbon from the air.”

1 – Lewis et al. (2019) Comment on “The global tree restoration potential.” Science. 2 – Griscom et al. (2017) Natural climate solutions. PNAS. 3 – Griscom et al. (2020) National mitigation potential from natural climate solutions in the tropics. Phil. Trans. R. Soc. B. 4 – Holl et al. (2020) Tree planting is not a simple solution. Science. 5 – Korner (2017) A matter of tree longevity. Science. 6 – Friedlingstein et al. (2019) Global carbon budget 2019. Earth System Science Data. 7 – Nabuurs et al. (2013) First signs of carbon sink saturation in European forest biomass. Nature Climate Change. 8 – Fuss et al. (2018) Negative emissions—Part 2: Costs, potentials and side-effects. Environmental Research Letters. 9 – Chazdon et al. (2019) Restoring forests as a means to many ends. Science.

Review: Initiatives to plant trees as a climate solution have sprouted up around the world over the past few years. One of these initiatives, 8 Billion Trees, recently published a video on Facebook featuring Pamela Anderson claiming that “trees provide a solution to almost all environmental crises we’re facing.” While planting trees can help mitigate some ongoing environmental crises, reducing fossil fuel emissions and avoiding deforestation are the most important climate solutions, as described by the reviewers below[1-4]. For example, an assessment of natural climate solutions strategies in Latin America, Africa, and Asia found that protecting forests, peatlands, and mangroves provided twice the climate mitigation potential as reforestation efforts (see figure below). From Griscom et al. (2020)[3]. The video also claims that “trees reverse climate change by cleaning carbon from the air.” Trees remove carbon from the air as they grow and can store carbon for long periods of time, however they only absorb a fraction of the carbon emitted by humans each year[5], and as such, it is incorrect to say that this approach can “reverse” climate change. “Global fossil fuel emissions totaled about 9.5 Gt C per year from 2009-2018, while Earth’s land ecosystems (i.e., forests, grasslands) sequestered about 3.2 Gt C per year from the atmosphere[6],” said Logan Berner, Assistant Research Professor at Northern Arizona University. “Thus, burning fossil fuels emitted about three times as much carbon each year as was taken up by all of Earth’s land ecosystems!” In addition, the amount of carbon sequestered by forests saturates over time and varies depending on tree species, tree age, and geographic location, as well as numerous other factors[2,4,7,8]. Although trees provide a variety of ecosystem services by stabilizing soil, preventing flooding, and creating and connecting habitat for a broad range of species[2,4], they can only mitigate some effects of climate change, not “reverse” or address “all environmental crises”, as claimed in the video. Tree plantings can also fail to deliver their intended climate benefits if efforts are not effectively designed, implemented, or monitored properly over time, as the reviewers describe below. Scientists’ Feedback: Erle Ellis Professor, University of Maryland, Baltimore County: [Comment from a previous evaluation of a similar claim] Tree growth can only slow down carbon accumulation in the atmosphere, not stop it. Ultimately, the only solution to climate change is to stop burning fossil fuels, which in turn requires a transition to inexpensive clean energy. Karen Holl Professor, University of California, Santa Cruz: [Comment from a previous evaluation of a similar claim] As Dr. Brancalion and I discuss in our brief article and a subsequent article that is currently in review, increasing tree cover is part of the solution to climate change but it is just one piece of the puzzle[4]. The most important steps are first reducing greenhouse gas emissions and second protecting existing forests and other high carbon storage ecosystems (e.g. wetlands). A few key points here: First, planting trees is not going to solve the problem of climate change if we don’t reduce greenhouse gas emissions. As temperatures rise and precipitation patterns change, large areas are becoming unsuitable habitat for trees due to direct water stress and indirectly through fires and insect outbreaks. Moreover, some existing forests are slowing in their capacity to uptake carbon[7]. Second, it is important to protect existing forests first. Existing forests, rain forests in particular, store large amounts of carbon both above- and below-ground. As a restoration ecologist who has spent over 25 years studying how to restore forests, I know that it is nearly impossible to restore exactly what was there before, and it makes much more ecological and economic sense to protect existing forests so that should be the priority. Yet, large scale forest clearing continues worldwide. For example, in the U.S. the Trump administration is proposing to allow logging in the Tongass National Forest, at the same time that they have expressed support for the Trillion Trees Act. Temperate rain forests store huge amounts of carbon. Likewise, in Brazil there are extensive efforts to restore the Atlantic forest ecosystem in southeastern Brazil at the same time that deforestation and forest fires have increased substantially in the past couple of years. Efforts should focus on reducing the drivers of deforestation and enforcing existing legislation that protects forest. Third, it is important to distinguish between tree planting and increasing tree cover or forest cover. Many forests are able to recover on their own if degrading factors are removed, so often it is not necessary to plant trees[9]. Allowing for natural recovery should be the first option for restoring forests, as it is more ecologically and economically sound. If it is necessary to plant trees either due to slow recovery or for socioeconomic reasons then the focus should be on restoring tree cover over the long-term. Many of these large-scale planting schemes focus on the number of trees put in the ground without considering who is going to care for and monitor the trees and whether the social conditions are in place for the trees to not be cleared. This has led to many massive tree planting failures. It also means that the cost of planting trees is substantially underestimated. The cost needs to include not only growing the seedling, digging the hole and planting the tree, but management such as clearing competitive vegetation and monitoring the outcomes of tree planting over the longer term. [Comment from a previous evaluation of a similar claim] The carbon sequestered in existing forests is far, far larger than planted trees, which further emphasizes that stopping deforestation should probably be a much higher priority than planting new forests. In addition, it will take decades for planted trees to store substantial amounts of carbon, which means that tree planting solutions are not a fast climate solution. By contrast, any effort that reduces fossil fuel or deforestation emissions are immediate climate solutions that benefit the atmosphere today and in the future. READ MORE Climate Feedback published an insight article exploring the potentials and limitations of tree planting as a climate solution.

https://science.feedback.org/review/article-by-cnn-exaggerates-studys-implications-for-future-greenland-ice-loss/

-1

CNN, by Brandon Miller, Max Claypool, on 2020-08-14.

"Greenland's ice sheet has melted to a point of no return, according to new study"

1 – King et al. (2020) Dynamic ice loss from the Greenland Ice Sheet driven by sustained glacier retreat. Communications Earth & Environment.2 – Aschwanden et al. (2019) Contribution of the Greenland Ice Sheet to sea level over the next millennium. Science Advances. 3 – Pattyn et al. (2018) The Greenland and Antarctic ice sheets under 1.5 °C global warming. Nature Climate Change. 4 – Horton et al. (2020) Estimating global mean sea-level rise and its uncertainties by 2100 and 2300 from an expert survey. npj Climate and Atmospheric Science.

Reviewers’ Overall Feedback: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Stefan Rahmstorf Professor, Potsdam University: While most of this article is correct, I have to give it a low credibility rating because the attention-grabbing headline conclusion is not supported by the study the article is about: “Greenland’s ice sheet has melted to a point of no return, and efforts to slow global warming will not stop it from disintegrating.” What the paper actually finds is well described in its press release: “Even if humans were somehow miraculously able to stop climate change in its tracks […] the ice sheet would continue to shrink for some time.”[1] The key phrase here is “for some time”. Based on the study, I conclude that the time scale meant here is decades, maybe a century. However, complete loss of the ice sheet would take about a millennium even with unmitigated warming, and the process which decides over the complete ice loss is surface melt—not the ice discharge by glaciers flowing into the ocean at the margins of the ice sheet, which the study is about. When the ice sheet shrinks, it will withdraw further and further from the coast and ice discharge into the ocean will become less important. This is shown by model simulations that continue all the way until complete ice loss. The study reported on here is an observational study looking at ice flow changes in the past decades, not a model projection for future ice loss. It does not provide evidence about the eventual fate of the Greenland ice sheet. The impression given by many media articles, namely that the Greenland ice sheet is already doomed to be lost completely, is not supported by the evidence in the paper. While the concern about Greenland ice loss is certainly very serious and justified, the conclusion that it is already doomed is an over-interpretation of the results of this study. Twila Moon Research Scientist, University of Colorado, Boulder: The article correctly notes most measurements and facts and figures. However, it fails to provide nuance in critical areas regarding how quickly ice may be lost, whether this is a new scientific insight, and the role of human climate action in determining the future of Greenland ice loss (and associated sea level rise). Luke Trusel Assistant Professor, Pennsylvania State University: Greenland ice sheet melt and its discharge of ice into the ocean has increased over the last few decades, making it one of the largest contributors to global sea level rise. This is important and concerning, and there’s a clear human fingerprint on Greenland ice sheet mass trends. The referenced study by King and coauthors represents important new observations of Greenland’s mass loss and the large increases that have recently occurred[1]. However, the CNN article’s suggestion that Greenland has passed a tipping point is not well established. For example, a paper published in Nature Climate Change in 2018 by Pattyn and coauthors found that the tipping point (that is, the point where potentially irreversible change is set in motion) would be in the neighborhood of 1.5 to 2°C warming above pre-industrial[3]. We’re close, but not quite there yet. In my opinion, the most important point that is missing in the article is that our emissions trajectories *right now and in the next few decades* are critical for determining the rates and magnitudes of mass loss and sea level contributions from the Greenland ice sheet. Lower emissions mean a lower likelihood of reaching a tipping point, as well as lower amounts of warming in the atmosphere and ocean. Less warming means lower rates of mass loss from the Greenland ice sheet and enables greater opportunity for humans to respond to changing sea levels[3]. Annotations: The statements quoted below are from the article; comments are from the reviewers (and are lightly edited for clarity). melted to a point of no return, and efforts to slow global warming will not stop it from disintegrating Stefan Rahmstorf Professor, Potsdam University: While the Greenland ice sheet is certain to shrink further even without further warming, it is not at all clear whether it has crossed the point where it will be lost completely. The new study by King et al. has not examined this issue and does not say anything about it[1]. Neither does their press release, which states: “Even if humans were somehow miraculously able to stop climate change in its tracks […] the ice sheet would continue to shrink for some time.” It does not say “until it’s gone.” Twila Moon Research Scientist, University of Colorado, Boulder: It is correct that there is no longer a reasonable scenario in which the Greenland Ice Sheet is fully stabilized or gains significant ice. However, this statement ignores the very important matter of how quickly ice is lost. An excellent recent study by Aschwanden et al. demonstrates what a dramatic difference there is in ice loss under a low emissions scenario v. a high emissions scenario[2]. The critical matter right now (which has already been understood by glaciologists for some time) is not whether or not we lose ice from Greenland but how quickly ice is lost. dumps more than 280 billion metric tons of melting ice into the ocean each year Twila Moon Research Scientist, University of Colorado, Boulder: Yes, this is accurate. The Greenland Ice Sheet began consistently losing ice year-after-year around the turn of the 21st century and this number is close to the recent average for annual ice loss. greatest single contributor to global sea level rise Twila Moon Research Scientist, University of Colorado, Boulder: Scientists may quibble over this. Glaciologists usually divide Earth’s ice into 3 categories: Greenland Ice Sheet, Antarctic Ice Sheet, all other glaciers/ice caps. The amount of ice lost annually from Greenland is now very similar to that lost each year from the “all other glaciers/ice caps” category. it has caused a measurable change in the gravitational field over Greenland Twila Moon Research Scientist, University of Colorado, Boulder: Measuring changes in gravity is one important method used to determine how much ice is lost (or gained). There actually does not need to be a large change in ice mass for it to create a measurable change in the gravitational field. So it is a bit misleading to suggest that “measurable change in the gravitational field” is synonymous with “massive” ice loss. It is not. But it IS true that Greenland has lost a lot of ice in recent years. In fact, 2012 and 2019 both set records for ice loss within the historical record. Sea levels are projected to rise by more than 3 feet by the end of the century Stefan Rahmstorf Professor, Potsdam University: This is only true under a very high global warming scenario (about 4 °C global warming by 2100). For a mitigation scenario in line with the Paris agreement, experts expect a likely range of 30-65 cm rise by 2100 (relative to 1986–2005). See Horton et al. 2020[4]. Coastal states like Florida, and low-lying island nations are particularly vulnerable. Just 3 feet of sea level rise could put large areas of coastline underwater Stefan Rahmstorf Professor, Potsdam University: This is a completely valid concern. Rising seas already cause major problems and this will get ever worse during the course of this century. The question of whether the Greenland Ice Sheet is doomed to disappear completely in the end or eventually stabilizes at a smaller size concerns the very long term; it has no bearing on what happens in this century. Twila Moon Research Scientist, University of Colorado, Boulder: It’s useful to note that sea levels will not rise the same everywhere. Some coastal locations will experience much more or less sea level rise than the global average. For example, the U.S. Gulf Coast will experience more sea level rise than the global average. the ice sheet is retreating in rapid bursts, leading to a sudden and unpredictable rise in sea levels, making it difficult to prepare for the effects Twila Moon Research Scientist, University of Colorado, Boulder: I do not agree with this statement. Ice sheet edge retreat is not a direct measure of ice mass loss. Even if ice edge retreat happens in bursts, we cannot determine from that measure how much total ice will be lost each year. Also, sea level rise is the result of a combination of changes that include land ice melt, ocean heat causing ocean volume to increase, and local vertical land motion. I would argue that the current spread in future projections of sea level rise is not highly influenced by Greenland glacier retreat rates. Entire coasts of ice are retreating at once due to climate change Twila Moon Research Scientist, University of Colorado, Boulder: Correct. There is widespread retreat of the ice edge around all of the Greenland Ice Sheet. This is well documented.

https://science.feedback.org/review/the-long-term-survival-of-polar-bears-is-threatened-by-loss-of-sea-ice-due-to-global-warming-new-study-confirms-henry-fountain/

Correct

The New York Times, Henry Fountain, 2020-07-20

"Global warming is driving polar bears toward extinction"

Correct: Sea-ice loss due to global warming is threatening polar bear survival and reproduction according to numerous studies and recently confirmed in a new scientific article forecasting sea ice extent for different CO2 emissions scenarios.

Sea-ice loss due to global warming is the most important threat to long-term survival and reproduction of polar bears. Under a high greenhouse gas emissions scenario, all but a few polar bear subpopulations are at risk of extinction by 2100. In the moderate greenhouse gas emissions scenario, some polar bear subpopulations could persist through the century.

"Global warming is driving polar bears toward extinction. Polar bears could become nearly extinct by the end of the century as a result of shrinking sea ice in the Arctic if global warming continues unabated."

1 – Molnar et al. (2020) Fasting season length sets temporal limits for global polar bear persistence. Nature Climate Change. 2 – Stirling et al (2018) Effects of climate warming on polar bears: a review of the evidence. Global Change Biology. 3 – Stern et al (2016) Sea-ice indicators of polar bear habitat. The Cryosphere. 4 – Bromaghin et al (2015) Polar bear population dynamics in the southern Beaufort Sea during a period of sea ice decline. Ecological Applications. 5 – Lunn et al (2016) Demography of an apex predator at the edge of its range: impacts of changing sea ice on polar bears in Hudson Bay. Ecological Applications. 6 – Regehr et al (2010) Effects of earlier sea ice breakup on survival and population size of polar bears in Western Hudson Bay. The Journal of Wildlife Management. 7 – Obbard et al (2016) Trends in body condition in polar bears (Ursus maritimus) from the Southern Hudson Bay subpopulation in relation to changes in sea ice. Arctic Science. 8 – Hamilton et al (2014) Projected polar bear sea ice habitat in the Canadian Arctic Archipelago. PLoS One. 9 – Castro de la Guardia et al (2013) Future sea ice conditions in western Hudson Bay and consequences for polar bears in the 21st century. Global Change Biology. 10 – Regehr et al (2016) Conservation status of polar bears (Ursus maritimus) in relation to projected sea-ice declines. Biology Letters. 11 – Stirling et al (1999) Long-term trends in the population ecology of polar bears in western Hudson Bay in relation to climatic change. Arctic. 12 – Pilfold et al (2016) Mass loss rates of fasting polar bears. Physiological and Biochemical Zoology. 13 – Durner et al (2017). Increased Arctic sea ice drift alters adult female polar bear movements and energetics. Global Change Biology. 14 – Smith et al (1975) The breeding habitat of the ringed seal (Phoca hispida). The birth lair and associated structures. Canadian Journal of Zoology. 15 – Stirling et al (2004) Implications of warm temperatures and an unusual rain event for the survival of ringed seals on the coast of Southeastern Baffin Island. Arctic. 16 – Stirling (2002) Polar bears and seals in the Eastern Beaufort Sea and Amundsen Gulf: a synthesis of population trends and ecological relationships over three decades. Arctic. 17 – Kingsley (1979) Fitting the von Bertalanffy growth equation to polar bear age–weight data. Canadian Journal of Zoology. 18 – Theimann et al (2008) Polar bear diets and arctic marine food webs: insights from fatty acid analysis. Ecological Monographs. 19 – Laidre et al (2018) Historical and potential future importance of large whales as food for polar bears. Frontiers in Ecology and the Environment.

Review: The claim has appeared in multiple media outlets, including The New York Times, The Guardian, BBC, Forbes, and Time, and has been shared on Facebook more than 18,000 times in total, according to Crowd Tangle. The claim is based on a study published July 2020 that projected range-wide declines in polar bear subpopulations under moderate and high greenhouse gas emissions scenarios due to losses of sea-ice habitat[1]. The article in The New York Times accurately describes results from this study. Sea-ice loss is currently the most important threat to the long-term survival of polar bears[2,3]. Polar bears rely on sea ice to feed on seals (their primary prey), mate, establish dens, and move throughout their range[2,3]. During the summer, sea-ice melt forces polar bears ashore where they often fast for months at a time due to inadequate food supplies[1]. While polar bears have energy reserves that facilitate their survival and ability to recruit cubs (i.e., lactation) during these fasts, body reserves are also limited[1]. Loss of sea-ice habitat has already led to lower survival, reproduction, and body condition in some polar bear subpopulations, including the southern Beaufort Sea, Western Hudson Bay, and Southern Hudson Bay populations[4-7]. To estimate how and when sea-ice loss will impact survival and reproduction in 13 polar bear subpopulations, Molnár et al. (2020) calculated how long polar bears could fast before adult survival and cub recruitment rapidly declined. Although data about how sea-ice loss affects population demographics is limited for most subpopulations, Molnár et al. used data from a subpopulation (Western Hudson Bay) as a baseline because it already experienced extended periods of fasting as a result of sea-ice declines (see figure below). Figure—Annual extent of sea ice in the Western Hudson Bay polar bear subpopulation derived from PMW data. Gray lines represent the daily extent of sea ice each year from 1979 – 2016 measured by satellite observations. Colored curves represent the means of the daily extent, with each color capturing a different time period: 1979-1988 (blue), 1989-1999 (green), 2000-2009 (yellow), and 2010-2016 (red). The study authors then calculated the energy needs of fasting polar bears for 13 subpopulations based on this baseline, while using sensitivity analyses to account for uncertainties and differences among subpopulations[1]. Molnár et al. then estimated losses of sea ice under moderate and high greenhouse gas emissions scenarios (RCP4.5 and RCP8.5, respectively) to project when declines in adult female and male survival and cub recruitment passed critical thresholds. As described in the study, “with high greenhouse gas emissions, steeply declining reproduction and survival will jeopardize the persistence of all but a few high-Arctic subpopulations by 2100. Moderate emissions mitigation prolongs persistence but is unlikely to prevent some subpopulation extirpations within this century,” (see figure below)[1]. Figure—Timelines of risk for when cub recruitment and adult survival of male and female polar bears will begin declining in 13 subpopulations across the species range. Subpopulations are listed along the y-axis and colored by ecoregion. Effects on adult female survival (orange), adult male survival (blue), and cub recruitment (magenta) are shown for each subpopulation under moderate (a) and high (b) greenhouse gas emissions scenarios. As the reviewers explain below, The New York Times article accurately describes results from this study. In addition, this study is consistent with previous scientific studies predicting declines in polar bear subpopulations with continued loss of sea ice due to global warming[8-13]. Scientists’ Feedback: The article is accurate and summarizes our findings very well. I only have one extremely minor comment, which doesn’t affect the overall accuracy of this article. In the second paragraph, the author writes that “the loss of sea ice would force the animals onto land and away from their food supplies for longer periods”. In some cases (e.g. the Beaufort Sea populations), the animals may choose not to go on land but instead follow the ice as it retreats over the Arctic Basin. As these are deep, dark, unproductive waters, the effect is therefore the same as going on land (food-deprivation), and this omission does not affect the overall accuracy of the article. I read the NYT article and thought it represented the findings well. Andrew Derocher Professor, University of Alberta: The statement of “nearly extinct” is consistent with the findings of Hamilton et al. (2014) which stated “Under business-as-usual climate projections, polar bears may face starvation and reproductive failure across the entire Archipelago by the year 2100.”[8] Further, the study concluded with “Nevertheless, by 2100 all regions of the study area may cross the critical point-of-no-return, putting the persistence of the CAA [Canadian Arctic Archipelago] polar bear populations in jeopardy.” This study examined the Canadian Arctic Archipelago populations where sea ice is expected to persist the longest. Castro de la Guardia et al. (2013) examined sea ice in Hudson Bay and that study stated “Our predictions suggest that the habitat of polar bears in WH [Western Hudson Bay] will deteriorate in the 21st century. Ice predictions in A1B [medium greenhouse gas emissions] and A2 [high greenhouse gas emissions] suggest that the polar bear population may struggle to persist after ca. 2050. Predictions under B1 [low greenhouse gas emissions] suggest that reducing GHG emissions could allow polar bears to persist in WH throughout the 21st century.”[9] Thus, the Molnár et al. study is supported by both Hamilton et al. (2014) and Castro de la Guardia et al. (2013)[1,8,9]. The time frame and approach in these two studies is similar to that of Molnár et al. and use a fasting duration limit relative to sea ice loss estimation. Regehr et al. (2016) stated “The estimated probabilities that reductions in the mean global population size of polar bears will be greater than 30%, 50% and 80% over three generations (35–41 years) were 0.71 (range 0.20–0.95), 0.07 (range 0–0.35) and less than 0.01 (range 0 – 0.02), respectively.”[10] Given that Molnár et al. consider a much longer timeframe and that it considers a severe climate change scenario (RCP 8.5) as the upper bound, the study is consistent with Regehr et al. (2016). They also examined a lower climate change scenario (RCP 4.5), which shows impacts on polar bears that would be consistent with projected changes noted by Regehr et al. (2016).[1,10] The statements about extended fasting, shorter feeding period, and traveling more, are consistent with the broader literature addressed in the review by Stirling and Derocher (2012) and both empirical and projection studies by Stirling et al. (1999), Lunn et al. (2016), Pilfold et al. (2016), and Durner et al. (2017)[11,5,12,13]. In summary, I find that the statement is consistent with the published work being addressed and that the statement overall is consistent with the broader peer-reviewed literature on polar bears. Ian Stirling Adjunct Professor, University of Alberta: Overall, I would say Molnar et al. 2020 should be regarded as scientifically correct, quantitative in terms of the data analyzed, and analytically supported[1]. I started and maintained the long-term monitoring of the polar bear population in Western Hudson Bay (WH). My early results were clear enough by the late 1990s for the analyses to be the first to confirm the negative effects of climate warming on polar bears. WH is the longest continuous data base on the effects of climate warming on polar bear abundance, survival, and reproduction anywhere in the Arctic. When I initially started the long-term monitoring of polar bears there it was because I wanted to learn more about the amount of natural variation inherent in the polar marine ecosystem because of its obvious importance to conservation practises. I had already seen the results of large scale interannual changes in the ecosystem on polar bears and ringed seals in the Arctic (Beaufort Sea) and on Weddell seals in the Antarctic and those experiences were enough to convince me that understanding more about natural fluctuations in the ecosystem was something we really needed to know a lot more about. It was only by the mid-1990s (the period identified by Molnar) that we began to realize from our data that something else was going on besides possible natural cycles and, because we had a long-term database, and the ability to continue the monitoring, that we were able to identify and confirm what was happening because of climate warming. I think it is fair to say that the physiological parameters with respect to reproduction and body condition, etc. measured in WH could be reasonably applied to polar bears elsewhere. What such focused models projecting into the future do not take into account overall though of course is that the whole arctic marine ecosystem (and the interrelationships of all species) is changing because of climate warming and the speed of such changes will likely accelerate as time progresses so exactly what might happen specifically to polar bears as an icon species becomes more difficult to predict precisely the farther out we get. That said, the modelling approach remains invaluable for what it clearly indicates is coming our way soon, regardless. I think a major strength of the Molnar paper is that it correctly assesses the populations (for which there are sufficient data) independently rather than as a single world population[1]. That appears to be the major weakness in the Hamilton et al. (2014) paper, which comes to the same conclusion as Molnar (see their Conclusion: s/Significance statement) but is based mainly only on bears in the Canadian Arctic Archipelago and treats the subpopulations resident there as a single population and not as several independent populations[8]. Still, the fact that these two papers basically come to a more or less identical conclusion, via different routes and levels of analysis is interesting. While I think the Molnar paper is quite correct overall, I think it overlooks two important ecological situations which don’t weaken their overall conclusions but could have given them a bit more ecological depth of understanding of some important qualifications for some populations and might have been important to include, though the space restrictions in journals like Nature might preclude doing so. In my opinion, a common flaw in almost all (if not all) the big overview papers that predict bears having problems loss of ice because of climate warming and then becoming extinct, or nearly so, by some date is that they tend to make a 1:1 relationship between the area of ice and its decline and the subsequent decline in the bears for nutritional reasons. However, ecologically, the relationship is much more complicated and geographically variable than a simple 1:1 relationship. Ringed seals, which are the major food source of polar bears throughout their range are reliant on having hard wind blown snow over the breathing holes of the adult females in their prime breeding habitat for giving birth to their young[14]. With the warmer weather and rain that will appear in most areas, probably at significantly increased levels well before 2100, the devastating decline in ringed seal reproduction and survival will have an immediate negative effect on the bears’ nutrition, survival, and reproduction[15]. We already know that reproductive failure of ringed seals (as seen on decadal scale intervals in the southern Beaufort Sea[16]) causes immediate and very strong negative effects on reproduction and survival of young polar bears as well as lowering the body condition in adults[17]. If such levels of loss of ringed seal pups is significant because of climate for several years in some populations, the negative effects on the bears there will be significant. Also, there are major differences in the availability of different prey species for polar bears in different populations[18]. In particular, the role of some of these prey species to provide carrion in some populations that could help a smaller number of bears survive for a protracted period has been overlooked. For example, the potential for walrus populations (which will be less negatively impacted by climate warming in some areas) to provide a long-term potential food source, at predictable locations, for both predation and scavenging in several areas. Similarly, where whale carcasses resulting from natural mortality occur in predictable locations, they may provide a long-term food source for bears in areas such as Chukotka[19].

https://science.feedback.org/review/greenhouse-gases-cause-global-warming-by-trapping-infra-red-radiations-not-by-causing-more-holes-in-the-ozone-layer/

Incorrect

Instagram, Otis Holland, 2020-07-11

Greenhouse gases emitted into the ocean are causing more holes in the ozone layer … “the ozone layer has holes in it causing global temperature to rise”

Incorrect: Global warming is caused by anthropogenic emissions of greenhouse gases, particularly CO2, which trap infra-red radiation and cause the atmosphere to retain heat, not by greenhouse gases creating holes in the ozone.Factually inaccurate: Chlorofluorocarbons, halons, and other ozone-depleting substances cause holes in the stratospheric ozone layer, not the greenhouse gas CO2, which was referred to in the post by stating it is emitted into the ocean. Ozone-depleting substances were limited in 1987, preventing the formation of more and deeper holes in the ozone.

It is a common misconception that Global Warming would be due to holes in the ozone layer caused by Greenhouse gases (GHG). Instead, GHGs warm the Earth’s surface by trapping infra-red radiations, limiting the natural process by which the Earth’s surface cools. Holes in the stratospheric ozone layer are caused by anthropogenic emissions of chlorofluorocarbons (CFC), halons, and other ozone-depleting substances. Reductions in ozone-depleting substances due to the Montreal Protocol have prevented the formation of more and deeper ozone holes.

