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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 11, NUMBER 1-2, JANUARY-FEBRUARY 1998

PROFESSIONAL PUBLICATIONS...
OF GENERAL INTEREST

Item #d98feb1

"Thermohaline Circulation, The Achilles Heel of Our Climate System: Will Man-Made CO₂ Upset the Current Balance?" W.S. Broecker (Lamont-Doherty Earth Observ., Rte. 9W, Palisades NY 10964), Science, 278(5343), 1582-1588, Nov. 28, 1997.

Surveys extensive paleoclimatic evidence that changes in deep ocean circulation are the key to rapid changes in climate, and discusses implications for climate research and policy. Coupled ocean-atmosphere models suggest that a large buildup of greenhouse gases might cause the ocean's thermohaline to collapse, an outcome that would inflict sudden and severe climatic stress on society. Until an improved next generation of models comes along, we must take this prediction seriously. Scientifically, this means greatly improving our knowledge of the deep water formation process. As insurance, we must rapidly develop an energy supply that does not load the atmosphere with CO₂. Extraction of hydrogen from fossil fuels (for use in fuel cells) and sequestration of the remaining CO₂ is a promising option.

Item #d98feb2

"Keeping Watch on the Earth: An Integrated Global Observing Strategy," C.F. Kennel (Vice Chancellor, Univ. California at Los Angeles; e-mail: ckennel@conet.ucla.edu), P. Morel, G.J. Williams,Consequences, 3(2), 21-29, 1997. The text is also available on the World Wide Web at: http://www.gcrio.org/CONSEQUENCES/introCON.html.

Although forty years have passed since the launch of the first orbiting satellite, we have yet to put in place the integrated, international observing system that is needed to track significant global changes, to identify the marks of man on the natural environment, and to help separate real concerns from false alarms. A permanent archive of what is changing where, and by how much, would be invaluable information on climate and many other aspects of the global environment. It would help our own and future generations sort out human-induced perturbations from natural changes.

Item #d98feb3

"A Pervasive Millennial-Scale Cycle in North Atlantic Holocene and Glacial Climates," G. Bond (Lamont-Doherty Earth Observ., Rte. 9W, Palisades NY 10964; e-mail: gcb@lamont.ldgo.columbia.edu), W. Showers et al.,Science, 278(5341), 1257-1266, Nov. 14, 1997.

Evidence from North Atlantic deep sea cores reveals abrupt climatic shifts during the Holocene, the period since the last ice age conventionally thought to have been quiescent. These and similar but stronger fluctuations that occurred during the last ice age have a cyclicity of 1470 (plus or minus 500) years. The Little Ice age appears to be the most recent cold phase in the series of such cycles. However, whether the climatic amelioration since the Little Ice Age marks the onset of a warming phase of this natural cycle is unclear; brief warmings often punctuated the cold phases of the millenial-scale fluctuations.

Item #d98feb4

Two related items in Nature, 388(6645), Aug. 28, 1997:

"Influence of CO₂ Emission Rates on the Stability of the Thermohaline Circulation," T.F. Stocker (Phys. Inst., Univ. Bern, Switz.; e-mail: stocker@climate.unibe.ch), A. Schmittner, 862-865. The thermohaline circulation of the North Atlantic Ocean, which has a large influence on climate and CO₂ uptake, is sensitive to the level of atmospheric CO₂. This study uses a simple coupled atmosphere-ocean model to show that the circulation also depends on the rate of change of CO₂. A modeled increase to 750 parts per million by volume over the next 100 years, corresponding roughly to today's growth rate, leads to a permanent shutdown of the thermohaline circulation. But if CO₂ increases more slowly, the circulation merely slows down. This sensitivity to the rate of change of CO₂ has potentially important implications for the choice of future CO₂-emission scenarios.

"Risk of Sea-Change in the Atlantic," S. Rahmstorf (Potsdam Inst. for Clim. Impact Res. [PIK], POB 60 12 03, D-14412 Potsdam, Ger.; e-mail: rahmstorf@pik-potsdam.de), 825-826. A research comment on the previous article, which serves as a reminder that swift action is needed to reduce the risk of unwelcome climatic surprises.

Item #d98feb5

"A 200-Year Record of Gale Frequency, Edinburgh, Scotland: Possible Link with High-Magnitude Volcanic Eruptions," A.G. Dawson (Ctr. Quaternary Sci., Coventry Univ., Coventry CV1 5FB, UK), K. Hickey et al.,The Holocene, 7(3), 337-341, Sep. 1997.

Examination of what is believed to be the longest historical record of gales in Europe shows three clear peaks in storminess that follow the volcanic eruptions of Tambora (1815), Krakatoa (1833), and El Chichon (1982). If this correlation has physical validity, the processes that link large volcanic eruptions to storminess in the North Atlantic need to be included in IPCC research that presently focuses on the effects of global warming on storm frequency.

Item #d98feb6

"Research Education," J. Hansen (NASA Goddard Inst. Space Studies, 2880 Broadway, New York NY 10025; e-mail: jhansen@giss.nasa.gov), C. Harris et al.,J. Geophys. Res., 102(D22), 25,677-25,678, Nov. 27, 1997.

Describes a new program at NASA-Goddard that involves students and educators working with scientists on problems at the top of their research agenda. The students and faculty are responsible for producing research results as well as educational materials that allow them to share the research experience with their peers. Research teams have been formed on several climate-related topics, and one team has coauthored a paper on climatic fluctuations (published in this same issue of J. Geophys. Res.).