Factcheck: Trump’s climate report includes more than 100 false or misleading claims

Factcheck: Trump’s climate report includes more than 100 false or misleading claims

Posted on 18 August 2025 by Guest Author

This is a re-post from Carbon Brief

A “critical assessment” report commissioned by the Trump administration to justify a rollback of US climate regulations contains at least 100 false or misleading statements, according to a Carbon Brief factcheck involving dozens of leading climate scientists.

The 140-page report – “A critical review of impacts of greenhouse gas emissions on the US climate” – was published by the US Department of Energy (DoE) on 23 July, just days before the government laid out plans to revoke a scientific finding used as the legal basis for emissions regulation.

The executive summary of the controversial report inaccurately claims that “CO2-induced warming might be less damaging economically than commonly believed”.

It also states misleadingly that “excessively aggressive [emissions] mitigation policies could prove more detrimental than beneficial”.

Compiled in just two months by five “independent” researchers hand-selected by the climate-sceptic US secretary of energy Chris Wright, the document has sparked fierce criticism from climate scientists, who have pointed to factual errors, misrepresentation of research, messy citations and the cherry-picking of data.

Experts have also noted the authors’ track record of promoting views at odds with the mainstream understanding of climate science.

Wright’s department claims the report – which is currently open to public comment as part of a 30-day review – underwent an “internal peer-review period amongst [the] DoE’s scientific research community”.

The report is designed to provide a scientific underpinning to one flank of the Trump administration’s plans to rescind a finding that serves as the legal prerequisite for federal emissions regulation. (The second flank is about legal authority to regulate emissions.)

The “endangerment finding” – enacted by the Obama administration in 2009 – states that six greenhouse gases are contributing to the net-negative impacts of climate change and, thus, put the public in danger.

In a press release on 29 July, the US Environmental Protection Agency said “updated studies and information” set out in the new report would “challenge the assumptions” of the 2009 finding.

Carbon Brief asked a wide range of climate scientists, including those cited in the “critical review” itself, to factcheck the report’s various claims and statements.

Flaws visualised

The responses can be explored below, with false statements highlighted in red and misleading statements shaded in orange. Any areas that remain uncoloured represent parts of the report that either have been stated as accurate by a cited author, or have not received any comment from invited experts.

The dropdown menu can be used to navigate to specific sections of the report.

Carbon Brief’s analysis also finds that, of the 350 references included in the report, almost 10% is work by the report’s own authors.

Amid the Trump administration’s attacks on science, some contributors have asked to be anonymised. The responses from scientists have been lightly edited for clarity and style.

Carbon Brief’s methodology and a glossary of key terms used by factchecking contributors can be found towards the end of the article.

The DoE had not responded to Carbon Brief’s request for comment at the time of going to press.

Executive summary

MISLEADING

Elevated concentrations of CO2 directly enhance plant growth, globally contributing to “greening” the planet and increasing agricultural productivity.

I see two main problems with this (very old) argument. The direct benefits of CO2 are widely acknowledged and nothing new. But we know that elevated CO2 leads to climate changes and so the question is whether the CO2 benefits are big enough to offset the climate losses. Their report does not address the net effects, which many studies have shown are negative, even for the US. The numbers they cite for direct effects of CO2 are mainly from co2science.org, which is not a reputable source. Their summaries are not peer reviewed and include many studies of pots in greenhouses which are known to be biased. The numbers cited in the report are more than 2x what the best literature shows, such as in Ainsworth & Long (2021).

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Part I: Direct human influence on ecosystems and the climate

1 Carbon dioxide as a pollutant

Page 2

MISLEADING

The growing amount of CO2 in the atmosphere directly influences the Earth system by promoting plant growth (global greening), thereby enhancing agricultural yields, and by neutralising ocean alkalinity.

This ignores other effects of rising CO2 concentrations, i.e.: on climate. It is also failing to mention that increased CO2 can reduce the nutrient density of some crops.

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2.1 CO2 as a contributor to global greening

Page 3

FALSE

While plant models predict increased photosynthesis in response to rising CO2, Haverd et al. (2020) reported a CO2 fertilisation rate much larger than model predictions. That is, CO2 fertilisation had driven an increase in observed global photosynthesis by 30% since 1900, versus 17% predicted by plant models. If true it would indicate that global models of the socioeconomic impacts of rising CO2 have understated the benefits to crops and agriculture.

