February 28, 2007
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FROM VOLUME 5, NUMBER 5, MAY 1992
EARTH SYSTEM SCIENCE: PALEOCLIMATOLOGY
Two items from Nature, 356(6368), Apr. 2, 1992:
"Molecules Record Sea Change," M. Lyle (Lamont-Doherty Geol.
Observatory, Columbia Univ., Palisades NY 10964), 385-386. Discusses
implications of the following article, which suggests new ways to investigate
global climate change.
"Molecular Record of Secular Sea Surface Temperature Changes on
100-year Timescales for Glacial Terminations I,II and IV," G. Eglington
(Org. Geochem. Unit, Univ. Bristol, Bristol BS8 1TS, UK), S.A. Bradshaw et al.,
423-426. Little is known about the variation of climate and of paleoceanographic
conditions throughout the Quaternary on time scales of less than 1,000 years.
This paper shows that such high time resolution is possible from molecular
stratigraphic studies based on "biomarker" organic molecules
(alkenones). Results from sediment cores off northwest Africa show a possible
link between SST oscillations and abrupt breakdowns in Atlantic deep-water
ventilation resulting from glacial meltwater events.
"Evidence from Southern Ocean Sediments for the Effect of North
Atlantic Deep-Water Flux on Climate," C.D. Charles (Lamont-Doherty Geol.
Observ., Columbia Univ., Palisades NY 10964), R.G. Fairbanks, Nature,
355(6359), 416-419, Jan. 30, 1992.
A carbon isotope record from benthic foramnifera indicates large and rapid
changes in the flux of North Atlantic Deep Water (NADW) during the last
deglaciation, and an abrupt increase in the NADW production rate that
immediately preceded large-scale melting of the Northern Hemisphere ice sheets.
These results are strong evidence for the importance of NADW in
glacial-interglacial climate change.
"Ancient Atmospheric CO2 Pressures Inferred from Natural Goethites,"
C.J. Yapp (Dept. Geol., Univ. New Mexico, Albuquerque NM 87131), H. Poths, Nature,
355(6358), 342-344, Jan. 23, 1992.
Data for geothites from an ironstone in the Upper Ordovician Neda formation
of Wisconsin suggest that 440 Myr ago atmospheric p(CO2) was about 16
times higher than today. However, these high CO2 levels were not accompanied by
unusually high temperatures in the tropics, and may have been contemporaneous
with continental glaciation on Gondwanaland.
"Sibling Species in Montastraea annularis, Coral Bleaching,
and the Coral Climate Record," N. Knowlton (Smithsonian Res. Inst., Apt.
2072, Balboa, Republic of Panama), E. Weil et al., Science, 255(5042),
330-333, Jan. 17, 1992.
The Caribbean coral taxon Montastraea annularis is shown to consist
of at least three sibling species in shallow waters, which show differences in
growth rate, isotope oxygen ratios and coloration. Interpretation or comparison
of past and present studies relating to global climate change and coral
bleaching can be jeopardized by ignoring these species boundaries.
"High Frequency Paleovariability in Climate and CO2 Levels from
Vostok Ice Core Records," P. Yiou (CEA, DESICP, IRDI, Geochim. Isotop Lab.,
F-91190 Gif sur Yvette, France), C. Genthon et al., J. Geophys. Res.,
96(B12), 20,365-20,378, 1991.
The high resolution of the Vostok records provides strong evidence for the
interaction between orbital forcing and internal, physico-chemical mechanisms of
variability, accounting for the wealth of spectral features found.
"The delta 18O of Atmospheric O2 from Air Inclusions in the Vostok
Ice Core: Timing of CO2 and Ice Volume Changes during the Penultimate
Glaciation," T. Sowers (Grad. Sch. Oceanog., Univ. Rhode Island,
Narragansett RI 02882), M. Bender, Paleoceanog., 6(6), 679-696,
As a means of understanding how rising CO2 levels affect the mass balance of
continental ice sheets, the record of delta 18O of atmospheric O2 trapped in the
Vostok ice core was used as a proxy for delta 18O of seawater and hence for ice
volume. Comparison with the CO2 record in the same core shows that atmospheric
CO2 started to increase at least 3 kyr before the introduction of meltwater to
Two items from Nature, 353(6346), Oct. 24, 1991:
"Long-Term Monsoon Regulators," T. Hagelberg (College Oceanog.,
Oregon State Univ., Corvallis OR 97331), A.C. Mix, 703-704. Discusses the
discrepancy between results of climate model predictions in the next paper, and
the wide variation in model predictions of the role of ice and snow feedback in
"Forcing Mechanisms of the Indian Ocean Monsoon," S. Clemens
(Geolog. Sci., Brown Univ., Providence RI 02912), W. Prell et al., 720-725.
Changes in the Indian Ocean summer monsoon over the past 350,000 years were
deduced from biological, biogeochemical and lithographic evidence in Arabian Sea
sediments. In contrast to results of general circulation models, these data
suggest that the climate change associated with variability in global ice volume
is not a primary factor determining the strength and timing of the monsoon
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