Americans are cooling to the idea of global warming, according to a Pew Research Center poll.

The study shows that only 57 percent now believe there's solid evidence the world is getting warmer. That's down from 77 percent just three years ago.

In addition, only 36 percent believe human activity is behind a temperature increase -- down from 47 percent last year.

"The priority that people give to pollution and environmental concerns and a whole host of other issues is down because of the economy and because of the focus on other things,'' said Andrew Kohut, director of the research center.

The poll of 1,500 adults was conducted from Sept. 30 to Oct. 4.