“the green house gasses that have been emitted into the ocean over that last 150 years would still be releasing slowly and causing more and more holes in the ozone layer as time goes on … the ozone layer has holes in it causing global temperature to rise. It would be so easy to plant a small tree of keep plants in you house or in your garden. This could create more oxygen and build up the ozone layer. ”

1 – IPCC (2014) Climate Change 2014: Summary for Policymakers. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. 2 – World Meteorological Organization (2018) Executive Summary: Scientific Assessment of Ozone Depletion: 2018. Global Ozone Research and Monitoring Project–Report No. 58. 3 – World Meteorological Organization (2018) Chapter 5: Stratospheric ozone changes and climate. Global Ozone Research and Monitoring Project–Report No. 58. 4 – Banerjee et al. (2020) A pause in Southern Hemisphere circulation trends due to the Montreal Protocol. Nature. 5 – Solomon et al. (2016) Emergence of healing in the Antarctic ozone layer. Science. 6 – Morgenstern et al. (2008) The world avoided by the Montreal Protocol. Geophysical Research Letters. 7 – Kroeger et al. (2014) Reforestation as a novel abatement and compliance measure for ground-level ozone. PNAS.

Review: The claim appeared in an Instagram post published by Otis Holland in July 2020. The post states that greenhouse gases that are emitted into the ocean, referring to CO2[1], cause holes in the ozone. Contrary to the claim, stratospheric ozone depletion is caused by anthropogenic emissions of chlorofluorocarbons (CFCs), halons, hydrochlorofluorocarbons, and other ozone-depleting substances[2]. These long-lived substances, which are found in aerosol spray cans, refrigerants, and industrial pollutants, break down ozone molecules causing holes in the ozone layer. While ozone can affect climate, the rise in global temperature is the result of human-caused emissions of CO2, methane, nitrous oxide, and other greenhouse gases that trap and re-emit infra-red radiation, not by causing holes in the ozone layer as claimed (see figure below)[1,3,4]. Figure—The estimated role of different factors influencing global surface temperatures from 1850 to 2017. Observed temperatures are shown in black dots. Global warming over the past 150 years was primarily driven by greenhouse gas emissions (red), not ozone (purple). From Carbon Brief. Contrary to the claim that holes in the ozone layer will become more prevalent over time, scientific studies have found that the Antarctic ozone is recovering[4,5]. According to the 2018 WMO/UNEP Scientific Assessment of Ozone Depletion, global and Antarctic ozone concentrations are projected to recover to 1960 levels by the end of the century, assuming future compliance with the Montreal Protocol, which limits the use of ozone-depleting substances (see figure below)[2]. Figure—Comparisons of total ozone observations (red points and lines) and chemistry climate models (black lines with grey regions showing uncertainty) for the globe (top) and Antarctic (bottom). Annual global total ozone is averaged over 60°N to 60°S latitudes, whereas Antarctic total ozone is averaged over 60°S to 80°S latitudes. Models project that ozone concentrations will return to levels observed in the 1960s by 2100, assuming future compliance with the Montreal Protocol. Black lines with arrows indicate the years that ozone abundances are projected to return to values observed in 1980. Adapted from World Meteorological Organization (WMO) Executive Summary: Scientific Assessment of Ozone Depletion (2018)[2]. In 1987, the United Nations passed an international treaty, the Montreal Protocol, to limit the use of CFCs and other ozone-depleting substances[6]. Models of the Arctic ozone demonstrate that the Montreal Protocol has prevented the formation of a deeper ozone hole, as well as additional holes (see figure below). Figure—Observed and modeled column ozone in the Arctic. Satellite observations from the Ozone Monitoring Instrument in March 2011 (a). Models of Arctic Ozone show projected changes in the ozone with (b) and without (c) the Montreal Protocol. From World Meteorological Organization (WMO) Executive Summary: Scientific Assessment of Ozone Depletion (2018)[2]. While planting trees in your house or garden to increase oxygen can potentially influence ground-level ozone, this approach will not alter stratospheric ozone on human life timescales[7]. Overall, the claim does not accurately describe the mechanism of global warming or the causes and trends of ozone depletion.

https://science.feedback.org/review/article-by-michael-shellenberger-mixes-accurate-and-inaccurate-claims-in-support-of-a-misleading-and-overly-simplistic-argumentation-about-climate-change/

-1

Forbes, by Michael Shellenberger, on 2020-06-28.

"On Behalf Of Environmentalists, I Apologize For The Climate Scare"

1 – IPCC (2014) Climate Change 2014: Summary: for Policymakers. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. 2 – National Academies of Sciences, Engineering, and Medicine (2016) Attribution of extreme weather events in the context of climate change. The National Academies Press. 3 – Diffenbaugh (2020). Verification of extreme event attribution: using out of-sample observations to assess changes in probabilities of unprecedented events. Science Advances. 4 – Swain et al. (2020) Attributing extreme events to climate change: A new frontier in a warming world. One Earth. 5 – Ceballos et al. (2015) Accelerated modern human–induced species losses: Entering the sixth mass extinction. Science Advances. 6 – Dirzo et al. (2014) Defaunation in the Anthropocene. Science. 7 – Young et al. (2016) Patterns, causes, and consequences of Anthropocene defaunation. Annual Review of Ecology, Evolution, and Systematics. 8 – Ceballos et al. (2017) Biological annihilation via the ongoing sixth mass extinction signaled by vertebrate population losses and declines. PNAS. 9 – Stona et al. (2018) Co-extinctions annihilate planetary life during extreme environmental change. Scientific Reports. 10 – IPBES (2018) The IPBES assessment report on land degradation and restoration. 11 – Barnosky et al. (2011) Has the Earth’s sixth mass extinction already arrived? Nature. 12 – Urban (2015) Accelerating extinction risk from climate change. Science. 13 – Barnosky et al. (2012) Approaching a state shift in Earth’s biosphere. Nature. 14 – Wake and Vredenburg (2008) Are we in the midst of the sixth mass extinction? A view from the world of amphibians. PNAS. 15 – Andela et al. (2017) A human-driven decline in global burned area. Science 16 – Doerr et al. (2016) Global trends in wildfire and its impacts: Perceptions versus realities in a changing world Philosophical Transactions of the Royal Society B. 17 – Schoennagel et al. (2017) Adapt to more wildfire in western North American forests as climate changes. PNAS. 18 – Abatzoglou et al. (2016) Impact of anthropogenic climate change on wildfire across western US forests. PNAS. 19 – Goss et al. (2020) Climate change is increasing the risk of extreme autumn wildfire conditions across California. Environmental Research Letters. 20 – U.S. Global Change Research Program (2018) Impacts, risks, adaptation in the United States: Fourth National Climate Assessment, Volume II. 21 – Behrenfeld et al. (2006) Climate-driven trends in contemporary ocean productivity. Nature. 22 – Dangendorf et al. (2019) Persistent acceleration in global sea-level rise since the 1960s. Nature Climate Change. 23 – Lyra et al. (2016) Sensitivity of the Amazon biome to high resolution climate change projections. Acta Amazonica. 24 – Wang et al. (preprint, in review) ESD Reviews: mechanisms, evidence, and impacts of climate tipping elements. Earth System Dynamics. 25 – Yang et al. (2014) Spatial and temporal patterns of global burned area in response to anthropogenic and environmental factors: Reconstructing global fire history for the 20th and early 21st centuries. Journal of Geophysical Research: Biogeosciences. 26 – Swain et al. (2018) Increasing precipitation volatility in twenty-first-century California. Nature Climate Change. 27 – Dong et al. (2019) Mechanisms for an amplified precipitation seasonal cycle in the U.S. west coast under global warming. Journal of Climate. 28 – Westerling. (2016) Increasing western US forest wildfire activity: sensitivity to changes in the timing of spring. Philosophical Transactions of the Royal Society B. 29 – Jolly et al. (2015) Climate-induced variations in global wildfire danger from 1979 to 2013. Nature Communications. 30 – Le Quere et al. (2019) Drivers of declining CO2 emissions in 18 developed economies. Nature Climate Change. UPDATES: 9 July 2020: This post has been updated with additional references clarifying the discussion on the sixth mass extinction within the scientific community. 10 July 2020: This post has been updated to include a comment from Kerry Emanuel.

Reviewers’ Overall Feedback: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: Shellenberger’s article promoting his new book “Apocalypse Never” includes a mix of accurate, misleading, and patently false statements. While it is useful to push back against claims that climate change will lead to the end of the world or human extinction, to do so by inaccurately downplaying real climate risks is deeply problematic and counterproductive. Shellenberger’s claims that climate plays no role in natural disasters and wildfires fly in the face of a large peer-reviewed scientific literature showing clear links between climate change and extreme heat events, drought, and extreme rainfall as well as links between hotter and drier conditions and wildfire areas burned in many regions of the world[1-4]. Shellenberger also falls into the trap of seeing a single technology (nuclear) as the one true solution to climate change, and mistakenly sees denigrating other clean energy technologies as the best way to promote it. The real world involves messy trade-offs and uncertainties, and decarbonization will involve a range of different technological solutions across industries and geographies rather than a single panacea. For more details on each, see my comments below. Stefan Doerr Professor, Swansea University: The article argues that society has been misled about causes and consequences of climate change, which has led to “climate alarmism.” The author advocates that we should be less concerned about climate change than many environmentalists argue. Whilst the latter is relative depending on how concerned an individual is and which specific (and perhaps extreme) view this aligns with, some of the supporting statements in the article related to wildfire are (i) inaccurate for key facts supporting argumentation, or (ii) omit important information that leads to flaws in the conclusions. “Climate change is not making natural disasters worse”. This is incorrect for wildfires. Several global climate trends promote fire: increased temperature, frequency, intensity and/or extent of heatwaves, droughts and extreme winds. This is very well established and summarised in the IPCC (2014) report[1,2]. “Fires have declined 25% around the world since 2003″. It is correct that the total global area burned has OVERALL declined over the last decades, BUT this is incorrectly used to argue that climate change is not affecting wildfires. The overall decrease is largely due a substantial reduction in flammable vegetation in African grasslands arising from human land use changes. Climate change has led to an increase in area burned in regions where fires burn more intensely and have a greater impact (e.g. western USA and Canada)[18,19]. This is omitted, leading to a false perception. “The build-up of wood fuel and more houses near forests, not climate change, explain why there are more, and more dangerous, fires in Australia and California”. Partially correct[17], but the assertion that the climate change related factors outlined above do not also contribute to increasingly “dangerous fires” is fundamentally flawed. It is comparable to suggesting that smoking alone and not obesity is responsible for an increased risk of cardiovascular disease. Both factors are clearly important. Daniel Swain Climate Scientist, University of California, Los Angeles: The article presents a mix of out-of-context facts and outright falsehoods to reach conclusions that are, collectively, fundamentally misleading. The author claims to reference specific sources, including “the IPCC, the Food and Agriculture Organization of the United Nations (FAO), [and] the International Union for the Conservation of Nature (IUCN).” However, the author’s claims are broadly unsupported by any of these authoritative bodies[1]. Gerardo Ceballos Professor, Universidad Nacional Autonoma de Mexico: This is not a scientific paper. It is intended, I guess, to be an article for the general public. Unfortunately, it is neither. It does not have a logical structure that allows the reader to understand what he would like to address, aside from a very general and misleading idea that environmentalists and climate scientists have been alarmist in relation to climate change. He lists a series of eclectic environmental problems like the Sixth Mass Extinction, green energy, and climate disruption. And without any data nor any proof, he discredits the idea that those are human-caused, severe environmental problems. He just mentions loose ideas about why he is right and the rest of the scientists, environmentalists, and general public are wrong. Being objective, this is a really bad article. It will cause confusion among the public—perhaps that is his idea. He indicates, with no data, that we are not in the Sixth Mass Extinction. I will explain here why he is wrong. For a long time, we have been aware that our activities have caused the extinction of many species. The case of the dodo, the first human-caused extinction in modern times (1600 AD) is relatively well-known for the general public[5]. In the last decade, there has been a plethora of scientific studies that have carefully analyzed the current extinction rates and have compared them with the natural or background rates occurring in the last million years[6-8]. Evolution of life proceeds as a dynamic balance of the extinction and speciation processes. While some species become extinct others are generated by speciation events. Under normal times, when Earth is not suffering a global catastrophe, the normal extinction rate is called the “background extinction rate.” However, in the last 600 million years life has experienced 5 mass extinctions, where most species on Earth have disappeared. These mass extinctions were each caused by a natural catastrophe, such as a meteorite, or happened over thousands or hundreds of thousands of years, causing the extinction of 70 to 90% of all living species. In 2015, I showed with my colleagues from the National Autonomous University of Mexico and Stanford University that we have entered the Sixth Mass Extinction (see figure below)[5]. Figure—Cumulative vertebrate species that have gone extinct or extinct in the wild according to IUCN data from 2012. Dashed black line represents the background extinction rate. From Ceballos et al. (2015)[5]. The 543 species of vertebrates (mammals, birds, reptiles, amphibians, and fishes) that were lost over the last 120 years would have become extinct in 10,000 years under the background extinction rates prevailing in the last million years. In other words, in the last century we lost in one year the same number of species that would have been lost in 100 years! We and other scientific groups have also shown that the extinction crisis is more severe because hundreds of millions of populations of animals and plants have disappeared in the last 40 years[5-9]. Those extinctions are accelerating, threatening the ecosystems that support life on Earth. If the current extinction crisis continues unchecked, we will lose entire ecosystems and the critical services they provide, including the proper combination of the gases of the atmosphere that make life on Earth possible, provision of fresh water, pollination and pest and disease control[8]. Jennifer Francis Senior Scientist, Woods Hole Research Center: Many statements are half-truths or based on cherry-picked information. Some are outright false. For example, it’s ludicrous to state “climate change is not making natural disasters worse.” An abundant and rapidly growing body of peer-reviewed scientific research identifies numerous ways that climate change is increasing the likelihood and intensity of various extreme weather events, exacerbating coastal flooding, and destroying ecological systems[1,2,6,18,19]. “Humans are not causing a ‘sixth mass extinction’” An exceptionally rapid loss of species is occurring and expected to continue. Climate change is not the only factor responsible—pollution, habitat deterioration, over fishing and hunting, and invasive species are also contributing. Human fingerprints are all over these factors[5-14]. “Climate change is not making natural disasters worse” This statement is refuted by numerous peer-reviewed scientific studies[1-4]. While disasters related to non-climate-change events (such as volcanoes, earthquakes, tsunamis) have not increased in frequency, those associated with climate change have tripled in frequency since the 1980s (see figure below). Figure—The number of geophysical, meteorological, hydrological, and climatological natural events that occurred globally from 1980-2017. From NatCatSERVICE. “Fires have declined 25% around the world since 2003” This is true in terms of a global average, mainly because forests have been cut down and replaced with agricultural land and because of fire suppression activities[15]. Some areas, however, are experiencing more frequent, larger, and more damaging fires—such as the U.S. western states, Alaska, northern Canada, and northern Eurasia[18,19]. This statement is misleading at best. “Carbon emissions are declining in most rich nations and have been declining in Britain, Germany, and France since the mid-1970s” This is true, but it’s in large part because high-emission industries have been moved to developing countries. Global carbon emissions are still increasing steadily (see figure below). “The build-up of wood fuel and more houses near forests, not climate change, explain why there are more, and more dangerous, fires in Australia and California” Both factors are contributing to increased fires[16]. Ryan Sriver Associate Professor, University of Illinois: First off, it is largely an opinion piece and many of the claims are unverifiable or written in a way that is misleading, such as: “Fires have declined 25% around the world since 2003”. What exactly does this mean, the number of fires, duration, area burned, etc.? Another such misleading claim is “Climate change is not making natural disasters worse”. Again, what natural disasters is the author referring to with this blanket statement, and what time frame, the last 5 years, 20 years, 100 years? The claim is vague and misleading in particular for climate and weather extremes. Temperature and precipitation extremes are getting worse with global warming leading to more severe and widespread heatwaves and drought[1-4]. This is well documented in the community assessments and observations, such as the 4th National Climate Assessment[20]. In addition, oceans are getting warmer and the atmosphere is wetter, which—combined with global sea-level rise—is making the flooding and precipitation damages from tropical cyclones and hurricanes more severe[1,2,21,22]. Finally, there is essentially no mention of arguably the biggest risk of climate change: sea-level rise! The only statement I see is the claim: “Adapting to life below sea level made the Netherlands rich not poor.” This statement acknowledges that sea-level rise is indeed happening and that adaptation will make nations better off economically. Statements such as these are dangerous and misleading. Sea-level rise poses a major threat to coastal communities with global socio-economic implications, and we are already seeing the negative impacts in more frequent and severe flood events in the US. These damages will only worsen as the polar ice sheets continue to melt, with potentially catastrophic effects on coastal cities and ecosystems, real estate markets, insurance industries, human migration, and national security. Kerry Emanuel Professor of Atmospheric Science, MIT: In his article, Michael Shellenberger claims that “climate change is not making natural disasters worse”. This begs the question of what exactly is meant by “natural disasters”, but no matter how one defines them, this statement is patently false. Let us assume that Shellenberger is defining natural disasters as deaths from events that could conceivably have a climate connection, such as floods, droughts, and hurricanes. In the period between 1900 and 2020, global deaths from these disasters have declined steeply. There is little question about why this has happened, and it is the immensely gratifying effects of greatly improved warnings, evacuations, and resilience. For example, in Bangladesh, where a single storm killed as many as 500,000 people in 1970, the government and non-governmental organizations have built many emergency evacuations shelters that have saved arguably millions of people in subsequent cyclones that have been meteorologically as bad or worse. If there is a climate change signal, it would appear as a lessening of this happy trend toward decreased fatalities, but it would be very difficult if not impossible to extract such a signal. We do not know from this data whether climate change is decreasing the rate of decline of deaths from natural disasters or not. If, on the other hand, we look at economic damage, normalized by world domestic product, the signal is equally clear but in the other direction….damages from weather-related natural disasters have been increasing greatly. One could plausibly argue that this is because of a global migration toward risky coastal regions, and so it is not unequivocal that this increase is owing to climate change. The cleanest way to look at climate effects on natural phenomena is to look at the phenomena themselves. Here there is strong and mounting evidence that climate change is increasing precipitation extremes (floods and droughts), conditions for wildfires, and the incidence of strong hurricanes[1,2]. Whichever way one looks at it, Shellenberger’s statement is not defensible. Annotations: The statements quoted below are from the article; comments are from the reviewers (and are lightly edited for clarity). as an energy expert…invited by the Intergovernmental Panel on Climate Change (IPCC) to serve as Expert Reviewer of its next Assessment Report Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: This credential sounds much more impressive than it actually is. Anyone who wants to can sign up as an expert reviewer for the IPCC. The Amazon is not “the lungs of the world” Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: While this phrase was inaccurately spread in some news stories earlier this year, climate scientists – and the majority of activists – have never claimed this to be the case. There is, however, a real danger that a combination of logging and climate change could transition much of the Amazon to a savannah-like ecosystem this century[23,24]. Climate change is not making natural disasters worse Daniel Swain Climate Scientist, University of California, Los Angeles: On the whole, this claim is incorrect. While there are clearly certain types of natural disasters unaffected by climate change (earthquakes and volcanic activity, for example), and certain kinds of disasters for which there is an absence of evidence regarding a detectable influence from climate change (tornadoes, for example), there is a long and growing list of extreme event/disasters types regarding which the scientific literature strongly supports links to climate change. These include, but are not limited to: extreme heatwave intensity and frequency, drought intensity, wildfire extent and severity, and the flood hazards associated with tropical cyclones/hurricanes (both from oceanic storm surge and freshwater flooding associated with heavy precipitation). Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: This is patently false. While there are some types of natural disasters with no (volcanoes, earthquakes) or very limited (tornadoes) climate links, others such as extreme heat events, droughts, and extreme rainfall have clear attribution to climate changes. The US National Academy of Science published a report in 2016 on the role of climate change in extreme events that is quite helpful in understanding where linkages are – and are not – well understood[2]. This figure from the report shows our understanding and attribution of climate change impacts on extreme events, by event type. Fires have declined 25% around the world since 2003 Daniel Swain Climate Scientist, University of California, Los Angeles: I cannot speak to this specific statistic, but I emphasize that it is largely irrelevant in context and certainly misleading, since it conflates both climate and non-climate related factors. There are strong links between climate change and wildfire extent and severity in many regions globally. It’s less clear whether there are links between climate change and wildfire frequency, but that’s not really the relevant metric here. Instead, climate change is clearly modulating the characteristics of wildfire in many regions—broadly increasing the dryness and flammability of vegetation, and allowing fires to become more intense and to burn more extensive areas. Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: This statement is accurate but misleading. The vast majority of fires globally are purposefully set for agricultural clearing, and these have declined in recent years. Conflating all fires with forest and wildfires – as Shellenberger does – is not helpful in understanding changing drivers of fire risk. A 2014 study in the Journal of Geophysical Research by Dr. Jia Yang at Auburn University and colleagues suggests that in the tropics climate change may have also reduced the area burned over the past 50 years, due, in part, to wetter conditions[25]. However, they find that climate change has likely increased fire risk in the high latitudes and mid-latitudes over recent decades. Figure—Contribution of different factors in changes since 1900 in forest-fire area globally and for different regions. Effects of climate change (including changes in temperatures and precipitation) are shown by the vertical stripes. Human land management activity is shown by the diagonal stripes, while the effect of CO2 fertilization and nitrogen deposition is shown by the dots. From Yang et al. (2014)[25]. Hotter and dryer conditions have been a major factor in the increase in areas burned by wildfires in many regions – such as the western US – in recent years. The amount of land we use for meat — humankind’s biggest use of land — has declined by an area nearly as large as AlaskaZeke Hausfather Director of Climate and Energy, The Breakthrough Institute: This statement is accurate (according to FAO data) and represents an important decoupling of land use and livestock production in spite of increasing global meat consumption – though some of the reduction is offset by increased land use for agricultural crops for animal feed. That said, there are large climate impacts of meat consumption apart from land use, and growing meat consumption is still driving deforestation in areas like the Amazon even as overall pasture use shrinks. So while peak pasture is certainly a positive thing, it does not translate into notable reductions in emissions to-date, as emissions from land use changes have remained largely unchanged. It does not – as Shellenberger seems to suggest – in any way indicate that climate change is a less serious problem than commonly thought, just that it’s possible to mitigate our impacts by changing practices and technologies. The build-up of wood fuel and more houses near forests, not climate change, explain why there are more, and more dangerous, fires in Australia and California Daniel Swain Climate Scientist, University of California, Los Angeles: This is misleading and incorrect as stated. While the legacy of 20th century forest management policies, as well as urban incursion into the wildlands, are indeed relevant in some areas, research has shown that such non-climate factors cannot account for the enormous increase in area burned by wildfire both in the broader American West and California specifically. In fact, drying of vegetation due to climate change is responsible for about half of the observed increase in western U.S. forest fire area burned over the past several decades[18]. More specifically in California, observed warming and drying more than doubled the occurrence of extreme fire weather conditions between 1979 and 2018—a trend that is attributable to human-caused climate change[19]. Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: Here Shellenberger sets up a false dichotomy. All three factors – buildup of vegetation due to fire suppression, more people living in the wildland-urban interface, and hotter and dryer conditions have contributed to severe wildfires in regions like the western US in recent years. For example, there is a strong year-to-year relationship between fuel aridity – driven by hotter and dryer conditions – and area burned in the western US. Figure—Western US forest fire area on a logarithmic scale compared to standardised fuel aridity, with datapoints during the 1984-1999 (blue dots) and 2000-2017 (red dots) periods highlighted. Map insert shows the western US forest areas. From Abatzoglou et al. (2016)[13]. A 2016 study showed that climate change is responsible for over half the increase in fuel aridity (drier fuel load), and has doubled the cumulative forest area burned[18]. Rising average global temperatures have led to higher spring and summer temperatures, which in turn have led to earlier spring snowmelt. Further, there is evidence that climate change is causing winter rains to come later in autumn, and stop earlier in spring[26,27]. This is extending the area and time periods in which forests become combustible, and in parts of California, fire season is now 50 days longer than in 1979[28,29]. From 4th National Climate Assessment, based on data from Abatzoglou et al. (2016)[13,15]. Carbon emissions are declining in most rich nations and have been declining in Britain, Germany, and France since the mid-1970sZeke Hausfather Director of Climate and Energy, The Breakthrough Institute: This claim substantially overstates the long-term success that rich countries have had in decarbonizing their economies. Rich nations as a whole (using OECD nations as the grouping of rich countries) emit 25% more CO2 today than they did in the mid 1970s. While a number of countries (Germany, France, UK) do emit less today than in the 1970s, their experience is not generalizable to rich countries as a whole. These calculations also do not include emissions associated with increased consumption of goods produced in places like China, which matters quite a bitin recent decades. Figure—Countries’ consumption (orange line) and production (blue) emissions as a percent of their 1990 emissions. The grey area represents the difference between the two. Based on data from the Global Carbon Project. Chart by Carbon Brief. OECD emissions as a whole have declined around 10% since 2007, with 18 (of 37) OECD countries experiencing sustained reductions in emissions. This is encouraging progress, and shows that absolute decoupling (growing economy with falling emissions) is possible – even taking changes in consumption-based emissions into account. Figure—Changes in CO2 emissions from fossil fuel combustion for 18 countries with declining emissions during 2005-2015. From Le Quere et al. (2019)[30]. Wood fuel is far worse for people and wildlife than fossil fuels Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: Shellenberger is correct here that burning wood in cookstoves in the developing world is terrible for the climate, human health, and nature. Replacing it with fossil fuels – or even better, grid-connected electricity – is an important step in reducing indoor air pollution and black carbon emissions. To the extent that modern biomass is used to replace fossil fuels for electricity generation, it is quite controversial and opposed by most environmental advocates. It also represents only a small fraction of the clean energy added globally each year – the vast majority of which is from solar, wind, and nuclear. Preventing future pandemics requires more not less “industrial” agriculture Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: There is broad agreement in the epidemiological and virological studies of zoonoses that the most important factor in the development of new zoonotic diseases is land-use change. The development of wild lands, whether caused by agricultural extensification, mining, or other factors, simultaneously shrinks the habitat of wildlife and brings that wildlife in close proximity to human settlements. To the extent that agricultural intensification reduces pressure on wildlands, it can help reduce risk of future pandemics. However interesting, this argument has little to do with climate impacts. As a result, half of the people surveyed around the world last year said they thought climate change would make humanity extinct. And in January, one out of five British children told pollsters they were having nightmares about climate change.Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: Climate change will not cause the end of the world, and scientists can do more to push back against misleading popular narratives about human extinction. At the same time, minimizing the impacts of climate change through misleading or cherry-picked examples – as Shellenberger does at times in this article – is not a particularly effective response. 100% renewables would require increasing the land used for energy from today’s 0.5% to 50%Zeke Hausfather Director of Climate and Energy, The Breakthrough Institute: While renewable sources use more land (and there are other reasons why 100% renewables – vs. a more expansive 100% clean energy – is not necessarily the best policy goal, this substantially overstates the required land. Accounting for land use from generation, resource production (e.g. mining), and resource transport, studies find that solar requires 3.6x more land, wind 5.8x more land, and hydro 26x more land than fossil fuels. This increase in required land area is important – particularly for countries like Japan where land availability is limited – but is far lower than the 100x land increase Shellenberger inaccurately claims. Greenpeace didn’t save the whales, switching from whale oil to petroleum and palm oil didZeke Hausfather Director of Climate and Energy, The Breakthrough Institute: Neither restrictions nor substitutes were the primary factor in the decline in industrial whaling during the 20th century. Scarcity was. Modern whaling vessels and technology hunted most whale populations into near-extinction and as that occurred, whaling fleets and catch declined. Whales have come back because of restrictions (enacted after whaling declined substantially as populations dwindled) and the fact that we do now have substitutes for almost everything we hunted whales for.

https://science.feedback.org/review/study-evaluates-natural-and-human-causes-of-recent-rapid-warming-rate-at-the-south-pole/

Accurate

The New York Times, Henry Fountain, 2020-06-29

Surface air temperatures at the bottom of the world have risen three times faster than the global average since the 1990s.