The paper by Haverd et al. focuses on natural ecosystems, not crops. So whilst the findings that CO2 fertilisation effects on global greening makes a larger share relative to other factors, the results are not directly transferable to the socio-economic impacts of rising CO2 on agriculture. Rising CO2 contributes to higher radiative forcing which increases global mean temperature and accelerates the global water cycle, causing increases in the severity and frequency of extreme weather events (e.g. droughts, heat-stress and wildfires), particularly threatening crop yields and production.

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2.1 CO2 as a contributor to global greening

Page 3

MISLEADING

The growing CO2 concentration in the atmosphere has the important positive effect of promoting plant growth by enhancing photosynthesis and improving water use efficiency.

Promoting plant growth is not always positive, because some species benefit more than others, which creates risks to biodiversity. For example, in tropical forests, elevated CO2 promotes the growth of lianas, which are parasites that threaten trees. Also increased CO2 fertilisation is playing a role in disrupting grassland and savannah ecosystems by promoting tree and shrub growth (“woody encroachment”).

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2.1 CO2 as a contributor to global greening

Page 3

FALSE

Section 2.1.1

The following section cites papers that are, in fact, showing evidence for other drivers of change, e.g. page 14 line 34 says “Piao et al. (2020) noted that greening was even observable in the Arctic”, but Piao et al (2020) actually show that warming is the dominant driver of greening in the Arctic, not CO2 fertilisation (see figure 4 and associated text). Also the authors of the DoE report contradict their own statement two paragraphs later by saying: “Chen et al. (2019) show that in China and India much of it is driven by land management changes.”

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2 Direct impacts of CO2 on the environment

Page 3

MISLEADING

Piao et al. (2020) and Chen et al. (2024) report that the greening trend continues with no evidence of slowdown.

The DoE authors fail to mention another study which shows the opposite, that greening was reversed around the year 2000 over 90% of the global vegetated area.

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2.1 CO2 as a contributor to global greening

Page 3

MISLEADING

Section 2.1

Chapters 2 and 9 assert that CO2 fertilisation will increase plant growth and crop yields. The proposed benefits of CO2 fertilisation are not realised in this set of DGVMs because this is only one of several mechanisms that control plant growth. As any farmer knows, plant growth is rarely limited by the abundance of the most abundant nutrient. It is usually limited by the abundance of the least abundant nutrient. While increased CO2 can accelerate plant growth in carefully controlled laboratory conditions, this rarely happens in nature or in large-scale agriculture. There, plant growth is usually limited by water, nitrogen, phosphorus, sunlight or temperature. These models include all of those effects. The range of outputs produced by the models reflects uncertainties in the relative roles of these processes and their potential evolution with climate change. This behaviour should foster serious concern (doubt) about the potential benefits of CO2 fertilisation in a changing climate. There is no discussion of this here or in chapters 2.1 or 9.

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2.1 CO2 as a contributor to global greening

Page 4

MISLEADING

Had atmospheric CO2 levels continued declining, plant growth would have declined and eventually ceased. Below 180ppm, the growth rates of many C3 species are reduced 40-60% relative to 350ppm (Gerhart and Ward (2010)) and growth has stopped altogether under experimental conditions of 60-140ppm CO2. Some C4 plants are still able to grow at levels even as low as 10ppm, albeit very slowly (Gerhart and Ward (2010)).

“Ward, however, told WIRED in an emailed statement that her experiments were conducted under ‘highly controlled growth conditions’ to create a ‘mechanistic understanding’ of CO2, and that climate change can cause a host of impacts on plants not accounted for in her study. ‘With rising CO2 in natural ecosystems, plants may experience higher heat loads, extreme weather events such as droughts and floods and reduced pollinators – which can have severe net negative effects on plant growth and crop yields,’ she says. ‘Furthermore, our studies indicate that major disruptions in plant development such as flowering time can occur in direct response to rising CO2, which were not mentioned in the report.’”

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2.1 CO2 as a contributor to global greening

Page 4

FALSE

Piao et al. (2020) and Chen et al. (2024) report that the greening trend continues with no evidence of slowdown, and CO2 fertilisation remains the dominant driver.

