Amid all the controversy about the hacked e-mails of climate scientists comes an ABC-Washington Post poll that says a majority of Americans believe that global warming is happening and that a cap on greenhouse gases should be imposed nationally.

That's a drop of 8 percentage points (thanks, Don!) compared with those believed in global warming a year ago (and a drop of 12 percentage points over the past three years). Juliet Eilperin of The Post explains the change in numbers this way:

The increase in climate skepticism is driven largely by a shift within the GOP. Since its peak 3 1/2 years ago, belief that climate change is happening is down sharply among Republicans -- 76 to 54 percent -- and independents -- 86 to 71 percent. It dipped more modestly among Democrats, from 92 to 86 percent. A majority of respondents still support legislation to cap emissions and trade pollution allowances, by 53 to 42 percent.

Among Democrats, 86 percent believe the world has been getting warmer (down 6 percentage points from 2006). Among Independents, believers number 71 percent (15 percentage points less than three years ago). A scant majority of Republicans also believe: 54 percent (22 percentage points less than in 2006).

Seventy-five percent of respondents 18 to 29 think that global warming is happening; along with 72 percent of those 30 to 64, and 68 percent of those over 65.

College grads were more likely to be believers that non-grads, 77 to 70 percent.

You can read the all the other questions that were asked and see the graphics about the poll answers here.

There was a Pew Research poll last month that had fewer people believing in climate change and more skeptics.

Will these changing attitudes have any effect on what happens at the upcoming climate-change conference in Copenhagen?

Politics Daily notes:

President Obama plans to go to Copenhagen next week to attend the early rounds of a U.N. climate summit, which is drawing delegations from 192 countries. Fifty-five percent of Americans believe that the U.S. should act on global warming even if other countries do less; 21 percent say the U.S. should take action only if other countries do; and 22 percent say the U.S. should not take action at all, according to the Post/ABC poll.

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