Accurate: Recorded temperatures at the South Pole weather station increased three times as much as the global average between 1989 and 2018. This is a statement about one station at the South Pole, specifically, and not broadly representative of global warming in Antarctica as a whole.

This statement accurately describes data analyzed in a recently published scientific study. As the article also explains, that study concluded that the temperature trend at this specific location was boosted by natural variability, and is not representative of the current human-caused climate change across Antarctica.

Surface air temperatures at the bottom of the world have risen three times faster than the global average since the 1990s[...] While the warming could be the result of natural climate change alone, the researchers said, it is likely that the effects of human-caused warming contributed to it.

1- Clem et al. (2020) Record warming at the South Pole during the past three decades, Nature Climate Change 2- Simpkins et al. (2014) Tropical Connections to Climatic Change in the Extratropical Southern Hemisphere: The Role of Atlantic SST Trends, Journal of Climate 3- van der Broeke and van Lipzig (2003) Factors Controlling the Near-Surface Wind Field in Antarctica, Monthly Weather Review: 4- Kowk and Comiso (2002) Spatial patterns of variability in Antarctic surface temperature: Connections to the Southern Hemisphere Annular Mode and the Southern Oscillation, Geophysical Research Letters 5- Marshall and Thompson (2016) The signatures of large‐scale patterns of atmospheric variability in Antarctic surface temperatures, JGR Atmospheres

This statement is based on recent study published by Clem et al. in Nature Climate Change[1]. (The study’s first author also described it in an article for The Conversation.) The study analyzed temperature data from the Amundsen-Scott South Pole Station, and then analyzes Southern Hemisphere weather patterns to evaluate the causes of the recent warming rate. Averaged over the 30-year period from 1989 to 2018, annual mean temperatures at the South Pole station have increased at a rate of about 0.61°C per decade. South Pole temperature data (top) and running 30-year trend calculation (bottom). Source: Clem et al./Nature Climate Change Over that same time period, global average surface temperatures have increased 0.6°C, equating to a rate of 0.2°C per decade. So it’s accurate to say that South Pole temperatures have increased at three times the global average. Calculated temperature change from 1989 to 2018.Source: NASA But it’s important to note that this is a statement about the South Pole, specifically, and not broadly representative of Antarctica as a whole. As illustrated in the figure below, other Antarctic stations recorded a slower rate of warming, while others have even cooled over this time period. Unlike the Arctic, which has seen a widespread and rapid rate of warming, the Antarctic experiences particularly variable weather patterns. These are driven by natural oscillations of regional ocean surface temperatures and atmospheric circulation[2,3,4,5]. Temperature change since 1989 for 20 Antarctic stations.Source: Clem et al./Nature Climate Change To understand why the South Pole station experienced such rapid warming in recent years, Clem et al.[1] analyzed wind patterns. They found that the last 30 years saw a higher frequency of winds from the warmer Weddell Sea rather than the colder interior of East Antarctica. In climate model simulations, they found that the observed trend is high compared to most simulated warming trends caused by human-caused greenhouse gas emissions. Clem et al.[1] concludes that the South Pole station warming trend likely requires a significant contribution from natural variability. Specifically, they find a correlation between sea surface temperature patterns in the tropical Pacific Ocean and the wind pattern that brings warmer air to the South Pole. They write, “While radiative forcing from greenhouse gas increases probably intensified the recent South Pole warming, the observed trend remains within the upper bounds of natural variability inferred from unforced, pre-industrial simulations and can be explained via a strong cyclonic anomaly in the Weddell Sea resulting from coupling of negative [Interdecadal Pacific Oscillation] and positive [Southern Annular Mode] during the twenty-first century.”

https://science.feedback.org/review/climate-scientists-agree-that-human-caused-greenhouse-gas-emissions-are-primarily-responsible-for-climate-change-contrary-to-claims-in-clear-energy-alliance-video/

Incorrect

Clear Energy Alliance, Mark Mathis, 2020-06-10

The scientific consensus on whether global warming is human caused is not 97 percent, it’s less than 1 percent. There is no way to measure the human impact on climate change.

Factually inaccurate: Studies analyzing the peer-reviewed scientific literature show that the vast majority of climate scientists (and research) conclude that anthropogenic factors are primarily responsible for climate change. Misunderstanding of science: The claim that human impacts on climate change cannot be measured or separated from natural causes contrasts with many lines of evidence demonstrating that human influences far outweigh natural effects.

The vast majority of climate scientists agree that anthropogenic factors are primarily responsible for climate change. Numerous scientific studies and summary reports demonstrate that natural and human influences on the climate can be studied and quantified.

The scientific consensus on whether global warming is human caused is not 97 percent, it’s less than 1 percent. There is no way to separate natural climate cycles from man made influences such as the burning of fossil fuels. Consequently, there is no way to measure the human impact. If we are having an impact, the question is how much? The honest answer is we just don’t know.

1 – Anderegg et al. (2010) Expert credibility in climate change. PNAS. 2 – IPCC (2014) Climate Change 2014: Summary: for Policymakers. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. 3 – Doran et al. (2009) Examining the scientific consensus on climate change. Eos. 4 – Santer et al. (2013) Human and natural influences on the changing thermal structure of the atmosphere. PNAS. 5 – Feldman et a. (2015) Observational determination of surface radiative forcing by CO2 from 2000 to 2010. Nature. 6 – Cook et al. (2013) Quantifying the consensus on anthropogenic global warming in the scientific literature. Environmental Research Letters. 7 – Cook et al. (2016) Consensus on consensus: a synthesis of consensus estimates on human-caused global warming. Environmental Research Letters. 8 – Wuebbles et al. (2017) Executive summary. In: Climate Science Special Report: Fourth National Climate Assessment, Volume I 9 – IPCC, 2013: Summary for Policymakers. In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change 10 – Powell (2015) Climate scientists virtually unanimous: anthropogenic global warming is true. Bulletin of Science, Technology and Society. 11 – Rosenberg et al. (2010) Climate change: a profile of US climate scientists’ perspectives. Climatic Change. 12 – Schmidt et al. (2014) Reconciling warming trends. Nature Geoscience. UPDATES: 26 June 2020: This post was updated to include a comment from William Anderegg.

Review: The claims appeared in a Facebook video published by Clear Energy Alliance in June 2020, and has received more than 90,000 views since it was published. The vast majority of climate scientists agree that human-caused greenhouse gas emissions are responsible for most of the change in global climate over the past century[1,2,3]. Climate scientists can also separate natural and man made influences on the climate and quantify anthropogenic impacts, contrary to claims made in the video[2,4,5]. In the video, Mark Mathis states that the scientific consensus that Earth’s recent warming is mostly man made is less than one percent, not 97 percent. This claim contradicts several scientific studies that have found 90 to 100 percent of scientists agree that anthropogenic factors are the main cause of recent climate change[1,3,6,7]. For example, a study by Anderegg and colleagues found that “97 – 98% of the climate researchers most actively publishing in the field surveyed here support the tenets of ACC [Anthropogenic Climate Change] outlined by the Intergovernmental Panel on Climate Change, and (ii) the relative climate expertise and scientific prominence of the researchers unconvinced of ACC are substantially below that of the convinced researchers.”[1] These results are consistent with findings from a study conducted by Cook et al. (2013), which was discussed in the video. The scientific consensus of climate experts on human contributions to climate change is not less than 1 percent as claimed. According to the IPCC, “It is extremely likely that more than half of the observed increase in global average surface temperature from 1951 to 2010 was caused by the anthropogenic increase in greenhouse gas concentrations and other anthropogenic forcings together.”[2] The 2017 US National Climate Assessment report states, “This assessment concludes, based on extensive evidence, that it is extremely likely that human activities, especially emissions of greenhouse gases, are the dominant cause of the observed warming since the mid-20th century. For the warming over the last century, there is no convincing alternative explanation supported by the extent of the observational evidence.”[8] Contrary to several claims made in the video, human influences on climate change can be separated from natural causes and measured, as the reviewers describe below[2,4,5]. For example, the IPCC demonstrates that anthropogenic drivers of global warming far outweigh the effects of solar forcing (see figure below)[9]. Figure—Radiative forcing estimates in 2011 relative to 1750. Values are global average radiative forcing, partitioned according to the emitted compounds or processes that result in a combination of drivers. Source IPCC AR5[9]. Finally, the video presents a figure comparing climate model predictions to balloon and satellite measurements. This figure, created by Dr. John Christy, suffers from a number of issues that ultimately mislead readers about differences between the balloon and satellite measurements and climate model predictions. It focuses on temperatures in the mid-troposphere, above the Earth’s surface, and plots the data in a highly misleading way, as described by the reviewers below. The measurements also stop at 2011, omitting the past 9 years of data. In addition, the figure does not show the distribution of error in the balloon and satellite measurements or the spread of model predictions, exaggerating discrepancies between the two. Scientists’ Feedback: William Anderegg Associate Professor, University of Utah: The video’s claims that the scientific consensus on whether climate change is human-caused is less than 1 percent is utterly false. The video completely misrepresents and misleads about one of the studies on scientific consensus, while completely ignoring that multiple independent studies done by different research teams across the world have separately arrived at consensus levels of 97% or greater. Our study arrived at a 97-98% estimate in 2010[1]. A separate study by Doran & Kendall-Zimmermann found very similar levels of consensus using entirely different methods[3]. Still another study estimated >99% consensus[10]. An entirely different study placed the consensus at over 94%[11]. Thus, there are multiple, independent studies that validate and confirm the Cook et al results[7]. The claims made in this video about the scientific consensus are blatantly false and completely at odds with the peer-reviewed literature. James Renwick Professor, Victoria University of Wellington:[Comment from a previous evaluation of a similar claim.] There are very reliable numerical estimates of the human contribution to warming, as detailed in the last IPCC report. The headline statement from IPCC AR5 was “It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century.” Gavin Schmidt Director, NASA Goddard Institute for Space Studies:[Comment from a previous evaluation of a similar claim.] There is indeed overwhelming evidence for warming in the last century. [The] claim that no one knows the attribution of this to human impacts is not a valid description of the state of knowledge. There are indeed plenty of studies that use statistical or model-based fingerprints to assess this and they overwhelmingly find a dominance of human activities over natural forcings or internal variability. For the more recent period (1950 onwards) the claims are even stronger—that effectively all the warming is caused by human activity with only a ~10% uncertainty due to internal variability. Patrick Brown Assistant Professor, San Jose State University:[Comment from a previous evaluation of a similar claim.] Careful analysis that attempts to take into account all major factors and their evolution in time indicates that anthropogenic increases in greenhouse gasses account for more than 100% of the observed warming on the century timescale (requiring cancellation from cooling influences). See the summary graphic from Carbon Brief, below. Figure—The estimated role of different factors influencing global surface temperatures from 1850 to 2017. Observed temperatures are shown in black dots. Global warming over the past 150 years was primarily driven by greenhouse gas emissions (red). From Carbon Brief. Comments on figure comparing models to balloon and satellite data Victor Venema Scientist, University of Bonn, Germany:[Comment from a previous evaluation of a similar claim.] John Christy has shown this plot for many years on his blog and in congressional hearings. If it were a robust result, it would be scientifically interesting, however in all these years Christy has not published a scientific article on his claims, and colleagues have had to reverse-engineer how it was made. One thing that is clear is that due the 5-year averages the strong warming in the last 3 years is strongly suppressed in this plot. Due to the averaging of the balloon datasets and the satellite datasets, the large uncertainty in the observations is no longer visible. It is not good practice to align measurements and models by selecting only one year that happened to have been warm; to reduce the influence of such an arbitrary choice scientists normally use a longer period to align different datasets. Several of these problems have been discussed at RealClimate, but unfortunately Christy has not updated his graph. Climate models inform us about long-term warming and have not been developed for short-term predictions, which are strongly influenced by fluctuations from, for example, El Niño. The timing of El Nino is not predictable more than a year in advance. This problem is even more the case for the upper air temperatures shown here by John Christy than for the surface temperature. The uncertainty of climate models results for short-term prediction is expected to be about twice the model spread of the CMIP models. Gavin Schmidt Director, NASA Goddard Institute for Space Studies:[Comment from a previous evaluation of a similar claim.] As I’ve discussed on RealClimate, Christy makes a number of minor and one major choice in his graph that all combine to exaggerate the discrepancy between models and observations of the mid-troposphere changes. The major issue is that he does not show the structural errors in the observations, nor does he compare to the spread in the model output. Better graphs that do not make those partial choices are available: This is not to say that there are no discrepancies—there are, just not as dramatic as Christy claims. The bulk of the trends in the models for this metric are above what is reported, but with any discrepancy, there are multiple potential causes which all need to be looked at[12]. 1) the observations may be wrong, 2) the models may be wrong, 3) the experiments may not have been realistic, or 4) the comparison is flawed. While #4 has historically been the case for many satellite-model comparisons in the past, it is no longer much of a problem. However, #1 remains a distinct possibility—and ongoing revisions to these datasets often give rise to systematic shifts in the trends. #2 is also possible—though assuming the only issue must relate to climate sensitivity is naive. But #3 is a known problem—the CMIP5 simulations did not have sufficient volcanoes, and did not predict the decrease in solar activity over the last decade or so[12]. Ignoring #1 and #3 in favor only of a claim about #2 is not good science. Note too that on other metrics the models are ok, or don’t shift as quickly as observed (sea ice, Hadley cell expansion, etc.)—only discussing issues where the bias is one specific way, is again a very partial approach.

https://science.feedback.org/review/article-in-the-guardian-misleads-readers-about-sensitivity-of-climate-models-by-narrowly-focusing-on-single-study-jonathan-watts/

-1

The Guardian, by Jonathan Watts, on 2020-06-13.

"Climate worst-case scenarios may not go far enough, cloud data shows"

1 – IPCC (2013) Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. 2 – Williams et al. (2020). Use of short‐range forecasts to evaluate fast physics processes relevant for climate sensitivity. Journal of Advances in Modeling Earth Systems. 3 – Palmer (2020). Short-term tests validate long-term estimates of climate change. Nature. 4 – Andrews (2020) Historical simulations with HadGEM3‐GC3.1 for CMIP6. Journal of Advances in Modeling Earth Systems. 5 – Tokarska et al. (2020). Past warming trend constrains future warming in CMIP6 models. Science Advances. 6 – Forster et al. (2020) Latest climate models confirm need for urgent mitigation. Nature Climate Change. 7 – Knutti et al. (2017) Beyond equilibrium climate sensitivity. Nature Geoscience. 8 – IPCC (2007) What explains the current spread in models’ Climate Sensitivity Estimates? UPDATES: 22 June 2020: This post was updated to include a comment by Mark Zelinka

Reviewers’ Overall Feedback: These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article. Richard Betts Professor, Met Office Hadley Centre & University of Exeter: Equilibrium climate sensitivity (ECS) is a very important topic of great interest, but also complex and still subject to considerable uncertainty and ongoing research. The article does recognise the uncertainty in the latest models and quotes a leading scientist in this regard, but the headline and first two sentences overstate the scientific confidence and give the impression of a more substantial update to scientific understanding than is actually the case. The caveat in the second sentence reads as if the high ECS in the new models is provisionally accepted and merely needs further checking, rather than being something that the modellers are not yet sure about either way. The article is not clear on the uncertainty in the previous estimates of ECS and gives the impression that there was previously a fairly precise estimate of “around 3°C”, but in fact that was already fairly uncertain, as explained by the IPCC[1]. The latest research would be more accurately characterised as still not yet ruling out high climate sensitivity that was previously thought possible but relatively unlikely, rather than suggesting that high climate sensitivity is now more likely than previously believed. Mark Richardson Research Associate, Colorado State University/NASA JPL: This article’s main theme is broadly accurate. Many new climate models, which better fit satellite cloud measurements, have a high value of “climate sensitivity.” It includes important doubts about how “such a high figure does not fit with historical records”. Technical errors like confusing the national origin of a model and the description of a provided percentage don’t affect these main conclusions. Readers should be aware that this article is slanted to the “shock” and “surprise” of these results and misses context from past work, such as the uncertainty ranges provided in past UN climate reports. However, the article is clear about these being mostly model results, reports how only around a quarter of these new models show very high sensitivity, and mentions the counterbalance of evidence from the historical record. Taken together I mark this article as “accurate”, with elements that are “exaggerating” and “imprecise/unclear”. Reto Knutti Professor, ETH Zürich: The main problem with this Guardian article is not incorrect statements, but that it is cherry picking one single result, misinterpreting it, surround it by strong quotes from people who have no expertise in that area, thereby painting a doomsday scenario (“modelling suggests climate is considerably more sensitive to carbon emissions than thought”) that is highly misleading and completely unsupported by the evidence. The oversimplification is in two steps, the first in a Nature comment on the original paper[3]. Here Tim Palmer is incorrect in saying that the results of the original paper “support the estimates [for climate sensitivity]”[2,3]. The fact that the new high climate sensitivity model does well on six hour forecasts does not imply a) that the model is fine in general, and does not imply b) that it is the only model that is capable of doing that. The relationship between short-term forecasts and climate feedbacks is not demonstrated, and the evidence from hundreds of other papers on the topic is ignored. On a) the agreement on short-term forecasts simply means that this model is doing this particular thing well. However, this particular model is one of the two worst in simulating the warming over the past 40 years. It shows basically no warming globally until 1980 or 1990, even cooling over land, and a massive surge after about 1990[4]. The details are likely complicated, but are probably related to too-strong feedbacks (high climate sensitivity), compensated by too strong aerosol cooling until 1990, a hypothesis put forward ages ago in energy balance models. Indeed the Guardian piece mentions that, but only briefly at the end. On b) as pointed out by others, nobody has demonstrated that the high sensitivity is related to short-term forecast skill in these newer models. Everything is different in the new model, so the improvement may have come from some other change. One would have to demonstrate that many versions of that model with low climatology are doing significantly worse on short-term forecasts, and would have to demonstrate that this is also true for models from other centers. The fact that one particular test cannot rule out a high climate sensitivity does not make it likely. It simply means that we do not know. But there are other lines of evidence that point to the canonical 2-4.5°C range. One is the recent warming since 1950 or so, the other is paleoclimate estimates, the third is process understanding and feedback estimates from cloud data and surface observations We and others have shown recently that almost all of the high climate sensitivity models in fact tend to overestimate recent warming[5], the Met Office model being one of the two worst, and taking that into account suggests that many of the new CMIP6 models are biased high, and that future warming is similar to what it was in earlier models. While it is correct that we are seeing models with high climate sensitivity, the evidence is growing that there are issues with at least some of these models. In summary, the Guardian article is cherry-picking a single technical paper and over-interpreting it as being relevant for the prediction of long term warming, without sufficient context on the vast amount of literature that does not support such a conclusion. Joeri Rogelj Professor, Centre for Environmental Policy at Imperial College London: The article correctly reports that the most recent versions of some climate models estimate more warming for a given increase in CO2 concentrations. It is also correct in highlighting that how clouds are represented in these models is the likely reason for these higher estimates. However, it does not report all the science available on this topic and its claims are thus misleading. The article suggests that the only information currently available from scientific studies is that things look much worse, and that otherwise more research is needed to understand whether this is really the case. However, available studies that have looked at what these new model projections mean have found that models with higher warming are worse in capturing global warming trends over the past decades, making their projections of very high warming less probable[4]. This is important context that was omitted from the article. Paulo Ceppi Senior Lecturer, Imperial College London: The article suggests that new modelling results have led scientists to revise their understanding of the role of clouds for climate change. This is misleading. Current scientific consensus is that clouds will amplify warming, but most evidence does not point towards an extreme amplifying effect. So while extreme high warming scenarios cannot be entirely ruled out, there is no convincing evidence that the amplifying effect of clouds is stronger than we previously thought. While the new Nature paper cited in the article is thought-provoking[2], its significance is overstated, and the paper should have been discussed in the context of other recent evidence that does not support the high-sensitivity modelling results. Piers Forster Professor, University of Leeds: In this article there is some science on the latest climate models and their cloud feedbacks that have been reported before. However, quotes by Rockstrom and the writer [Watts] are unsupported opinions that make misleading interpretations of the new science that warming will be worse than we thought. These claims are not supported by other lines of evidence showing our estimates of warming rates have been stable over time. Mark Zelinka Research Scientist, Lawrence Livermore National Laboratory: I would characterize the article as overstating the importance of a single result from a single model without sufficient context. A highly sensitive model might have a great-looking climatological state and perform really well on short-term weather forecasts, but even a broken clock is right twice a day. This is hyperbole of course: This is an excellent model and by no means “broken”, but it remains to be rigorously shown that this model is giving a more accurate picture of our future than what we previously thought. More generally, the consequences of continued greenhouse gas emissions are dire enough if climate sensitivity is in line with the existing scientific consensus; whether this new more sensitive model is more accurate is mostly immaterial to that fact. Annotations: The statements quoted below are from the article; comments are from the reviewers (and are lightly edited for clarity). “Worst-case global heating scenarios may need to be revised upwards in light of a better understanding of the role of clouds, scientists have said.” Richard Betts Professor, Met Office Hadley Centre & University of Exeter: This appears to be based on the view of a scientist who was not involved in developing the new models. A quote later in the article shows that a scientist with a leading role in the latest models is much more cautious and said it needs more research before conclusions can be drawn. Piers Forster Professor, University of Leeds: There is no consensus in the community what these would be. Different scientists have different views, so there is no standard worst-case scenario to revise, see our CCC blog. “Recent modelling data suggests the climate is considerably more sensitive to carbon emissions than previously believed” Richard Betts Professor, Met Office Hadley Centre & University of Exeter: This statement is not correct. Equilibrium Climate Sensitivity (ECS) has always been quite uncertain, and the high values in the new models are within the range previously thought possible, although relatively unlikely. A value of around 5°C in some of the CMIP6 models is outside the “likely range” of ECS assessed in the IPCC 5th Assessment Report (AR5), but it is still not in the AR5 “very unlikely” range of above 6°C[1]. The recent studies cited in this report conclude that the high ECS values cannot be ruled out by the methods used in those studies, but they do not conclude that high ECS is more likely than previously believed. Piers Forster Professor, University of Leeds: The latest models might also be over sensitive[6]. “25% of them show a sharp upward shift from 3C to 5C in climate sensitivity” Richard Betts Professor, Met Office Hadley Centre & University of Exeter: It’s not clear what this statement is based on, as no source is given. Although several CMIP6 models produce an ECS above the upper end of the range of the CMIP5 models, this range was 1.2°C – 4.7°C so it is not clear where the description of a shift from 3°C to 5°C comes from. Mark Richardson Research Associate, Colorado State University/NASA JPL: I don’t see where this statement comes from either. The top 25% of models out now have climate sensitivity of about 4.8°C or above, so one part of this statement gives a broadly accurate summary. But several of those are new versions of models that previously had climate sensitivity quite a bit higher than 3°C, so there wasn’t a “shift” of those models. “For 40 years, it has been around 3C” Richard Betts Professor, Met Office Hadley Centre & University of Exeter: Actually the estimates of Equilibrium Climate Sensitivity (ECS) have long been around 1.5°C – 4.5°C, with higher values still thought possible. The IPCC 5th Assessment Report judged that there was up to a 10% chance of ECS being greater than 6°C, and the likelihood of an ECS of 5°C was assessed as less than 33% but more than 10%[1]. Piers Forster Professor, University of Leeds: I completely agree with Richard Betts, and in fact the latest models agree very well with this range of ECS in general[6]. “He said climate sensitivity above 5C would reduce the scope for human action to reduce the worst impacts of global heating. “We would have no more space for a soft landing of 1.5C [above preindustrial levels]. The best we could aim for is 2C,” he said.” Mark Richardson Research Associate, Colorado State University/NASA JPL: This is a fair interpretation of the consequences: climate sensitivity of 5°C would make it almost impossible to achieve the stated temperature targets. But there is still plenty of evidence for climate sensitivity being in the historically likely 1.5 – 4.5°C range, so this should be kept in mind. “the EU’s Community Earth System Model” Mark Richardson Research Associate, Colorado State University/NASA JPL: The Community Earth System Model is from US institutions, but it’s accurate to say that it’s from “leading research bodies” and has a high climate sensitivity. “Previous IPCC reports tended to assume that clouds would have a neutral impact because the warming and cooling feedbacks would cancel each other out.” Mark Richardson Research Associate, Colorado State University/NASA JPL: “Assume” is ungenerous—this was based on calculations using physics and the available observations. For example, in 2007 they looked at how climate model clouds affected their climate sensitivity and talked about a “very large inter-model spread”, i.e., you could get net warming or cooling, and we didn’t have the information to rule out either[8]. Reto Knutti Professor, ETH Zürich: IPCC does not “assume”, they quantify based on observations and models. And while cloud feedbacks are uncertain, in 2013 the conclusion was already that the overall effect was likely positive (i.e., contributing to warming), specifically only 17% probability for it being negative (cooling).[1] IPCC AR5 WG1 page 592: “Based on the preceding synthesis of cloud behaviour, the net radia­tive feedback due to all cloud types is judged likely to be positive. This is reasoned probabilistically as follows. First, because evidence from observations and process models is mixed as to whether GCM cloud feedback is too strong or too weak overall, and because the positive feedback found in GCMs comes mostly from mechanisms now sup­ported by other lines of evidence, the central (most likely) estimate of the total cloud feedback is taken as the mean from GCMs (+0.6 W m–2 °C–1). Second, because there is no accepted basis to discredit individual GCMs a priori, the probability distribution of the true feedback cannot be any narrower than the distribution of GCM results. Third, since feed­back mechanisms are probably missing from GCMs and some CRMs suggest feedbacks outside the range in GCMs, the probable range of the feedback must be broader than its spread in GCMs. We estimate a probability distribution for this feedback by doubling the spread about the mean of all model values in Figure 7.10 (in effect assuming an additional uncertainty about 1.7 times as large as that encapsu­lated in the GCM range, added to it in quadrature). This yields a 90% (very likely) range of −0.2 to +2.0 W m–2 °C–1, with a 17% probability of a negative feedback.”[1] “But in the past year and a half, a body of evidence has been growing showing that the net effect will be warming. This is based on finer resolution computer models and advanced cloud microphysics.” Mark Richardson Research Associate, Colorado State University/NASA JPL: I think this is generally fair: the available satellite data in particular have shown that clouds seem to act in a way that coincides with higher climate sensitivity. The fusion of satellite data with climate models has been vital for this. “Scientists caution that this is a work in progress and that doubts remain because such a high figure does not fit with historical records.” Richard Betts Professor, Met Office Hadley Centre & University of Exeter: It’s correct to have included this, but the message here seems less confident than that conveyed by the headline and opening sentence. “Catherine Senior, head of understanding climate change at the Met Office Hadley Centre, said more studies and more data were needed to fully understand the role of clouds and aerosols. “This figure has the potential to be incredibly alarming if it is right,” she said. “But as a scientist, my first response is: why has the model done that? We are still in the stage of evaluating the processes driving the different response.” Richard Betts Professor, Met Office Hadley Centre & University of Exeter: It’s correct to have included this statement from a leading authority on the new models, but the headline and opening sentence of the article do not reflect the caution given here. “The more we learn, the more fragile the Earth system seems to be and the faster we need to move,” he said. “It gives even stronger argument to step out of this Covid-19 crisis and move full speed towards decarbonising the economy.” Piers Forster Professor, University of Leeds: In fact the more we learn, quite often we find that nature is quite robust, even when trying our best to destroy it, see our CCC blog.

https://science.feedback.org/review/video-from-prageru-makes-several-incorrect-and-misleading-claims-about-climate-change-richard-lindzen/

-2

PragerU, by Richard Lindzen, on 2020-05-08.

