A Skeptical Response to Science Denial

John Cook

Science denial has significant consequences. AIDS denial caused over 300,000 deaths in South Africa. Vaccination denial has allowed preventable diseases to make a comeback. Climate science denial helped delay sorely needed mitigation policies, committing us to direr climate impacts for decades to come.

Skepticism (by which I mean an evidence-based approach) is the antidote to denial. But skepticism doesn’t just apply to how we practice our science. It must also apply to how we communicate our science. There is a wealth of psychological research into the phenomena of denial and how to neutralize the influence of misinformation. To ignore this evidence when countering science denial and pseudoscience is, ironically, not a skeptical approach.

So what is an evidence-based response to science denial? To illustrate, allow me to use an example from my own area of research: the scientific consensus on climate change. The psychological principles emerging from this topic have implications that can be applied to many areas of science.

Scientific Consensus on Climate Change

What percentage of publishing climate scientists accepts human-caused global warming? This isn’t just an academic question; the answer has real-world consequences. On complicated scientific matters such as climate change, the average layperson uses expert opinion as a mental shortcut or heuristic. Psychologists have identified perceived consensus as a “gateway belief” influencing their views on climate change and, most importantly, their level of support for climate action.

A number of studies have quantified the scientific consensus on human-caused global warming. A 2009 survey of Earth scientists found that among publishing climate scientists, 97.4 percent agreed that humans are significantly raising global temperature (Doran and Zimmerman 2009). A 2010 analysis of public statements about climate change found that among the scientists who had published peer-reviewed climate research, 97 to 98 percent agreed with the consensus position (Anderegg et al. 2010). I was part of a team that analyzed published climate research, finding 97.1 percent consensus among papers stating a position on human-caused global warming (Cook et al. 2013). In 2015, a survey of University scientists found 96.7 percent consensus among scientists conducting research about climate change (Carlton et al. 2015).

For what is arguably the definitive work on the scientific consensus on climate change, I was privileged to coauthor a study with scientists who authored six of the other major consensus studies published over the last decade or so (Cook et al. 2016). In synthesizing all the published research on the level of scientific agreement on climate change, we found a number of studies, adopting a range of independent methodologies, consistently finding around 97 percent consensus among publishing climate scientists on human-caused global warming.

So, study after study confirms an overwhelming scientific consensus on climate change. But what does the average person think about the consensus? A Yale survey of Americans found that on average, people think that 67 percent of climate scientists agree that humans are causing global warming. That already sounds disturbingly low, but it’s even worse when you consider that only 12 percent of Americans are aware that the consensus is over 90 percent. There is a gaping chasm between public perception of consensus and the actual 97 percent consensus.

How do we explain this “consensus gap”? One contributor is misinformation. An analysis of opinion pieces about climate change by conservative columnists found that their most common argument was “there is no scientific consensus” (Elsasser and Dunlap 2012). Long before social scientists had identified perceived consensus as a gateway belief, opponents of climate action had pinpointed consensus as a key target of attack. A 2002 memo by Frank Luntz recommended that Republican politicians cast doubt on the scientific consensus in order to win the public debate on climate change.

Politicians follow this advice to this day. Former presidential hopeful Senator Ted Cruz argues that there is no consensus on climate change, claiming that the 97 percent consensus is based on “one bogus study.” He ignores, of course, that the 97 percent consensus is in fact based on a multitude of independent studies.

Criticism of the 97 Percent Consensus from the Opposite Direction

Interestingly, the 97 percent consensus has also been criticized from the opposite direction. In an earlier issue of Skeptical Inquirer (Powell 2015) as well as a recent paper in Bulletin of Science, Technology & Society (Powell 2016), James Lawrence Powell argued that the 97 percent consensus was too low and is actually 99.9 percent.

Ironically, Powell’s approach was similar to Senator Cruz’s, dismissing the wide range of surveys and analyses all arriving at the same 97 percent consensus.

How does Powell reach a different result than the many studies into consensus? He assumes that any paper that doesn’t explicitly reject the consensus in its abstract must therefore endorse the consensus. On the one hand, he has a point. As we discuss in our own paper, Naomi Oreskes predicted in 2007 that as a consensus strengthens, we should see fewer people bother to explicitly mention the consensus position in their paper’s abstract (Oreskes 2007). This pattern was exactly what we observed in our own data.

However, our data also demonstrated that there are instances where Powell’s assumption is false. There were a small number of papers that stated no position on human-caused global warming in their abstract, but also minimized or rejected the human contribution to global warming in the full paper. We can’t assume that because a paper doesn’t express a position on the consensus in its abstract, then the authors must endorse the consensus.

Ultimately, it’s worth taking a step back and considering that this particular dispute is between a 97 percent or 99.9 percent consensus, while the vast majority of people don’t even realize the consensus is over 90 percent. Both Powell and the many studies into consensus all find an overwhelming scientific agreement among climate scientists on human-caused global warming. This is the key message that the public needs to hear.

The Bull in a Teashop

Given the crucial role of perceived consensus as a gateway belief, it should come as no surprise that opponents of climate action have expended so much effort manufacturing doubt about the level of scientific agreement among climate scientists. But how do we respond to such misinformation campaigns? The answer lies in psychological research.

The psychology of consensus has been a topic of growing interest to researchers in recent years. Some of their research findings have significant implications, not just for climate change but also for science communicators in many different disciplines.

