H. Cheng, R. L. Edwards, W. S. Broeker, G. H. Denton, X-G. Kong, Y-J. Wang, R. Zhang, X-F. Wang, Science, 326(5950), Ice age terminations

Science (9 October 2009), Vol. 326, No. 5950, pp. 248-252; DOI: 10.1126/science.1177840

Ice Age Terminations

Hai Cheng, R. Lawrence Edwards* (Department of Geology and Geophysics, University of Minnesota, Minneapolis, MN 55455, U.S.A.), Wallace S. Broeker (Lamont-Doherty Earth Observatory of Columbia University, 61 Route 9W, P. O. Box 1000, Palisades, NY 10964–1000, U.S.A.), George H. Denton (Department of Earth Sciences, Bryand Global Sciences Center, Climate Change Institute, University of Maine, Orono, ME 04469, U.S.A.), Xinggong Kong, Yongjin Wang (College of Geography Science, Nanjing Normal University, Nanjing 210097, China), Rong Zhang (National Oceanic and Atmospheric Administration (NOAA)/Geophysical Fluid Dynamics Laboratory, Princeton, NJ 08540, U.S.A.) and Xianfeng Wang (Department of Geology and Geophysics, University of Minnesota, Minneapolis, MN 55455, U.S.A.)

Abstract

²³⁰Th-dated oxygen isotope records of stalagmites from Sanbao Cave, China, characterize Asian Monsoon (AM) precipitation through the ends of the third- and fourth-most 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.

* Correspondence e-mail: edwar001@umn.edu

Link to abstract: http://www.sciencemag.org/cgi/content/abstract/sci;326/5950/248