PerspectivePALEOCLIMATE

Uncorking the Southern Ocean's Vintage CO2

Science  28 May 2010:
Vol. 328, Issue 5982, pp. 1117-1118
DOI: 10.1126/science.1190765

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Summary

Antarctic ice cores provide a well-documented link between Earth's climate and the CO2 content of the atmosphere over the past 800,000 years (1). Many hypotheses to explain this relationship envision releases of CO2 to the atmosphere from the deep waters of the Southern Ocean around Antarctica (2), but there has been limited evidence. On page 1147 of this issue, Skinner et al. (3) use the radiocarbon (14C) content in the shells of surface- and bottom-dwelling organisms (foraminifera) recovered from the Southern Ocean to track how CO2 moved from the deep sea to the atmosphere during the warming transition out of the last ice age (deglaciation). First, bottom-dwelling foraminifera record the buildup of 14C-depleted CO2 in the deep ocean during the last glacial period, more than 21,000 years ago. Second, the shells of surface dwellers record the transfer of 14C-depleted CO2 to the surface between ∼17,000 and 21,000 years ago.