A Rasmussen Reports telephone survey has found that 44 percent Americans believe global warming is the result of long-term planetary trends.
According to the survey, only 35 percent of Americans agreed to this view in 2006.
The percentage of voters who blame global warming on human activity fell to 41 percent from 46 percent. Seven percent blame other reasons and 9 percent were unsure, Fox News quoted the survey, as saying.
Democrats were more likely to blame human activity than Republicans with Democrats polling at 59 percent and Republicans at 21 percent.
Republicans were more likely to blame planetary trends for global warming. Two-thirds of Republicans and 23 percent of Democrats polled said planetary trends cause global warming.
Most voters said global warming was a problem. Sixty-four percent said it was somewhat serious and 41 percent said it was very serious.