Chen et al (2024) does not back up this statement. In the abstract, the author concluded that greening, whilst still increasing, has slowed down: “Our study highlighted that drought trend did not necessarily trigger vegetation browning, but slowed down the rate of greening.” Piao et al. (2019) looked at the driver of global greening. They did not look at whether trends in global greening are rising or decreasing. In addition they analysis focused on historical observation (1980-2010) and did not assess future trends.

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2.1 CO2 as a contributor to global greening

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MISLEADING

Had atmospheric CO2 levels continued declining, plant growth would have declined and eventually ceased. Below 180ppm, the growth rates of many C3 species are reduced 40-60% relative to 350ppm (Gerhart and Ward (2010)) and growth has stopped altogether under experimental conditions of 60-140ppm CO2. Some C4 plants are still able to grow at levels even as low as 10ppm, albeit very slowly (Gerhart and Ward (2010)).

The decline in atmospheric CO2 levels over the last few tens of millions of years stopped naturally, and for the last 800,000 years up until the Industrial Revolution did not show much of a trend, just fluctuating between about 170 and 280 parts per million. The hypothetical scenario of a further decline below these levels is not relevant – it is not the case that human-driven CO2 emissions have somehow saved us from declining CO2 levels and declining plant growth, as seems to be the implication behind this paragraph.

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2.1 CO2 as a contributor to global greening

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MISLEADING

The overwhelming theme is that plants, especially C3 plants, benefit from extra CO2.

While individual plants benefit in isolation, the overall effect on an ecosystem and biodiversity can be detrimental due to some species benefitting more than others and out-competing them – for example, lianas responding more than trees, which they damage, encroachment of trees and shrubs into grasslands and savannahs, and the promotion of invasive species and weeds.

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2.1 CO2 as a contributor to global greening

Page 5

MISLEADING

There are two mechanisms by which CO2 confers a growth benefit

A “growth benefit” to the plant is not necessarily beneficial in other ways – for example, from IPCC AR6: “Perennial crops and root crops may have a greater capacity for enhanced biomass under elevated CO2 concentrations, although this does not always result in higher yields. For some food crops, nutrient density declines due to elevated CO2.” And: “Elevated CO2 reduces some important nutrients such as protein, iron, zinc and some grains, fruit or vegetables to varying degrees depending on crop species and cultivars.”

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2.1 CO2 as a contributor to global greening

Page 5

MISLEADING

The gains induced by increasing CO2 from 150ppm to 350ppm continue under a further doubling to 700ppm.

This very simplistic illustration from a small laboratory study ignores key effects such as nutrient availability, which in the real world can constrain the response to elevated CO2.

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2.2 The alkaline oceans

Page 6

MISLEADING

Section 2.2.1

“The first subsection builds towards the conclusion in the summary that ‘ocean life is complex and much of it evolved when the oceans were acidic relative to the present’. Leaving aside the vacuity of this argument for the moment – life itself evolved when there was little oxygen in the atmosphere, the biochemical innovations that flooded the atmosphere with oxygen were catastrophic for life then, but see how we would do without it now – their citations are spare and strange particularly within the context of later arguments about the value of models and the contention that this is some sort of meaningful ‘critical review’. The first paper they cite regarding long-term change in ocean pH is Krissansen-Totton et al. (2018), which uses a model to constrain climate and ocean pH of the early Earth up to the present. They find that ocean pH evolves monotonically from 6.6 (see the abstract of the paper for the broad uncertainty ranges) at 4.0 Ga to 7.0 at the Archean-Proterozoic boundary, and to 7.9 at the Proterozoic-Phanerozoic boundary reaching a modern value of 8.2. While we might raise an eyebrow that the ‘critical review’ finds models are good enough for the herculean task of reproducing almost the whole of Earth’s climate history, but not for understanding the past 200 years, the eyebrow is likely to go shooting off your face when you reach the sentence in the ‘critical review’ that says: ‘Even if the water were to turn acidic, it is believed that life in the oceans evolved when the oceans were mildly acidic with pH 6.5 to 7.0.’ I derive little comfort from the fact that simple life forms evolved in such conditions. The gist of the ‘critical review’ isn’t that simple life forms will survive the current warming, but that human society supported by a flourishing biosphere will not just survive but thrive. Anyway, this is only part of an argument and the whole of the argument is never really spelled out. It seems to go something like this: pH of the ocean varied in the past and we exist today, therefore we will always exist and pH of the ocean is unimportant.

