November 17, 2012 — andyextance

People in Australia overestimate how many of their fellow citizens don’t think climate change is happening, but still think their own opinion is the most common. That’s according to a survey run by Zoe Leviston from Australia’s national science agency, the Commonwealth Scientific and Industrial Research Organisation (CSIRO), in Perth and her teammates. Roughly one person in 20 surveyed fell in the ‘not happening’ group, but on average people thought that one person in five did. That’s partly down to a well-known effect called ‘false consensus bias’, where we tend to think more people agree with us than really do. However, how politicians and the media in Australia discuss climate change could be making the effect stronger than usual.

“There is a mis-estimation of community sentiment,” Zoe told me. “Our perception of what others think is a dynamic process, and if we have these misperceptions, they can actually reinforce our own patterns of thinking. Other research has shown that people can be hesitant to speak out if they think their opinion is on the decline, because they think that they risk social censure. It’s important to communicate accurately what the consensus is, otherwise you can needlessly propagate this myth of widespread denial.”

As part of a major CSIRO research program, known as the Climate Adaptation Flagship, Zoe surveyed more than 5,000 Australians in both 2010 and 2011, 1,355 of whom completed both surveys. Among other questions, they were asked which of four statements best described their view. They could choose: climate change is not happening; don’t know whether it’s happening or not; it’s happening but natural fluctuations; or it’s happening and caused by humans.

But Zoe and her fellow CSIRO scientist Iain Walker wanted to look beyond this basic opinion. “In Australia the media and political debate surrounding climate change have often rested on these competing claims about what Australians support and what they think,” Zoe said. “We knew that people are very bad estimators of what others are thinking, so we decided to ask about that as well.” So straight after the first question, Zoe and Iain asked what proportion of Australians would choose each of the four answers.

Peer pressure

In the survey, 18 out of 20 people said that they thought climate change definitely was happening. More thought it was human caused than natural, though the gap shrunk noticeably between 2010 and 2011. Only around one in 20 thought climate change wasn’t happening in 2010, which increased slightly in 2011. But people’s estimates of what others thought were much more evenly spread. When Zoe and Iain looked at the estimates made by the people who’d chosen each answer, a telling fingerprint emerged, they write in Nature Climate Change this week. Each group thought its opinion was the most common, ranking it as more popular than all the other groups, which is exactly what the false consensus effect causes. However in this case those who thought climate change was happening actually underestimated how many shared their opinion compared with the true survey results.

“False consensus effects happen in gun control, racism, sexism, stereotypes, even things like thinking about water conservation,” Zoe said. “They see a moderate effect size, and we found a moderate effect size in 2010, but when we repeated it in 2011 the effect sizes were actually large. It seems like in statistical terms that effect is stronger than in most issues it’s applied to.” The people who most overestimated how much other people agreed with them were also least likely to have changed opinion between the two surveys, the researchers found.

The unusual strength of this bias could be because political and media attention surrounding the topic adds to how people normally interact, Zoe suggested. “These influences can perpetuate throughout society,” she said. “A false consensus of minority opinions gets reproduced in media outlets, which compounds people’s false consensus estimates of the amount of people who don’t think that climate change is happening.”

Journal Reference:

Leviston, Z., Walker, I., & Morwinski, S. (2012). Your opinion on climate change might not be as common as you think Nature Climate Change DOI: 10.1038/NCLIMATE1743