The number of Americans who believe there is solid evidence the Earth is warming because of pollution is at its lowest point in three years, according to a survey released Thursday. The poll of 1,500 adults by the Pew Research Center for the People & the Press found that only 57 percent believe there is strong scientific evidence the Earth has gotten hotter over the past few decades, and as a result, people are viewing the situation as less serious. That's down from 77 percent in 2006, and 71 percent in April 2008.  ***MARLAR: Upon hearing the news, Al Gore said it really burns him up, makes him hot under the collar, and gets his blood boiling.