“The second, shorter, long-term perspective, which feeds into this argument, mixes up surface pH (as shown in Figure 2.3 from the CMEMS dataset) with deep ocean pH (from Rae et al. (2018)) who (according to their abstract) ‘present deep-sea coral boron isotope data that track the pH – and thus the CO2 chemistry – of the deep Southern Ocean over the past forty thousand years’. ‘Deep’ and ‘track’ are the operative words here. The estimated changes are ‘deep’, from a depth of around 750 metres and not the surface. Regarding ‘track’, the numbers quoted in the ‘critical review’ – pH of 7.4 to 7.5 20,000 years ago – came presumably from Figure S1 in the Rae paper, which provides an approximate conversion of the boron isotopes to pH. How very very approximate they are is shown by an inset uncertainty range, which extends from well below 7.4 to well above 7.6 suggesting great care is needed in the interpretation of the absolute pH values.”

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2.2 The alkaline oceans

Page 6

MISLEADING

Section 2.2.2

“The first two paragraphs of the ‘critical review’ are on that famous American landmark the Great Barrier Reef. And why not? Well. One ‘why not’ can be found in the IPCC report (AR6 WG2). Chapter 11 has a box (‘Box 11.2 | The Great Barrier Reef in Crisis’). It doesn’t mention ocean acidification as a risk to the GBR at all (though OA is mentioned frequently elsewhere). The two big risks mentioned are bleaching in response to marine heatwaves and erosion caused by tropical cyclones. Neither of these factors is unconnected to climate change. Ocean acidification may not be a risk to the GBR, but climate change certainly is. The AIMS website which is referenced in the ‘critical review’ even notes ‘a high tolerance in massive Porites to ocean acidification’. The GBR is introduced here as a 2,300km long straw man.

“The rest of the section concerns itself with the more general impacts of ocean acidification. But only glancingly. They cite Browman (2016) on the lack of null results in the literature and offer, as an example, Clements et al. (2021) which is about the direct effects of OA on the behaviour of fish specifically (not the reefs themselves) though it does have a juicy metascientific quote that serves their purpose of suggesting that discussion of the topic is one-sided. If anything, Clements et al. shows that the literature is no longer one-sided so it rather weakens the point they are trying to make…The Browman article is also somewhat meta and points out that papers on ocean acidification were appearing at an average rate of 300 per year between 2006 and 2015, with around 600 articles per year in each of 2013, 2014 and 2015. How many are there now? I don’t know. The Browman and Clements articles are both old-as in the context of a fast-moving field. A simple Google Scholar search will show you that not only are there huge numbers of papers mentioning the topic in the past five years, but there are even lots of review papers and meta analyses on the topic which cover a much broader range of impacts. Summarising that literature with just 12 references (including links to the data used) is not adequate by any definition.”

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2.1 CO2 as a contributor to global greening

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MISLEADING

Derying et al. (2016) surveyed evidence on crop water productivity (CWP), the yield per unit of water used, drawing attention to the potential for CO2 both to enhance photosynthesis and to reduce leaf-level transpiration (water loss during leaf respiration). They surveyed all available FACE data (Free Air CO2 Enrichment – see Chapter 9) on crop yield changes for maize (corn), wheat, rice, and soybean and combined it with crop model data simulating yield responses as of 2080 under the extreme RCP8.5 emissions scenario in four growing regions (tropics, arid, temperate and cold) each of which were split into rainfed and irrigated sub-regions. They reported that models without CO2 fertilisation predicted CWP losses in every region, but those were more than offset by CO2 fertilisation so that all regions showed a net CWP gain. Deryng et al. (2016) also reported that negative impacts of warming on wheat and soybean yields were fully offset by CWP gains and mitigated by up to 90% for rice and 60% for maize.

While those are general conclusions of the paper, they are misleading by not mentioning the considerable discrepancy among modelled results. In fact, this paper was the first of its kind to present findings from the first global modelling intercomparison initiative of global gridded crop models, focusing specifically on how state-of-the-art models represented CO2 effects on crop yield and evapotranspiration, highlighting these effects as a dominant source of uncertainty in the results, outpassing the uncertainty resulting from the use of different climate change projections. The supplementary information of the paper includes the detailed uncertainty analysis. A key message of the paper was also to highlight the needs for further research on the effects of CO2 on crops and their representation in crop models. Toreti et al. (2020) provides a comprehensive review of the uncertainties associated with the effects of elevated CO2 on crops,

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