Gee, I wonder why?  After the coldest first two weeks in October for Minnesota in recorded history, small wonder Pew Research finds rising skepticism for the hypothesis that man causes global warming.  Only slightly over a third of Americans believe that any warming to be found should be blamed on humans, the product of ten years of declining temperatures despite increases in CO2 emissions:

There has been a sharp decline over the past year in the percentage of Americans who say there is solid evidence that global temperatures are rising. And fewer also see global warming as a very serious problem – 35% say that today, down from 44% in April 2008.

The latest national survey by the Pew Research Center for the People & the Press, conducted Sept. 30-Oct. 4 among 1,500 adults reached on cell phones and landlines, finds that 57% think there is solid evidence that the average temperature on earth has been getting warmer over the past few decades. In April 2008, 71% said there was solid evidence of rising global temperatures.

Over the same period, there has been a comparable decline in the proportion of Americans who say global temperatures are rising as a result of human activity, such as burning fossil fuels. Just 36% say that currently, down from 47% last year.

Some might attribute this to a partisan divide over cap-and-trade policies, but Pew’s internals show a broad-based retreat on athropogenic global warming (AGW), now given the politically-correct euphemism of “climate change.”  Support for the hypothesis fell among Republicans, independents, and Democrats over the last three years.  In 2006, 91% of Democrats believed in AGW; that number has declined 16 points to 75%.  Two years ago, almost two-thirds of Republicans believed it, now down 27 points to 35%.

Most politically damaging, though, is the sharp decline in support from independents.  AGW has lost 26 points in three years among unaffiliated voters, and 22 points of that drop came in the past year.  The arc has bent sharply towards decline, and with cap-and-trade legislation percolating in Congress, that could present some real problems.  Additionally, Pew notes that regional declines in AGW belief have been strongest in the Midwest — not surprising, given the damage cap-and-trade will do to interior states — and the West, where belief has fallen 19 points.  Belief has fallen by double digits in all age demographics and all education demographics.

Pew finds that a majority of adults support limits on carbon emissions, 50%/39% — but that the public has not heard much about the legislation.  That will also be a problem for Democrats, as Pew finds.  Those who have heard “a lot” about cap-and-trade oppose it 64%/32%, which does not bode well especially for moderate Democrats.