The percentage of Americans who believe in global warming continues to decline, after reaching a peak of 75 percent in 2001.
Since 2007, when 71 percent of Americans believed in global warming, the percentage has taken a precipitous fall, to just 51 percent, according to a recent Harris Interactive poll.
About 29 percent of Americans don't believe in global warming, while 21 percent are unsure, according to the survey "Big Drop in Those Who Believe that Global Warming is Coming" (PDF).
The "unsure" category has grown from 6 percent in 2007, and is now nearly double the percentage from 1997, when 12 percent were unsure.
The belief patterns tend to fall along party lines, with 73 percent of Democrats believing in global warming, compared to just 28 percent of Republicans.
The new research falls in line with an October consumer survey from the Pew Research Center for the People & the Press. In that poll, about 35 percent of Americans said they see global warming as a very serious problem, down from about 44 percent in April of 2008.
In the nation's heartland, residents are unconvinced that human activities are the cause of global warming, according to anecdotal information from a Reuters article.
"There have been times in the past when there was global warming in the absence of man. It is all part of a natural cycle. I think it is a little vain to think man could destroy this great planet," said Sharon Byers, a Lees Summit, Mo., resident, in the article.
Beliefs may be influenced by the fact that about 25 percent of the U.S. population are evangelical Christian, who generally believe in a cataclysmic end to life on Earth, according to the article.
"If you are an evangelical Christian in the American vein then you believe it is our responsibility to look after the planet but it will be ultimately destroyed no matter what we do," Bart Barber, a Southern Baptist preacher in Farmersville, Texas, told Reuters.
