February 28, 2007
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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 12, DECEMBER 1993
"Evidence for Large Upward Trends of Ultraviolet-B Radiation Linked
to Ozone Depletion," J.B. Kerr (Atmos. Environ. Serv., 4905 Dufferin St.,
Downsview ON M3H 5T4, Can.), C.T. McElroy, Science, 262(5136),
1032-1034, Nov. 12, 1993.
Spectrally-dependent measurements made in Toronto since 1989 show that the
intensity of light near the peak of ozone absorption (300 nanometers) has
increased by 35 percent per year in winter and 7% in summer. The lack of a trend
at other wavelengths strongly implies that the trend reflects decreasing levels
of stratospheric ozone. (See related news comment on pp. 990-991 of same issue.)
"Geological Assessment of the Greenhouse Effect," T.J. Crowley
(Dept. Oceanog., Texas A&M Univ., College Sta. TX 77843), Bull. Amer.
Meteor. Soc., 74(12), 2363-2373, Dec. 1993.
Geologic studies provide a valuable perspective on the importance of
greenhouse forcing. Changes in climate are positively correlated with greenhouse
gas variations, but the sensitivity of the system to greenhouse gas changes
cannot yet be constrained by paleoclimatic data below its present large range.
Geologic records conflict with substantial features of model projections of
greenhouse warming, suggesting that changes in model design are needed. But
uncertainties related to this conclusion demand more geologic data collection
and compilation, a slow process, so that uncertainties may persist for some
"The Contribution of Explosive Volcanism to Global Atmospheric
Sulphur Dioxide Concentrations," G.J.S. Bluth (Univ. Space Res. Assoc.,
Code 921, NASA-Goddard, Greenbelt MD 20771), C.C. Schnetzier et al., Nature,
366(6453), 327-329, Nov. 25, 1993.
The amount of sulfur dioxide emitted sporadically from explosive volcanic
eruptions is hard to quantify, but estimates have ranged up to one-quarter of
the current anthropogenic contribution. Satellite observations of explosive
emissions presented here indicate, however, that total volcanic emissions are
only 5-10% of the anthropogenic flux.
"Uncertainties in Carbon Dioxide Radiative Forcing in Atmospheric
General Circulation Models," R.D. Cess (Inst. Terr. Atmos., Marine Sci.
Res. Ctr., SUNY, Stony Brook NY 11794), M.-H. Zhang et al., Science,
262(5137), 1252-1255, Nov. 19, 1993.
Comparison among 15 GCMs showed a wide variation in the amount of radiative
forcing induced by a doubling of CO2. The largest factor responsible for the
differences was the CO2 radiation parameterizations of the models.
"Whole-Ecosystem Nitrogen Effects Research in Europe," T.J.
Sullivan (E&S Environ. Chem., Corvallis OR 97339), Environ. Sci.
Technol., 27(8), 1482-1486, Aug. 1993.
Describes several ongoing international umbrella projects on nitrogen
effects. A new project, the CLIMate Change EXperiment (CLIMEX), which was
scheduled to begin in 1993, will study the interactions between climate change
and acidic deposition.
"Environmental Impacts of Atmospheric Nitrous Oxide," O. Badr
(Dept. Appl. Energy, Cranfield Inst. Technol., Bedford MK43 0AL, UK), S.D.
Probert, Appl. Energy, 44(3), 197-231, 1993.
A lengthy summary of the contributions of N2O to ozone depletion and the
"Earth-Sun System Energetics and Global Warming," P.C. Jain
(Dept. Phys., Univ. Zambia, POB 32379, Lusaka, Zambia), Clim. Change,
24(3), 271-272, July 1993. Calculates the energy required to increase
the diameter of the Earth's orbit around the sun as a way of countering global
warming, presuming a future technological development makes such a tactic
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