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

FROM VOLUME 10, NUMBER 4, APRIL 1997

PROFESSIONAL PUBLICATIONS...
GENERAL INTEREST AND POLICY

Item #d97apr1

"The Use and Abuse of Climate Models," K.E. Trenberth (Clim. Analysis Sect., NCAR, POB 3000, Boulder CO 80307; e-mail: trenberth@ncar.ucar.edu), Nature, 386(6621), 131-133, Mar. 13, 1997.

A commentary giving a detailed but non-technical explanation of the rationale for using mathematical models, despite their inherent limitations, to understand global climate change, and their contribution to formulating policy. Opinion is polarized as to the value of such models in projecting future climate; the truth lies in between. Many-but not all-models are very useful, but their results must be interpreted properly.

Discusses model errors and how they can be minimized or circumvented to obtain useful information; model validation; and future developments in modeling. Concludes with a summary of the IPCC projections of future global warming by greenhouse gases. Such projections cannot offer uncertainty, but they are far better than declaring ignorance and saying nothing at all. The debate over what, if any, remedial action the world should take must be based on an appreciation of both the strengths and the weaknesses of climate models.

Item #d97apr2

"Spurious Trends in Satellite MSU Temperatures from Merging Different Satellite Records," J.W. Hurrell (NCAR, POB 3000, Boulder CO 80307) and K.E. Trenberth, ibid., 164-167.

(See NEWS, this Global Climate Change Digest issue--Apr. 1997.) The trends in global temperature for the period 1979-1995 inferred from surface observations (warming) and from satellite measurements (cooling) are at odds with each other, and have been a matter of spirited debate. The satellite record for this period consists of nine different segments from different instruments, each with its own error characteristics. This study investigates the implications of the lack of a single satellite record on the derived temperature trend. Because the temperature measured by the satellite instruments is heavily influenced by sea surface temperatures (SSTs), the authors make statistical inferences about the satellite temperature record by generating equivalent satellite temperatures using an atmospheric general circulation model forced with observations of tropical SSTs. Results strongly suggest that two spurious downward jumps in the satellite record occurred coincident with changes of instruments during the period, and that the real temperature trend is likely to be small but positive.

Item #d97apr3

"Rapid Sea Level Rise Soon from West Antarctic Ice Sheet Collapse?" C.R. Bentley (Geophys. & Polar Res. Ctr., Univ. Wisconsin, Madison WI 53706; e-mail: bentley@geology.wisc.edu), Science, 275(5303), 1077-1078, Feb. 21, 1997.

A glaciologist comments on theoretical and observational evidence that the West Antarctic Ice Sheet could collapse, with a subsequent rapid rise in sea level. Cites evidence of stability in the recent past, to conclude that it is difficult to see how climate warming (whether anthropogenic or natural) could trigger a collapse in the next century or two. It is questionable whether ice shelf thinning would have any drastic effect on the inland ice.

Item #d97apr4

"The Decoupling of Terrestrial Carbon and Nitrogen Cycles," G.P. Asner (CIRES, Univ. Colorado, Boulder CO 80309), BioScience, 47(4), 226-232, Apr. 1997.

Reviews how human influences on land cover and nitrogen supply are altering natural biogeochemical links in the biosphere, and how the terrestrial carbon cycle will respond to and influence changes in atmospheric CO₂ and temperature. Although elevated levels of nitrogen and CO₂ are stimulating the uptake of anthropogenic CO₂, the effect is only temporary. The rapidly changing global nitrogen cycle, with its increasing nitrogen depositon, can also lead to increases in greenhouse gases such as methane, nitrous oxide, and tropospheric ozone, which counterbalance the uptake of CO₂. As natural linkages between the terrestrial carbon and nitrogen cycles continue to deteriorate in coming decades, such changes are likely to become even more pronounced.

Item #d97apr5

"Environmental Science Under Siege in the U.S. Congress," G.E. Brown Jr. (U.S. House of Representatives, Washington DC 20515), Environment, 39(2), 12-20, 29-31, Mar. 1997.

The author, the ranking Democratic member of the U.S. House Committee on Science, draws from and comments on a series of Congressional hearings on three key environmental issues: global climate change, ozone depletion, and dioxin health risks. He argues that the testimony offered by skeptic scientists during these hearings presents a distorted interpretation of the environmental science underlying policy and research funding decisions, and it reflects a troubling devaluation of the process of peer review. Suggests that scientists must do a better job of educating the public, and find new ways to respond to the arguments of skeptics given the rapid-fire political process, so that the proper balance between policy and science can be restored.

Item #d97apr6

"Environmental Change and Social Justice," F.O. Hampson (Intl. Affairs, Carleton Univ., Ottawa, Can.), J. Reppy, ibid., 39(3), 12-15 ff, Apr. 1997.

Outlines some of the moral dilemmas created by climate change and provides an overview of different approaches to those dilemmas. To achieve social justice we not only need guidelines for moral reasoning, but also need to analyze the distribution of political and economic power and to think critically about the use of other sources of authority, such as scientific knowledge. The central question for social justice is, "Who counts?" Only after we have answered this question can we begin to construct responsible solutions to the practical problems posed by climate change.