Thursday, December 07, 2006



Skepticism is what motivates most if not all of us in scientific research. So it is hardly surprising that a title such as climate skeptic or "skeptical environmentalist" would appeal to many working scientists as well as bloggers, science writers, and even novelists like Michael Crichton. On the other hand, most of us who have devoted our lives to the study of the Quaternary period have been aware of strong evidence for global warming since at least 1994, when I attended my first meeting of the American Quaternary Association. The causes for recent climate changes have taken somewhat longer to establish, particularly the role of carbon dioxide and other "greenhouse gases" emitted from fossil fuel combustion. This is hardly a recent finding or a "hysterical" one, as is indeed evident from the fact that our "consensus" view is facing new challenges from young researchers as well as older scientists drawn into the fray from other fields of specialization.

Throughout science, and earth science in particular, we must consider and even employ "multiple working hypotheses" to account for phenomena. With respect to the 20th century temperature trend, we have endeavored to untangle the role played by competing causes through the use of computer models. Models developed for weather forecasting have a mathematical basis which is at least as rigorous as the statistical weighting of hypotheses favored by Lomborg and others in the current crop of climate skeptics. Quaternary scientists also pioneered the long term perspective on the current trends, which ironically is now championed by skeptics such as Patrick Michaels of the University of Virginia. While the "proxy" records for past changes are nowhere as precise as the data from the period of meteorological record, the magnitude and rate of the present temperature rise appears to be unique and to exceed what can be explained by solar forcing and other natural causes for long-term climate change.

No doubt there has been some simplification of scientific findings, both for the sake of flashy publications and for presentation to national and international policy makers. I happen to believe that the exaggeration has been far greater on the part of the climate "skeptics" than on the part of those reporting the evidence for anthropogenic global warming. A helpful guide to facts and fictions about climate change is posted on the webpage of the Royal Society of the United Kingdom. The debate over anthropogenic global warming is but one interesting example in science where the subject of our hypotheses is one which can be affected by our own conduct as a species. May we plan responsibly on the basis of what appears to me to be a strong hypothesis that has survived every empirical test.

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