Fight climate change misinformation with inoculation theory

The only way to fight climate change is by countering misinformation. I say that because while the fact that our climate is changing and that humans are the primary cause for this change is known, public opinion about these facts is not only divided - its highly polarised.

While more than 97 per cent of climate scientists agree that humans are warming the planet only 60 per cent of Australians trust the science that says that humans are causing climate change.

This doubt among non-scientists allows some political parties to refuse to take serious action to prevent or mitigate the damage from climate change.

So what can people do about this problem? Well a study released this week suggests that inoculation theory can help to convince the doubters (van der Linden et al., 2017).

Inoculation theory is a technique to make a target audience resistant to persuasion, particularly persuasive misinformation. The theory is that you can reduce the effects of persuasion by exposing individuals to a weak dose of opposing arguments coupled with a strong criticism of those arguments. This works in the same way as many vaccines by exposing people to a weak form of the disease you are trying to make people resistant to (McGuire, 1964, Perloff, 2014 pp. 180-188, Krcmar, Roskos-Ewoldsen and Koerner, 2016).

Associate Professor John Cook explains the technique well in the following video:

More than 2000 subjects in van der Linden et al.'s study were asked what percentage of climate scientists conclude that humans are causing climate change (or more correctly, their research does). On average the subjects believed that around 72 per cent of climate scientists held that view.

When they were presented with evidence that the real answer was 97 per cent, the subjects changed their minds and on average believed that 90 per cent of climate scientists conclude that humans are causing climate change.

However, when those subjects were then shown the Oregon Petition - a fraudulent piece of misinformation suggests there was no scientific consensus on climate change, subjects again changed their minds to their original position, believing only 73 per cent of climate scientists conclude that humans are causing climate change.

This highlights the problem of discussions about climate change debates and debates about scientific matters. People can be easily persuaded by misinformation, particularly in scientific areas where the evidence is hard for most people to understand and interpret.

But the good news is that when one group of subjects were told that "some politically motivated groups use misleading tactics to try to convince the public that there is a lot of disagreement among scientists" (van der Linden et al., 2017 p.3) before they read the Oregon Petition, this resulted in subjects believing that 80 per cent of climate scientists conclude that humans are causing climate change.

And even better, when a different group of subjects were told more information, such as "highlighting that some of the signatories are fraudulent, including Charles Darwin and members of the Spice Girls, that fewer than 1% of the signatories have a background in atmospheric/climate science" (van der Linden et al., 2017 p.3), subjects said an average of 84 per cent of climate scientists conclude that humans are causing climate change.

This is important because there is reasonable evidence that many people look to the cue of expert opinion when trying to form their own views about complex scientific matters (Lewandowsky, Gignac and Vaughan, 2012).

To some extent the fact that this works this should come as no surprise as there is already solid evidence that inoculating against misinformation is highly effective (Banas and Rains, 2010).

However what is particularly interesting is that the inoculation effects appear to work, regardless of a person's political disposition. This would appear to run contrary to the "cultural cognition" theory, that people will discount facts that run contrary to their perceived identity, particularly their political identity.

"We found that inoculation messages were equally effective in shifting the opinions of Republicans, Independents and Democrats in a direction consistent with the conclusions of climate science," leaded author Sander van der Linden said.

"What's striking is that, on average, we found no backfire effect to inoculation messages among groups predisposed to reject climate science, they didn't seem to retreat into conspiracy theories."

Often in these sorts of matters people can be persuaded by whoever they hear from last, however this test shows that in a contest of ideas, inoculating people against misinformation can make them highly resistant to it.

In practice this study supports the "Fact, myth, fallacy" technique about talking about climate change with doubters advocated in this excellent online course.

The challenge now will be to convince enough doubters to pay attention to inoculation messages in the first place in real world conditions - and hope that the effects last long enough for them to support politicians that are also willing to fight climate change.


  • Banas, J. and Rains, S. (2010). A Meta-Analysis of Research on Inoculation Theory. Communication Monographs, 77(3), pp.281-311.

  • Krcmar, M., Roskos-Ewoldsen, D. and Koerner, A. (2016). Communication science theory and research. 1st ed. New York: Routledge.

  • Lewandowsky, S., Gignac, G. and Vaughan, S. (2012). The pivotal role of perceived scientific consensus in acceptance of science. Nature Climate Change, 3(4), pp.399-404.

  • McGuire, W. (1964). Inducing Resistence to Persuasion Some Contemporary Approaches. In: G. Lindzey and E. Aronson, ed., Advances in Experimental Social Psychology, 1st ed. New York: Academic Press, pp.192-229.

  • Perloff, R. (2014). The dynamics of persuasion. 1st ed. New York: Routledge.

  • van der Linden, S., Leiserowitz, A., Rosenthal, S. and Maibach, E. (2017). Inoculating the Public against Misinformation about Climate Change. Global Challenges, p.1600008.