WASHINGTON — Scientists say evidence from around the globe clearly shows that human activity is changing the climate. Many Republican candidates in U.S. Senate races nationwide, however, don't agree.
It's a point that scores well with tea party activists, but contradicts what NASA, the National Academy of Sciences and other prominent science organizations have been saying.
Victories by these candidates Tuesday could make Senate action on reducing emissions of greenhouse gases — already stalled — even more unlikely to restart next year. Still, even with the complex energy and climate bill looking dead, Republicans have used it — especially the cap-and-trade part about reducing emissions — to bash Democrats. In doing so, they've also cultivated uncertainty about climate change.
Beyond that, some Republican candidates also are denying that manmade climate change is real.
John Raese, the Republican candidate in West Virginia, put it bluntly in a debate this month when he spoke of the "myth of global warming and the other myth that man is causing global warming."
* Florida: Republican Marco Rubio questions whether global warming is manmade.
* Missouri: Republican Roy Blunt, in a recent debate, said: "I think climate change is real. I don't know how much of it is being instigated by people."
* Alaska: Republican write-in candidate and incumbent Sen. Lisa Murkowski, in a debate Wednesday, said climate change is "one of the tough issues before us" that must be addressed with emissions reductions, but that she opposed the cap-and-trade bill the Senate was considering until this summer.
Tea party Republican Joe Miller, who beat her in the primary, doesn't think global warming is real. "The science supporting manmade climate change is inconclusive," Miller says on his website.
* Kentucky: Republican candidate Rand Paul, when asked whether human activity was making the planet warmer, replied: "I think it's complicated, first of all. And I think anyone who makes an absolute conclusion is probably overstating their conclusion."
* California: Republican Carly Fiorina was asked at a meeting with Sacramento Bee reporters in March, "Do you believe in man-made climate change?" She replied: "I don't know. I don't know. But I think we should have the courage always to examine the science."
Some Democrats fight back by citing arguments from scientists.
"The science is overwhelming," said Rep. Baron Hill, D-Ind., an House Energy and Commerce Committee member in a close race in a conservative district. "There is no question about that."
"There is compelling, comprehensive, and consistent objective evidence that humans are changing the climate in ways that threaten our societies and the ecosystems on which we depend," 255 scientists who are members of the National Academy of Sciences wrote in May.
Scott Denning, a professor in the Department of Atmospheric Sciences at Colorado State University, said it's been about 150 years since scientists first figured out that accumulating carbon dioxide in the atmosphere would trap heat and emit it back to Earth.
"This is a very well understood scientific phenomenon," he said.
The amount of extra carbon dioxide in the atmosphere roughly matches the amount released from fossil fuels. An analysis of the makeup of the carbon atoms also pegs the extra gas to fossil fuels, Denning said.
NASA scientists say they've ruled out natural causes for the current warming, such as changes in sun activity. Global warming, NASA says, is "primarily due to the greenhouse gases released by people burning fossil fuels."
Most congressional campaigns haven't spent much time on climate change, except where Republicans have brought up their objections to the cap-and-trade legislation.
"American campaigns are not educational," said Ross Baker, a professor of political science at Rutgers University. "They're more designed for people to express frustration in years like this . . . and subtleties are driven out of the market."
A recent Pew Research Center poll showed that 59 percent of adults say there's solid evidence that Earth's average temperature has increased in the past few decades, and 34 percent of those polled said the warming is mostly because of burning fossil fuels. Those numbers are down dramatically from 2006, when 79 percent said there was evidence of global warming and 50 percent said it was mostly caused by human activity.