The biggest change in the polling is among people who trust scientists only a little or not at all. About 1 in 3 of the people surveyed fell into that category.

Within that highly skeptical group, 61 percent now say temperatures have been rising over the past 100 years. That’s a substantial increase from 2009, when the AP-GfK poll found that only 47 percent of those with little or no trust in scientists believed the world was getting warmer.

This is an important development because, often in the past, opinion about climate change doesn’t move much in core groups — like those who deny it exists and those who firmly believe it’s an alarming problem, said Jon Krosnick, a Stanford University social psychologist and pollster. Krosnick, who consulted with The Associated Press on the poll questions, said the changes the poll shows aren’t in the hard-core “anti-warming” deniers, but in the next group, who had serious doubts.