Three out of four Americans believe that the Earth has been gradually warming as the result of human activity and want the government to institute regulations to stop it, according to a new survey by researchers at the Woods Institute for the Environment at Stanford University.
The survey was conducted by Woods Institute Senior Fellow Jon Krosnick, a professor of communication and of political science at Stanford, with funding from the National Science Foundation. The results are based on telephone interviews conducted from June 1-7 with 1,000 randomly selected American adults.
"Several national surveys released during the last eight months have been interpreted as showing that fewer and fewer Americans believe that climate change is real, human-caused and threatening to people," Krosnick said. "But our new survey shows just the opposite."
For example, when respondents in the June 2010 survey were asked if the Earth's temperature probably had been heating up over the last 100 years, 74 percent said yes. And 75 percent said that human behavior was substantially responsible for any warming that has occurred. Krosnick has asked similar questions in previous Woods Institute polls since 2006.
"Our surveys reveal a small decline in the proportion of people who believe global warming has been happening, from 84 percent in 2007 to 74 percent today," Krosnick said. "Statistical analysis of our data revealed that this decline is attributable to perceptions of recent weather changes by the minority of Americans who have been skeptical about climate scientists."
In terms of average Earth temperature, 2008 was the coldest year since 2000, Krosnick said. "Scientists say that such year-to-year fluctuations are uninformative, and people who trust scientists therefore ignore this information when forming opinions about global warming's existence," he added. "But people who do not trust climate scientists base their conclusions on their personal observations of nature. These 'low-trust' individuals were especially aware of the recent decline in average world temperatures; they were the ones in our survey whose doubts about global warming have increased since 2007."
According to Krosnick, this explanation is especially significant, because it suggests that the recent decline in the proportion of people who believe in global warming is likely to be temporary. "If the Earth's temperature begins to rise again, these individuals may reverse course and rejoin the large majority who still think warming is real," he said.
Several questions in the June survey addressed the so-called "climategate" controversy, which made headlines in late 2009 and early 2010.
"Growing public skepticism has, in recent months, been attributed to news reports about e-mail messages hacked from the computer system at the University of East Anglia in Britain – characterized as showing climate scientists colluding to silence unconvinced colleagues – and by the discoveries of alleged flaws in reports by the Intergovernmental Panel on Climate Change (IPPC)," Krosnick said. "Our survey discredited this claim in multiple ways. "
For example, only 9 percent of respondents said they knew about the East Anglia e-mail messages and believed they indicate that climate scientists should not be trusted, and only 13 percent said the same about the controversial IPPC reports.
"Overall, we found no decline in Americans' trust in environmental scientists," Krosnick said. "Fully 71 percent of respondents said they trust scientists a moderate amount, a lot or completely."
In the June 2010 survey, 86 percent of respondents said they wanted the federal government to limit the amount of air pollution that businesses emit, and 76 percent favored government limitations on greenhouse gas emissions generated by businesses. Only 14 percent said that the United States should not take action to combat global warming unless other major industrial countries like China and India do so as well.
Among other survey results:
For additional information on Krosnick's research, visit: http://woods.stanford.edu/research/surveys.html
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