Foundations of climate change denial: Anti-environmentalism and anti-science

PLOS One | https://doi.org/10.1371/journal.pone.0334544 November 12, 2025 6 / 23 knowledge and media (reflecting limited public understanding of climate science), federal and state-level politics, and the economic and political costs of enacting AGW policy (pp. 94–95). The 30 topics include examples of the early four key denial claims as well as suspicion of the IPCC and scientific authority (representative of the newer emphasis on scientific integrity), primarily within the large “scientific evidence” cluster. For our purposes, the key outcomes of both the Bousallis and Coan (15) and Farrell (34) studies is their evidence that the original denial emphasis on trend, attribution, impact and policy denial remain prominent but continually evolve in response to new evidence and policy proposals, while the newer emphasis on climate science/scientists’ integrity (stimulated by the controversies over Al Gore’s and the IPCC’s Nobel Prize, Mann’s hockey stick model and the related “Climategate” affair created by the CCCM) has emerged as a major denial theme. The third and most recent major study reinforces these points. Coan, Bousallis, Cook and Nanko [25] built directly on the detailed catalog of denial claims posted on “Skeptical Sci- ence” (a website run by Cook for several years), and prior studies of denial claims, especially [24], with their ambitious study of the claims issued by 20 prominent CTTs in the USA and Canada along with the claims posted on 33 “prominent

climate contrarian blogs” (a majority from the USA but over a third from seven other nations) from 1998 to 2020—yielding 255,499 documents. Coan and colleagues carefully developed and refined a detailed taxonomy of what they term “climate contrarian claims,” involving the five “super-claims” reflecting the themes found in past studies: (1) “global warming is not happening,” (2) “human-caused Greenhouse Gases are not causing global warming,” (3) “Climate change impacts are not bad,” (4) “Climate solutions won’t work” and (5) “Climate movement/science is unreliable”—clearly reflecting trend, attribution, impact and policy denial along with broader challenges to the evidence put forth by climate science and those promoting efforts to reduce carbon emissions. They also developed “sub-claims” for many of the major ones and “sub- sub-claims” for most of the former. They then employed a supervised learning approach to classify the themes, first using a “team of climate-literate coders” to code a huge sample of paragraphs into the typology and refining the latter when necessary, and then trained a computational model to classify claims in their corpus into the taxonomy. They also added in data on the major funders of the CTTs and key legislative and societal events. Their impressive data set and methodology enabled Coan, Bousallis, Cook and Nanko [25] to provide a rich analysis of denial claims over time and the factors that influenced variation within and among them. Of utmost importance is that their

taxonomy of claims was validated, with all five being used over the 22 years studied but with varying frequencies. Cru- cially, they found growing attention to policy denial (“solutions won’t work”) over time—especially from the CTTs. They also found high but slightly declining levels of “science is unreliable” from both CTTs and blogs. The three categories of claims reflecting trend, attribution and impact denial have been stable or slightly declining for the CTTs, but remain stronger for the blogs—particularly for trend and attribution denial [25, Fig 2]. According to the authors, “these results suggest that the blogs seem to be acting as the pseudo-scientific arm of the AGW counter-movement” (Ibid., p. 4). The three studies just reviewed, using huge samples of documents produced by major elements of the CCCM, cov- ering long time periods and employing sophisticated analytical techniques, have clearly shown that while denial claims evolve over time in response to advances in climate science and socio-political events, the four original denial claims (mainly from the 1990s and early 2000s) have never disappeared but have been supplemented with newer ones (espe- cially scientific integrity). Further, several other studies using somewhat more limited data sets (in terms of their corpora), but covering a wider variety of sources and nations than the above three, have overall yielded compatible results: the continuing use of trend, attribution and impact denial, the growing importance of policy denial and of challenging the integ-

rity of climate scientists, climate science, the IPCC, climate policy-makers and activists [31,44,50–52]. As a true “coun- termovement,” the CCCM constantly reacts to the claims issued by climate scientists and policy-makers and modifies its counterclaims in response. The empirical evidence on the nature and evolution of AGW denial claims has rapidly grown and matured, but Lejano and Dodge [22] argue that “Future work involves going deeper into the roots of the climate skeptical narrative, perhaps