Mountains of research have been conducted into how to effectively communicate the realities of climate change. This is important work, and it is imperative that scientists heed this research when educating the public about science. But for too long, a deadly Achilles heel for science communicators has been overlooked.

Misinformation can undo the good work of science communication. In one study, Aaron McCright and his colleagues (2015) tested various climate messages, finding that the messages were effective in raising acceptance of climate change. They then tested the same messages accompanied by misinformation that cast doubt on climate change. The misinformation cancelled out some of the positive influence of the accurate scientific information. This result is echoed by upcoming research from Yale University (van der Linden et al. 2016), which tested the effect of communicating the 97 percent consensus as well as misinformation about the consensus. The researchers found that the two conflicting messages cancelled each other out, with no net effect. The misinformation completely neutralized the 97 percent consensus message.

This research has grave implications for all science communicators. Even if we painstakingly craft the perfect piece of empirically tested, market-researched science communication, all our good work can be undone by misinformation. Science denial is the bull in our teashop of delicately understood scientific concepts. So long as science denial persists in generating misinformation, it will undermine public understanding of climate change and erode public support of climate action.

The corrosive influence of misinformation is more relevant than ever, in light of new research by U.K. scientists who analyzed tens of thousands of publications on climate change by conservative think tanks (Boussalis and Coan 2016). They found that over the last decade, science denial has been on the increase. Science denialists are doubling down on their science denial. The researchers posed the question: “Is the era of climate denial over?” The answer emerging from their data is sadly “no.” Climate science denial has no intention of fading quietly into the night.

Stopping the Spread of Science Denial

Can we wrap our science in cotton wool as we send it out into the big, myth-infested world? The answer is yes, we can safeguard our science by applying a branch of psychological research known as inoculation theory (McGuire and Papageorgis 1961).

Inoculation theory borrows the metaphor of inoculation but applies it to knowledge. We develop resistance against a virus when we’re exposed to a weak form of the virus through vaccination. In the same way, we can develop resistance against misinformation by exposing people to a weak form of the misinformation.

By “weak form” of misinformation, I mean the misinformation accompanied with an explanation of the techniques it uses to distort the science. What fallacy does the myth use? Does it cherry-pick the data? Does it rely on fake experts? Does it use a logical fallacy such as jumping to conclusions or red herrings?Inoculation theory suggests that communicators should couple science information with inoculating messages. When you communicate a scientific concept, you should also explain the techniques or fallacies that might be used to distort that science. When people subsequently encounter the myth, they’ve acquired the critical thinking skills to discern how that myth attempts to distort the science and mislead them. The bull has lost its horns.

While my research has focused on inoculating people against misinformation about climate change, the principles of inoculation theory apply generally to any form of misinformation. If you’re trying to communicate the benefits of vaccination, explain the science of evolution, or debunk some pseudoscience, adopting the approach of inoculation theory is an effective, evidence-based way to convey both the science and neutralize misinformation that casts doubt on the science.



  • Anderegg, W.R.L., J.W. Prall, J. Harold, et al. 2010. Expert credibility in climate change. Proceedings of the National Academy of Sciences of the United States of America 107: 12107–12109.
  • Boussalis, C., and T.G. Coan. 2016. Text-mining the signals of climate change doubt. Global Environmental Change 36: 89–100.
  • Carlton, J.S., R. Perry-Hill, M. Huber, et al. 2015. The climate change consensus extends beyond climate scientists. Environmental Research Letters 10(9): 094025.
  • Cook, J., D. Nuccitelli, S.A. Green, et al. 2013. Quantifying the consensus on anthropogenic global warming in the scientific literature. Environmental Research Letters 8(2): 024024+.
  • Cook, J., N. Oreskes, P.T. Doran, et al. 2016. Consensus on consensus: A synthesis of consensus estimates on human-caused global warming. Environmental Research Letters 11(4): 048002.
  • Doran, P.T., and M.K. Zimmerman. 2009. Examining the scientific consensus on climate change. Eos, Transactions American Geophysical Union 90(3): 22–23.
  • Elsasser, S.W., and R.E. Dunlap. 2012. Leading voices in the denier choir: Conservative columnists’ dismissal of global warming and denigration of climate science. American Behavioral Scientist 57: 754–776.
  • McCright, A.M., M. Charters, K. Dentzman, et al. 2015. Examining the effectiveness of climate change frames in the face of a climate change denial counter-frame. Topics in Cognitive Science doi: 10.1111/tops.12171.
  • McGuire, W.J., and D. Papageorgis. 1961. The relative efficacy of various types of prior belief-defense in producing immunity against persuasion. Public Opinion Quarterly 26: 24–34.
  • Oreskes, N. 2007. The scientific consensus on climate change: How do we know we’re not wrong? In Climate Change: What It Means for Us, Our Children, and Our Grandchildren. Cambridge, MA: MIT Press.
  • Powell, J. 2015. The consensus on anthropogenic global warming. Skeptical Inquirer 39(6): 42–45. Available online at http://www.csicop.
  • ———. 2016. Climate scientists virtually unanimous: Anthropogenic global warming is true. Bulletin of Science, Technology & Society, 1–4.
  • Van der Linden, S.L., A.A. Leiserowitz, S.A. Rosenthal, et al. 2016, in revision. Inoculating the public against misinformation about climate change.

John Cook

John Cook is the Climate Communication Fellow for the Global Change Institute at the University of Queensland, Australia. He created and maintains the Skeptical Science website and is co-author of Climate Change Denial (2011) and the 2013 college textbook Climate Change Science: A Modern Synthesis.