The percentage of Americans who say there is solid evidence of global warming has increased modestly over the past two years. Currently, 63% say there is solid evidence that that the earth’s average temperature has been getting warmer over the past few decades. In October 2009, 57% expressed this view.

The number saying global warming is a very serious problem also has ticked up – to 38% currently from 32% last year; 35% said this in 2009.

Nonetheless, substantially fewer Americans say there is solid evidence of global warming than did so from 2006 to 2008. And in those years, higher percentages viewed global warming as a very serious problem than do so today.

The national survey by the Pew Research Center for the People & the Press, conducted Nov. 9-14 among 2,001 adults, finds that nearly four-in-ten (38%) say that global warming is occurring mostly because of human activity, such as the burning of fossil fuels, which also is slightly higher than last year (34%). From 2006-2008, 47% said global warming was mostly caused by human activity.

Read the full report, Modest Rise in Number Saying There Is ‘Solid Evidence’ of Global Warming, on the Pew Research Center for the People & the Press’ Web site.