The latest survey on the American public's beliefs and attitudes regarding global warming offers few surprises. "Overall," the executive summary of Climate Change in the American Mind: Americans' Global Warming Beliefs and Attitudes in March 2012 summarizes (PDF), "Americans' beliefs and attitudes about global warming have remained relatively stable over the past several months, with a few exceptions." (The report provides longitudinal data back to November 2008 for most of the questions about beliefs and attitudes regarding global warming.)
Presented with a definition of global warming as "the idea that the world's average temperature has been increasing over the past 150 years, may be increasing more in the future, and that the world's climate may change as a result" and asked whether they thought that global warming is happening, 66% of respondents said yes — a slight increase — while 14% said no and 20% indicated that they didn't know. Asked about the cause of global warming, on the assumption that it is happening, 46% of respondents said that global warming is caused mostly by human activities — a slight decrease — while 37% said that it is caused mostly by natural changes in the environment, 9% volunteered that it is caused by both human activities and natural changes, 5% opted for "none of the above because global warming isn't happening," 2% offered other views, and 1% volunteered that they did not know.
Asked for their views about what scientists believe, 35% of respondents agreed that most scientists think that global warming is happening — a slight decrease — 3% agreed that most scientists think global warming is not happening, 41% agreed that there is a lot of disagreement among scientists about whether or not global warming is happening, and 21% said that they don't know enough to say. Respondents were also asked to estimate the proportions of Americans who take various positions on global warming. The average responses were that 38% believe that global warming is happening due mostly to human activities (which is correct, according to the survey data), 25% believe that global warming is happening due mostly to natural causes (actually 19%), 21% don't believe that global warming is happening (actually 14%), and 20% haven't yet made up their mind about whether or not global warming is happening (correct).
The study was conducted by the Yale Project on Climate Change Communication and the George Mason University Center for Climate Change Communication. The surveys were administered from March 12 to March 30, 2012, using an on-line research panel of 1008 American adults. According to the report, "These results come from nationally representative surveys of American adults, aged 18 and older. The samples were weighted to correspond with US Census Bureau parameters for the United States." The margin of sampling error was plus or minus 3% at the 95% confidence level.