Last Updated:
February 28, 2007

GCRIO Program Overview

Library 
Our extensive collection of documents.

Privacy Policy

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

FROM VOLUME 7, NUMBER 2, FEBRUARY 1994

PROFESSIONAL PUBLICATIONS...

• GENERAL INTEREST--SCIENCE: PALEOCLIMATE

Item #d94feb21

"Tropical Temperature Variations Since 20,000 Years Ago: Modulating Interhemispheric Climate Change," T.P. Guilderson (Lamont-Doherty Earth Observ., Palisades NY 10964), R.G. Fairbanks, J.L. Rubenstone, Science, 263(5147), 663-665, Feb. 4, 1994.

Results from two independent isotope techniques show that 19,000 years ago, during the last ice age, tropical sea surface temperatures were 5·C colder than present. This suggests that tropical temperatures are not maintained at present values by a thermostat mechanism, as some have argued, and could change under increased CO2 levels.

Item #d94feb22

Two related items from Nature, 367(6462), Feb. 3, 1994:

"An Unstable Superconveyor," W.S. Broecker (Lamont-Doherty Earth Observ., Palisades NY 10964), 414-415. The research described in the following paper is a valuable exercise, particularly since greenhouse gases are rising, but is haunted by the questionable reliability of ice-core results for the Eemian period and the suitability of the models used.

"Rapid Interglacial Climate Fluctuations Driven by North Atlantic Ocean Circulation," A.J. Weaver (Ocean Sci., Univ. Victoria, POB 1700, Victoria BC V8W 2Y2, Can.), T.M.C. Hughes, 447-450. Recent ice core data suggest that the climate of the last (Eemian) interglacial period fluctuated much more than that of the present interglacial. Results from an idealized global ocean model suggest that the North Atlantic has three distinct circulation modes, and rapid transitions between them can be induced by a random component of freshwater flux. Increased hydrologic cycle variability in the warmer Eemian climate may have caused such transitions.

Item #d94feb23

"Glacial-Interglacial Changes in Moisture Sources for Greenland: Influences on the Ice Core Record of Climate," C.D. Charles (Scripps Inst. Oceanog., La Jolla CA 92093), D. Rind et al., Science, 263(5146), 508-511, Jan. 28, 1994.

Abrupt fluctuations in the oxygen isotope ratio observed in Greenland ice cores during the last ice age could indicate regional temperature fluctuations, but other factors might also have influenced the isotopic composition. Support for this possibility comes from general circulation model results presented here, indicating that the geographical sources of Greenland precipitation varied with different climatic states.