"Climate Change: What Do Scientists Say"

1 – IPCC (2007) Summary: for Policymakers. In: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. 2 – IPCC (2014) Climate Change 2014: Summary for Policymakers. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. 3 – Hausfather (2017) The extent of the human contribution to modern global warming is a hotly debated topic in political circles, particularly in the US. Carbon Brief. 4 – Neukom et al. (2019) No evidence for globally coherent warm and cold periods over the preindustrial Common Era. Nature. 5 – Friedlingstein et al (2019) Global carbon budget 2019. Earth System Science Data. 6 – Doney et al (2009) Ocean acidification: The other CO2 problem. Annual Review of Marine Science. 7 – Mbow et al. (2019) IP Food Security. In: Climate Change and Land: an IPCC special report on climate change, desertification, land degradation, sustainable land management, food security, and greenhouse gas fluxes in terrestrial ecosystems. IPCC report. 8- Tubiello et al. (2007). Crop and pasture response to climate change. PNAS. 9 – Nolan et al (2018) Past and future global transformation of terrestrial ecosystems under climate change. Science. 10 – Burke et al (2018) Pliocene and Eocene provide best analogs for near-future climates. PNAS.

Reviewers’ Overall Feedback: Katrin Meissner Professor, University of New South Wales: If you watched this video, you have unfortunately wasted 5 minutes of your day. Richard Lindzen is reiterating a few wrong statements on climate change that have been debunked repeatedly in the past (e.g. “there is no evidence that CO2 emissions are the dominant factor” of climate change)[1,2]. He is also very skilled at presenting a few statements on climate change that are right in a misleading way, so that the overall message becomes wrong (“climate is always changing”, “there are many reasons why the climate changes”). He misrepresents the way the IPCC works. He also claims that there is a significant number of specialists (a whole “group”) sharing his “understanding” of climate science, which is also not true. Patrick Brown Assistant Professor, San Jose State University: There are many inaccuracies contained within the video in question. The text below deals with just the first one of them. At the 8 second mark, Dr. Lindzen claims that the climate has changed “remarkably little” over the past 30 years without any reference to what “remarkably little” is relative to. When put in proper context, it is not true that the climate has changed “remarkably little” over the past 30 years. Over the past 30 years, the global average temperature has warmed by about 0.7 degrees Celsius (red line from 1990 to 2020 in the global temperature dataset below): Source: NASA GISTEMP: https://data.giss.nasa.gov/gistemp/graphs_v4/ Now we want to put this 0.7 degrees Celsius warming over 30 years in context of other large climate changes in earth’s history. Some of the largest and fastest global climate changes in the geological record are associated with the Milankovitch cycles. The most recent Milankovitch cycle transition was that from the last glacial maximum about 20,000 years ago (when about a mile of ice was on top of Boston) to the Holocene climate starting about 10,000 years ago and this transition was characterized by a global warming of about 5 degrees Celsius. Thus, this rather dramatic climate change was characterized by a rate of change of 5 degrees Celsius over 10,000 years or 0.005 degrees Celsius per year[9]. Now we can put the global warming of the past 30 years in context. 0.7 degrees Celsius over 30 years is 0.023 degrees Celsius per year. So the warming of the past 30 years has been about 5 times (0.023/0.005 = 4.6) faster than the warming that occurred over the transition from the last glacial maximum to the preindustrial climate. I have made an animation placing contemporary global warming in the context of previous climate changes: Contemporary Global Warming placed in geological context. https://t.co/DMuiKptjPi pic.twitter.com/WI4jRQhrs4 — Patrick T. Brown (@PatrickTBrown31) August 20, 2018 Below is a static graph of a similar analysis: Source: Burke et al (2018)[10]. Additionally, Dr. Lindzen implicitly supports his claim of “remarkably little” warming with a misleading figure. At the 18-second mark, the video shows a graph of what I believe are satellite-derived monthly temperature anomalies. However, this time period has been cherry-picked to show “remarkably little” warming. Below is their graph overlain on the full satellite record (which began in 1978). The full satellite record shows that extending their graph in either direction (forward or backward in time) would reveal a clear warming trend. Source: University of Alabama Huntsville: https://www.nsstc.uah.edu/climate/ When these satellite derived temperature products (RSS and UAH in the graph below) are displayed as annual values and plotted on the same axis as the instrumental temperature datasets (Met Office, NASA and NOAA in the graph below), they largely agree with each other. In particular, they all show the same large (in a geological context) rate of warming over the past several decades: Source: Carbon Brief. Overall, Dr. Lindzen makes both a verbal claim and a visual claim that the rate of contemporary global warming is small, and both claims are false. Sara Vicca Postdoctoral research fellow, University of Antwerp: CO2 is indeed fundamental for most life on Earth. Plants need CO2 to grow and they are at the base of the food chain. However, this fact is often abused to claim that increasing CO2 concentrations is mainly a good thing. Although plant growth is often stimulated by increasing CO2 concentrations, CO2 also causes ocean acidification and warms the planet, thereby generating a cascade of effects from melting of glaciers and sea level rise to altered precipitation patterns and increasing frequency and intensity of extreme weather events such as heatwaves and droughts[5-8]. These in turn threaten water and food supplies, and as climate change progresses, this is also likely to undo much of the beneficial effect that CO2 has on plant growth[8]. I would say this claim is thus misleading in the context of this video.

https://science.feedback.org/review/low-solar-activity-has-little-effect-on-earths-climate-contrary-to-claim-in-the-sun/

Incorrect

The Sun, Chris Pollard, 2020-05-13

"The sun has gone into ‘lockdown’ which could cause freezing weather, earthquakes and famine, say scientists"

Incorrect: Solar activity cycles have little effect on the Earth’s climate and are not related to earthquakes or volcanic eruptions. Inadequate support: The article does not provide references to support predictions about solar activity and its effects on climate.

Although solar activity is currently in a quiet phase, this is typical of the 11-year cycle in the Sun’s energy output. The effect of low solar activity on the Earth’s climate is small compared to global warming caused by greenhouse gas emissions.

“The sun has gone into ‘lockdown’ which could cause freezing weather, earthquakes and famine, say scientists. Nasa scientists fear it could be a repeat of the Dalton Minimum, which happened between 1790 and 1830 — leading to periods of brutal cold, crop loss, famine and powerful volcanic eruptions.”

1 – Feulner et al (2010) On the effect of a new grand minimum of solar activity on the future climate on Earth. Geophysical Research Letters. 2 – Love et al (2013) Insignificant solar‐terrestrial triggering of earthquakes. Geophysical Research Letters. 3 – Benestad (2013) Are there persistent physical atmospheric responses to galactic cosmic rays? Environmental Research Letters. 4 – Palle et al (2016) Earth’s albedo variations 1998–2014 as measured from ground‐based earthshine observations. Geophysical Research Letters.

Review: This claim appeared in multiple outlets including The Sun, PJ Media, and the New York Post, and has been viewed on Facebook more than 40.5 million times in the past week. This claim, along with several others made in the article, contradict or are unsupported by scientific evidence. While the Sun varies in energy output in approximately 11 year cycles, this cycle has little effect on Earth’s climate, particularly compared to global warming caused by greenhouse gas emissions[1]. The claim “Nasa scientists fear it could be a repeat of the Dalton Minimum, which happened between 1790 and 1830 — leading to periods of brutal cold, crop loss, famine and powerful volcanic eruptions,” is unsupported and contrasts with scientific evidence showing no relationship between low solar activity and Earth’s climate[1]. The latest sun cycle forecast data shows a solar minimum occurring this year (see figure below), but there is no evidence of a prolonged “grand minimum” occurring, as the reviewers explain below. Source: NOAA. The article relies on a quote from Dr. Tony Phillips stating that “Solar Minimum is under way,” but the quote does not mention temperature, earthquakes, or famine. Contrary to this claim, NASA explains, “the current scientific consensus is that long and short-term variations in solar activity play only a very small role in Earth’s climate. Since 1750, the warming driven by greenhouse gases coming from the human burning of fossil fuels is over 50 times greater than the slight extra warming coming from the Sun itself over that same time interval.” A study evaluating the relationship between low solar activity and Earth’s climate found that a grand solar minimum may offset -0.3°C at most, a decrease much smaller than the warming expected from greenhouse gas emissions (see figure below)[1]. Figure – Rise of global temperature for two different emission scenarios (A1B, red, and A2, magenta). The dashed lines show the slightly reduced warming in case a Maunder-like solar minimum should occur during the 21st century. The blue line represents global temperature data. Source: PIK. The article is misleading to readers by suggesting the volcanic eruption of Mount Tambora in 1815 was linked to the Sun’s activity. The article claims, “NASA scientists fear it could be a repeat of the Dalton Minimum, which happened between 1790 and 1830 — leading to periods of brutal cold, crop loss, famine and powerful volcanic eruptions…On April 10, 1815, the second-largest volcanic eruption in 2,000 years happened at Mount Tambora in Indonesia, killing at least 71,000 people.” However, as the reviewer explains below, this eruption was not related to solar activity and the article provides no support for its claim of a link. There is also no scientific evidence to support the claim that a solar minimum can cause earthquakes, as claimed in the headline[2]. According to the USGS, “it has never been demonstrated that there is a causal relationship between space weather and earthquakes. Indeed, over the course of the Sun’s 11-year variable cycle, the occurrence of flares and magnetic storms waxes and wanes, but earthquakes occur without any such 11-year variability.” Although solar activity is currently low, this is typical of the 11-year cycle. There is no scientific evidence to support the claims that low solar activity can cause freezing weather, famine, earthquakes, and volcanic eruptions. UPDATE (22 May 2020):After this post was published, the headlines and bodies of articles in The Sun and the New York Post were corrected to clarify that low solar activity does not cause brutal cold, crop loss, famine, or volcanic eruptions. These articles now include disclaimers saying previous versions of the articles included misleading claims. UPDATE (27 May 2020):After this post was published, the headline and body of an article in The Daily Mail was corrected to clarify that solar activity cycles have little effect on the Earth’s climate. Scientists’ Feedback: Rasmus Benestad Senior scientist, The Norwegian Meteorological institute:There are indeed some indications that the solar activity is declining, e.g. as seen from the sunspot number during the most recent solar max in ~2014. Figure – Updated sunspot record shows a lower number of sunspots during the most recent solar maximum. The solar minima, on the other hand, tend to be on a similar level with few sunspots, and we are currently heading into a solar minimum as is typical every ~11 years. Source: http://sidc.oma.be/silso/DATA/SN_m_tot_V2.0.txt Claim: “Sunspot counts suggest it is one of the deepest of the past century. The sun’s magnetic field has become weak, allowing extra cosmic rays into the solar system.” This sentence is also consistent with the sunspot record, but the solar max in ~1885 was almost on the same level as the recent solar max in ~2014. The solar maxima in ~1805 and ~1817 were at lower levels, however. Claim: “Nasa scientists fear it could be a repeat of the Dalton Minimum, which happened between 1790 and 1830 — leading to periods of brutal cold, crop loss, famine and powerful volcanic eruptions.” The implication of this sentence is not supported by science. In 1815, there was a big volcanic eruption (Tambora in Indonesia) which was responsible for a drop of temperature (the year without summer) and poor crop yields, but it was completely unrelated to the solar activity. There is anecdotal evidence for low temperatures in Europe in 1816, but there is little data from the rest of the world available from that time. The longest ongoing instrumental temperature record is the Central England Temperature (CET), shown in the figure below, and it suggests that while 1816 was cold, there were also other years with colder or comparable summer temperatures. There is little reliable information to say whether the cold summers in England are part of a global phenomenon. We know today that England can have a cold summer without the rest of the planet being cold. Figure – Central England Temperature: June-July-August mean. Source: http://hadobs.metoffice.com/hadcet/cetml1659on.dat Claim: “Temperatures plummeted by up to 2C over 20 years, devastating the world’s food production.” The implications of this sentence are misleading since it suggests that these changes are due to changes in solar activity. There are no convincing links between solar activity/cosmic rays and climate variations[1,3]. If there were a strong connection between solar activity and climate, that would indeed be interesting, as it would suggest that our climate is quite sensitive to external forcing. The climate sensitivity is influenced by amplifying feedback mechanisms, such as changes in snow/ice-cover (changed albedo) or changes in atmospheric humidity (water vapour is a greenhouse gas). However, many of these feedback mechanisms act on changes in temperature, and would play a role for any type of forcing—also anthropogenic forcing. In that sense, there is no reason to think that a sensitivity to solar activity would rule out sensitivity to greenhouse gases—quite the opposite. The global warming trend in the last decades cannot be explained in terms of solar activity because there has not been any trend in solar activity. There is additional evidence that the trend cannot be due to galactic cosmic rays (GCRs) because (a) there has been no trend in GCRs, (b) the warming has been strongest during the polar night (winter in the Arctic) and at nighttime, where the mechanisms proposed for GCR is absent (changes in cloudiness and albedo), (c) there is no trend in the global albedo[4]. Georg Feulner Senior Scientist, Potsdam Institute for Climate Impact Research (PIK): Claim: “leading to periods of brutal cold, crop loss, famine and powerful volcanic eruptions.” While there were volcanic eruptions coinciding with the Dalton Minimum, there is no evidence whatsoever to suggest that solar activity causes volcanic eruptions! The volcanic eruptions during that time, and in particular the eruption of the Tambora in 1815, did cause the climate to cool and affected harvests, but this had little to do with the low solar activity of the Dalton Minimum. Studies also show that most of the cooling was due to volcanic aerosols, and that even a prolonged solar minimum could not offset future warming from human greenhouse gas emissions[1]. Claim: “On April 10, 1815, the second largest volcanic eruption in 2,000 years happened at Mount Tambora in Indonesia, killing at least 71,000 people. It also led to the so-called Year Without a Summer in 1816 — also nicknamed “eighteen hundred and froze to death” — when there was snow in July.” Again, these are the effects of the Mount Tambora eruption which has no connection to the low solar activity at that time. Doug Biesecker, Space Weather Prediction Center, NOAA:[Comment from a previous evaluation of a similar claim in February 2020.][Dr. Biesecker was co-chair of NOAA’s Solar Cycle 25 Prediction Panel.] There is no evidence we are headed into a grand minimum. With Cycle 25 predicted to be similar to Cycle 24 [2009-2020], we do not see anything approaching a grand minimum, at least not in the near future. What we cannot say is what Cycle 26 will look like—mainly because no one has a demonstrated method for predicting that far ahead. As for solar minimum, the panel only addressed the timing of minimum, not the intensity. However, it would be fair to say that no one on the panel expects an extreme minimum. Based on the panel prediction of minimum occurring in April of 2020 (+/-6 months), we would expect this minimum to be very similar to the last minimum between Cycles 23 and 24.

https://science.feedback.org/review/the-global-polar-bear-population-is-threatened-by-loss-of-sea-ice-contrary-to-pragerus-video-claim/

Incorrect

PragerU, Anonymous, 2020-05-05

The polar bear population has been growing. Polar bears are thriving even where sea ice is diminishing.

Cherry-picking: There is no scientific evidence that the global polar bear population is growing and there is evidence that several subpopulations are declining. Only two of the 19 polar bear subpopulations are likely increasing in size. The claim does not discuss data from other subpopulations that are declining or stable. Incorrect: The claim that “Polar bears are thriving even where sea ice is diminishing” runs counter to scientists’ understanding: sea ice loss due to climate change is recognized as the most important threat to the long-term survival of polar bears.

There is no scientific evidence that the global polar bear population is growing in size. Climate change induced losses in sea ice habitat is the most important threat to polar bear survival. Two polar bear subpopulations have already been negatively impacted by sea ice loss.

The polar bear population has been growing. The polar bear population is higher than it's been in over 50 years. Polar bears are thriving even where sea ice is diminishing.

1 – Stirling et al (2012) Effects of climate warming on polar bears: a review of the evidence. Global Change Biology. 2 – Stern et al (2016) Sea-ice indicators of polar bear habitat. The Cryosphere. 3 – Regehr et al (2016) Conservation status of polar bears (Ursus maritimus) in relation to projected sea-ice declines. Biology Letters. 4 – Derocher et al (2013) Rapid ecosystem change and polar bear conservation. Conservation Letters. 5 – Hunter et al (2010) Climate change threatens polar bear populations: a stochastic demographic analysis. Ecology. 6 – Bromaghin et al (2015) Polar bear population dynamics in the southern Beaufort Sea during a period of sea ice decline. Ecological Applications. 7 – Lunn et al (2016) Demography of an apex predator at the edge of its range: impacts of changing sea ice on polar bears in Hudson Bay. Ecological Applications. 8 – Regehr et al. (2018) Integrated population modeling provides the first empirical estimates of vital Rates and abundance for polar bears in the Chukchi Sea. Scientific Reports. UPDATES: 19 May 2020: This post was updated to correct the publication dates for two references.

Review: The claims appeared in a Facebook video by PragerU in May 2020, and has received more than 1 million views since it was published. There is no scientific evidence that the entire polar bear population has been growing, contrary to what this video claims. Of the 19 subpopulations measured by the IUCN Polar Bear Specialist Group, only two are likely increasing over the short-term. Currently, sea ice loss due to climate change is the most important threat to polar bears, contradicting the claim that “polar bears are thriving even where sea ice is diminishing”[1-3]. The global polar bear population is currently estimated to be approximately 20,000 – 25,000 bears, distributed among 19 subpopulations[4]. There is no scientific evidence that the global polar bear population is growing as the video claims, as the reviewers describe below. In 2019, two small polar bear subpopulations were estimated to have increased, four declined, and five were stable. The other subpopulations did not have enough data to demonstrate short or long-term trends (see figure below). Figure—Geographic distribution, size, and trends of 19 polar bear subpopulations measured by the IUCN Polar Bear Specialist Group. Colors reflect subpopulation trends in 2019. Shape and size of the circle represent subpopulation size, measured in number of bears. Adapted from the IUCN Polar Bear Specialist Group. Prior to the late 1970s, data on polar bear populations was limited or non-existent, as described by the reviewers below. During this time, hunting, killing, and capturing polar bears were the biggest threats to their survival until an agreement was signed to control these practices in 1973[4]. This agreement likely led to an increase in the global polar bear population in the 1970s[5]. But as stated in Hunter et al. (2010), “there is no evidence that these increases continued, and such recoveries, where they occurred, are irrelevant to the effects of recent changes in the availability of sea ice.”[5] More recent data from several subpopulations shows stable or declining trends in polar bear population size over time (see figures below). Figure—Estimated size of the Western Hudson Bay polar bear subpopulation using data from capture-recapture models from 1984-2011. From Lunn et al. 2016[7]. Figure—Estimated size of the Chukchi Sea polar bear subpopulation using capture data from 2009-2011, 2013, and 2015-2016. From Regehr et al. 2018[8]. The most important threat to the long-term survival of polar bears is the loss of sea ice habitat due to climate change[1-3]. Polar bears rely on sea ice to hunt seals (their primary prey), mate, establish dens, and move to new regions seasonally[2]. Loss of sea ice is occurring in almost all polar bear subpopulations and has already negatively affected some subpopulations[6,7]. “Long-term monitoring studies in Canada suggest that polar bear body condition, survival and population growth rates are all negatively impacted by declines in the availability of sea ice habitat and there are no data to suggest that polar bears are thriving in areas where sea ice has significantly declined,” said Gabrielle Lamontagne, a communication advisor for Environment and Climate Change Canada. In 17 of the 19 polar bear subpopulations, sea ice is retreating earlier in the spring. Sea ice is advancing later in the fall in 16 subpopulations. For example, in the Hudson Bay subpopulation, scientists found that earlier break-up of sea ice was associated with lower rates of survival for all age classes of female polar bears (see figure below). Figure—Estimated survival of female polar bears aged 1 – 19 years old declines as sea ice breaks up earlier in the year. Live-recapture and dead-recovery data was collected in the Hudson Bay subpopulation from 1984 – 2011. From Lunn et al. 2016[7]. Overall, the claims that the polar bear population is growing and that polar bears are thriving in areas where sea ice diminishing are not supported by scientific evidence. Scientists’ Feedback: Andrew Derocher Professor, University of Alberta: For the claims, and the “inconvenient facts”: “The polar bear population has been growing.” – Incorrect. There are 19 subpopulations of polar bears across the Arctic. Four are likely decreasing (according to the IUCN/SSC Polar Bear Specialist Group – of which I am a member). Five are likely stable and two are likely increasing. The remainder are unknown. However, one of the unknown subpopulations is likely also decreasing but the Government of NWT won’t release the analyses showing that it has declined as well. If one considers the “global” population as if there is 1 population in the Arctic, the claim of “growing” cannot be supported. For the claim that “The polar bear population hasn’t been this high in over 50 years”—well, if one wants to start the numbers at the pre-1973 start point, perhaps this one is OK because while we have zero data on polar bear abundance until the late 1970s, polar bears were commercially harvested until ca. 1973 when the Agreement on the Conservation of Polar Bears was signed that introduced harvest controls. Polar bears, while based on poor or no data, were heavily depleted in the 1950s-1960s. So, from 1970 to 2020, fine, polar bear populations overall increased. This of course ignores areas that have now declined (Western Hudson Bay, Southern Hudson Bay, Southern Beaufort Sea) and M’Clintock Channel that was severely overharvested post-1973. It’s a word game. Past increases were due to harvest controls. Current declines are due to climate change associated loss of sea ice[1,2,3]. For the claim that “Polar bears are thriving even where sea ice is diminishing”—again, this is spin. In Western Hudson Bay, Southern Hudson Bay, and Southern Beaufort Sea, population declines are associated with sea ice loss (lower survival, lower successful reproduction that lead to abundance declines). Some polar bear populations are doing OK and are experiencing some sea ice loss. We know, however, that that pattern cannot be sustained. The Barents Sea polar bears appear to be doing OK yet they are losing sea ice at high rates. Why are they doing OK and others are not? That area has a very large area of continental shelf/shallow water. Polar bear habitat is widespread. It is experiencing the highest rate of sea ice loss in days of cover per decade of the 19 polar bear populations. We’ve just not hit the point where their habitat is affected enough to cause problems. It will happen. Regardless, this area has seen many changes (e.g. loss of maternity den areas, loss of habitat). I worked in the Barents Sea for 7 years—this population will lose with the current trend in sea ice. Ian Stirling Adjunct Professor, University of Alberta: The sources the video cites are nonsense scientifically and, worse, deliberately misrepresent the facts. As for real numerical information on polar bears, if anyone wants to know how much can be said with as much reliability as is possible, they should go to the web site for the IUCN Polar Bear Specialists Group (which I am also a member of). Note on the left hand side there are headings that give estimates and summaries (with references) of knowledge for all the 19 populations. The estimates for some populations are labelled as current, outdated, and nonexistent for others, particularly in Russia, so it is not technically possible to have a “total estimate”. In reality, it is the status and trends of the 19 individual populations that count. Several populations, such as those in western and southern Hudson Bay, and the southern Beaufort Sea are confirmed unequivocally, from long-term data, to have declined significantly as a direct result of climate warming causing steady loss of sea ice[6,7]. Some other populations are likely also declining, just judging from the extent of the steady loss of ice but we lack long-term data with which to make that assessment, and a couple are doing OK, such as Foxe Basin and Davis Straight, and one seems to be increasing (M’Clintock Channel). However, unless we are able to stop global warming and maybe even start to cool the planet, all populations will decline severely and some will be lost forever[5]. The steady loss of sea ice in all subpopulation regions is well summarized by Stern and Laidre[2]. Dr. Derocher and I also published a review a few years ago that gives the state of knowledge about the effects of climate warming on polar bears[1]. READ MORE We wrote a review on a picture published by National Geographic, in which scientists explain that it was unclear whether this particular polar bear was a victim of climate change. In another Climate Feedback review of a Financial Post article, scientists explained that the claim “polar bears are thriving” rather than being threatened by losses in Arctic sea ice misrepresents scientific research on this topic.

https://science.feedback.org/review/article-in-business-insider-accurately-describes-results-from-a-study-estimating-up-to-3-billion-people-could-live-in-much-warmer-temperatures-by-2070/

0.3

Business Insider, by Sarah Al-Arshani, on 2020-05-05.

"3 billion people — up to half the current global population — could be living in unbearable heat in 50 years"

1 – Xu et al (2020) Future of the human climate niche. PNAS. 2 – Riahi et al (2011) RCP 8.5—A scenario of comparatively high greenhouse gas emissions. Climatic Change.3 – Fujimori et al (2017) SSP3: AIM implementation of Shared Socioeconomic Pathways. Global Environmental Change.

Reviewers’ Overall Feedback: Marten Scheffer Professor, Wageningen University: [Prof. Scheffer was an author of the study that was the topic of this article.] It is slightly misleading to compare the future amount of people under severe climate stress to the current total population, as in the meantime the global population will have grown. It is not wrong, but it somehow suggests half the people get in severe climate trouble whereas it would be one third (for the high end forcing scenario). Steven Sherwood Professor, University of New South Wales: The study does not address temperatures that are “survivable,” only those which humans evidently prefer and thrive in. We know the warmer temperatures are not unsurvivable because people have been surviving in them for millenia. Thus the story is misleading and overhyped. It appears that the fault for this lies more with overzealous statements by some of the ecologists than the journalist who wrote the story. Nonetheless the warmer temperatures will be more difficult and undoubtedly lead to all kinds of problems, and it is valuable to have this new study highlighting that past societies in these climates have not progressed in the same way as those in cooler climates. So I applaud the study and the choice to write about it, they just needed to stay to what they’d actually shown. Andrew King Research fellow, University of Melbourne: Overall, this article provides a fair representation of the study it’s based on. It accurately portrays the study’s main results in the headline, key points and throughout the text. I think the focus of the article on the worst-case scenario ahead of more likely scenarios may not be the most helpful, but this is at least explicit in the article. As Xu et al. note[1], the analyses are statistical associations not process-based understanding of the multiple drivers of the location of human settlements over time. The authors note there are many variables they did not investigate because data were not available; this does not mean the variables are unimportant. Some of these variables are likely also to be associated with geographic location of humans, crops, and livestock. It would be interesting to hear from agricultural specialists about variables related to the geographic location of crops (such as growing degree days, day length, timing of precipitation, and others). The perspectives of anthropologists on the drivers of successful human settlements also would be interesting. The scenario in the main text combines RCP 8.5 and SSP 3, resulting in very high greenhouse gas emissions, leading to greater climate change in 2100 than in other scenarios. The Paris Agreement committed governments to significantly reduce their GHG emissions, decreasing the probability of RCP 8.5.

https://science.feedback.org/review/diesel-cars-are-a-major-source-of-no2-emissions-in-european-cities-contrary-to-online-claim/

Flawed reasoning

Tichys Einblick, Holger Douglas, 2020-04-12

The drop in NO₂ content has only been “slight”. So it cannot be the evil diesel engine cars that are “choking” our cities.

Inadequate support: The article does not provide any scientific evidence to support its claims about recent trends in car traffic and NO2 emissions in Stuttgart, Germany. Flawed reasoning: The argument that diesel engine cars are not polluting cities because NO2 concentrations haven’t changed even though traffic has declined is flawed. Studies show that diesel car emissions are a major contributor of nitrous oxide emissions in European cities.

Road transport accounts for almost half of nitrous oxide emissions in European cities, including Stuttgart, Germany. Scientific studies have shown that diesel-fueled vehicles are the primary source of nitrous oxide emissions from road transport in Europe.

Although car traffic in the German city of Stuttgart has decreased significantly due to COVID-19, the drop in NO₂ content has only been “slight”. So it cannot be the evil diesel engine cars that are “choking” our cities.

