Global climate and the atmospheric partial pressure of carbon dioxide () are correlated over recent glacial cycles, with lower during ice ages, but the causes of the changes are unknown. The modern Southern Ocean releases deeply sequestered CO2 to the atmosphere. Growing evidence suggests that the Southern Ocean CO2 ‘leak’ was stemmed during ice ages, increasing ocean CO2 storage. Such a change would also have made the global ocean more alkaline, driving additional ocean CO2 uptake. This explanation for lower ice-age , if correct, has much to teach us about the controls on current ocean processes.
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We thank J. F. Adkins, R. F. Anderson, and J. Lynch-Stieglitz for discussions. Support was provided by the US NSF, the German DFG, the Humboldt and MacArthur Foundations, the Siebel Energy Grand Challenge at Princeton, and O. Happel.
The authors declare no competing financial interests.
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Sigman, D., Hain, M. & Haug, G. The polar ocean and glacial cycles in atmospheric CO2 concentration. Nature 466, 47–55 (2010) doi:10.1038/nature09149
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