Biological and physical controls in the Southern Ocean on past millennial-scale atmospheric CO 2 changes

• Published in: Nature Communications
• Main Authors: Gottschalk, Julia, Skinner, Luke C., Lippold, Jörg, Vogel, Hendrik, Frank, Norbert, Jaccard, Samuel L., Waelbroeck, Claire
• Other Authors: University of Cambridge UK (CAM), Oeschger Centre for Climate Change Research (OCCR), Universität Bern / University of Bern (UNIBE), Helmholtz Zentrum für Umweltforschung = Helmholtz Centre for Environmental Research (UFZ), Universität Heidelberg Heidelberg = Heidelberg University, Laboratoire des Sciences du Climat et de l'Environnement Gif-sur-Yvette (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Paléocéanographie (PALEOCEAN), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA))
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2016
• Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces; environment; Antarctic; Southern Ocean; Antarc*
• 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

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 .