1 – Driscoll et al. (2018) Real world CO2 and NOx emissions from 149 Euro 5 and 6 diesel, gasoline and hybrid passenger cars. Science of the Total Environment. 2 – Degraeuwe et al. (2017) Impact of passenger car NOx emissions on urban NO2 pollution – Scenario analysis for 8 European cities. Atmospheric Environment. 3 – Sims et al. (2014) Transport. In: Climate Change 2014: Mitigation of Climate Change. Contribution of Working Group III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. 4 – UNEP 2013. Drawing down N2O to protect climate and the ozone Layer. A UNEP Synthesis Report. United Nations Environment Programme (UNEP). 5 – Reay et al. (2012) Global agriculture and nitrous oxide emissions. Nature Climate Change. 6 – Khaniabadi et al. (2016) Exposure to PM10, NO2, and O3 and impacts on human health. Environmental Science and Pollution Research. 7 – Pleijel et al. (2016) A method to assess the inter-annual weather-dependent variability in air pollution concentration and deposition based on weather typing. Atmospheric Environment.

Review: This claim appeared in Tichys Einblick and NoTricksZone in April 2020 and has been shared over 8,500 times since it was published. The article does not provide scientific evidence to support their claims that car traffic has “significantly” decreased and NO2 has only slightly declined in response to the novel coronavirus (SARS-CoV-2). The argument that reductions in car traffic, but stable NO2 levels mean that diesel cars do not pollute cities is flawed. Although NO2 concentrations can fluctuate over time and space, several scientific studies that measured sources of NO2 emissions in European cities demonstrate that road traffic and diesel cars, in particular, are major contributors of NO2 emissions[1,2,3]. Nitrous oxides (NOx) are a family of air pollutants that includes seven chemical compounds. According to a report published by the United Nations, nitrogen oxide is “the most significant ozone-depleting substance emission and the third most important greenhouse gas.”[4] Nitrous oxide (N2O) and nitrogen dioxide (NO2) are the most prevalent pollutants in the air. These compounds are produced by human activities, including agriculture, fuel combustion, and industrial processes[4,5]. By diminishing air quality, nitrous oxides can impact human health. For example, Khaniabadi et al. (2016) state, “approximately 5–7% of the lung cancers among ex-smokers and non-smokers can be associated with exposure to high levels of air pollutants containing NO2 or vicinity to roads with heavy-traffic.”[6] As described by the reviewer below, NO2 concentrations are challenging to measure over short time periods (e.g. weekly, monthly) because they are influenced by season, weather patterns (e.g. wind, temperature), and man-made emissions[3,7]. Despite this variation, scientific studies have found that road traffic accounts for 47% of annual nitrous oxide emissions in European cities, including Stuttgart (see figure below). Figure—Annual nitrous oxide emission (NOx) of 30 European cities. Pie charts show the share of emissions attributed to different sources. Source EU Science Hub. The article in which the claim appeared does not specify how car traffic and NO2 concentrations were measured in Stuttgart or over what time period, providing no adequate support for the claim that car traffic has declined “significantly” or that “the drop in NO2 content has only been ‘slight’.” A separate article claims there has been a 37% reduction in car traffic at the Am Neckartor station in Stuttgart when comparing data from March 2020 to March 2019. While these estimates support a decline, there is still car traffic on the road and this data is only from a single station. Furthermore, the claim that diesel cars do not pollute cities contradicts available scientific evidence showing diesel cars are responsible for the vast majority of NO2 emissions in urban environments. To determine the amount of air pollution attributed to different vehicle types, O’Driscoll et al (2018) measured real world NOx emissions from diesel, gasoline, and hybrid passenger vehicles sold in Europe using portable emissions measurement systems. Diesel cars produced, on average, 8 – 11 times more NOx in urban environments than gasoline cars, depending on the European emissions standard category (see figure below). The authors also estimated that, “gasoline vehicles delivered an 86 – 96% reduction in NOx emissions compared to diesel cars.”[1] Figure—In urban areas, diesel cars (green) emit 8 – 11 times more NOx than gasoline cars (blue). Cars are grouped by European emission standards (G6: Euro 6 Gasoline, G5: Euro 5 Gasoline, D6: Euro 6 Diesel, D5: Euro 5 Diesel). Adapted from O’Driscoll et al. (2018)[1]. This study is consistent with data from across 33 European cities, which identified diesel cars as the primary source of NOx emissions from road traffic (see figure below). Figure—Across Europe, diesel cars are the major source of annual nitrous oxide (NOx) emissions from road traffic. Source EU Science Hub. Overall, these data directly contradict the claim that diesel cars are not polluting cities. Scientists’ Feedback: Tim Butler Research Group Leader, Institute for Advanced Sustainability Studies: Firstly, it’s very well established that urban NO2 concentration is highly influenced by both weather conditions and nearby emissions. For example, on a still day, pollution will accumulate, leading to higher concentrations near the emission sources, while on a windy day, pollution will be quickly blown away, leading to relatively lower concentrations near the emission sources. The chemical lifetime of NO2 is also shorter during warm, sunny days, and longer in winter, when the days are shorter and darker. For these reasons, European air quality legislation specifies ambient NO2 limit values in terms of the annual mean concentration. By measuring the annual mean, the seasonal variations and the short term fluctuations due to weather are averaged out, and a more reliable indication of the exposure at the measurement locations is obtained. Man-made NO2 emissions are primarily from combustion sources. This combustion may be in industrial facilities, residential heating units, or the internal combustion engines which still power most vehicles. The relative mix of these sources can vary between cities, but on average road traffic is thought to account for about half of the man-made NO2 in most European cities. Regarding the claims in the article, these are vague and hard to verify. The reduction in traffic in Stuttgart is supposed to have decreased “significantly”, but this is not quantified in the article. The article also claims that the air quality has “hardly changed”, but does not specify what this means. Over which period? Compared to what? By how much exactly? The article mentions a pre-restriction measurement of 40 µg/m3 NO2 concentration at the station Am Neckartor (only for a 2-month period), but doesn’t give a number for post-restriction. Without many actual numbers backing things up, the reasoning behind the claims in the article appears weak. I visited the website of the Amt für Umweltschutz of the city Stuttgart, to look for some recent reports on traffic and air quality, and found the following article. Apparently the amount of traffic at the Am Neckartor site has reduced by about a third due to the restrictions. Perhaps that’s “significant”, but it’s not a complete shutdown. This article also discusses a reduction in the measured NO2 concentration at that site, and gives a number of possible reasons, including the Coronavirus restrictions. Rightly, this article is cautious about interpreting these short-term variations in NO2, since the legal limit value is defined as an annual average, and we are only in April now. 2020 still has 8 months to go.

https://science.feedback.org/review/claim-that-co2-is-cooling-the-planet-is-misleading-anthropogenic-co2-emissions-overall-cause-global-warming/

Imprecise

Express, Sebastian Kettley, 2020-02-18

Global warming slowing down? 'Ironic' study finds more CO₂ has slightly cooled the planet

Flawed reasoning: Human-caused CO2 emissions can enhance plant growth and increase absorption of atmospheric CO2 that causes global warming, thus acting as a negative feedback. This negative feedback can reduce the amount of global warming, but has not cooled the planet as claimed in this headline. Misrepresents source: The review paper the claim is based on does not show that CO2 has “cooled the planet”, but that CO2 absorption by plants leads to a smaller global temperature increase than would otherwise occur.

Human-caused CO2 emissions are responsible for approximately 100% of the global warming trend observed since 1950. Although enhanced plant growth absorbs some of the CO2 emitted by human activities, reducing the amount of global warming that can occur, this negative feedback has not caused warming to slow in recent years.

Global warming slowing down? 'Ironic' study finds more CO₂ has slightly cooled the planet[...] The process, known as evapotranspiration, occurs when plants consume the heat-trapping greenhouse gas and release water. Much like humans sweating on a hot day, evapotranspiration can have a cooling effect on the air. In other words, with more carbon dioxide feeding plant growth, the planet is slightly cooler than otherwise expected.

1 – Piao et al (2019) Characteristics, drivers and feedbacks of global greening. Nature Reviews Earth & Environment. 2 – Zhu et al. (2016) Greening of the Earth and its drivers. Nature Climate Change. 3 – Piao et al (2006) Effect of climate and CO2 changes on the greening of the Northern Hemisphere over the past two decades. Geophysical Research Letters. 4 – Yuan et al (2017) Vegetation changes and land surface feedbacks drive shifts in local temperatures over Central Asia. Scientific Reports.5- De Graaff et al. (2006) Interactions between plant growth and soil nutrient cycling under elevated CO2: a meta-analysis. Global Change Biology.

Summary: The claim, which appeared as the headline of an article published by Express in February 2020, uses flawed reasoning to argue that the rate of global warming has slowed because plants absorbed CO2 emitted by human activities in some regions around the world. Global land and ocean temperatures continue to rapidly increase, contrary to the article headline of a change in the rate of warming (see figure below). Figure—Global temperature anomaly data relative to the 20th century average temperature from the Global Historical Climatology Network-Monthly data set and International Comprehensive Ocean-Atmosphere Data Set. These data sets show consistent global warming trends. From NOAA. The article misrepresents findings of the review paper it is based on. The paper describes how CO2 uptake by plants acts as a negative feedback, reducing the potential rate of warming by removing some CO2 from the atmosphere[1,2]. Increased plant growth can also reduce local land surface temperatures in some regions where the cooling effects of evapotranspiration outweigh the warming effects of greener canopies reflecting less sunlight back to space. As described in Piao et al (2019), “In warm regions such as the tropics and subtropics, evaporative cooling effects are generally larger than albedo warming effects, leading to a net cooling effect when vegetation greenness increases.”[1] In other regions, albedo warming effects outweigh evaporative cooling, increasing local land surface temperatures[1,3,4]. According to the article, Jarle Bjerke of the Norwegian Institute for Nature Research explained: “It is ironic that the very same carbon emissions responsible for harmful changes to climate are also fertilising plant growth which in turn is somewhat moderating global warming.” Although this negative feedback has lessened the temperature increase of global warming caused by anthropogenic CO2 emissions (“somewhat moderating global warming”), it has not “cooled the planet” or caused a recent reversal in temperature trend, as claimed in the article’s headline. While the headline of the Express article is wrong in claiming this feedback cools the planet, the body of the article gets it right when saying “with more carbon dioxide feeding plant growth, the planet is slightly cooler than otherwise expected.” This is not a new discovery, but a long-understood function of the Earth’s carbon cycle—a portion of the CO2 we emit is absorbed by land plants and by the ocean rather than accumulating in the atmosphere. Finally, greening effects of anthropogenic CO2 are expected to weaken or disappear over time with continued global warming[1,3]. UPDATE (27 April 2020): After this post was published, the headline of the article in Express was corrected. The body of the Express article was also edited to clarify that the planet is not cooling. Specifically, the author clarified that the greening trends caused by CO2 emissions are only observed in certain parts of the world, such as the tropics and sub-tropics. He added the following sentences, “Although the effect has not cooled the planet, the planet is slightly cooler than otherwise expected,” and “Unfortunately, the overall effects of CO2 emissions are overwhelmingly contributing to the planet’s rising temperatures.” Finally, he clarified that greening trends are expected to decline over time by adding, “In time, however, the positive effects of CO2 are expected to weaken in the face of human-led global warming.”

https://science.feedback.org/review/human-activities-have-dramatically-increased-atmospheric-co2-levels-causing-imbalances-in-the-global-carbon-cycle/

Incorrect

I Love Carbon Dioxide, Cole Ryan, 2020-04-12

Human additions of CO₂ are in the margin of error of current measurements and the gradual increase in CO₂ is mainly from oceans degassing as the planet slowly emerges from the last ice age.

Factually inaccurate: Human activities have increased atmospheric CO2 levels from 280 ppm to more than 400 ppm since industrialization, which is an increase greater than the margin of error of current measurements. Oceans presently serve as a sink for CO2, not a source. Misleading: Humans have caused an unprecedented rise in atmospheric CO2 levels in the last 800,000 years. This is because the natural flows in the global carbon cycle were previously in balance.

Atmospheric CO2 has increased rapidly as a result of human activities. Although human-caused emissions of CO2 are small relative to natural flows into and out of the atmosphere, the human contribution has caused an imbalance in the global carbon cycle that jeopardizes land and ocean ecosystems.

Human additions of CO₂ are in the margin of error of current measurements and the gradual increase in CO₂ is mainly from oceans degassing as the planet slowly emerges from the last ice age.

1 – IPCC (2007) Summary for Policymakers. In: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. 2 – IPCC (2014) Climate Change 2014: Summary for Policymakers. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. 3 – Gruber et al (2019) The oceanic sink for anthropogenic CO2 from 1994 to 2007. Science. 4 – Friedlingstein et al (2019) Global carbon budget 2019. Earth System Science Data. 5 – Doney et al (2009) Ocean acidification: The other CO2 problem. Annual Review: of Marine Science.6 – Zhao et al (2006) Estimating uncertainty of the WMO mole fraction scale for carbon dioxide in air. Journal of Geophysical Research.

Summary: The claim appeared in multiple outlets, including Watts Up With That, the Daily Signal, and a Facebook post published by I Love Carbon Dioxide in April 2020. While human additions of CO2 are small relative to natural processes, atmospheric CO2 measurements are currently much higher than pre-industrialization CO2 levels and not within the “margin of error of current estimates,” as described by the reviewers below[1,2]. The ocean does release CO2, but scientific evidence demonstrates that oceans have absorbed approximately 23% of global anthropogenic CO2 emissions since the Industrial Revolution, thus serving as a net sink rather than a source of CO2[3,4]. This claim also fails to recognize that human-induced CO2 emissions have caused imbalances in the global carbon cycle. Pre-industrialization atmospheric CO2 levels were around 280 parts per million (ppm)[2]. Since 1950, the burning of fossil fuels, agricultural development, and other human-caused land-use changes have led to steady increases in atmospheric CO2. According to the IPCC, “This has led to atmospheric concentrations of carbon dioxide, methane, and nitrous oxide that are unprecedented over at least the last 800,000 years.”[1,2]Today, atmospheric CO2 exceeds 400 ppm, as shown in the figure below. Figure—The Keeling Curve, a daily record of global atmospheric CO2, shows relatively stable CO2 concentrations from 1700 to 1950, as measured by ice-cores. After 1950, CO2 concentrations rose rapidly from 300 to over 400 ppm, as measured at the Mauna Loa Observatory. From Scripps Institute of Oceanography. Pre-industrialization atmospheric CO2 levels remained relatively constant because the global carbon cycle was balanced. In other words, the amount of CO2 being released into the atmosphere from natural sources, such as the ocean and respiring organisms, was balanced by the amount of CO2 absorbed from the atmosphere. Human-caused increases in CO2 emissions have created an imbalance in the global carbon cycle, where more CO2 is being released than can be absorbed by natural carbon sinks (see figure below). Excess CO2 in the atmosphere warms the planet and excess CO2 in the oceans causes acidification that jeopardizes marine ecosystems[1,2,5]. Figure—The global carbon cycle from 2009 to 2018 shows that human contributions to atmospheric CO2 outweigh the amount of carbon cycled each year, leading to an annual budget imbalance of 2 GtCO2. From The Global Carbon Budget 2019. Scientists’ Feedback: Peter Landschützer Group Leader, Max Planck Institute for Meteorology: First of all, the claim that current changes in atmospheric CO2 are within the uncertainty of measurements is absurd. Since pre-industrial times atmospheric CO2 levels increased from roughly 280 ppm to now roughly 412 ppm (globally on January 2020) with growth rates currently exceeding 2 ppm/yr. These atmospheric CO2 (as well as other trace gas) measurements are highly accurate with errors estimated at 0.07 ppm[6]. Secondly, the claim that the increase results as “the Planet emerges from the last ice age” is wrong for multiple reasons. Firstly, ice-core atmospheric CO2 records suggest that such a strong increase (from 280ppm to 412 ppm) is unprecedented in the last 800,000 years. Secondly, these records also show that the speed at which atmospheric CO2 increases is unprecedented in the ice-core record history. Finally, the ocean degassing CO2 is causing this “gentle and welcome” increase is fundamentally wrong and not supported by observations. While the anthropogenic perturbation might be small compared to the large natural carbon fluxes in the ocean , they are well detectable from measurements[1,2]. Current science suggests that the ocean is taking up (NOT releasing) roughly 2.5 PgC/yr of carbon from the atmosphere which corresponds to roughly 23% of annual human CO2 emissions[3,6]. This is supported by observation-based estimates using the partial pressure of CO2 collected in the Surface Ocean CO2 Atlas, repeat hydrography measurements of the dissolved inorganic carbon content, and estimates based on atmospheric inversions[1,4]. In summary, there are multiple, independent measurement-based flux estimates that highlight that the ocean is a significant net CO2 sink. [Comment from a previous evaluation of a similar claim.] Global human emissions are indeed only a small percentage of what ecosystems cycle, but the reasoning is completely flawed. Regarding the impact on climate, it is the net emissions that matter, not the amount of carbon that is being cycled over and over. Terrestrial ecosystems take up and re-emit about 12 times more CO2 than humans emit, and oceans cycle about 9 times more CO2 than we emit. BUT! This carbon uptake and release is more or less balanced at the annual scale, and net ecosystem emissions are even negative. Without these ecosystems, atmospheric CO2 concentration would have risen even more as a consequence of fossil fuel burning; the CO2 concentration in the air would already be around 550 ppm (instead of the current ~400 ppm). Hence, it is absolutely misleading to compare amounts of CO2 cycling through the ecosystems with human CO2 emissions in this context. If anything, the CO2 cycling through the ecosystems should be taken as a reason to safeguard them: if we lose these carbon sinks, CO2 in the air will increase no matter what we do.

https://science.feedback.org/review/human-induced-increases-in-greenhouse-gases-are-the-primary-driver-of-global-warming-contrary-to-claims-in-cfact-article/

Incorrect

CFACT, Jay Lehr, 2020-04-08

They tell us that we are the primary forces controlling earth temperatures by the burning of fossil fuels and releasing their carbon dioxide. I hope my readers can recognize the absurdity of their claims. … increasing sunspots are linked to increases in earth temperature

Incorrect: Anthropogenic increases in greenhouse gas emissions account for 100% of the rapid global warming trends observed after 1950. Solar forcing cannot exclusively explain climate change patterns. Inadequate support: None of the article’s claims that argue the Sun is responsible for current global warming are supported by published research.

The effects of CO2 and other greenhouse gas emissions far outweigh the effects of solar forcing on global warming. 100% of the global warming trends observed after 1950 can be attributed to anthropogenic factors.

They tell us that we are the primary forces controlling earth temperatures by the burning of fossil fuels and releasing their carbon dioxide. I hope my readers can recognize the absurdity of their claims. … increasing sunspots are linked to increases in earth temperature.

1- Feldman et al (2015) Observational determination of surface radiative forcing by CO2 from 2000 to 2010. Nature. 2 – Santer et al (2017) Tropospheric warming over the past two decades. Scientific Reports. 3 – Hausfather (2017) The extent of the human contribution to modern global warming is a hotly debated topic in political circles, particularly in the US. Carbon Brief. 4 – IPCC, 2013: Summary for Policymakers. In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change 5 – Li et al (2018) Multiresolution analysis of the relationship of solar activity, global temperatures, and global warming. Advances in Meteorology.

Summary: The claim appeared in an article published by CFACT in April 2020. This claim directly contradicts ample scientific evidence showing that human-caused increases in greenhouse gas emissions, such as CO2, have been the primary driver of global warming[1,2]. Feldman et al (2015) demonstrate that “increasing atmospheric CO2 concentrations between 2000 and 2010 have led to increases in clear-sky surface radiative forcing,” (as seen in the figure below)[1]. When radiative forcing is positive, the Earth absorbs more energy from the Sun than it radiates back to space, causing warming. The authors describe that “Fossil fuel emissions and fires contributed substantially to the observed increase… If CO2 concentrations continue to increase at the current mean annual rate of 2.1 ppm per year, these spectroscopic measurements will continue to provide robust evidence of radiative perturbations to the Earth’s surface energy budget due to anthropogenic climate change.” Figure—Increases in CO2 concentrations measured by CarbonTracker 2011 (CT2011) have led to increases in CO2 surface forcing observed at experimental sites in the continental South Great Plains (SGP). From Feldman et al. 2015[1]. Anthropogenic drivers of global warming far outweigh the effects of solar forcing[3,4]. As described in the 2013 IPCC report, “Greenhouse gases contributed a global mean surface warming likely to be in the range of 0.5°C to 1.3°C over the period 1951 to 2010. The contribution from natural forcings is likely to be in the range of −0.1°C to 0.1°C.” These findings contrast with claims made in the CFACT article that the shape of the Earth’s orbit, tilt of the Earth relative to the Sun, and the Sun itself are the main drivers of current climate change. While these mechanisms can cause climate changes over long time periods (e.g. in 20,000 and 100,000 year cycles), these processes occur too slowly to drive patterns of global warming observed in the past 100 years. Specifically, the article claims that “increasing sunspots are linked to increases in earth temperature,” however, this claim is not supported by scientific evidence. Li et al (2017) analyzed the relationship between the number of sunspots and global warming and found that “solar activity is not a representation of the driving force of the upward trend of global temperature after the industrial age. The Granger causality test results demonstrate that the phenomenon of global warming is caused by excessive CO2 emissions.”[5]. Figure—The monthly average number of sunspots (left) and global surface temperature time series from the Goddard Institute for Space Studies (right). Although sunspot number varies in approximately 11 year cycles, global temperature has steadily increased since 1950. While natural and anthropogenic factors can affect changes in the climate, multiple lines of scientific evidence demonstrate that recent global warming trends can be attributed to human-caused increases in greenhouse gas emissions and not to the Sun[1,3,4]. Scientists’ Feedback: Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: [Comment from a previous evaluation of a similar claim.] Global temperature datasets, developed by a number of independent research groups, show robust warming in the troposphere and at the Earth’s surface. The radiative effect of carbon dioxide has also been observed[1]. Considering multiple lines of evidence, the IPCC concluded that it is “extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century.” More recent analysis of satellite data shows that tropospheric warming from the satellite record is pronounced and cannot be explained by natural climate variability alone[2]. [This comment comes from a previous review of a similar claim.] Careful analysis that attempts to take into account all major factors and their evolution in time indicates that anthropogenic increases in greenhouse gasses account for more than 100% of the observed warming on the century timescale (requiring cancellation from cooling influences). See the summary graphic from Carbon Brief, below. Figure—The estimated role of different factors influencing global surface temperatures from 1850 to 2017. Observed temperatures are shown in black dots. Global warming over the past 150 years was primarily driven by greenhouse gas emissions (red). From Carbon Brief[3]. Britta Voss Postdoctoral Research fellow, U.S. Geological Survey: [This comment comes from a previous review of a similar claim.] Solar forcing is much smaller than CO2 forcing. As this figure from the 2013 IPCC report shows, CO2 radiative forcing (1.68 W/m2) dwarfs solar forcing (0.05 W/m2)[4]. Along with other greenhouse gases, CO2 dominates the total radiative forcing when all positive and negative factors are taken into account. Figure—Radiative forcing estimates in 2011 relative to 1750. Values are global average radiative forcing, partitioned according to the emitted compounds or processes that result in a combination of drivers. Source IPCC AR5[4].

https://science.feedback.org/review/scientists-observe-most-widespread-bleaching-event-ever-recorded-at-the-great-barrier-reef/

Accurate

ABC News, Michael Slezak, Penny Timms, 2020-04-06

The Great Barrier Reef is experiencing the most widespread bleaching ever recorded

Accurate: For the first time, coral reefs in the northern, central, and southern regions of the Great Barrier Reef were affected by bleaching at the same time. At the time, there is no peer-reviewed study yet to fully document this bleaching event; it should be verified by underwater observations in the coming months.

Increased sea surface temperatures boosted by climate change have triggered five mass bleaching events in the Great Barrier Reef since 1998. In March 2020, scientists conducted aerial surveys and found that all three regions of the Great Barrier Reef were affected by bleaching, making this the most geographically widespread bleaching event observed to date.

The Great Barrier Reef is currently experiencing the most widespread bleaching ever recorded, with 60 per cent of reefs across all three regions affected, according to a detailed survey of the system.

1 – Hughes et al. (2020) We just spent two weeks surveying the Great Barrier Reef. What we saw was an utter tragedy. The Conversation. 2 – Ainsworth et al. (2016) Climate change disables coral bleaching protection on the Great Barrier Reef. Science. 3 – Hughes et al. (2017) Global warming and recurrent mass bleaching of corals. Nature.4 – Hughes et al. (2018) Ecological memory modifies the cumulative impact of recurrent climate extremes. Nature.

Summary: The claim that “The Great Barrier Reef is experiencing the most widespread bleaching ever recorded” appeared in several media outlets, including an article published by ABC News in April 2020. This claim is based on data collected from aerial surveys conducted in March 2020, which found that 60% of coral reefs across all three regions of the Great Barrier Reef had moderate or severe levels of bleaching[1]. Bleaching occurs when corals expel algae and photosynthetic pigments from their tissues[2]. Although some coral species can recover from light levels of bleaching, severe bleaching can lead to mass mortality of corals[2,3]. Increased sea surface temperatures caused by climate change have triggered five mass bleaching events in the Great Barrier Reef since 1998[3,4]. These events occurred in 1998, 2002, 2016, 2017, and 2020[2,3,4]. In March 2020, Terry Hughes and James Kerry conducted aerial surveys of 1,036 reefs along the Great Barrier Reef in Australia. For the first time, they observed bleaching in the northern, central, and southern regions of the Great Barrier Reef, consistent with the claim that this is the most widespread bleaching event recorded. In addition, “2020 is the second-worst mass bleaching event of the five experienced by the Great Barrier Reef since 1998,” Hughes wrote in The Conversation[1]. About a quarter of the coral reefs the scientists measured were severely bleached, where more than 60% of the corals in each reef were affected by bleaching. The aerial data collected by Hughes will be verified by underwater observations in the coming months. Although this data is currently not peer-reviewed, it does support the claim that this is the most widespread bleaching event recorded in the Great Barrier Reef. Scientists’ Feedback: Terry Hughes Professor, ARC Centre of Excellence for Coral Reef Studies, James Cook University: The claim published by ABC that bleaching in 2020 is more widespread than earlier bleaching events (and second in intensity to 2016) is correct. It comes from the article I wrote in The Conversation on Tuesday, April 6[1]. My article provides three maps that show “For the first time, severe bleaching has struck all three regions of the Great Barrier Reef – the northern, central and now large parts of the southern sectors. The north was the worst affected region in 2016, followed by the centre in 2017.” The maps show unbleached reefs in green, and severely bleached reefs in red. Figure—Surveys of the Great Barrier Reef show the location and severity of bleaching events in 2016, 2017, and 2020. Red circles indicate the most severe bleaching, whereas green circles represent little or no bleaching. Although 2016 was the most severe bleaching event ever recorded, the impacts were primarily in the northern regions. In 2020, severe bleaching was observed across all three regions of the Great Barrier Reef. From The Conversation.

https://science.feedback.org/review/the-antarctic-ozone-layer-is-recovering-but-the-independent-claim-fails-to-grasp-significance-of-study-it-relies-on/

Mostly accurate

The Independent, Louise Boyle, 2020-03-26

The ozone layer is healing

Correct: Scientific studies have shown that the Antarctic ozone is recovering. Fails to grasp significance of observation: The study the claim is based on analyzed changes in atmospheric circulation patterns influenced by the Antarctic ozone hole, not the recovery of the ozone hole itself.

The Antarctic ozone layer is healing and has the potential to recover to 1960 levels by the end of the century. Atmospheric circulation trends in the Southern Hemisphere, which are driven by ozone depletion, have also paused or reversed. These changes are attributed, in large part, to reductions in ozone-depleting substances, such as chlorofluorocarbons.

