Atmospheric CO2 and Climate on Millennial Time Scales During
the Last Glacial Period.
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Atmospheric CO2 and Climate on Millennial Time Scales During
the Last Glacial Period.
Science
Vol. 322, No. 5898, pp. 83-85, 3 October 2008, doi:10.1126/science.1160832.
Jinho Ahn and Ed Brook
Department of Geosciences, Oregon State University, Corvallis, OR 97331-5506, USA.
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Figure 1.
Atmospheric CO2 composition and climate during the last glacial period
(Click for larger version).
(A) Greenlandic temperature proxy, δ18Oice. Red numbers denote DO events.
(B) Byrd Station, Antarctica temperature proxy, δ18Oice. A1 to A7, Antarctic warming events.
(C) Atmospheric CO2 concentrations. Red dots and green circles (results from University of Bern)
are from Byrd ice cores. Red dots are averages of replicates, and red open circles at ~73 and 76 ka
are single data. The chronology used for Byrd CO2 is described in the SOM.
Blue line is from Taylor Dome ice core on the GISP2 time scale. Purple line is
from EPICA Dome C.
(D) CH4 concentrations from Greenland (green) and Byrd ice cores (brown).
Black dots, new measurements for this study. Vertical blue bars, timing of Heinrich
events (H3 to H6). Brown dotted lines, abrupt warming in Greenland.
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ABSTRACT:
Reconstructions of ancient atmospheric carbon dioxide (CO2) variations
help us better understand how the global carbon cycle and climate are
linked. We compared CO2 variations on millennial time scales between
20,000 and 90,000 years ago with an Antarctic temperature proxy and
records of abrupt climate change in the Northern Hemisphere. CO2
concentration and Antarctic temperature were positively correlated
over millennial-scale climate cycles, implying a strong connection
to Southern Ocean processes. Evidence from marine sediment proxies
indicates that CO2 concentration rose most rapidly when North Atlantic
Deep Water shoaled and stratification in the Southern Ocean was reduced.
These increases in CO2 concentration occurred during stadial (cold)
periods in the Northern Hemisphere, several thousand years before
abrupt warming events in Greenland.
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