Mid-way through the Des Moines Register GOP debate in Iowa Wednesday, Carolyn Washburn, editor of the Register and debate moderator, asked the candidates to raise their hands if they believe global warm is "a serious threat" that human activity is contributing to it.
With the exception of Sen. John McCain, R-Ariz., global warming is an issue the Republicans rarely bring up on their own.
Several hands went up, then down as former Tennessee Sen. Fred Thompson objected. He said he wouldn't raise his hand but asked instead for a minute to answer. The moderator said no.
"Well, then I'm not going to answer it," Thompson said. "You want a show of hands. I'm not giving it to you."
Last spring, Thompson seemed to mock the issue of climate change, writing in the National Review Online that warming on other planets led some to "wonder if Mars and Jupiter, non-signatories to the Kyoto Treaty, are actually inhabited by alien SUV-driving industrialists who run their air condition at 60 degrees and refuse to recycle."
'Climate Change is Real'
As Thompson balked, McCain saw an opening and went for it.
"I think that climate change is real," he said. "Put it to you this way: Suppose that climate change is not real and all we do is adopt green technologies, which our economy and our technology is perfectly capable of. Then all we've done is given our kids a cleaner world."
McCain has long advocated for caps on greenhouse gas emissions, a "cap and trade" policy as a market-based way to spur industries to take action, and higher fuel standards for vehicles.
Former New York Mayor Rudolph Giuliani chimed in: "I agree with John. Climate change is real. It's happening. I believe human beings are contributing to it. I think the best way to deal with it is through energy independence."
Earlier this year, Giuliani said climate change was "not an hysterical emergency that has to be dealt with … as a one- or two-year emergency."
He also criticized Al Gore's documentary "An Inconvenient Truth," saying it was scaring people.
Former Massachusetts Gov. Mitt Romney called for developing new technologies to reduce America's dependence on oil from foreign sources.
"As we get ourselves off of foreign oil, we also dramatically reduce our CO2 emissions," he said.
"That's good for the environment. It's also good for our economy because buying $300 billion or $400 billion worth of oil a year from other people who use it against us, that's bad for our economy," Romney said. "It's also bad for the environment. Is global warming an issue for the world? Absolutely. Is it something we can deal with by becoming energy independent and energy secure? We sure can."
But how fast can these new technologies be developed? A U.N. Panel on climate change recently warned that the world must begin reducing greenhouse gas emissions in the next five to seven years or face catastrophic consequences.
Former Arkansas Gov. Mike Huckabee, who sometimes refers to environmental stewardship as a "spiritual issue," called on the federal government to take the lead in using alternative forms of energy to create a market for it.
Economist and former Ambassador Alan Keyes gave a rambling answer that ended: "I believe in reducing global warming because I think the most important emission we need to control is the hot air emission of politicians who pretend one thing and don't deliver."
Carole Florman, of the Northeastern environmental group Clean Air-Cool Planet said, "We are glad that global warming is a topic in the debate, but most of these guys have a long way to go if they want to show they are seriously grappling with the issue."
"Energy independence isn't the answer," she said. "What we need is real commitment to a comprehensive climate initiative in the first 150 days following the election, including a domestic cap on emissions."