The ozone layer is continuing to heal and has the potential to fully recover, according to a new study

1 – Banerjee et al. (2020) A pause in Southern Hemisphere circulation trends due to the Montreal Protocol. Nature. 2 – Solomon et al. (2016) Emergence of healing in the Antarctic ozone layer. Science. 3 – SPARC/IO3C/GAW (2019) SPARC/IO3C/GAW Report on long-term ozone trends and uncertainties in the stratosphere. I. Petropavlovskikh, S. Godin-Beekmann, D. Hubert, R. Damadeo, B. Hassler, V. Sofieva (Eds.), SPARC Report No. 9, GAW Report No. 241, WCRP-17/2018. 4 – World Meteorological Organization (2018) Executive Summary: Scientific Assessment of Ozone Depletion: 2018. Global Ozone Research and Monitoring Project–Report No. 58. 5 – Morgenstern et al. (2008) The world avoided by the Montreal Protocol. Geophysical Research Letters. 6 – Rigby et al. (2019) Increase in CFC-11 emissions from eastern China based on atmospheric observations. Nature. 7 – Dhomse et al. (2019) Delay in recovery of the Antarctic ozone hole from unexpected CFC-11 emissions. Nature Communications. 8 – Dhomse et al. (2019) Estimates of ozone return dates from Chemistry-Climate Model Initiative simulations. Atmospheric Chemistry and Physics. 9 – World Meteorological Organization (2018) Chapter 3: Update on global ozone: Past, present, and future. Global Ozone Research and Monitoring Project–Report No. 58. 10 – Thompson et al. (2012) The mystery of recent stratospheric temperature trends. Nature. 11 – World Meteorological Organization (2018) Chapter 5: Stratospheric ozone changes and climate. Global Ozone Research and Monitoring Project–Report No. 58. 12 – Thompson & Solomon (2002) Interpretation of recent Southern Hemisphere climate change. Science. 13 – Polvani et al. (2011) Stratospheric ozone depletion: The main driver of twentieth-century atmospheric circulation changes in the Southern Hemisphere. American Meteorological Society. UPDATES: 8 April 2020: This post was updated to include a comment by Antara Banerjee.

Summary: The claim that “The ozone layer is continuing to heal and has the potential to fully recover” appeared in an article published by The Independent in March 2020, and has been shared on Facebook more than 11,000 times. The claim relies on a study recently published in Nature by Banerjee et al.[1]. Previous studies have demonstrated that global total ozone is recovering and has the potential to fully recover by the end of the century[2,3,4], providing support for this claim. However, scientists emphasize that the article misrepresents the focus of the Banerjee paper, as described in their comments below. The claim and study it is based on focus on the Antarctic ozone layer, which has shown patterns of healing in response to reductions in ozone-depleting substances, such as chlorofluorocarbons (CFCs)[1-4]. But rather than showing that the Antarctic ozone is healing, Banerjee et al. (2020) demonstrate that atmospheric circulation trends that were driven by ozone depletion have paused or reversed in the Southern Hemisphere[1]. Scientists’ Feedback: William Seviour Senior Lecturer, University of Exeter: The claim that “the ozone layer is healing and has the potential to fully recover” I believe is accurate. I’ll break this claim into its two parts. First, whether the ozone layer is healing: The focus of the article and paper is on Antarctic ozone, and there have now been some studies suggesting we are starting to see a healing signal there. This is quite tricky to detect because there is a lot of natural variability from year-to-year. Solomon et al. (2016) was probably one of the first[2]. Trends are a bit clearer looking at ozone over the whole globe (not just Antarctica). The SPARC LOTUS report is a good reference here—Fig. 1 of the Executive summary shows increasing ozone trends after 1997 in most places[3]. Figure—Satellite and ground-based records show ozone trends (% change in ozone amount) at different levels in the stratosphere before 1997 (top row) compared to post-2000 (bottom row). Columns represent different latitudes around the world: southern latitudes (left), tropical latitudes (middle), and northern latitudes (right). Note the trends in ozone concentrations are negative pre-1997 (upper panel), but neutral and positive post-2000 (bottom panel). From the SPARC LOTUS report (2019)[3]. Second, the potential to fully recover: The authoritative reference on this subject is the latest (2018) WMO/UNEP Scientific Assessment of Ozone Depletion—e.g. see Figure ES-1 of the Executive Summary[4]. This shows that ozone concentrations (both global and Antarctic) are projected to recover to 1960 levels by the end of this century. Figure—Comparisons of total ozone observations (red points and lines) and chemistry climate models (black lines with grey regions showing uncertainty) for the globe (top) and Antarctic (bottom). Annual global total ozone is averaged over 60°N to 60°S latitudes, whereas Antarctic total ozone is averaged over 60°S to 80°S latitudes. Models project that ozone concentrations will return to levels observed in the 1960s by 2100, assuming future compliance with the Montreal Protocol, which is an international treaty designed to limit ozone-depleting substances, and an increase in greenhouse gas emissions following the RCP-6.0 scenario@. Black lines with arrows indicate the years that ozone abundances are projected to return to values observed in 1980. Adapted from World Meteorological Organization (WMO) Executive Summary: Scientific Assessment of Ozone Depletion (2018)[4]. The evidence linking ozone recovery to reductions in CFCs is very strong, so this claim is accurate. There have been a series of papers, such as Morgenstern et al. (2008), looking at “world avoided” scenarios without the Montreal Protocol and they all show much larger ozone depletion[5]. There has been some recent evidence of violations in the Montreal Protocol with production of a particular CFC (CFC-11) linked to China[6]. Dhomse et al. (2019) has suggested that this violation might delay ozone recovery if it continues[7]. My main criticism of the article is that it largely misses the point of the paper. The paper is not directly about whether the ozone layer is healing, but whether atmospheric circulation changes that have been attributed to ozone depletion are pausing or reversing. Plenty of previous studies (linked above) have looked at recovery of ozone trends, but looking at the circulation trends is new. The fact that the paper shows they are reversing is good news because these changes have been linked to droughts over Australia for instance. I think this Guardian article does a better job at focusing on the winds, not just the ozone. In summary, I think the article is accurate but does not do a very good job of focusing on the results of the paper. Paul Young Lecturer, Lancaster University: The claim that “the ozone layer is healing and has the potential to fully recover” is broadly accurate, backed up by several studies. In general, the best sources of information for those interested in the state of the ozone layer, and the levels and emissions of the synthetic substances that can harm it, are the 4-yearly scientific reports produced under the auspices of the World Meteorological Organisation (WMO) and United Nations Environment Program (UNEP). These reports are written by scientists from all over the world, who assess and review the body of scientific evidence in the peer-reviewed literature. The most recent of these reports was published in 2018[4]. For the specific case of the Antarctic ozone hole, the WMO/UNEP report concluded that there is evidence to show that the hole is beginning to shrink in size, all as a result of the actions of the 1987 Montreal Protocol (and its amendments), which has strong controls on the emissions of halogen-containing ozone depleting substances. However, it is important to note that the ozone hole still continues to appear in southern hemisphere spring every year, and will likely continue to do so beyond the middle of this century (e.g., see Dhomse et al., 2019)[8]. This is because of the long lifetime of many ozone depleting substances in the atmosphere, meaning that they persist even after emissions are essentially zero (e.g. chlorofluorocarbons, CFCs). As the Banerjee et al. Nature paper discusses, the Antarctic ozone hole has also been an important driver of southern hemisphere (SH) climate change, sometimes in a way that is opposite to the effects of the most important human-emitted greenhouse gas, CO2[4]. One of the most important ways in which the ozone hole has impacted SH climate is through pulling the SH jet stream more towards the poles. Among other effects, this has led to a poleward (=southward) trend in rainfall, since the jet stream is basically synonymous with where storms happen. Consistent with the emergence of healing of the ozone hole, their work demonstrates that the ozone hole-driven climate effects are beginning to reverse. In terms of recovery of the world-wide ozone layer, the story is a little more nuanced. As the UNEP/WMO report notes (chapter 3), there is no statistically significant recovery of the total amount of ozone[9]. Detection of recovery is hampered by large, natural year-to-year variability in the atmosphere (“the weather”), which in turn drives large ups and downs in the ozone layer. Nevertheless, one place where the ozone layer is showing clear signs of recovery is the upper stratosphere, which is 35-45km, or ~20-30 miles, up. The recovery here is being driven both by the gradual decreases in ozone depleting substances, but also a slow down in the chemical reactions that destroy ozone. This slowdown is because the upper atmosphere is cooling due to the increases in greenhouse gases (e.g. Thompson et al. (2012); see Box 5-1 of the WMO/UNEP report for an explanation)[10,11]. A. R. Ravi Ravishankara Distinguished Professor, Colorado State University: The findings of the paper are not unexpected since this is what should happen as the ozone hole is starting to heal. The indicators that the ozone hole is showing signs of healing has been known for a few years. This paper shows that the trends in tropospheric circulation due to the ozone hole not getting bigger and showing some healing is detectable. This is great. I want to change the phraseology of the paper. The ozone hole is not really “healing,” it is not getting worse and has stayed just as bad for the past few years as the equivalent effective stratospheric chlorine (EESC) has been nearly constant. I hasten to add that the ozone hole is one indicator of the ozone layer depletion. It is just that the ozone hole is a large signal that is periodic. So, the consequences of its changes are much larger than the global ozone layer depletion starting its course towards its pre-ozone depleting gases state. So, one should expect to detect these changes due to ozone hole changes (but it is really not getting better—just not getting worse!) The Ozone Layer Assessments have clearly indicated that the ozone hole and its “recovery” is least influenced by climate changes. It has also shown that the EESC controls the ozone hole well into the future, unlike the global ozone layer changes that are more influenced by climate change (especially stratospheric cooling and the chemical activity of “climate gases” such as methane and N2O). So, I wonder how circulation changes play out in the future globally. This paper has mixed up the issues between the global ozone layer and the ozone hole. So, I hasten to add that there are no indicators of the changes in tropospheric climate from the global ozone layer depletion or its changes. One should ask what is happening in the Arctic ozone changes (larger depletions than globally but less than the ozone hole) in the Northern winter/spring. That would be nice to know. There has been much written about the “world avoided” by not continuing to increase ODS and the influence of the Montreal Protocol. So, one should also ask what major tropospheric climate changes have been avoided by the Montreal Protocol. I was surprised to not see anything about it. Also, it is important to know that the ozone hole is still pretty large. It is to be expected to continue for decades. The EESC is not changing much. Their Figure 1a shows the small change in EESC. The responses shown in the paper should be viewed as responses due to the absence of continued increases in the ozone hole. I wonder what the circulation changes signals would be when there are sudden stratospheric warmings and hence much smaller ozone holes (i.e., if we focused only on the sudden warming years). Lastly, I want to note that chemically, the ozone hole is not linearly dependent on EESC. That is why it appeared only in the 1980s and one would expect the changes to be small as long as the EESC is still high. Antara Banerjee CIRES Visiting Postdoctoral Fellow, University of Colorado Boulder: Indeed, our study supports this claim. There already exists observational evidence that the actions of the Montreal Protocol in 1987 have led to declines in atmospheric concentrations of ozone-depleting substances (the CFCs). The production and consumption of these substances was banned by the treaty in an effort to prevent further destruction of the ozone layer. This seems to have been effective: there have been signs that the ozone layer is recovering[2,4]. Measurements show that ozone in the upper stratosphere outside of the polar regions has been increasing by 1-3% per decade since around 2000. The Antarctic ozone hole – the most severe example of ozone depletion – has also started to shrink since around 2000, even though the hole is still occurring every year. In the last few decades of the 20th century, there have been some striking changes in the large-scale wind patterns of the Southern Hemisphere during summertime. Notably, the midlatitude jet stream has been shifting towards the South Pole and the tropics have been widening[12]. Antarctic ozone depletion has been shown to be the main driver of these changes[11,13]. The new finding in our paper is that these trends in the Southern Hemisphere circulation have stopped, and might even be reversing, since around the year 2000. Crucially, we use model simulations to attribute this lack of trends to the reduction in ozone-depleting substances due to the Montreal Protocol and the healing of the Antarctic ozone hole. This is therefore yet another sign, this time in the wind patterns, of the effects of the Montreal Protocol. NOTES @: A Representative Concentration Pathway (RCP) is a greenhouse gas concentration trajectory used by the IPCC. RCP-6.0 is an intermediate scenario in which radiative forcing stabilizes at 6.0 W m-2 after 2100.

https://science.feedback.org/review/deforestation-can-facilitate-the-emergence-and-spread-of-some-infectious-diseases/

Mostly accurate

Now This, Lani Chan, Tom McKenna, 2020-03-20

Deforestation has made humans more vulnerable to pandemics

Correct: Scientists have established direct and indirect links between deforestation and the emergence and spread of some infectious diseases. Misrepresents a complex reality: The effects of deforestation on disease dynamics are complex and multifaceted. Scientists do not fully understand how anthropogenic land use changes, including deforestation, affect human vulnerability to pandemics.

Deforestation can facilitate the emergence and spread of infectious diseases by creating habitats well suited for disease vectors and increasing connectivity between humans and wildlife. However, the effects of deforestation, and other land use changes, on human vulnerability to pandemics is a complex process that is not entirely understood.

Deforestation has made humans more vulnerable to pandemics. Years of scientific research shows that deforestation has led to a rise in the spread of diseases affecting humans. By reducing the amount of available habitat, species are forced into smaller, shared areas, and brought into closer contact with cities and towns.

1 – Patz et al. (2004) Unhealthy landscapes: Policy recommendations on land use change and infectious disease emergence. Environmental Health Perspectives. 2 – MacDonald and Mordecai (2019) Amazon deforestation drives malaria transmission, and malaria burden reduces forest clearing. PNAS. 3 – Jones et al. (2008) Global trends in emerging infectious diseases. Nature. 4 – Wolfe et al. (2005) Bushmeat hunting, deforestation, and prediction of zoonotic disease. Emerging Infectious Diseases. 5 – Plowright et al. (2015) Ecological dynamics of emerging bat virus spillover. Proceedings of the Royal Society B. 6 – Afelt et al. (2018) Bats, coronaviruses, and deforestation: Toward the emergence of novel infectious diseases? Frontiers in Microbiology. 7 – Weiss & McMichael (2004) Social and environmental risk factors in the emergence of infectious diseases. Nature Medicine. 8 – Epstein (2001) Climate change and emerging infectious diseases. Microbes and Infection. 9 – Patz et al. (1996) Global climate change and emerging infectious diseases. JAMA.

Summary: The claim that “deforestation has made humans more vulnerable to pandemics” appeared in a Facebook video published by NowThis Future in March 2020, receiving more than 140,000 views in the first 10 days after it was posted. Scientific studies have established links between deforestation and the emergence and spread of infectious diseases, providing support for this claim[1,2,3]. However, the effects of deforestation on human vulnerability to pandemics are complex and multifaceted. As a result, scientists do not fully understand this process, as the reviewers describe in their comments below. More than two-thirds of emerging infectious diseases come from wildlife, including HIV, Ebola, and SARS[3]. Deforestation can directly increase the likelihood that a pathogen will be transferred from wildlife species to humans through the creation of suitable habitats for vector species. For example, clearing forest patches in the Brazilian Amazon created moist environments ideal for a mosquito species that is the primary vector of malaria in the region[2]. As described in MacDonald and Mordecai (2019), “Our results suggest [that] a 10% increase in deforestation leads to a 3.3% increase in malaria incidence,” (see the figure below)[2]. Figure—Annual area of forest loss within a given municipality in the Brazilian Amazon increased the incidence of malaria, measured by the number of reported malaria cases by municipality from 2003 to 2015. Adapted from MacDonald and Mordecai (2019)[2].Habitat destruction and fragmentation due to deforestation can also increase the frequency of contact between humans, wildlife species, and the pathogens they carry[1]. This can occur through direct transfer of pathogens from animals to humans or indirectly through cross-species transfer of pathogens from wildlife to domesticated species[1]. By reducing the availability of natural habitats, some wildlife species are driven to find new food resources in urban and suburban areas[4,5]. These patterns are consistent with the claim that “species are forced into smaller, shared areas, and brought into closer contact with cities and towns.” As described in Alfet et al. (2018), “Houses and barns offer shelter for cave-dwelling bats while orchards and fields attract frugivorous bats. This attractive effect of anthropized environments on bats with differing biological needs results in a higher concentration and biodiversity of bat-borne viruses. This increases the risk of transmission of viruses through direct contact, domestic animal infection, or contamination by urine or feces.”[6] The construction of logging roads is another aspect of deforestation that can facilitate the emergence and spread of infectious diseases. Logging roads have been linked to increases in bushmeat consumption as well as travel between rural and urban areas[4]. Wildlife markets for consumption, medicine, trophies, and pets bring many wildlife species together, creating opportunities for disease spillover from animals to humans. As described in a study by Wolfe et al. (2005), “Increasing densities of human populations in urban centers close to bushmeat hunting areas and the increasing rates of movement of people between village, town, and city, will increase R0 [the reproduction number of an infection] and the risk for new epidemic zoonoses”.[4] Increases in human population growth and density drive deforestation, as well as a variety of other land use changes that influence the emergence and spread of infectious diseases, potentially making humans more vulnerable to pandemics[1,3,7]. Although scientists have established some connections between deforestation and infectious diseases, many effects in this complex process remain unresolved. Scientists’ Feedback: Kate JonesProfessor of Ecology & Biodiversity, University College London & David Redding MRC UKRI/Rutherford Fellow, University College London: I don’t think the system is as simple as deforestation causes diseases—it is a pretty complex and not well understood process. Land use change probably does act to change the composition of the species that humans are exposed to—and this may change the transmission dynamics between people and wildlife and cause jumps to be more likely. For example, deforestation for economic activity such as mining and agricultural development can create open sunlight areas with abundant rainfall, the ideal habitat for the main malaria vector in the Amazon region, Anopheles darlingi. We are changing the transmission dynamics between wildlife and people by converting landscapes, developing agriculture, and moving domestic species into areas that we haven’t before, exposing ourselves to new pathogens. Over two thirds of human infectious diseases are originally from animals, including diseases such as HIV, Lassa fever, and Ebola. It is likely that the new coronavirus also spilled over into humans from wildlife, potentially from a live wildlife market, although this is still being investigated. We are also moving wildlife around the world like never before and mixing species in wild animal markets—creating new virus cocktails. Rapid uncontrolled urbanisation combined with international travel and trade is facilitating the emergence and re-emergence of viruses. Jessie Abbate Post-doctoral Research Associate, French Institute of Research for Development: I think everything in this is true. Climate change, including deforestation which drives it, is a key driver of cross-species transmission which is where zoonotic emerging diseases come from[8,9]. The more often this happens, the more chances there are that a pathogen which normally is adapted to its natural animal host but happens to be randomly good at transmitting between humans will do so. READ MORE Several other media outlets have covered the science linking deforestation and wildlife habitat destruction to infectious disease pandemics. A National Geographic article describes how deforestation can facilitate the spread of novel diseases from wildlife species to humans. A recent article in Scientific American discusses how we can use knowledge about the effects of deforestation on infectious diseases to better prepare for viral outbreaks, such as the coronavirus.

https://science.feedback.org/review/global-data-contradict-claim-of-no-acceleration-in-sea-level-rise/

Inaccurate

Watts Up With That?, Willis Eschenbach, 2020-03-08

The long-term tide gauge datasets are all in agreement that there is no acceleration

Factually Inaccurate: Quantitative analysis of global data clearly demonstrates that sea level rise has accelerated. Misrepresents a complex reality: This claim focuses primarily on individual tide gauge stations rather than a global compilation while failing to account for causes of regional variation.

Peer-reviewed global analyses of both tide gauge and satellite data have demonstrated that sea level rise has, in fact, accelerated in recent decades.

The long-term tide gauge datasets are all in agreement that there is no acceleration, neither in the early nor in the recent parts of the records. Yes, they often porpoise a bit above and a bit below the trend line, but there is no evidence of any CO2-caused recent increase in the rate of sea-level rise. The satellite dataset, on the other hand, is a splice of a selected four of the nine available satellite sea-level datasets. The changes in trend seem to be associated with the splices. Unfortunately, this spliced record is both too short and too fractured to draw any conclusions about acceleration.

1- Woodworth et al. (2010) A Note on the Nodal Tide in Sea Level Records, Journal of Coastal Research 2- Dangendorf et al. (2019) Persistent acceleration in global sea-level rise since the 1960s, Nature Climate Change 3- Kopp et al. (2016) Temperature-driven global sea-level variability in the Common Era, PNAS 4- WCRP Global Sea Level Budget Group (2018) Global sea-level budget 1993–present, Earth System Science Data 5- Dangendorf et al. (2017) Reassessment of 20th Century Global Mean Sea Level Rise,PNAS.

This article on the blog “Watts Up With That?” attempts to show that sea level rise is not accelerating by removing “underlying cycles” in the data that are incorrectly assumed to be tidal cycles. The author smooths a selection of individual coastal sea level records and simply looks for visible acceleration. This fails to account for regional variation in sea level or to measure acceleration with an actual calculation. In fact, a proper quantitative analysis of global data—even after this smoothing process—would clearly show acceleration. The article also claims that satellite sea level data cannot show acceleration because of problems lining up data from different satellites with overlapping mission timeframes. However, the article describes none of the processing procedures that scientists use to correct biases between instruments and instead falsely claims that scientists “simply picked some convenient records from the group above, spliced them together, and called it a valid record fit for all purposes”. In reality, rigorous analysis of satellite data also demonstrates that sea level rise has accelerated. Scientists’ Feedback: Thomas Frederikse Postdoctoral researcher, Jet Propulsion Laboratory/California Institute of Technology: There’s a lot that goes disastrously wrong in this analysis. The idea is to use a variant of EMD (empirical mode decomposition) to remove cycles in sea-level data to find out whether there’s an acceleration in sea level. While EMD and its variants are powerful tools, there’s one big issue: it does not quantify the presence or non-presence of an acceleration. It is just another approach to low-pass filter a data set. Low-pass filtering is basically drawing a smooth curve through a noisy data set. An acceleration, on the other hand, is a well-defined phenomenon. We say that there’s an acceleration when we fit a second-order polynomial (a parabola) to the data and the quadratic coefficient is positive. There are rigorous mathematical tools available to determine the presence or absence of accelerations in sea-level records, which are of course not shown here. The article just shows some smoothed sea-level curves from tide gauges, and it is up to the reader to quantify the presence or non-presence of an acceleration. This of course does not make sense, as we do have good statistical methods to objectively determine this. Then from a purely visual inspection, it’s claimed that because of the multi-decadal cycles in sea-level records—which are falsely attributed to tides (see Woodworth et al.[1] for more details)—we cannot detect an acceleration in the 27-year-long satellite record of sea level. This is a classic and wrong extrapolation. At first, only a few isolated tide-gauge records are discussed. Mainly because of ocean dynamics, local and regional sea level shows large decadal and multi-decadal variations, and therefore it is indeed difficult to find an acceleration in a single tide gauge record. Only European and US tide-gauge records are shown. Because these tide gauges are relatively close to the places where most of the ice melt that has driven sea-level changes since ~1900, they will see much less sea-level rise from ice melt than the global mean due to gravity and solid-Earth effects. Therefore, without explicitly taking this into account, we cannot say anything about global sea levels based on records in Europe and North America alone. When all available tide-gauge records are combined to compute global sea levels, a clear acceleration in sea level since 1900 is visible[2]. Combined with longer proxy records, the data shows that global sea levels have risen at a faster pace than any other century over the last 3,000 years, and that the 21st-century rate of global sea level is already three times as high as the twentieth-century rate[3]. Secondly, the satellite record: Contrary to tide gauges, satellites do cover the global oceans (except some small parts around the poles due to the specific satellite orbits). Regional sea level can show all sorts of decadal fluctuations due to weather and ocean dynamics, which is some sort of redistribution of sea level, but this cancels out on a global scale. Tides, for example, don’t add or remove water from the oceans. Therefore, it’s much easier to detect an acceleration in global sea level. We also track where the extra water is coming from with in-situ floats and satellite gravity observations. These observations tell us remarkably accurately that the acceleration in global sea level is driven by accelerated ice mass losses from Greenland and Antarctica, and due to accelerating thermal expansion because the oceans absorb almost all the excess heat that gets trapped due to the Greenhouse effect (see this paper[4] for all the numbers). Summarizing, we can determine an acceleration in sea level from altimetry and we know what’s causing it. Benjamin Horton Professor, Earth Observatory of Singapore: [This comment is taken from a previous evaluation of a similar claim.] There is so much evidence from satellites, tide gauges, and geological records to show sea-level is rising[5]. For example, from my research, we have shown that the 20th-century rise was extraordinary in the context of the last three millennia—and the rise over the last two decades has been even faster[3].

https://science.feedback.org/review/global-warming-and-the-covid-19-pandemic-are-unrelated-issues-one-will-not-protect-us-from-the-other-life-site-news/

Flawed reasoning

LifeSite News, Andrea Widberg, 2020-03-17

If we want to protect ourselves from the coronavirus, we must back away from all the climate change efforts we've been making

Flawed reasoning: The article containing this claim fails to acknowledge that disease outbreaks and global warming occur at very different time scales. In addition, it failed to calculate the magnitude of global warming that would be necessary to have a significant effect on the COVID-19 pandemic. Misrepresents a complex reality: The article containing this claim omits the other factors that actually drive COVID-19 transmission, including the level of existing immunity within a population and population density.

Some preliminary scientific publications report that SARS-CoV-2 may be less prevalent or less contagious in warm and humid climates. However global warming does not occur at a pace or magnitude that would prevent further SARS-CoV-2 propagation. In addition, scientists emphasize that virus propagation primarily depends on other factors such as existing immunity and there is currently no way to reliably predict the spread of COVID-19 on a warmer Earth.

If we want to protect ourselves from the coronavirus, we must back away from all the climate change efforts we've been making

1 – Wang et al. (2020) High Temperature and High Humidity Reduce the Transmission of COVID-19. SSRN (pre-publication). 2 – Sajadi et al. (2020) Temperature, Humidity and Latitude Analysis to Predict Potential Spread and Seasonality for COVID-19. SSRN (pre-publication). 3 – Li et al. (2019) Global patterns in monthly activity of influenza virus, respiratory syncytial virus, parainfluenza virus, and metapneumovirus: a systematic analysis. The Lancet. 4 – Baker et al. (2019) Epidemic dynamics of respiratory syncytial virus in current and future climates. Nature Communications. 5 – Luo et al. The role of absolute humidity on transmission rates of the COVID-19 outbreak. medRxiv (pre-publication). 6 – Frieden and Lee. (2020) Identifying and Interrupting Superspreading Events—Implications for Control of Severe Acute Respiratory Syndrome Coronavirus 2. Emerging Infectious Diseases. 7 – Wang et al. (2020) Evolving Epidemiology and Impact of Non-pharmaceutical Interventions on the Outbreak of Coronavirus Disease 2019 in Wuhan, China. medRxiv (pre-publication). 8 – Liu et al. (2020) The reproductive number of COVID-19 is higher compared to SARS coronavirus. Journal of Travel Medicine. 9 – Biggerstaff et al. (2014) Estimates of the reproduction number for seasonal, pandemic, and zoonotic influenza: a systematic review of the literature. BMC Infectious Diseases. 10 – Viboud et al. (2006) Influenza in tropical regions. PLoS Medicine. 11 – Bloom-Feshbach et al. (2013) Latitudinal variations in seasonal activity of influenza and respiratory syncytial virus (RSV): a global comparative review. PLoS One. 12 – Li et al. (2019) Global patterns in monthly activity of influenza virus, respiratory syncytial virus, parainfluenza virus, and metapneumovirus: a systematic analysis. The Lancet Global Health. 13 – Tamerius et al. (2011) Global influenza seasonality: reconciling patterns across temperate and tropical regions. Environmental Health Perspectives. 14 – Memish et al. (2020) Middle East respiratory syndrome. The Lancet. 15 – Shaman and Kohn. (2009) Absolute humidity modulates influenza survival, transmission, and seasonality. Proceedings of the National Academy of Sciences. 16 – Hansen et al. (2005) Earth’s energy imbalance: Confirmation and implications. Science. 17 – Van Doremalen et al. (2020) Aerosol and Surface Stability of SARS-CoV-2 as Compared with SARS-CoV-1. New England Journal of Medicine. 18 – Wang et al. (2020) Temperature significant change COVID-19 Transmission in 429 cities. medRxiv (pre-publication).

