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44 national geographic • March 2015 Then he correlated that with the subjects’ science literacy. He found that higher literacy was asso- ciated with stronger views—at both ends of the spectrum. Science literacy promoted polariza- tion on climate, not consensus. According to Ka- han, that’s because people tend to use scientific knowledge to reinforce beliefs that have already been shaped by their worldview. Americans fall into two basic camps, Kahan says. Those with a more “egalitarian” and “com- munitarian” mind-set are generally suspicious of industry and apt to think it’s up to something dangerous that calls for government regulation; they’re likely to see the risks of climate change. In contrast, people with a “hierarchical” and “individualistic” mind-set respect leaders of on climate change. That’s not about to go poof with the next thermometer reading. But industry PR, however misleading, isn’t enough to explain why only 40 percent of Amer- icans, according to the most recent poll from the Pew Research Center, accept that human activity is the dominant cause of global warming. The “science communication problem,” as it’s blandly called by the scientists who study it, has yielded abundant new research into how people decide what to believe—and why they so often don’t accept the scientific consensus. It’s not that they can’t grasp it, according to Dan Kahan of Yale University. In one study he asked 1,540 Americans, a representative sample, to rate the threat of climate change on a scale of zero to ten. STORMY DEBATE Hurricane Sandy was not caused by human-made climate change, but the damage it did to the Jersey Shore was exacerbated by sea-level rise—which is caused in part by climate change. For those who question the consensus on this and other polarizing issues of science, skeptical beliefs become “almost like badges of membership, of loyalty to the group,” says Yale researcher Dan Kahan.