The percentage of Americans who think global warming is just another planetary trend has increased, though Democrats and more likely than Republicans to blame human activity for environmental change a new Rasmussen Reports national telephone survey finds.

Forty-four percent of voters polled said global warming is the result of long-term planetary trends, according to the survey. In 2006, 35 percent agreed.

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, the survey found.

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.

The survey also showed that 46 percent of voters polled said they believe a conflict exists between economic growth and environmental protection while 32 percent saw no conflict and 22 percent were not sure.

Click here to read more on this Rasmussen Reports survey.