Biological and physical controls in the Southern Ocean on past millennial-scale atmospheric CO2 changes
Résumé
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 .
Origine : Publication financée par une institution
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