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Global Climate Change Digest

A Guide to Information on Greenhouse Gases and Ozone Depletion
Published July 1988 through June 1999



Item #d94oct86

A draft summary for policymakers approved by the Science Working Group of the Intergovernmental Panel on Climate Change has created more controversy over its manner of presentation than over its content. The summary is limited to new scientific findings concerning the radiative forcing of climate, which will eventually be included in the next full scientific assessment of climate change by the IPCC, to be completed in 1995.

It concludes that a "substantial" reduction of greenhouse gas emissions below 1990 levels will be necessary to stabilize atmospheric concentrations of greenhouse gases at twice pre-industrial levels. It also estimates that the overall radiative impact of aerosols may be enough to offset as much as half the warming by greenhouse gases, but this effect is unevenly distributed geographically. The warming effect of methane is revised upwards.

The summary was presented for approval at the start of a September meeting of the IPCC Science Working Group in Maastricht, The Netherlands, in apparent violation of an IPCC rule of procedure that any document presented for approval be circulated at least three weeks prior. Some meeting participants expressed frustration when called upon to approve a summary of a report that was neither complete nor available for review. Even more controversial was a press release distributed by the IPCC secretariat before the meeting, announcing the approval of the summary and containing conclusions that critics say exceed the limited scope of the working group study. For instance, the release states that the scientific consensus on the fundamentals of climate science established by the IPCC in 1990 still holds, a much broader conclusion than was addressed by the working group.

An anonymous participant quoted by Nature (p. 467, Oct. 6), said lead authors of the report were upset that the summary makes changes to conclusions not based on the supporting material. The article goes on to say that supporters of the argument that greenhouse gas emissions must be reduced claim critics, having lost the scientific debate, are now trying to discredit the IPCC process.

At a congressional briefing, Robert Watson, an IPCC member and an associate director of the U.S. Office of Science and Technology Policy, said the press release shows "a complete breakdown in process" and that he would be "extremely disappointed if it ever occurs again." The situation prompted a letter from the Global Climate Coalition and other U.S. industry representatives to Clinton administration officials, pointing out that these "apparently deliberate" deviations from carefully negotiated procedures could threaten the credibility of the IPCC.

For discussion of the draft findings, see the following articles, bearing in mind that some reflect the apparently unwarranted broader conclusions contained in the IPCC press release: Intl. Environ. Rptr., pp. 757-758, Sep. 21; Nature, p. 274, Sep. 22; Science News, P. 198, Sep. 24; Chem. Eng. News, p. 7, Sep. 26; New Scientist, p. 5, Sep. 17; Energy, Econ. & Clim. Change, pp. 4-5, Oct. The following dwell more on the press release and manner of presentation of the policymakers' summary: Nature, p. 269, Sep. 22 (an editorial on "science by press release"); ibid., p. 467, Oct. 6; Energy, Econ. & Clim. Change, pp. 2-3, Oct.

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