What question did this study set out to answer?

This research aims to investigate how the Southern Ocean contributed to past increases in atmospheric CO2 during deglaciation.

May 27, 2010Open Access

Ventilation of the Deep Southern Ocean and Deglacial CO 2 Rise

Key Points

This research aims to investigate how the Southern Ocean contributed to past increases in atmospheric CO2 during deglaciation.
Radiocarbon dating of deep sea water samples from the Atlantic sector of the Southern Ocean.
Comparison of deep water ages relative to present atmospheric CO2 levels.
Analysis of the Antarctic overturning circulation and its effects on atmospheric CO2.
Deep water around Antarctica during the last glacial period was over twice as old as today relative to the atmosphere.
The release of CO2 from this old deep water significantly influenced atmospheric CO2 concentrations during deglaciation.
Old, CO2-enriched deep water contributed to the variability in atmospheric CO2 rise by affecting the upwelling branch of the overturning circulation.

Abstract

Past glacial-interglacial increases in the concentration of atmospheric carbon dioxide (CO2) are thought to arise from the rapid release of CO2 sequestered in the deep sea, primarily via the Southern Ocean. Here, we present radiocarbon evidence from the Atlantic sector of the Southern Ocean that strongly supports this hypothesis. We show that during the last glacial period, deep water circulating around Antarctica was more than two times older than today relative to the atmosphere. During deglaciation, the dissipation of this old and presumably CO2-enriched deep water played an important role in the pulsed rise of atmospheric CO2 through its variable influence on the upwelling branch of the Antarctic overturning circulation.

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