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Science 9 October 2009:
Vol. 326. no. 5950, pp. 248 - 252
DOI: 10.1126/science.1177840
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Research Articles

Ice Age Terminations

Hai Cheng,1 R. Lawrence Edwards,1,* Wallace S. Broecker,2 George H. Denton,3 Xinggong Kong,4 Yongjin Wang,4 Rong Zhang,5 Xianfeng Wang1

230Th-dated oxygen isotope records of stalagmites from Sanbao Cave, China, characterize Asian Monsoon (AM) precipitation through the ends of the third- and fourthmost recent ice ages. As a result, AM records for the past four glacial terminations can now be precisely correlated with those from ice cores and marine sediments, establishing the timing and sequence of major events. In all four cases, observations are consistent with a classic Northern Hemisphere summer insolation intensity trigger for an initial retreat of northern ice sheets. Meltwater and icebergs entering the North Atlantic alter oceanic and atmospheric circulation and associated fluxes of heat and carbon, causing increases in atmospheric CO2 and Antarctic temperatures that drive the termination in the Southern Hemisphere. Increasing CO2 and summer insolation drive recession of northern ice sheets, with probable positive feedbacks between sea level and CO2.

1 Department of Geology and Geophysics, University of Minnesota, Minneapolis, MN 55455, USA.
2 Lamont-Doherty Earth Observatory of Columbia University, 61 Route 9W, Post Office Box 1000, Palisades, NY 10964–1000, USA.
3 Department of Earth Sciences, Bryand Global Sciences Center, Climate Change Institute, University of Maine, Orono, ME 04469, USA.
4 College of Geography Science, Nanjing Normal University, Nanjing 210097, China.
5 National Oceanic and Atmospheric Administration (NOAA)/Geophysical Fluid Dynamics Laboratory, Princeton, NJ 08540, USA.

* To whom correspondence should be addressed. E-mail: edwar001{at}umn.edu

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THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Monsoons and Meltdowns.
J. P. Severinghaus (2009)
Science 326, 240-241
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