The southward migration of the Antarctic Circumpolar Current enhanced oceanic degassing of carbon dioxide during the last two deglaciations

• Published in: Communications Earth & Environment
• Main Authors: Ai, Xuyuan, E, Auderset, Alexandra, Schmitt, Mareike, Moretti, Simone, Studer, Anja, S, Michel, Elisabeth, Wegmann, Martin, Mazaud, Alain, Bijl, Peter, K, Sigman, Daniel, M, Martínez-García, Alfredo, Jaccard, Samuel, L
• Other Authors: Max Planck Institute for Chemistry (MPIC), Max-Planck-Gesellschaft, 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)), Climat et Magnétisme (CLIMAG)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2024
• Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces; environment; Antarc*; Antarctic; Southern Ocean
• Online Access: https://hal.science/hal-04426496; https://hal.science/hal-04426496/document; https://hal.science/hal-04426496/file/s43247-024-01216-x.pdf; https://doi.org/10.1038/s43247-024-01216-x

International audience Previous studies suggest that meridional migrations of the Antarctic Circumpolar Current may have altered wind-driven upwelling and carbon dioxide degassing in the Southern Ocean during past climate transitions. Here, we report a quantitative and continuous record of the Antarctic Circumpolar Current latitude over the last glacial-interglacial cycle, using biomarker-based reconstructions of surface layer temperature gradient in the southern Indian Ocean. The results show that the Antarctic Circumpolar Current was more equatorward during the ice ages and shifted ~6°poleward at the end of glacial terminations, consistent with Antarctic Circumpolar Current migration playing a role in glacial-interglacial atmospheric carbon dioxide change. Comparing the temporal evolution of the Antarctic Circumpolar Current mean latitude with other observations provides evidence that Earth's axial tilt affects the strength and latitude range of Southern Ocean wind-driven upwelling, which may explain previously noted deviations in atmospheric carbon dioxide concentration from a simple correlation with Antarctic climate.