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FROM VOLUME 10, NUMBER 6, JUNE 1997

NEWS...
MAINSTREAM SCIENTISTS EXPRESS CAUTION

Item #d97jun77

A news article in the May 16, 1997, issue of Science takes a close look at the uncertainties involved in detecting human-induced climate change, emphasizing that many climate experts feel it is not at all clear yet that human activities have begun to warm the planet-or how bad greenhouse warming will be when it arrives. (See "Greenhouse Forecasting Still Cloudy," R.A. Kerr, pp. 1040-1042.)

Direct quotes from several climate scientists are given, starting with Benjamin Santer, a lead author of the IPCC assessment who has taken some heat for the wording of the document's executive summary. (See, for instance, comment by K.Ya. Kondratyev in PROF. PUBS./GENERAL INTEREST & COMMENTARY, this Global Climate Change Digest issue--June 1997.) Santer states it is "unfortunate that many people read the media hype before they read the [assessment] chapter" on the detection of greenhouse warming, maintaining his view that the appropriate caveats are there.

The Science article pins down and updates some of these caveats with statements from an array of climate modelers, and says most of them now agree that climate models will not be able to link greenhouse warming unambiguously to human actions for a decade or more. Even the effects of anthropogenic aerosols (which were beginning to be seen in the last year or so as the key to why the observed temperature increase is not in step with the rise in CO₂) remain quite uncertain. An accompanying piece ("Model Gets It Right-Without Fudge Factors," p. 1041) describes results from the Climate System Model of the National Center for Atmospheric Research, the first complete model that can simulate climate as well as other models without resorting to many arbitrary adjustments of the output needed to keep their simulations realistic. This model projects a very modest temperature rise--at the low end of the range estimated by the IPCC--over the next century in response to doubled CO₂.

Kerr concludes that the new uncertainties which keep cropping up "only add to the skepticism of scientists who might be called the 'silent doubters': those [who] rarely give voice to their concerns and may not have participated even peripherally in the IPCC." The June 9, 1997, issue of World Climate Report, edited by the decidedly not silent climate change skeptic Patrick Michaels, is ecstatic over the Kerr article, because "for the first time, a respected science journalist writes that the scientific community's discontent over the magnitude of and even the detection of anthropogenic global warming is wide and deep." This theme underlies most of the material in World Climate Review, which is funded by the Western Fuels Association and is excerpted on the World Wide Web at http://www.nhes.com.

A climatologist's recent comment on detecting global warming is the topic of the first paper listed in PROF. PUBS./GEN. INTEREST & COMMENTARY, this Global Climate Change Digest issue--June 1997.