Climate of Opinion
The latest U.N. report shows the "warming" debate is far from settled.
Monday, February 5, 2007 12:01 a.m. EST
Lastweek‘s headlines about the United Nation‘s latest report on globalwarming were typically breathless, predicting doom and human damnationlike the most fervent religious evangelical. Yet the real news in thefourth assessment from the Intergovernmental Panel on Climate Change(IPCC) may be how far it is backpedaling on some key issues. Bewareclaims that the science of global warming is settled.
Thedocument that caused such a stir was only a short policy report, asummary of the full scientific report due in May. Written mainly bypolicymakers (not scientists) who have a stake in the issue, thesummary was long on dire predictions. The press reported the bulletpoints, noting that this latest summary pronounced with more than "90%confidence" that humans have been the main drivers of warming since the1950s, and that higher temperatures and rising sea levels would result.
Morepertinent is the underlying scientific report. And according to peoplewho have seen that draft, it contains startling revisions of previousU.N. predictions. For example, the Center for Science and Public Policyhas just released an illuminating analysis written by Lord ChristopherMonckton, a one-time adviser to Margaret Thatcher who has become avoice of sanity on global warming.
Takerising sea levels. In its 2001 report, the U.N.‘s best high-endestimate of the rise in sea levels by 2100 was three feet. LordMonckton notes that the upcoming report‘s high-end best estimate is 17inches, or half the previous prediction. Similarly, the new reportshows that the 2001 assessment had overestimated the human influence onclimate change since the Industrial Revolution by at least one-third.
Suchreversals (and there are more) are remarkable, given that the IPCC‘sprevious reports, in 1990, 1995 and 2001, have been steadily moreurgent in their scientific claims and political tone. It‘s worth notingthat many of the policymakers who tinker with the IPCC reports work forgovernments that have promoted climate fears as a way of justifyingcarbon-restriction policies. More skeptical scientists are routinelyvetoed from contributing to the panel‘s work. The Pasteur Institute‘sPaul Reiter, a malaria expert who thinks global warming would havelittle impact on the spread of that disease, is one example.
U.N.scientists have relied heavily on computer models to predict futureclimate change, and these crystal balls are notoriously inaccurate.According to the models, for instance, global temperatures weresupposed to have risen in recent years. Yet according to the U.S.National Climate Data Center, the world in 2006 was only 0.03 degreesCelsius warmer than it was in 2001--in the range of measurement errorand thus not statistically significant.
Themodels also predicted that sea levels would rise much faster than theyactually have. The models didn‘t predict the significant cooling theoceans have undergone since 2003--which is the opposite of what you‘dexpect with global warming. Cooler oceans have also put a damper onclaims that global warming is the cause of more frequent or intensehurricanes. The models also failed to predict falling concentrations ofmethane in the atmosphere, another surprise.
Meanwhile,new scientific evidence keeps challenging previous assumptions. Thelatest report, for instance, takes greater note of the role ofpollutant particles, which are thought to reflect sunlight back tospace, supplying a cooling effect. More scientists are also studyingthe effect of solar activity on climate, and some believe it alone isresponsible for recent warming.
Allthis appears to be resulting in a more cautious scientific approach,which is largely good news. We‘re told that the upcoming report is alsomissing any reference to the infamous "hockey stick," a study byMichael Mann that purported to show 900 years of minor fluctuations intemperature, followed by a dramatic spike over the past century. TheIPCC featured the graph in 2001, but it has since been widely rebutted.
Whileeveryone concedes that the Earth is about a degree Celsius warmer thanit was a century ago, the debate continues over the cause andconsequences. We don‘t deny that carbon emissions may play a role, butwe don‘t believe that the case is sufficiently proven to justify arevolution in global energy use. The economic dislocations of such anabrupt policy change could be far more severe than warming itself,especially if it reduces the growth and innovation that would help theworld cope with, say, rising sea levels. There are also otherproblems--AIDS, malaria and clean drinking water, for example--whoseclaims on scarce resources are at least as urgent as climate change.
TheIPCC report should be understood as one more contribution to thewarming debate, not some definitive last word that justifies radicalpolicy change. It can be hard to keep one‘s head when everyone else ispredicting the Apocalypse, but that‘s all the more reason to keep cooland focus on the actual science.
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