He doesn't say -- probably because even the most radical climate-change policies promise no more than a negligible reduction.

As Fred S. Singer, president of the Science & Environmental Policy Project, told the Heartland Institute in 2007, "All these schemes are quite ineffective in reducing the global growth of atmospheric CO2 -- never mind in having any effect on climate. The schemes do have one thing in common: They will damage the U.S. economy and hurt the pocketbooks of every consumer..."

In other words, economic growth will be stifled -- for what?

Roy W. Spencer, a research scientist at the University of Alabama in Huntsville and author of "Climate Confusion," says he's "increasingly convinced" that climate change has far more to do with natural phenomena like El Nio and the Pacific Decadal Oscillation than carbon dioxide. "Maybe the amount of CO2 in the atmosphere is higher now than it has been in hundreds of thousands of years. So what?" he wrote in a recent article for the National Review.

"Even though there has never been a single scientific paper published that has ruled out natural variability for most of the warming we've seen since 1850, Big Science has managed to convince politicians and much of the public that the science is settled. Apparently, our addition of nine molecules of carbon dioxide to each 100,000 molecules of air over the last 150 years can now be blamed for anything and everything ... Hurricanes, tornadoes, heat waves, floods, glaciers flowing toward the sea ... these used to happen naturally, but no more".

Spencer is one of many scientists who doubt the "consensus" that CO2 will cause a global warming "crisis." But politicians still want to act.McCain's hero is Teddy Roosevelt, a hectoring, activist president. To justify government interference in our lives, it helps to have a crisis. In Islamic extremism, McCain has his foreign affairs crisis. In global warming, he has his domestic crisis.