There’s a Scientific Consensus on Climate Change?
A resounding 97 percent of climate experts agree that climate change is both real and, at least in part, caused by human activities. But a huge chunk of the American public remains ignorant of this consensus, making it difficult to start conversations on the subject on firm factual ground.
According to the most recent numbers from Gallup, only 60 percent of Americans expressed agreement with the understated assertion that “most scientists believe global warming is occurring.” Eight percent disagreed, while 29 percent were unsure if scientists are of one mind on the issue.
This is not only frustrating but vitally important, since “the evidence suggests that understanding the expert consensus is a ‘gateway’ belief,” writes a research team led by Edward Maibach and Teresa Myers of George Mason University. Awareness that there is no real controversy within the scientific community “predisposes people to be more certain that climate change is happening, human-caused, serious, and solvable.”
"These studies provide solid evidence that simple, clear messages can be used to increase Americans’ understanding of the scientific consensus about human-caused climate change, and their confidence in that assessment."
The good news: Those same researchers have identified two simple methods of shifting people’s beliefs in the direction of actual reality. In the journal PLoS One,they report specific numbers are more effective than generalities, and it’s worthwhile to ask people to give their own estimates before steering them to a more accurate figure.
In their first study, the 1,116 participants looked at a fake newspaper page which, for most, included an ad by the American Association for the Advancement of Science. (Those in the control condition, about 185 people, saw an ad for a mobile phone.)
For one group of participants, the copy read: “97.5 percent of climate scientists have concluded that human-caused climate change is happening.” Those in subsequent groups read similar statements starting with “97 percent of climate scientists,” “97 out of 100 climate scientists,” “More than 9 out of 10 climate scientists,” or “An overwhelming majority of climate scientists....”
After closing that page, all participants were asked to give their own estimate. After inserting a number from zero to 100, they were asked how certain they were of their answer.
Not surprisingly, those who read one of the AAAS statements believed the level of agreement to be significantly higher than those who saw the cell phone ad (by a margin of nine percentage points). More significantly, perhaps, those who had seen an ad with a specific percentage gave estimates about 13 points higher than those who read the one stating there was agreement among “an overwhelming majority” of experts.
All in all, “More precise estimates resulted in higher estimates of scientific agreement,” the researchers report. They add that, while this effect was “strongest for liberals,” it was “still positive and significant for conservatives.”
In the second study, approximately half of the 809 participants were initially asked “what percentage of climate scientists they believe had concluded that human-caused climate change is occurring.” All then read one of four messages by AAAS, three of which included the 97 percent consensus figure.
Afterwards, all participants gave their own estimates of the scientific consensus, either for the first or second time. By far the highest number was offered by those who initially offered a number, and then answered again after being exposed to the true figure: Their estimate went up from 65 to 89 percent. For those who did not give a first-guess estimate, their final answer was 81 percent—seven points lower.
“Numbers are not perceived in a vacuum,” the researchers write. “Whether a number seems large of small, substantial or insubstantial, can depend on a number of factors, including comparison to other numbers.”
In this case, offering a ballpark figure apparently gave participants a jumping-off point that made higher figures (although ones that were below the real number) seem more plausible.
“Taken together, these two studies provide solid evidence that simple, clear messages can be used to increase Americans’ understanding of the scientific consensus about human-caused climate change, and their confidence in that assessment,” the researchers conclude.
They concede that it’s uncertain how long these effects will last, and how resistant they are to counterclaims.
Nevertheless, with more ominous news (most recently about the thinning of a massive Antarctic ice shelf) emerging every week, any and all wake-up calls are welcome.
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