Almost half of Americans in the Yale Project on Climate Change's new study on global warming said strong action needs to be taken. But the amount who think it's all a hoax has doubled. Nearly everyone, however, supports regulating carbon dioxide as a pollutant. More results:

39% Alarmed or Concerned At the top of the scale are people who consider themselves 'Alarmed' by climate change, convinced that global warming is happening, caused by human activity and is an urgent threat. This group amounts to 10% of the population, down from 18% in 2008.

'Concerned' Americans, who believe global warming demands a strong national response but who are less personally involved in their concern than the 'Alarmed', are now 29% of the public. That was a full third in 2008.

One Third Cautious or Disengaged The 'Cautious', those people who believe global warming is a problem but not an urgent one, and are not sure it is caused by human activity, has increased to 27% of the population, up 8% from two years ago.

The 'Disengaged' part of the populace, those people who don't know much about global warming or haven't even thought about it, has halved, now amount to 6% of the population.

27% Doubtful or Dismissive Those who classify themselves as 'Doubtful' about whether global warming is happening and/or the cause of it has increased slightly, now up to 13%, from 11% in 2008.

At the entirely skeptical end of the scale are the "Dismissive". These people believe global warming is not happening and is probably a hoax. This segment of the population has doubled since 2008, to 16% of the American public at the start of 2009.

Only the Dismissive Don't Support CO2 Regulation If you've even partially followed the state of the climate change debate perhaps these findings aren't surprising. But this is: When asked if carbon dioxide should be regulated as a pollutant, as is being considered by the EPA, a majority of every group save the Dismissive support it.

91% of the Alarmed believe is should be done, 93% of the Concerned, 79% of the Cautious, 92% of the Disengaged, and 52% of the Doubtful. Only 15% of the Dismissive support CO2 regulation.

From our friends at Treehugger