...Among those who doubt global warming, a Stanford University poll last year found that their skepticism had grown even stronger: Those who are extremely or very certain that global warming is not happening rose from 35 percent in 2010 to 53 percent in 2011. But those skeptics are a minority among Americans over all. The same poll found that 83 percent of adult Americans believe that the world's temperature has been going up. An even larger proportion of scientists actively working in climate change have similar views: 97 percent of them believe human-caused global warming is under way, although there is plenty of disagreement about the details (see related article, Page A15).

Academic pollsters, sociologists, historians, and anthropologists have been sorting through public attitudes about global warming for some time, but even though human behavior is central to the debate, the voices of social scientists are often lost in the din.

"In the end, all of the changes come down to what makes us behave the way we do and think the way we do," says Anthony Leiserowitz, director of the Yale Project on Climate Change Communication. "We need to understand us, not just the natural world."...

Two historians, Erik M. Conway and Naomi Oreskes, point to another source of polarization in their 2010 book Merchants of Doubt. There Mr. Conway, a historian affiliated with the California Institute of Technology, and Ms. Oreskes, a professor of history and science studies at the University of California at San Diego, write about the efforts of a handful of physicists to emphasize uncertainty on some key science-policy issues, including acid rain, the ozone hole, and global warming.

As early as the 1960s, climate scientists were trying to warn such political leaders as President Johnson that the "greenhouse effect" could be a problem, the historians write, and in 1995 the Intergovernmental Panel on Climate Change reported a scientific consensus that humans were creating climate change. But the historians showed that long after the majority of climate scientists believed in global warming, the physicists sowed confusion and delayed action. The physicists' motives weren't entirely clear, although at times they expressed concern over the expense of mitigating global warming and conveyed the view that human migration to cooler parts of the earth would solve any problem caused by climate change.

They borrowed tactics from the tobacco companies' fight against the antismoking movement, launching assaults in the letters-to-the-editor pages of scientific journals, at White House meetings with the Bush administration, and in supposedly neutral forums like a 1983 National Academy of Science report. Journalists, feeling compelled to present "both sides" of the issue and drawn to the drama of contrarian views, often served as handmaidens to the denialists. At least one young researcher, the graduate student of a climate-change scientist who objected to one of the physicist's tactics, found himself slapped with a libel suit. Without resources to defend himself, he was forced to settle, issuing a retraction and submitting to a 10-year gag order.

Mr. Conway remembers having to take breaks to "detoxify" when he was doing research on the book. He says he avoids keeping up on the climate-denial movement. "It's not a happy story; it's kind of a disturbing one," he says....