Biological and physical controls in the Southern Ocean on past millennial-scale atmospheric CO 2 changes
International audience Millennial-scale climate changes during the last glacial period and deglaciation were accompanied by rapid changes in atmospheric CO 2 that remain unexplained. While the role of the Southern Ocean as a 'control valve' on ocean-atmosphere CO 2 exchange has been emphas...
Published in: | Nature Communications |
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Main Authors: | , , , , , , |
Other Authors: | , , , , , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
HAL CCSD
2016
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Subjects: | |
Online Access: | https://hal.science/hal-02916846 https://hal.science/hal-02916846/document https://hal.science/hal-02916846/file/ncomms11539.pdf https://doi.org/10.1038/ncomms11539 |
Summary: | International audience Millennial-scale climate changes during the last glacial period and deglaciation were accompanied by rapid changes in atmospheric CO 2 that remain unexplained. While the role of the Southern Ocean as a 'control valve' on ocean-atmosphere CO 2 exchange has been emphasized, the exact nature of this role, in particular the relative contributions of physical (for example, ocean dynamics and air-sea gas exchange) versus biological processes (for example, export productivity), remains poorly constrained. Here we combine reconstructions of bottom-water [O 2 ], export production and 14 C ventilation ages in the sub-Antarctic Atlantic, and show that atmospheric CO 2 pulses during the last glacial-and deglacial periods were consistently accompanied by decreases in the biological export of carbon and increases in deep-ocean ventilation via southern-sourced water masses. These findings demonstrate how the Southern Ocean's 'organic carbon pump' has exerted a tight control on atmospheric CO 2 , and thus global climate, specifically via a synergy of both physical and biological processes . |
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