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Climate of Uncertainty

Why global warming is back in the headlines.

Feb 27, 2006, Vol. 11, No. 23 • By STEVEN F. HAYWARD
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CLIMATE CHANGE IS HEATING UP again in American politics, the result of an orchestrated campaign to push the issue to the forefront. Al Gore is hitting the road with his animated computer slide show and has a documentary movie coming out. Climate action advocates skillfully exploited the Bush administration's clumsy moves to limit the public statements of NASA's chief climate scientist, Dr. James Hansen, and landed panicky stories about climate "tipping points" and scientific censorship on the front pages of the New York Times and Washington Post. The real head-turner, however, was the recent launch of the Evangelical Climate Initiative, in which nearly 100 evangelical leaders signed on to the environmentalist party line. Some are the same liberal evangelicals who tub-thumped for the nuclear freeze during the Reagan years, but some are conservative evangelicals important to Bush's red-state base, such as Rick (The Purpose Driven Life) Warren. When the eco-apocalypse meets the New Testament apocalypse, you know something is up. That something is a sense of political desperation among climate change alarmists, as the world slowly turns against them.

If there is any subject more certain than the federal budget process to bring on eye-glaze, it is global warming and the drearily repetitive argument about the Kyoto Protocol to reduce greenhouse gas emissions. The issue combines the worst of wonky numerology (parts per million of various gases, complex computer models, opaque cost-benefit analyses), an alphabet soup of unctuous international bureaucracies (IPCC, UNFCCC, SRES, TAR, USGCRP, etc., etc.), and the incessant braying of interest groups. No wonder Al Gore loves it so much. Yet the issue, seemingly stuck in a rut for almost two decades, is starting to shake loose and head in new directions.

How do you go about sorting out sense from nonsense? Very few people who follow closely the subject of climate change argue that there's nothing to it. There is unanimity that the planet has warmed by about 1 degree over the last century. Just about everyone agrees that the growth of greenhouse gas emissions from fossil fuels cannot continue forever. That's where the agreement ends. The range of possible temperature increase over the next century is fairly wide in the official forecasts, from 1.4 degrees Celsius on the low side, which might not be difficult to cope with, to 5.8 degrees Celsius on the high side, which would mean major environmental problems for the planet. How probable is any point along the distribution? For reasons having to do with the cascading statistical uncertainties of the thousands of variables in computer climate models, we can't assign a probability to any narrower range of temperature forecasts, though very clever people are trying.

So for most of the last decade we have been playing a back and forth game with signs and wonders that are offered as confirmation that catastrophic global warming is well under way. But these tend to be as controversial as the computer climate models. As good as our measurement techniques are, there is still large disagreement about basic facts. Are the polar ice caps melting or growing thicker? Both, depending on what data set you consult. Is the last decade the hottest in 2,000 years? You need a flak jacket to survive the crossfire on this one. Can variance in solar radiation account for some or most of the warming we've experienced to date? Better put on a second flak jacket. Do clouds warm or cool the planet? Both, and understanding the balance between their conflicting effects remains a huge problem for climate models. Are ocean temperatures rising and Gulf Stream currents changing? Probably, but we need better data to be sure. Will hurricanes get worse? Get a helmet to go with your flak jacket, and put FEMA on speed-dial. Aren't scientists overwhelmingly in agreement that the science is "settled"? Well, yes, except for the hundreds of scientists who've signed various statements and resolutions saying we lack adequate mastery of the subject.