A July 2009 Pew Research survey found that 84% of scientists say that the earth is getting warmer because of human activity such as burning fossil fuels. This consensus, however, is not apparent to the public. In fact, as many Americans say scientists do not agree on global warming (44%) as say they are in agreement (44%). As with most questions relating to global warming, there is a large partisan split in opinion. A 59%-majority of Democrats say most scientists agree the earth is warming as a result of human activity, while just 30% of Republicans — and 19% of Tea Party Republicans – agree. Independents, like the overall public, are split — 41% think scientists agree, 45% say they do not. The division on the question of scientific consensus is an example of increased skepticism about global warming. In April 2008, 71% of Americans said there is solid evidence the earth is warming. Currently, 59% say there is solid evidence of global warming, with only 34% saying that global warming is the result of human activity. Similarly, in July 2006, six-in-ten Americans (59%) said that scientists agree that global warming is caused by humans, while just 29% said there was no scientific consensus. Read More

Russell Heimlich  is a former web developer at Pew Research Center.