Summary: An article published on 17 March 2020 on Life Site News claims that “[i]f we want to protect ourselves from the coronavirus, we must back away from all the climate change efforts we’ve been making.” However, scientists who reviewed this claim unanimously reject this conclusion, explaining that global warming and virus seasonality are two phenomena of different time scales so that one cannot be harnessed to control the other. They also point out the paucity of data regarding SARS-CoV-2 transmission. This claim is based on the unpublished findings of several research groups, which recently reported a possible effect of local temperature and humidity on the transmission of SARS-CoV-2, the coronavirus responsible for the current pandemic of COVID-19. A team in China published a preprint article comparing the transmission of SARS-CoV-2 in different Chinese cities, relating it to local temperature and humidity levels[1]. Their overall conclusion was that the virus is transmitted more efficiently in colder and drier environments. Similarly, a study led by researchers from the University of Maryland observed that most SARS-CoV-2 transmission occurs along a latitude corridor where temperatures averaged 5-11°C[2]. Based on these results, the author of the Life Site News article suggested that a warmer Earth would mitigate the transmission of SARS-CoV-2 and that stopping current efforts to limit global warming would be an appropriate response to COVID-19 propagation. Scientists who reviewed this claim unanimously rejected this conclusion, citing flawed reasoning. It is true that certain viruses have a transmission advantage at certain times of the year. Examples of seasonality can be seen with the influenza virus and the respiratory syncytial virus which peak preferentially during colder months in temperate regions[3,4]. Many direct or indirect factors can explain seasonality. For example, UV radiation tends to be more intense during the warmer season, leading to more rapid deterioration of virus particles, while higher humidity may hamper their dissemination in the air, as explained in this news article by Science. However, Prof. Mohammad Sajadi, a virologist at the University of Maryland School of Medicine and first author of one of the research pre-prints mentioned in the Life Site News article[2], specifies that “in tropical and subtropical regions, seasonal respiratory viruses can be present year-round and cause several peaks of infection”. Because the outbreak of COVID-19 is very recent, the data are still scant: “there is a chance that SARS-CoV-2 transmission will be somewhat weakened by summer temperatures if it behaves like the Influenza virus does, but at this point we really do not know enough to say that”, explains Dr. Devin Kirk who investigates the effect of climate change on infectious diseases at Stanford University. While some pre-print studies predict a decline in the rate of spread of COVID-19 in warmer climates, others disagree[5]. And recent outbreaks in tropical countries such as Singapore and Brazil confirm that temperature or humidity alone is not sufficient to prevent COVID-19 epidemics. Consistently, several reviewers emphasized that other factors besides temperature or humidity are actually the dominant drivers of the current pandemic. “At this stage, the fact that there is no population immunity means we will likely see significant spread of the virus, even in warmer climates,” highlights Dr. Rachel Baker, a researcher in epidemiology and environmental studies at Princeton University. Micaela Martinez, an infectious disease specialist at Columbia University, shares this view: “Currently, environmental factors, such as temperature and humidity, will likely be overridden by the fact that so much of the world is susceptible to this infection and can act as kindling to allow this pandemic to grow.“ Therefore, active efforts to mitigate virus propagation that target human behavior and to develop treatments are more likely to offer an effective solution. Even if the virus were less virulent under warmer or more humid conditions, it will still jump from one person to another in cases of close contact, warns Prof. Akiko Iwasaki, an immunobiologist at Yale University: “Even in warm and humid conditions, people should still wash hands and practice social distancing measures. If someone sneezes close to you, no amount of temperature and humidity can prevent droplet spray containing the virus from coming into contact with your face.” The scientists who reviewed this claim also unanimously rejected the idea that allowing global warming to intensify may be a valid response to the COVID-19 pandemic. Global warming occurs at a completely different pace than the progression of epidemics. Current average global temperatures are 1°C higher relative to the early 20th century. This rise in Earth’s average temperature would therefore have no impact on disease epidemics “because there are significant lag times in the climate’s response to human behavior. Were we to cease climate change mitigation efforts now, the effects would only be felt 40 years down the line,” Dr. Baker says. Finally, based on available data, there is inconsistency between the magnitude of global warming and the rise in temperature that would be required to stop SARS-CoV-2 transmission. One of the studies that the Life Site News article is based on reports that a 1°C increase in ambient temperature correlates with a 0.0383 decrease in the SARS-CoV-2 reproduction number (R0)@[1]. Recent reports suggest an initial average reproduction number of 2.8 to 3.8[6,7,8], while a meta-analysis indicates that the reproduction number of seasonal influenza is around 1.28[9]. Based on the same premises and publications referenced in the Life Site News article, and assuming a linear correlation, a staggering increase of between 39°C and 66°C would be required to reduce SARS-CoV-2 propagation down to the level of the seasonal flu if one were to solely rely on temperature. At this point, the Earth would be entirely uninhabitable to humans. In conclusion, there is no basis whatsoever to claim that “backing away from climate change efforts” would help “protect ourselves from the coronavirus”. Scientists’ Feedback: Micaela MartinezAssistantProfessor, Mailman School of Public Health, Columbia University: In my expert opinion, as a specialist on infectious diseases seasonality and also a professor in climate change and human health, I can say that the logic behind this statement is inaccurate because: It is wrongly assuming that long-term changes in global surface temperature (i.e., climate change) are equivalent to changes in the weather seasonally. It is the weather (which operates on a shorter time scale) that is important to consider when evaluating transmission of coronavirus. We are still very early on in this pandemic and it will take multiple seasons (i.e., years) to properly evaluate how weather conditions may influence transmission. Currently, environmental factors, such as temperature and humidity, will likely be overridden by the fact that so much of the world is susceptible to this infection and can act as kindling to allow this pandemic to grow. Mohammad Sajadi Associate Professor , University of Maryland School of Medicine: Those seeking to roll back climate change efforts in part because of our findings of the potential seasonality of the SARS-CoV-2 neither understand climate science nor virology. Seasonal viruses have the potential to significantly affect every part of the planet, but at different times[10,11,12,13]. In the Arabian Peninsula, MERS was unable to have significant community transmission (majority of outbreaks were in the hospital)[14]. The solution is not for everyone to go and live in a desert environment, or create a planet that is inhospitable to countless forms of life. I believe we can find a more efficient solution to this problem than ruining the planet for future generations. [It] is our prediction, based on what we have seen thus far, [that regions with warmer/more humid climate will see less COVID-19 than colder/drier regions]. However, in tropical and subtropical regions, seasonal respiratory viruses can be present year round, and cause several peaks of infection, so a more accurate picture would be to do a yearly tally and comparison of the areas. From what I have read, with global warming, different areas will be affected differently. If the R0 [the basic reproduction number]@ will change with different temperatures as we hypothesize (and shown by a different group), then changes in the temperatures/humidity could increase risk for certain areas and decrease those for others. Rachel Baker Postdoctoral Research Associate, Princeton Environmental Institute: There appear to be two main themes in the article. One suggesting that if the virus is sensitive to temperature, we should abandon efforts to mitigate climate change. The second, suggesting some individual actions to promote sustainability such as reusable bags, straws, or taking public transport should be altered to lower individual risk. To address the first theme: we currently have only a limited understanding of the virus’s link with climate drivers. However, other coronaviruses as well as influenza and RSV (respiratory syncytial virus) all exhibit seasonal cycles that appear to be climate-driven[4,15]. It may well be that the virus is sensitive to warmer temperatures. However, there are several other factors that also affect transmission. Most importantly, at this stage, the fact that there is no population immunity means we will likely see significant spread of the virus even in warmer climates. Furthermore, because there are significant lag times in the climate’s response to human behavior, were we to cease climate change mitigation efforts now the effects would only be felt 40 years down the line[16] — not the most practical option for helping limit the current pandemic. To address the second theme: the virus has been shown to survive for hours to days, depending on the surface[17]. While there have been no specific studies on plastic bags versus cloth bags, my guess is carrying your own bag is less risky than touching a plastic bag that may have been sitting out in the store for days, with similar logic applying to straws. Of course, during this phase of the pandemic, individual changes to behavior are required to reduce disease transmission, including minimizing travel. Devin Kirk Postdoctoral Scholar, Stanford University: The author of [this claim] argues throughout the article that “if we want to protect ourselves from the coronavirus, we must back away from all the climate change efforts we’ve been making.” There are several inaccuracies and illogical arguments throughout this article. First, I’ll cover the foundation of their argument: the link between temperature and SARS-CoV-2 transmission. They use three different manuscripts to support their point that SARS-CoV-2 is negatively affected by warming temperatures. None of these three manuscripts are peer-reviewed, and each has what I would consider significant flaws that makes me doubt their conclusions. A couple notes on the different papers: Wang, J. et al.[1] Their country-level analyses use number of cases, even though that is likely to depend more on timing since introduction or number of tests being run than climate. To determine the effects of summer weather on COVID-19 transmission, they are extrapolating far beyond their data to July temperatures. The pattern between temperature and transmission in Chinese cities here could easily be unimodal rather than the linear model they fit. Sajadi, M. et al.[2] They claim that [COVID-19] is establishing in the 30-50 degree north corridor at similar weather patterns (5-11°C), and that there is a lack of establishment based on where there is travel and we should expect it. However, Scandinavia is getting cases and is out of this weather range, Mexico is out of this range and likely doesn’t have cases due to limited testing (according to the head of internal medicine at the ABC Medical Center in Mexico City), Australia is growing, Southeast Asia is growing now, Toronto isn’t in the weather range. Wang, M. et al.[18] Epidemiological data and their R0 proxy are relatively limited, especially spatially. Weather data (using just the capital of a province) is limited. It does not appear they are controlling for factors like population size. In summary, none of the three pre-print manuscripts the author relies on to link transmission to temperature are peer-reviewed and each has flaws in my opinion. There is a chance that SARS-CoV-2 transmission will be somewhat weakened by summer temperatures if it behaves like the Influenza virus does, but at this point we really do not know enough to say that. Moreover, this (also not yet peer-reviewed) pre-print analyzes data and finds that changes in temperature “will not necessarily lead to declines in COVID-19 case counts”[5]. At this point, there aren’t peer-reviewed papers regarding temperature’s effects on SARS-CoV-2, and we probably won’t know if it has an effect until temperatures really start to warm. I think the best explainer about what we do or do not know about temperature’s effects on SARS-CoV-2 is found in this blog post by Marc Lipsitch, the director of the Center for Communicable Disease Dynamics at Harvard. Marc Lipsitch is easily one of the global leaders in the field, so in my opinion that blog post carries a lot of weight. He concludes that seasonality will probably not lead the disease to go away on its own. Finally, I just want to note the pretty ridiculous logical argument that if higher temperatures harm SARS-CoV-2 transmission (which, as I explain above, we do not know yet), this means that climate change is good for us to protect from the disease. This is a bad argument because climate change operates over a relatively very long time scale compared to the speed of this pandemic. Even if extremely high temperatures decreased viral transmission, we may need over a hundred years of global warming to get to those kinds of temperatures. It simply doesn’t make sense. Akiko Iwasaki Professor, Yale School of Medicine: The claim that we should promote global warming to counter coronavirus is absurd. Global warming happens very slowly: 0.86°C increase [from] 1880 – 2012. Even if we did everything possible to increase global temperature fast, this will have dire consequences on Earth without having any impact on COVID-19 spread. While high temperature and humidity will likely reduce airborne transmission rate, the virus will still spread through direct contact or through contaminated surfaces. Even in warm and humid conditions, people should still wash hands and practice social distancing measures. If someone sneezes close to you, no amount of temperature and humidity can prevent droplet spray containing the virus from coming into contact with your face. Jeffrey Shaman Professor, Mailman School of Public Health, Columbia University: There’s no basis for that assertion. Halting global warming will not stop the spread of this virus. Sounds like an effort to advance an anti-climate change agenda. NOTES @: The reproduction number R0 describes how many individuals a contagious person will infect. For instance, a R0 of 2 means that each person will on average infect two other individuals. The reproduction number is not a constant as it highly depends on the epidemiological and environmental context. READ MORE Full Fact also fact-checked similar claims that warmer weather will stop the outbreak of the novel coronavirus, explaining that “even if it ultimately turns out to be a seasonal virus, it is unlikely to behave like similar viruses in the short term. This is because it is so new that very few people are immune from it.” Health Feedback has produced a number of other claim reviews on COVID-19. You can view them here.

https://science.feedback.org/review/temperature-trends-in-the-u-s-are-consistent-with-warming-around-the-world-contrary-to-electroverse-claim-cap-allon/

Flawed reasoning

Electroverse, Cap Allon, 2020-01-22

Historical data of temperature in the U.S. destroys global warming myth

Flawed reasoning: The U.S. occupies a very small percentage of the world. Global warming trends cannot be determined based on local daily temperature records in a small number of locations.

Land surface, sea surface, and atmospheric temperature data all show trends of global warming. The warming trend observed over the past century is correlated with increased levels of CO2.

Historical data destroys the global warming myth, and people are waking to it. According to NOAA’s own historical data, of the 50 U.S. state all-time record high temperatures, 23 were set during the 1930s, while 36 occurred prior to 1960 — climate change proponents are feeding us a fairy tale, and I’m sick of it.

1- Santer et al (2017) Tropospheric warming over the past two decades. Scientific Reports. 2- Hausfather et al. (2017) Assessing recent warming using instrumentally homogeneous sea surface temperature records. Science Advances. 3- Neukom et al. (2019) No evidence for globally coherent warm and cold periods over the preindustrial Common Era. Nature. 4- King (2017). Attributing Changing Rates of Temperature Record Breaking to Anthropogenic Influences. Earth’s Future. 5- Donat et al. (2016). Extraordinary heat during the 1930s US Dust Bowl and associated large-scale conditions. Climate Dynamics. 6- Feldman et al (2015) Observational determination of surface radiative forcing by CO2 from 2000 to 2010. Nature.

Summary: The claim that historical temperature data in the U.S. “destroy the global warming myth” appeared in an article published by Electroverse in January 2020, receiving almost 1,500 shares on Facebook since then. By focusing solely on maximum daily temperature records in one small region of the world, the claim uses flawed reasoning to argue that global warming is a myth. Even if the U.S. showed steady or cooling temperature trends, this would not prove that global warming isn’t happening given warming elsewhere. Scientific studies have demonstrated consistent warming trends around the world (see the figures below)[1,2]. As described in Neukom et al. (2019), “the warmest period of the past two millennia occurred during the twentieth century for more than 98 percent of the globe.”[3] Figure—Global temperature anomaly data relative to the 20th century average temperature from the Global Historical Climatology Network-Monthly data set and International Comprehensive Ocean-Atmosphere Data Set. These data sets show consistent global warming trends. From NOAA. Historical data from NOAA clearly shows a warming trend in the U.S. as well from January 1895 to December 2019 (see the figure below). Figure—Monitoring networks of temperature anomalies relative to baseline temperatures in the contiguous U.S. (USCRN, ClimDiv, USHCN) from January 1895 to December 2019 show consistent warming trends. From NOAA. The global warming trends in the U.S. are “noisier” than the global data set, primarily because the U.S. only occupies ~2 percent of the world and regional, natural oscillations in temperature are more apparent. Although the specific claim that “of the 50 U.S. state all-time record high temperatures, 23 were set during the 1930s, while 36 occurred prior to 1960” is consistent with NOAA data, this data does not follow maximum temperature trends observed in other regions around the world. King (2017) describes, “Many heat records in the central U.S. still date from the 1930s Dust Bowl period when unusual atmospheric flow and very dry spring periods allowed severe heat extremes to develop (Donat et al., 2016), but in most other parts of the world, current temperature records date from the last few decades.”[4,5] Furthermore, local daily temperature records are not suitable measurements for assessing global warming trends. This claim relies on maximum temperature records collected at a single station in each state. Temperature data from a single station can be influenced by several factors, including time of day the measurement was taken, the angle of the sun, and instrument variation, as Victor Venema explains in the comments below. Lastly, maximum temperature records do not necessarily reflect the warmest years on record nor the average number of warmest days for each state. For example, although the 1930s were relatively warmer than the 1920s and 1960s, it was not warmer than the past two decades. In conclusion, the fact that some local daily heat records were set in the 1930s can not be used as evidence that a warming trend is not happening at the global scale. Scientists’ Feedback: Victor Venema Scientist, University of Bonn, Germany: The post does not support the erroneous claim that historical data destroys the global warming myth. It did not even look at global warming, in other words it did not look whether the global mean temperature shows a long-term increase. The post looked at station data in America, which only covers about 2% of the Earth. Global warming is about the globe. America is known for the Dust Bowl in the 1930, which produced many heat records. While we also expect heat waves to increase, the relationship between the average temperature and record temperatures is complicated, if records would not increase that would not invalidate the increase in the mean. That would require study of the mean temperature. The post did not look at the mean temperature, but at the maximum temperature. Also the minimum temperature shows many record cold temperatures in the first half of the period, which the post conveniently did not mention. Records are rare and hard to measure. For that reason alone they are more spread out over the measurement period and show a less clear trend than the mean temperature. The post looked at raw data, which is not well suited to study warming. For example modern automatic weather stations measure a somewhat smaller temperature than traditional Cotton Region Shelters. You can see this by making side by side measurements with both instruments. In as far as this difference is due to the sun influencing the temperature observations it will be larger for summer temperatures, for the maximum temperature and especially for heat waves and droughts. Global warming is about actual warming, not about changes in the instrumentation. It is just a post on the internet, not a scientific study. In a scientific study the authors would have had to describe exactly what they did. It is not even clear what a record in a certain US state means in this post. Is this one station in a state having a record or the average temperature over the state having a record? For all of the above reasons the claim about global warming does not fit to the presented evidence and would never hold up in the scientific literature, which the authors bypass to directly deceive their readers most of whom will not be aware of the above problems. Stephen Po-Chedley Research Scientist, Lawrence Livermore National Laboratory: [Comment from a previous evaluation of a similar claim.] Global temperature datasets, developed by a number of independent research groups, show robust warming in the troposphere and at the Earth’s surface. The radiative effect of carbon dioxide has also been observed[6]. Considering multiple lines of evidence, the IPCC concluded that it is “extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century.” More recent analysis of satellite data shows that tropospheric warming from the satellite record is pronounced and cannot be explained by natural climate variability alone[1]. [Comment from a previous evaluation of a similar claim.] World temperatures measurements began in the 1800s and show a warming burst since the 1970s. Last year we checked with satellite scans of the ocean, confirming the accuracy of the surface measurements[2]. Global warming is a measured fact.

https://science.feedback.org/review/co2-can-increase-plant-growth-in-greenhouses-while-also-negatively-affecting-ecosystems-and-human-societies-mike-adams-natural-news/

Flawed reasoning

Natural News, Mike Adams, 2013-06-22

CO2 is a plant nutrient...it’s not a pollutant that threatens human civilization. If CO2 was so terrible for the planet, then installing a CO2 generator in a greenhouse would kill the plants.

Flawed reasoning: CO2 can increase plant growth in a greenhouse, but the argument that CO2 is not harmful to the planet because plants don’t die is flawed. To assess the overall impact of CO2 emissions on “human civilization”, effects on ecosystems and human societies should also be taken into account. Misleading: Plants require CO2, water, and other nutrients to grow. Although CO2 emissions can increase plant growth in some regions, they also increase heat stress, water stress, and pest prevalence.

CO2 can increase plant growth but its effects, which decrease with higher concentrations, are limited by the availability of other plant nutrients, such as nitrogen and phosphorus. CO2 emissions can negatively impact natural ecosystems through global warming—e.g. by increasing evaporation and drying up soils in some regions or increasing heavy precipitation in others.

CO2 is a plant nutrient...it’s not a pollutant that threatens human civilization as has been ridiculously claimed by global warming doomsday pushers. CO2 actually increases plant yields, accelerates "re-greening" and improves reforestation of the planet. If CO2 was so terrible for the planet, then installing a CO2 generator in a greenhouse would kill the plants.

1- Zhu et al. (2016) Greening of the Earth and its drivers. Nature Climate Change. 2- Mbow et al. (2019) IP Food Security. In: Climate Change and Land: an IPCC special report on climate change, desertification, land degradation, sustainable land management, food security, and greenhouse gas fluxes in terrestrial ecosystems. IPCC report. 3- Rosenzweig et al. (2014). Assessing agricultural risks of climate change in the 21st century in a global gridded crop model intercomparison. PNAS. 4- Moore et al. (2017) New science of climate change impacts on agriculture implies higher social cost of carbon. Nature. 5- Zhang et al. (2014) Nitrogen and phosphorous limitations significantly reduce future allowable CO2 emissions, Geophysical Research Letters. 6- De Graaff et al. (2006) Interactions between plant growth and soil nutrient cycling under elevated CO2: a meta-analysis. Global Change Biology. 7- Shakun et al. (2012) Global warming preceded by increasing carbon dioxide concentrations during the last deglaciation. Nature. 8- Tubiello et al. (2007). Crop and pasture response to climate change. PNAS.

Summary: The claim that CO2 is a plant nutrient and not a pollutant appeared in an article published by Natural News in June 2013, and has gone viral in 2020 with over 1.6 million shares on Facebook over the past three months. This claim uses flawed reasoning to argue that elevated levels of CO2 are not bad for the planet because it doesn’t kill plants in a greenhouse. Although CO2 can increase plant growth in a greenhouse, this effect does not necessarily apply to more complex natural environments where the benefits of CO2 can be outweighed by nutrient limitation and negative climate impacts, such as increasing water stress, heat stress, and the prevalence of pests and pathogens. In order to assess the overall impact of CO2 on the planet, all known effects of CO2 on land ecosystems and human societies should be evaluated, instead of focusing on just one aspect as this claim does[1,2,3,4]. Vegetation has absorbed some of the CO2 emitted by human activities and converted it into leaf biomass, particularly in southeast North America, the northern Amazon, Europe, Central Africa, and Southeast Asia, as seen in the figure below[1]. Figure- Increased CO2 emissions have increased plant growth (leaf area index (LAI)) around the world. From Zhu et al. (2016)[1]. But in addition to CO2, plants require water and other nutrients to grow. Scientific studies show the effects of CO2 on plant growth depend on the availability of other nutrients, such as phosphorus and nitrogen, as seen in the figure below[2,5,6]. Figure- Under high concentrations of CO2 (RCP8.5), crop models (GGCMs) predict that nitrogen (N) stress will reduce crop yields (%) in 2070-2099 relative to yields from 1980 to 2010. From Mbow et al. (2019)[2]. CO2 emissions are also predicted to produce less nutritional crops and reduce crop yields over time[2]. “While increased CO2 is projected to be beneficial for crop productivity at lower temperature increases, it is projected to lower nutritional quality,” according to the IPCC report on food security[2]. Because CO2 emissions contribute to global warming, crop yields are predicted to decline with increasing temperatures due to increases in heat stress, water stress, and the persistence of pests and pathogens, as seen in the figure below[3,4]. Figure- A meta-analysis of 56 studies predicts that crop yields for maize, rice, wheat, and soy decline as temperatures increase relative to local baseline growing-season temperatures. From Moore et al. (2017)[4]. More broadly, increases in plant growth due to increased CO2 emissions may be offset by negative effects on land ecosystems due to rising global temperatures, prolonged droughts, and increases in intense rainstorms[2,6]. In tropical and semi-arid regions, even moderate increases in temperature could lead to drier conditions that induce water stress, disrupt plant reproduction, and reduce crop yields[7]. Nitrogen stress due to soil degradation is predicted to result in even greater declines in crop yields in the tropics[2]. Additionally, the effects of climate change are not limited to terrestrial plant productivity. Impacts on weather extremes, coastal infrastructure, human health, and marine ecosystems—among other things—are also relevant to the question of whether CO2 is a “pollutant that threatens human civilization”, in the article’s words. Scientists’ Feedback: Pierre Friedlingstein Professor, University of Exeter: [Comment from a previous evaluation of a similar claim.] This is the usual misleading argument that if CO2 is good for plants, it cannot be bad for the climate. CO2 is needed for plant growth (along with water, nutrients, and energy from the sun)—but it does not change the fact that CO2 is a greenhouse gas. It increases the radiative forcing of the planet and leads to warming, as observed over the last century[6]. Frances Moore Assistant Professor, University of California Davis: [Comment from a previous evaluation of a similar claim.] In a meta-analysis of over 1,000 studies of the effects of climate change on agriculture, we find that, while CO2 is beneficial for crops, this effect rapidly decreases with increasing concentrations[4]. The net effects of climate change on agriculture, including both the benefits of CO2 fertilization and the negative effects of warming, is negative for almost all regions. The effects of CO2 emissions on agriculture cost approximately $8.5 per ton, even accounting for the positive effects of CO2 fertilization. Sara Vicca Postdoctoral research fellow, University of Antwerp: [Comment from a previous evaluation of a similar claim.] Plants don’t only need CO2 and water, but also nutrients like nitrogen and phosphorus. If the latter are not sufficiently available, plants may not respond to elevated CO2 at all[5,6]. Moreover, climatic changes (and particularly extreme events) are an important threat to ecosystems and to the land carbon sink[2,3,7,8]. Alexis Berg Research Associate, Harvard University: [Comment from a previous evaluation of a similar claim.] Yes, we are seeing an increase in vegetation around the world, with satellites showing up to 50% of the land surface greening over the last 30 years, most of it being indeed attributed to increased atmospheric CO2[1]. This is not a surprise. This vegetation increase is consistent with the fact that we know that about a quarter of our CO2 emissions is being taken up by the land biosphere (another quarter going into the oceans, and the remainder staying in the atmosphere). This greening is taken into account in climate models. The real question is how long this greening is going to go on (there are already indications that it is slowing down), as we expect that as climate warms further, adverse impacts on ecosystems may start to offset the positive impact of increased atmospheric CO2—particularly in places where regional climate is moving away from the “comfort zone” of current ecosystems. Amber Kerr Researcher, Agricultural Sustainability Institute, University of California, Davis: [Comment from a previous evaluation of a similar claim.] CO2 is not a pollutant in the sense of being acutely toxic to life, but this framing is highly misleading. Water is also non-toxic and essential to life on Earth, but too much water in the wrong places can be devastating.

https://science.feedback.org/review/electroverse-article-incorrectly-claims-the-sun-is-behind-climate-change/

Incorrect

Electroverse, Roger Higgs, 2020-03-11

the IPCC is wrong − the sun, not CO2, drove modern global warming

Misleading: Many things the article claims climate scientists "assume" are actually conclusions supported by extensive research and evidence. This includes the role of CO2 and other greenhouse gases in driving global warming. Inadequate Support: The article's claims are not supported by published research. Of the two papers cited in the article, one does not support the article's claim and the other was criticized by scientists for errors in its methods.

