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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 6, NUMBER 2, FEBRUARY 1993

PROFESSIONAL PUBLICATIONS...
GENERAL INTEREST--SCIENCE

Item #d93feb9

Three items from Nature, 360(6402), Nov. 26, 1992:

"Keeping the Sun in Proportion," A.A. Lacis (NASA Goddard Inst. Space Studies, 2880 Broadway, New York NY 10025), B.E. Carlson, p. 297. Discusses implications of the following two papers, which do not find the sun to be the major determinant of recent observed warming. Arguments concerning the solar influence should not distract policy makers from controlling greenhouse emissions.

"Solar Cycle Length, Greenhouse Forcing and Global Climate," P.M. Kelly (Clim. Res. Unit., Univ. E. Anglia, Norwich NR4 7TJ, UK), T.M.L. Wigley, 328-330. Models the effects of a combination of greenhouse and solar-cycle-length forcing, and compares with observed temperatures. This forcing combination can explain many features of the recent temperature record, although results must be interpreted cautiously. Even with optimized solar forcing, most of the recent warming trend is explained by greenhouse forcing.

"Implications for Global Warming of Intercycle Solar Irradiance Variations," M.E. Schlesinger (Dept. Atmos. Sci., Univ. Illinois, Urbana IL 61801), N. Ramankutty, 330-333. A simple climate-ocean model provides strong circumstantial evidence that there have been intercycle variations in solar irradiance which have contributed to the observed temperature changes since 1856. However, since the nineteenth century, greenhouse gases have had the dominant influence on temperature changes.

Item #d93feb10

"Atmospheric Lifetimes of Long-Lived Halogenated Species," A.R. Ravishankara (NOAA, 325 Broadway, Boulder CO 80303), S. Solomon et al., Science, 259(5092), 194-199, Jan. 8, 1993.

The lifetimes of several perfluoro and similar inert compounds, already in use or being considered as CFC substitutes, were assessed by combining laboratory observations with a 2-D atmospheric model. The lifetimes of all studied perfluoro compounds exceed 2,000 years, and those of CF3Cl, CF3CF2Cl and CF2ClCF2Cl exceed 300 years. The effects of these molecules will persist for centuries or millennia after their release.

Item #d93feb11

"A Model-Based Approach to the Calculation of Global Warming Potentials (GWP)," J. Rotmans (Nat. Inst. Public Health & Environ. Protec., POB 1, 3720 BA Bilthoven, Neth.), M.G.J. Den Elzen, Intl. J. Climatol., 12(8), 865-874, Dec. 1992.

Calculates GWP values with the integrated climate assessment model IMAGE, using two different methods, for 16 of the most important greenhouse gases and eight potential CFC substitutes. Resulting values, which depend on the emission scenario used, are substantially higher than the IPCC estimates, because the IMAGE model has a balanced carbon budget. The model yields lower projections of future atmospheric CO₂ compared with the IPCC projections.

Item #d93feb12

"Action Spectrum for DNA Damage in Alfalfa Lowers Predicted Impact of Ozone Depletion," F.E. Quaite (Biol. Dept., Brookhaven Nat. Lab., Upton NY 11973), B.M. Sutherland, J.C. Sutherland, Nature, 358(6387), 576-578, Aug. 13, 1992.

Calculations based on a new action spectrum predict significantly smaller increases in biologically effective UV resulting from ozone depletion, particularly at high latitudes, than calculations based on the widely used generalized action spectrum encompassing wavelengths from 280 to 313 nm. (For discussion of the work by the authors and other scientists, see "Plant Study Questions Nature of Ozone Risk," New York Times, p. C2, Aug. 25, 1992.)

Item #d93feb13

Five installments of Geophysics News 1992, a series of concise research updates appearing in the American Geophysical Union's weekly Eos:

"Including Eddies in Global Ocean Models," A.J. Semtner (Naval Postgrad. Sch., Monterey CA 93943), R.M. Chervin, p. 59, Feb. 2, 1993. Successful simulations of the oceanic "conveyor belt" that include mesoscale eddies signal a new era for climate modeling.

"Do Solar Variations Change Climate?" G.C. Reid (Aeronomy Lab., NOAA, 325 Broadway, Boulder CO 80303), p. 23, Jan. 12, 1993. There is mounting evidence for the Sun's control of our past climate, but human activities are still important.

"Deglaciation Triggered by the Resumption of North Atlantic Deep Water," J.D. Wright (Lamont-Doherty Earth Observ., Palisades NY 10964), ibid., p. 24. New evidence supports a stronger connection between deep ocean circulation changes and warming trends.

"A New Perspective on Global Warming," T.R. Karl (NCDC, Fed. Bldg., 37 Battery Pk. Ave., Asheville NC 28801), ibid., p. 25. Discusses the recently identified global decrease in diurnal temperature range.

"Harmful UV Radiation May Increase after Volcanic Eruptions," A.M. Vogelmann (Dept. Meteor., Pennsylvania State Univ., Univ. Pk. PA 16802), T.P. Ackerman, ibid., p. 25. Anthropogenic emissions have increased ozone layer sensitivity to volcanic eruptions.

Item #d93feb14

"The Greenhouse Effect," A. Berger (Inst. Astron., Univ. Catholique de Louvain, B-1348 Louvain-la-Neuve, Belg.), C. Tricot, Surveys Geophys., 13(6), 523-549, Nov. 1992.

A review of recent findings on the Earth radiation balance and climatic feedback mechanisms, particularly the role of clouds.