The survey was funded by the National Science Foundation and administered in June 2010 by Woods Institute Senior Fellow Jon Krosnick, a professor of communication and political science at Stanford University. From June 1-7, 1,000 randomly selected American adults were chosen to participate in the survey via telephone interviews. 

According to the June 2010 survey, 74 percent of Americans think the Earth's temperature probably has been heating up over the last 100 years, and 75 percent think human activity is the reason why. 

"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," said Krosnick. "But our new survey shows just the opposite."

While the number of people who believe in global warming has increased, Krosnick says there are people who do not trust climate scientists and they "base their conclusions on their personal observations of nature." According to Krosnick, 2008 was the coldest year since 2000 in terms of average Earth temperature, and these "low-trust individuals were especially aware of the recent decline in average world temperatures" and "they were the ones in our survey whose doubts about global warming have increased since 2007."

"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," said Krosnick. "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."

The survey also included questions concerning the "climategate" controversy, where thousands of e-mails and other documents were leaked from the University of East Anglia's Climatic Research Unit. Only nine percent of American's said they knew about this controversy and that it caused them to distrust climate scientists. Despite all the skeptics, there has been no decline in trust for environmental scientists.

Krosnick believes that the decline in proportion of people is likely temporary, and the skeptics will probably join the majority who think global warming is real if the Earth's temperature begins to rise again.

Out of those respondents who believe global warming exists, 86 percent want the government to "limit the amount of air pollution that businesses emit," 76 percent of respondents want government limitations on greenhouse gas emissions "generated by businesses" and 14 percent think the government should not take action at all unless other countries like China and India do so as well. Though, in the UK, Professor Seamus Garvey at the University of Nottingham has designed a plan to power the UK completely by renewable energy by 2030 through the use of off-shore energy farms.

Other survey results include four out of five participants wanting the government to offer tax breaks to encourage more fuel efficient vehicles, 84 percent want tax breaks for utilities that use more green methods for power generation, and 80 percent want more energy efficient appliances.