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FROM VOLUME 9, NUMBER 8, AUGUST 1996
GENERAL INTEREST & COMMENTARY
Two related items in Nature, 382(6586), July 4, 1996:
"An Incriminating Fingerprint," N. Nicholls (Meteor. Bureau Res.
Ctr., POB 1289K, Melbourne, Vic. 3001, Australia), 27-28. Gives a scientific
perspective on the following article, which, despite several caveats, provides
the most convincing demonstration yet that human actions may have contributed to
global air temperature changes in this century.
"A Search for Human Influences on the Thermal Structure of the
Atmosphere," B.D. Santer (Clim. Model Diagnosis, Lawrence-Livermore Natl.
Lab., POB 808, Livermore CA 94550), K.E. Taylor et al., 39-46. Uses climate
model simulations to examine changes in the vertical structure of atmospheric
temperature as a "fingerprint" of human influence on climate. The
study differs from similar ones in four respects: (1) it includes the combined
influence of CO2 and anthropogenic sulfate aerosols on the vertical pattern; (2)
two different models are used, to examine model-dependent uncertainties; (3) the
possible effects of changes in stratospheric ozone are examined; (4) control
runs with coupled ocean-atmosphere models are used to estimate internally
generated natural climate variability. Simulations of the spatial patterns of
temperature change in the free atmosphere from 1963 to 1987 are similar to those
observed, and the degree of similarity increases through the period. The
observed trend is probably partly due to human activities, although many
uncertainties remain, particularly relating to estimates of natural variability.
The investigation shows a clear need for modeling experiments that combine
simultaneous changes in CO2, O3 and anthropogenic sulfate aerosols.
"El Niņo-Like Climate Change in a Model with Increased
Atmospheric CO2 Concentrations," G.A. Meehl (NCAR, POB 3000, Boulder CO
80307), W.M. Washington, ibid., 56-60.
Warming of the tropical Pacific Ocean surface was observed during the 1980s
and early 1990s, and contributed to observed global warming. Uses a coupled
ocean-atmosphere model, incorporating increasing concentrations of atmospheric
CO2, to investigate possible causes of this warming. The model demonstrates
anomalies of ocean temperature and the atmosphere that resemble some aspects of
El Niņo events. This resemblance complicates the problem of detection and
attribution of climate change, and suggests that depletion of freshwater
resources may be an additional hazard of greenhouse warming for populations in
the western Pacific region.
"Increased Activity of Northern Vegetation Inferred from Atmospheric
CO2 Measurements," C.D. Keeling (Scripps Inst. Oceanog., La Jolla CA
92093), J.F.S. Chin, T.P. Whorf, ibid., 382(6587), 146-149, July
Monitoring shows that the annual amplitude of the seasonal cycle of
atmospheric CO2 has increased since the early 1960s by 20% in Hawaii and by 40%
in the Arctic. In addition, there is evidence that the start of the growing
season has lengthened by a week. The authors propose that the amplitude
increases reflect increasing assimilation of CO2 by land plants in response to
climate changes accompanying recent rapid increases in temperature.
"Direct Radiative Forcing by Anthropogenic Airborne Mineral
Aerosols," I.N. Sokolik (Earth Sci. Div., NASA-Ames, MS-245-4, Moffett
Field CA 94035), O.B. Toon, ibid., 381(6584), June 20, 1996.
Estimates of anthropogenic inputs of mineral dust to the atmosphere,
combined with observations of its optical properties, suggest that the forcing
by anthropogenic mineral aerosols (from grazing, construction, mining
and the like) may be comparable to the forcing by other anthropogenic aerosols
(sulfate and smoke). On a regional scale, the forcing due to mineral aerosols
can greatly exceed that due to sulfate aerosols and can be comparable to that of
clouds. Specifies the key quantities that must be better characterized to reduce
the large uncertainties in these estimates.
"Television News Coverage of Global Warming," M. Nitz (Sch.
Communications, Univ. Idaho, Moscow ID 83855), S. Jarvis, H. Kenski, World
Resour. Rev., 8(2), 158-177, June 1996.
Evaluates nightly newscasts by the three major U.S. networks for their
global warming coverage after the 1992 Earth Summit, and finds serious
inadequacies. The majority of news stories simplify the issue by blaming one
party or no party at all. The news media should present more thematic stories
that provide background and context for understanding the problem. Stronger
emphasis needs to be placed on the negative impacts of warming, and coverage of
responsibility for treating the problem must be improved. Concludes that policy
makers must find a better way of communicating the threat of global warming, and
that scientists and government officials need to resist the allure of media
coverage. Policy makers should force the media and others to realize that there
are serious economic and even environmental costs associated with preventive
measures against global warming.
"Potential Environmental Impacts of Future Halocarbon Emissions,"
K.J. Holmes (Dept. Geog., Johns Hopkins Univ., Baltimore MD 21218), J.H. Ellis,
Environ. Sci. & Technol., 30(8), 348A ff., Aug. 1996.
Reports an analysis which integrates all major components of the problem:
demographic, economic, and regulatory processes; technological factors that
translate production into emissions; and environmental processes that determine
impacts. If even a small percentage of nations continues to expand halocarbon
production at modest rates, the ozone hole will not be eliminated. Continued use
of small amounts of ozone-depleting substances for essential uses and the
failure to adequately replace all of them can eliminate the possibility of
returning the atmosphere to pre-ozone hole conditions.
"Ozone Layer: The Road Not Taken," S.O. Andersen (Stratospheric
Protect. Div., US EPA, 401 M St. SW, Washington DC 20460), A. Miller, Nature,
382(6590), 390, Aug. 1, 1996.
A comment on the article with the same title by Prather et al., (Global
Climate Change Digest, Prof. Pubs./General Interest, July 1996), which looks
a little more deeply at some of the reasons why protection of the ozone layer
was so successful. Concludes that the Montreal Protocol was none too early, and
possibly a little too late.
"Managing the Global Environmental Risks in Russia: Missing Links
and External Influences," V. Sokolov (Inst. of USA & Canadian Studies,
Russian Acad. Sci., 2/3 Khlebny pereulok, Moscow 121814, Russia), World
Resour. Rev., 8(2), 198-214, June 1996.
Suggests some explanations for the failure to forge a national strategy to
manage global risks, based on analysis of three global environmental issues in
Russia and the former USSR: climate change, ozone depletion, and acid rain.
Emphasizes internal factors such as the domination of global change issues by
the state agency Hydromet; the interest of the Soviet military in atmospheric
issues; the absence of any major input from the public or the media; and the
manner in which the discussion of these issues was nested within the Soviet
government's broader foreign policy agenda. Despite scientific evidence and
pressure from national scientists, government attention to these issues was
prompted mainly by external factors, and the implementation of national measures
was successful only when environmental goals coincided with economic goals. The
integration of the newly independent states into the world economy bodes well
for national efforts to reduce global risks.
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