As the scientific consensus for climate change has strengthened over the past decade, the arguments against the science of climate change have been on the increase.

That’s the surprise finding of a study, published in the journal Global Environmental Change last month, which analysed and identified the key themes in more than 16,000 publications about climate change by conservative organisations.

Conservative think-tanks are organisations that oppose policies, such as regulation of pollution caused by the fossil fuel industry (some have also opposed regulation of the tobacco industry in the past and, in fact, some continue to do so today).

One study found that from 1972 to 2005, over 92% of climate contrarian books originated from conservative think-tanks. They are often ground zero for misinformation casting doubt on climate science, with their messages spread by contrarian blogs, conservative media and politicians opposing climate policy.

Examining the articles

Computer science offers tools in analysing the publications of conservative think-tanks over time. UK scientists Constantine Boussalis and Travis Coan compiled the largest database to date of conservative articles, a collection of over 16,000 webpages, reports, media releases, interviews and speeches from 1998 to 2013.

In order to analyse so many documents, Boussalis and Coan employed machine learning algorithms that automatically detected clusters of words. They identified 47 key topics, ranging from arguments against climate science to policy-related topics, such as emissions reductions and international agreements.

To see how the think-tanks’ focus evolved over time, the authors divided the topics into two categories: arguments against the science of climate change, and arguments against climate policies.

Common wisdom is that as evidence for human-caused global warming accumulates, and the scientific consensus strengthens (as seen in my own research as well as in research citations), the public debate should shift from questioning the science to exploring possible policy options.

Instead, this is what they observed:

Boussalis & Coan

In 2009, you’d be forgiven for thinking that the emphasis was indeed shifting from science to policy. But the authors were surprised to find that the relative prevalence of science denial has been on the increase since around 2009.

Conservative think-tanks aren’t shifting from questioning the science to a more appropriate policy debate. On the contrary, they continue to cast doubt on climate science with a determined persistence.

How is climate science denial able to persist in the face of accumulating evidence and strengthening consensus? I explored this question in a psychological study published (full paper available here) in Topics in Cognitive Science earlier this month.

I presented information about the 97% scientific consensus on human-caused global warming to a representative sample of Americans. Overall, acceptance of climate change increased in response. But for a small proportion of participants, acceptance of climate change actually went down.

This group were those with the strongest support for free, unregulated markets. In other words, strong political conservatives. The study also found that conservatives were more likely to have a lower-than-average trust in climate scientists.

The conspiracy theorists

When this small group of strong free-market supporters were told about the 97% consensus, their trust in scientists fell even lower. My research indicated that this response was driven by an expectation that climate scientists would falsify evidence to support human-caused global warming – a thought pattern characteristic of conspiratorial thinking.

This result is consistent with other research linking climate science denial with conspiratorial thinking. This has been found in surveys as well as research that observed that the number one contrarian response to climate change is conspiracy theories.

Smith & Leiserowitz, 2012

Conspiratorial thinking is problematic because it is immune to new evidence. Any evidence against the conspiracy is viewed as part of the conspiracy. As a consequence, climate science denial, and the generation of misinformation that comes with it, is not disappearing any time soon.

This matters because several new studies have confirmed what many of us already suspected – misinformation is effective. Just a handful of cherry-picked statistics can reduce people’s acceptance of climate change.

Of more concern to science communicators is the recent finding that misinformation can cancel out the positive effect of accurate information.

How to get the right message out

There’s a great deal of research into how to communicate science more effectively and science communication should be evidence-based. But scientists and science communicators cannot afford to ignore the potential of misinformation to undermine good science communication.

One way to reduce the influence of misinformation is inoculation: we can stop the spread of science denial by exposing people to a weak form of science denial.

The findings of psychology underscore the importance of this new study into the production of misinformation by conservative think-tanks. To paraphrase the authors, the era of science denial is not over. Climate science communicators would be prudent not to start waving a “mission accomplished” banner just yet.