Global warming skeptics come in many forms. Richard Muller is a physics professor at UC Berkeley with an extensive background in climatology, but for years even he found himself at odds with the theory.
He was troubled, he said, by unreliable data from temperature stations located on asphalt lots or near buildings. Further doubts were fueled by "Climategate" -- the 2009 revelation that researchers with the University of East Anglia's Climatic Research Unit had manipulated facts.
It wasn't until he did his own study, at the urging of daughter Elizabeth, that he arrived at conclusions he could support. He surprised colleagues when he shared them recently in an article in the New York Times: "The Conversion of a Climate-Change Skeptic."
If his was abrupt about-face, it came with some caveats. Polar bears aren't dying from receding ice, the Himalayan glaciers won't melt in 20 years and ocean property is not about to be swamped. ("The sea level should rise two to three feet in the next 100 years," he said. "That's about three inches per decade.")
Consider Muller's the voice of reason on a topic that has tilted toward frenzy. He sees a gradual rise in temperature not as reason for panic but for change.
His research, detailed in a new book, "Energy for Future Presidents: The Science Behind the Headlines," found that land temperature on earth has risen by 2½ degrees Fahrenheit over the last 250 years -- more half of that in
"We re-examined thermometer data back to the mid-1700s, when Benjamin Franklin and Thomas Jefferson started collected information," he said. "We wanted to use all of the data. Previous groups had used only part of it."
That data enabled Muller's research group to see reasons for patterns of change, he said, whereas previous studies had relied on complex computer programs to separate human factors from natural ones.
His team, including Nobel Prize winner Saul Perlmutter, compared the temperature bumps to likely causes such as volcanic activity and solar flares. "We could see the effects of volcanoes," he said, "but the thing that matched temperature rise almost perfectly was the rise in human carbon dioxide."
Muller's Berkeley Earth Surface Temperature project arrived at the same basic finding as the Intergovernmental Panel on Climate Change: Increased greenhouse gases cause climate change.
Muller does not, however, believe global warming has increased hurricane or tornado activity. Citing 150 years of records from the Miami Hurricane Center, he explained that recent hurricane trending is level or decreasing. He thinks climate-change advocates falsely link storms to global warming to grab public attention.
Nor does he endorse Al Gore's documentary "An Inconvenient Truth," which won an Academy Award with drastic overstatement. "The projections he showed were for 1,000 years from now," Muller said. "We don't have enough fossil fuels to last 1,000 years."
The biggest misconception about climate change, he said, is that the U.S. controls its fate. Compact fluorescent light bulbs and hybrid cars are swell feel-good gestures, but they are inconsequential alongside the clouds escaping from China's coal-fired power plants.
"The Chinese economy has averaged 10 percent growth over 20 years," he said. "By the end of this year, it will be producing twice the carbon dioxide of the U.S."
We need to rely on natural gas power, he said. We need to help China do the same. Every conversion from coal cuts greenhouse gas by two-thirds and buys time to develop clean-energy solutions.
If you're not buying it, no need for apologies. Not long ago, he was a skeptic himself.