This article presents a long list of inaccurate claims, but focuses on the idea that the Sun—rather than human-caused greenhouse gas emissions—is responsible for global warming. The available evidence and research clearly shows that this claim is incorrect. Measured patterns of warming, and monitoring of incoming solar energy, rule out the Sun as the source of warming.

the IPCC is wrong − the sun, not CO2, drove modern global warming

The article mentions cosmic rays, claiming that changes in cosmic ray nucleation of clouds (via solar magnetic activity) can explain global warming. The effect of cosmic rays has been studied extensively1,2, leading to the conclusion that cosmic rays have not correlated with global cloud cover or temperature. Pierce and Adams conclude that: “changes in cloud condensation nuclei from changes in cosmic rays during a solar cycle are two orders of magnitude too small to account for the observed changes in cloud properties; consequently, we conclude that the hypothesized effect is too small to play a significant role in current climate change”1, While Agee et al conclude: “the observational results presented, showing several years of disconnect between Galactic Cosmic Rays and lower-troposphere global cloudiness, add additional concern to the cosmic ray–cloud connection hypothesis.” An experiment at CERN that directly tested the ability of cosmic rays to nucleate cloud droplets found that “variations in cosmic ray intensity do not appreciably affect climate through nucleation in the present-day atmosphere.”3 The 2013 IPCC report summarized research on this topic when it stated, “Cosmic rays enhance new particle formation in the free troposphere, but the effect on the concentration of cloud condensation nuclei is too weak to have any detectable climatic influence during a solar cycle or over the last century.”4 The scientists’ comments below explain that besides this cosmic ray hypothesis, the solar radiative forcing fluctuations are also insufficient to explain climate changes over the past decades—in contrast to the radiative forcing due to the increased greenhouse gases released by human activities, which matches the magnitude of the observed warming. 1- Pierce and Adams (2009) Can cosmic rays affect cloud condensation nuclei by altering new particle formation rates?, Geophysical Research Letters 2- Agee et al (2011) Relationship of Lower-Troposphere Cloud Cover and Cosmic Rays: An Updated Perspective, Journal of Climate 3- Dunne et al (2016) Global atmospheric particle formation from CERN CLOUD measurements, Science 4- IPCC (2013) Chapter 7, Climate Change 2013: The Physical Science Basis Patrick Brown Assistant Professor, San Jose State University: [This comment comes from a previous review of a similar claim.] Careful analysis that attempts to take into account all major factors and their evolution in time indicates that anthropogenic increases in greenhouse gasses account for more than 100% of the observed warming on the century timescale (requiring cancellation from cooling influences). See the summary graphic from Carbon Brief, below. Source: Carbon Brief Britta Voss Postdoctoral Research fellow, U.S. Geological Survey: [This comment comes from a previous review of a similar claim.] Solar forcing is much smaller than CO2 forcing. As this figure from the latest IPCC report shows, CO2 radiative forcing (1.68 W/m2) dwarfs solar forcing (0.05 W/m2). Along with other greenhouse gases, CO2 dominates the total radiative forcing when all positive and negative factors are taken into account. Figure – Radiative forcing estimates in 2011 relative to 1750. Values are global average radiative forcing, partitioned according to the emitted compounds or processes that result in a combination of drivers. Source IPCC AR5 Timothy Osborn Professor, University of East Anglia, and Director of Research, Climatic Research Unit: [This comment comes from a previous review of a similar claim.] There is strong evidence that solar forcing cannot explain much of the observed warming at all. The “fingerprint” of solar forcing does not match the observed changes at all, neither over time nor space. Solar forcing would warm both the stratosphere and the surface of the Earth, whereas CO2 warms the surface (and the troposphere) but cools the stratosphere. Using radiosondes and (more recently) satellites, we have observed a warming surface and troposphere together with a cooling stratosphere. See Santer et al (2013)* for one of many studies providing this evidence. Figure –Zonal-mean atmospheric temperature trends in satellite observations from January 1979 to December 2012 showing warming of the lower atmosphere (troposphere) and cooling of the upper-atmosphere (stratosphere), from Santer et al (2013)* Santer et al (2013) Human and natural influences on the changing thermal structure of the atmosphere, PNAS Baird Langenbrunner Associate Editor, Nature Climate Change: [This comment is taken from an earlier review of a similar claim.] First, greenhouse gases are well studied, and their properties are nonnegotiable: They absorb and re-emit longwave radiation, whether they’re in a laboratory setting or in the real atmosphere. To back this up with historical evidence, scientists have known since the 1860s that CO2 is a greenhouse gas and since the 1890s that this will affect the heat budget of the Earth through warming. Even then, these claims were based on empirical evidence, and they’re supported by decades of laboratory research. Second, the link between increased greenhouse gas concentrations and warming continues to be supported by research in the last two decades. One study from 2001[1]used satellites to measure the type of energy entering and exiting Earth’s atmosphere and concluded that increases in greenhouse gases were responsible for extra heat measured between 1970 and 1997. The authors state that their results “provide direct experimental evidence for a significant increase in the Earth’s greenhouse effect that is consistent with concerns over radiative forcing of climate.” (Here, the term “radiative forcing” refers to the extra energy trapped in the atmosphere by greenhouse gases, cause warming.) A more recent study[2]arrived at similar conclusions, confirming predictions of the greenhouse effect in Earth’s atmosphere and providing “empirical evidence of how rising CO2 levels … are affecting the surface energy balance.” In other words, rising CO2 was linked directly to warming, even when things like plant uptake of CO2 were considered. 1 – Harries et al (2001) Increases in greenhouse forcing inferred from the outgoing longwave radiation spectra of the Earth in 1970 and 1997, Nature 2 – Feldman et al (2015)Observational determination of surface radiative forcing by CO2 from 2000 to 2010, Nature Mark Richardson Research Associate, Colorado State University/NASA JPL: [This comment is taken from an earlier review of a similar claim.] [These] comments would have been fair in 1896 when Svante Arrhenius calculated that we could cause serious global warming[1]. World temperatures measurements began in the 1800s and show a warming burst since the 1970s. Last year we checked with satellite scans of the ocean[2], confirming the accuracy of the surface measurements. Global warming is measured fact. Working out the culprits has been like Crime Scene Investigation: Physics Edition. Some evidence comes from a facility in Billings, Oklahoma. Parts of air like water vapour and carbon dioxide naturally glow with infrared heat at very specific frequencies. The Billings site has a device that measured an incredibly precise “fingerprint” of the sky’s heating. Investigators reported in 2015[3] that they found fingerprints across the sky with a clear match on the heating trigger. Below the blue line is the file fingerprint for carbon dioxide (CO2) heating, which we release into the air when we do things like burn coal & oil. This file fingerprint comes from basic physics backed by precise lab readings. The red line is the measured fingerprint in the sky over Billings and is a rock solid match. Each spike is extra heat coming down from the extra CO2 molecules that is heating us up. Measurements in Alaska and from satellites[4]confirm this. This is just one slide in the huge folder of empirical evidence showing human activity to be the main cause of recent warming. 1 – Arrhenius (1896)On the Influence of Carbonic Acid in the Air upon the Temperature of the Ground,Philosophical Magazine and Journal of Science 2 – Hausfather et al (2017)Assessing recent warming using instrumentally homogeneous sea surface temperature records, Science Advances 3 – Feldman et al (2015)Observational determination of surface radiative forcing by CO2 from 2000 to 2010, Nature 4 – Harries et al (2001) Increases in greenhouse forcing inferred from the outgoing longwave radiation spectra of the Earth in 1970 and 1997, Nature

https://science.feedback.org/review/sea-levels-rose-faster-in-the-past-century-than-in-previous-time-periods/

Inaccurate

American Thinker, Thomas Lifson, 2020-03-07

Sea level rise has been slow and a constant, pre-dating industrialization

Factually inaccurate: Scientific studies clearly show that rates of sea level rise have increased since industrialization. Misrepresents source: The article incorrectly describes results from a scientific paper published in Geophysical Research Letters (according to an author of that paper) to support its claim that sea level rise is slow and not caused by human factors.

Sea levels have risen at increased pace since industrialization, with the fastest rates of sea level rise occurring in the late 20th century. At local geographic regions, sea levels can rise faster or slower than the global average, and in the past, these local variations might have been large in magnitude. However, at the global scale, sea levels are rising at an accelerated rate due to human-induced global warming.

Sea level rise has been slow and a constant, pre-dating industrialization ... A study by the University of York found evidence for a period of enhanced pre-industrial sea-level rise of about 2-3 millimetres per year in three locations — Nova Scotia, Maine and Connecticut, which were largely natural, without any human constructions or man-made factors.

1- Kemp et al. (2011) Climate related sea-level variations over the past two millennia. PNAS. 2- Gehrels et al. (2020) A Preindustrial Sea‐Level Rise Hotspot Along the Atlantic Coast of North America. Geophysical Research Letters. 3- Kopp et al. (2016) Temperature-driven global sea-level variability in the Common Era. PNAS. 4- Slangen et al. (2016) Anthropogenic forcing dominates global mean sea-level rise since 1970. Nature Climate Change 5- Dangendorf et al. (2015) Detecting anthropogenic footprints in sea level rise. Nature Communications. 6- Gehrels and Long (2008) Sea level is not level. Geography. 7- Chen et al. (2009) Accelerated Antarctic ice loss from satellite gravity measurements. Nature Geoscience. 8- Meyssignac and Cazenave (2012) Sea level: a review of present-day and recent-past changes and variability. Journal of Geodynamics. 9- Kjeldsen et al. (2015) Spatial and temporal distribution of mass loss from the Greenland Ice Sheet since AD 1900. Nature. 10- Shepherd et al. (2018) Mass balance of the Antarctic Ice Sheet from 1992 to 2017. Nature. 11- Church and White (2006) A 20th century acceleration in global sea‐level rise. Geophysical Research Letters. 12- Jevrejeva et al. (2014) Trends and acceleration in global and regional sea levels since 1807. Global and Planetary Change. 13- Watson et al. (2009) Unabated global mean sea-level rise over the satellite altimeter era. Nature Climate Change. 14- Nerem et al. (2018) Climate-change–driven accelerated sea-level rise detected in the altimeter era. PNAS. 15- Kemp et al. (2009). Timing and magnitude of recent accelerated sea-level rise (North Carolina, United States). Geology. 16- Woodworth et al. (2009) Evidence for the accelerations of sea level on multi‐decade and century timescales. International Journal of Climatology 17- Church and White (2011). Sea-level rise from the late 19th to the early 21st century. Surveys in Geophysics. 18- Gehrels and Woodward (2013). When did modern rates of sea-level rise start? Global and Planetary Change. 19- Sallenger et al (2012) Hotspot of accelerated sea-level rise on the Atlantic coast of North America. Nature Climate Change. 20- Kopp et al. (2013) Does the mid-Atlantic United States sea level acceleration hot spot reflect ocean dynamic variability? Geophysical Research Letters. 21- Garner et al. (2018) Evolution of 21st Century Sea Level Rise Projections. Earth’s Future. UPDATES: 13 March 2020: This post was updated to include a comment by Thomas Frederikse.

Summary: The claim that sea level rise has been slow and constant, pre-dating industrialization appeared in several outlets, including American Thinker and The Global Warming Policy Forum, going viral in March 2020 with nearly 8,000 interactions on Facebook. This claim contradicts ample scientific evidence showing that the rate of sea level rise has increased over time, as seen in the figure below. Figure – Sea level data from the US Atlantic Coast shows an overall rise from 1850 to 2000, with the fastest increases occurring in the 20th century. Adapted from Kemp et al. 2011[1]. Sea level rise is primarily driven by glacial ice melting and the expansion of seawater as it warms. Although natural factors such as land mass movements and ocean circulation patterns influence sea levels, human-induced climate change is accelerating the rate of sea level rise[2,4]. Specifically, greenhouse gas emissions have increased global temperatures, causing ice sheets to melt and oceans to thermally expand, as Margot Saher describes in the reviewer comments below. Natural and anthropogenic drivers of sea level rise also differ across geographic locations. For example, the Atlantic Coast of North America shows faster rates of sea level rise compared to the global average[2]. A recent study found that these rapid rises in sea level occurred in the 20th and 18th centuries[2]. The claim that sea level rise is slow and constant misinterprets the results of this study. Although there were two periods of rapid increases in sea level, there were also periods of limited rise in sea level along the Atlantic Coast, showing the overall rate of sea level rise is not constant. Despite these fluctuations over time and across geographic regions, global average sea level rose faster in the 20th century than in any previous time period. Scientists’ Feedback: Roland Gehrels Professor, University of York: The blog is a misrepresentation of our paper [published in GRL[2]]. Sea-level rise in our study area (the North American Atlantic coast north of Cape Hatteras) has been neither slow nor gradual nor constant. We found that sea-level rise in the 20th century was the fastest (at least in the last 3,000 years—this we also published in PNAS in 2016 in a paper led by Bob Kopp[3]) but there was also a rapid sea-level rise, albeit somewhat slower, in the 18th century. The rates in both centuries are not slow at all; there haven’t been any other centuries in the last 3,000 years that saw similar rates. Sea-level during most of the 19th century did not rise by much, so the sea-level rise is not constant either; there was a clear break between the 18th and the 20th century. What it all means is that there is an underlying natural mechanism in this “hotspot”, which we hypothesize is related to Arctic ice melt and the North Atlantic Oscillation. In the 20th century (and in the future) this mechanism operates IN ADDITION to anthropogenic forcing, which was significant and since 1970 has been the dominant control on global sea-level rise (e.g. Slangen et al. 2016[4]; Dangendorf et al. 2015[5]; Kopp et al. 2016[3]). Our original press release is here: https://www.york.ac.uk/news-and-events/news/2020/research/sea-levels-atlantic/ The last sentence [in our paper] is quite clear (my emphasis in bold here): Our findings suggest that enhanced rates of sea level rise along eastern North America are not only symptomatic of human activity, but might additionally arise from natural processes in the climate system. Benjamin Horton Professor, Earth Observatory of Singapore: Please see the two papers that use a global dataset which clearly shows that the rate of [sea level rise] in the 20th century is faster than anything of the past 2000 and 3000 years respectively[1,3]. Jonathan Gregory Professor, University of Reading and UK Met Office Hadley Centre: I would say that the article in American Thinker is a misrepresentation of the state of science. Furthermore, Dr. Singer’s conclusion (in his second paragraph) is completely untrue. The GRL paper cited[2] doesn’t say anything about the causes of 20th-century global-mean sea-level rise. They are about sea-level change in a particular location. For the global mean, it is generally accepted that 20th-century sea-level change is partly anthropogenic and partly natural[5]. A substantial part of it is due to contraction of glaciers worldwide, beginning before the 20th century, and not likely to be anthropogenic. However, the increasing rate of glacier retreat and warming of the ocean, causing thermal expansion, is probably anthropogenic[4]. It is also generally accepted that sea-level in any particular location can show considerably different trends from the global mean, even for long periods, because of unforced variability in the climate system[3]. Margot Saher Lecturer, Bangor University, Wales, UK: Sea level is not level. Global sea level rises due to thermal expansion and ice melt, but neither of these processes leads to the same amount of sea level rise all over the globe. There are many aspects that cause this: vertical land movement, ocean currents, wind patterns, etc. Gehrels and Long wrote a good introductory text on that, be it applied to the UK[6]. That sea level is rising should surprise nobody; rising CO2 levels in the atmosphere lets the same amount of solar energy in, while letting less long-wave radiation out. It’s a question of simple physics that means the Earth system is warming, which leads to the oceans thermally expanding and ice bodies melting. And these effects have been extensively documented[7-10]. That sea level is not only rising but also accelerating has been found in a plethora of records, both from tide gauges (see figure above)[11,12], satellite measurements[13,14], proxy records[2,15] and combinations thereof[16-18]. The important thing here is that the global average records[17,12] show this increase, as when looking at individual reconstructions, the signal can be dominated by local effects. When looking at an individual record it is important to see it in context. One could, for example, look at the Stockholm tide gauge record (available on PSMSL.org); this shows a sea level drop. Does that prove that sea level isn’t rising at all? No, it means that Sweden is rising up after having been pushed down by the ice sheets of the last glacial period. Does a period of rapid pre-industrial sea level rise on the US east coast, as seen in Gehrels et al. (2020)[2], mean that sea level rise isn’t accelerating? Of course not. It just means that the various factors that determine sea level at that location can result in much more than average sea level rise there, and have done so in the past. This can happen again. And this means its citizens would be well-advised to be even better prepared for future sea level rise than people living in other areas along the US east coast. Thomas Frederikse Postdoctoral researcher, Jet Propulsion Laboratory/California Institute of Technology: Let’s start with the title: ‘New study shows sea level rise has been slow and a constant, pre-dating industrialization’. That statement is wrong, and does not come from the article it’s based on. A comprehensive 2016 studyunambiguously shows using proxy and modern sea-level records that 20th-century global-mean sea-level rise is larger than during any century over the past 3000 years[3]. The scientific article the text refers to sea level along the US East Coast, which is not representative for global sea level at all. Over the last 60 years or so, sea-level rise along the US East coast has been accelerating much faster than the global mean, and is therefore often called a sea-level hotspot[19]. There’s a lot of discussion of its causes[20], and it is not yet known whether this anomaly is human-caused or not. So, the article discusses an anomaly in regional sea level. Regional sea level often deviates a lot from global sea level, so this anomaly does not say much about the global mean sea level, and definitely not about sea level on Pacific islands mentioned in the article. The new study shows that similar anomalous acceleration patterns have happened during the 18th century as well, which implies that the anomalously high rate of sea level along the US east coast is not an indicator of anthropogenic climate change per se. Since this large acceleration comes on top of the global rise in sea level due to climate change[4,5], this study does not refute at all anthropogenic sea-level rise, and the news article deliberately frames it that way, despite the clear message in the conclusions: “Our findings suggest that enhanced rates of sea‐level rise along eastern North America are not necessarily symptomatic of anthropogenic forcing, as was argued in past work[19], but might arise from other forcing mechanisms in the coupled climate system. Our results also suggest that these multidecadal‐centennial periods of low or high sea level might dampen or amplify any future sea‐level signal that is generated by greenhouse‐gas forcing, and should be taken into account in projections of future coastal vulnerability and risk.” It’s in a sense similar to saying after a very hot summer, that because in the 18th century, we also had some hot summer that the climate isn’t changing. After misinterpreting the scientific article, the classic and debunked repertoire of Fred Singer and co is repeated, falsely claiming that sea-level rise projections are constantly being revised downwards. A thorough analysis of all available sea-level projections[21] shows that high-end sea-level rise projections generally project more sea-level rise since the IPCC report in 2007. Finally, the concluding takeaways are all factually wrong: “The takeaways include the realization that sea level rise is gradual and has been going on for centuries, may or may not be related in some small way to CO2 emissions, and can be adapted to because it is so slow.” Sea-level rise is not gradual Sea-level rise has not been going on for centuries Global sea-level rise is caused by CO2-induced thermal expansion of sea water and glacier and ice-sheet mass loss Many coastal locations inside and outside the US already struggle with its consequences

https://science.feedback.org/review/data-from-glaciers-around-the-world-show-most-are-shrinking-as-a-consequence-of-global-warming/

Inaccurate

Principia Scientific, IceAgeNow, 2016-11-26

90 percent of the world’s glaciers are growing.

Cherry-picking: This claim is based on a single study from 2015 which suggests that the East Antarctic Ice Sheet is growing, and ignores dozens of other published studies which contradict these findings. Furthermore, while the East Antarctic Ice Sheet accounts for over 80% of the world’s ice mass, that does not mean it represents 90% of the world’s glaciers. Overstates scientific confidence: The overall gain or loss of ice from the East Antarctic Ice Sheet is still being investigated. Recently improved satellite-based methods for measuring ice mass offer more accurate estimates, which do not corroborate the claim that this ice sheet is growing.

This claim is an inaccurate representation of a single study’s results, which concluded that the Antarctic Ice Sheet is gaining mass and is therefore not contributing to global sea level rise. Other scientific studies contradict the results of this study. There is also a large body of peer-reviewed research by glacial scientists which concludes that the Antarctic Ice Sheet is, in fact, contributing to sea level rise due to prominent ice loss on the West Antarctic Ice Sheet.

90 percent of the world’s glaciers are growing.

1 – Zwally et al. (2015) Mass gains of the Antarctic ice sheet exceed losses. Journal of Glaciology. 2 – Zemp et al. (2008) Global Glacier Changes: Facts and Figures. UNEP and World Glacier Monitoring Service. 3 – Scambos and Shuman. (2016) Comment on “Mass gains of the Antarctic ice sheet exceed losses” by H. J. Zwally and Others. Journal of Glaciology. 4 – McMillan et al. (2014) Increased ice losses from Antarctica detected by CryoSat-2. Geophysical Research Letters. 5 – Helm et al. (2014) Elevation and elevation change of Greenland and Antarctica derived from CryoSat-2. The Cryosphere.

An article posted by IceAgeNow.info in November 2016 and republished on the blog Principia Scientific, makes this claim about the world’s glaciers based entirely on a single study published in the Journal of Glaciology in 2015 by Dr. H. Jay Zwally, a scientist at NASA, and colleagues[1]. The claim began trending on Facebook in early 2020 and received 1.6 million views on Facebook over the past 3 months. The study showed that the East Antarctic Ice Sheet (see Figure 1) is gaining ice faster than other parts of the Antarctic ice sheet are losing ice. IceAgeNow’s article claims that since Antarctica represents about 90% of the world’s glacial ice and the East Antarctic Ice Sheet holds the majority of that ice, this means that 90% of the world’s glaciers are growing. However, the article fails to mention conflicting results found in numerous other studies, and therefore presents a biased view of the scientific understanding of this topic. The Zwally paper’s results are, in fact, an outlier among similar studies of the Antarctic ice mass balance* and have been challenged by more recent papers. [*Mass balance is a measure of the overall ice gain or loss in a given year, and these results are given in meters water equivalent to account for varying densities of ice and snow.] Figure 1 – Map of the East and West Antarctic ice sheets (made by Carbon Brief). The Antarctic Ice Sheet holds much of the world’s glacial ice, but glaciers are widespread around the world near the poles and in alpine regions. Glaciers are individual bodies of ice that deform and flow under their own weight, following the topography beneath them. An ice sheet is a continent-spanning region of ice, within which a number of glaciers can be found at its edges. This means that Antarctica’s share of the world’s glacial ice mass is not the same as its share of the world’s number of glaciers. The World Glacier Monitoring Service (WGMS) has reported a clear trend of global glacial ice loss, as shown in Figure 2, for all glaciers and a subset of “reference glaciers” which have been continuously monitored since 1976[2]. Of the 151 glaciers included in the 2018 WGMS measurements, about 12% showed a trend of ice growth. Glaciers can grow either due to reduced losses from melting, sublimation, or calving, or due to increased additions from snowfall. Figure 2 – Cumulative mass balance (overall glacier growth or retreat) from 1945 to 2005 for all glaciers and a subset of continuously monitored “reference” glaciers. Source: World Glacier Monitoring Service[2]. Another figure (Figure 3) from a paper by Ted Scambos of the National Snow and Ice Data Center and Christopher Shuman from NASA’s Goddard Space Flight Center directly displays the differences between the Zwally paper’s results and those of 12 other published studies[3]. The figure compares ice mass changes in the Antarctic Ice Sheet as reported by each study. The Zwally paper’s results, as indicated by the brown rectangle in the figure, present the only data indicating an overall gain in mass to the Antarctic Ice Sheet. Therefore, the Zwally paper’s data are clear outliers to the estimates from other studies which indicate that Antarctic ice mass is declining. Figure 3 – Antarctic Ice Sheet mass balance estimates from studies published from 2012 to 2015. Each box represents the range of error (vertical) and the time span of the data (horizontal). Source: Scambos and Shuman (2015)[3]. Scambos and Shuman pointed to the methods of Zwally et al. as the reason for their vastly different estimates. Satellite methods are widely used to detect changes in elevation of the ice surface, which inform estimates of mass gain or loss over time. To ensure accurate measurements, a reference surface with a well understood elevation is needed for calibration. Zwally’s team used patches of open ocean as their reference surface, which Scambos and Shuman point out could be problematic because a dark surface, such as the ocean, provides a less accurate signal to satellites than do bright surfaces such as ice. The Zwally study also used data from different satellites than the more recent studies, which found much smaller elevation gains[4,5]. The author of the claim reviewed here also fails to recognize that even the Zwally paper’s results illustrate a decreasing snowfall trend, and it predicted that in about 20 years’ time, Antarctica would be losing ice mass and contributing to sea level rise. To wrap up, the IceAgeNow article claims that 90% of the world’s glaciers are growing, but according to the WGMS’s 2018 dataset, only about 12% of glaciers are gaining mass globally[2]. The article cites a single study which supports the claim that the Antarctic Ice Sheet is not contributing to sea level rise and does not consider numerous studies with differing results, therefore presenting a cherry-picked view of the body of research on the subject.

https://science.feedback.org/review/current-climate-warming-is-rapid-and-occurring-on-a-global-scale-unlike-past-periods-of-regional-climate-fluctuations/

Misleading

PragerU, Patrick Moore, 2020-01-21

Of course the climate is changing. It always has. It always will.

Misleading: Misrepresents past climate epochs as similar and comparable to the current pattern of global climate change, though they were significantly smaller in spatial extent, magnitude, and rate of change.

Although periods of regionally warmer and cooler temperatures have been recorded over the last 2,000 years, the patterns of warming and cooling were not globally coherent. In contrast, the current period of climate warming is unprecedented, occurring simultaneously on 98%[1] of Earth’s surface and at a significantly faster rate than past fluctuations in global temperature.

Over the past 2,000 years, the globe has seen the Roman Warm Period, the cooler Dark Ages, the Medieval Warm Period, the Little Ice Age, a gradual 300-year warming. Of course the climate is changing. It always has. It always will.

1 – Neukom et al. (2019) No evidence for globally coherent warm and cold periods over the preindustrial Common Era. Nature. 2 – Neukom et al. (2019) Consistent multidecadal variability in global temperature reconstructions and simulations over the Common Era. Nat. Geosci. 3 – Marcott et al. (2013)A Reconstruction of Regional and Global Temperature for the Past 11,300 Years. Science. 4 – Wuebbles et al. (2017) Executive Summary: in: Climate Science Special Report: Fourth National Climate Assessment, Volume I. U.S. Global Change Research Program, Washington, DC, USA.

This claim made in a viral Instagram post and a video by PragerU states that Earth’s climate has always changed and always will, and cites as evidence past periods of climatic anomaly such as the Roman Warm Period and the Little Ice Age. Although the occurrence of such climate epochs is not disputed—they are well-known from both written records and paleoclimate proxies such as lake sediment cores and tree rings—these periods of climate fluctuation are not comparable to the current pattern of climate warming, contrary to the claim that “of course the climate is changing” today just as it had been in the past. The current period of climate warming is globally coherent, meaning that surface temperature warming is occurring simultaneously across the planet. In contrast, none of the climate epochs over the last 2,000 years were globally coherent, and past climate fluctuations were smaller in magnitude and changed at a slower rate than current surface temperature warming. Although the Little Ice Age (15th-19th century CE) is generally associated with cooler temperatures, the pattern of cooling during this epoch was not globally coherent. Using paleoclimate reconstructions, scientists at the University of Bern demonstrated that the temperature minimums during the Little Ice Age occurred hundreds of years apart in different regions[1]. The eastern Pacific region hit its coldest temperature by the 15th century, while northwestern Europe did not reach its temperature minimum until about 200 years later. The same is true for the other well-known periods of climate fluctuation that have occurred over the last 2,000 years, such as the Medieval Warm period (see Figure 1). In contrast, the same study showed that the current pattern of climate warming is occurring simultaneously across 98% of the planet’s surface (Figure 1c). The spatial and temporal coherence of the current warming period is unprecedented over the last 2,000 years, marking current climate change as fundamentally different from past regional climatic fluctuations. Figure 1 – Years with the warmest (A, B, C) and coldest (D, E) temperatures across the globe, based on paleoclimate reconstructions. Source: Neukom et al. 2019[1]. This study, along with additional paleoclimate reconstructions, shows that the magnitude and rate of temperature change during the current warming period are also significantly greater than what the planet has experienced over the last 2,000 years[2] (Figure 2). Figure 2 – Warming/cooling rates averaged across 51 years and based on paleoclimate records. Modern thermometer records shown in black. (Source: University of Bern.) Robust paleoclimate reconstructions extending even further back—to the beginning of the Holocene 11,000 years ago—show that the current global surface temperature is warmer than it was for 90% of the Holocene, and that the temperature by 2100 is projected to be warmer than the planet has experienced during recorded human history[3]. Furthermore, the rate of warming over the last century is about ten times faster than previous rates of long-term global temperature change in the last million years, even those occurring at the end of ice ages. This shows that the current pattern of climate warming is not comparable to past, natural fluctuations in climate. These findings support a plethora of other evidence that current climate warming is human-caused, not natural[4].