In the Northeast, 77 percent say a snow or ice storm is most likely to affect them, while 79 Midwesterners agree and 89 percent of them fear tornadoes.

In the South, 66 percent worry about tornadoes, 54 percent hurricanes and 50 percent drought. In the West, earthquakes are a concern for 66 percent. Only 11 percent across the country think a nuclear power accident would affect them.

Only 44 percent say they “believe the theory” that carbon dioxide emissions are warming the Earth, down from 51 percent in 2009 and 71 percent in 2007, but most movement has been into the “not sure” column.