Five million years of Antarctic Circumpolar Current strength variability

• Published in: Nature
• Main Authors: Lamy, Frank, Winckler, Gisela, Arz, Helge, W, Farmer, Jesse, R, Gottschalk, Julia, Lembke-Jene, Lester, Middleton, Jennifer, L, van der Does, Michèlle, Tiedemann, Ralf, Alvarez Zarikian, Carlos, Basak, Chandranath, Brombacher, Anieke, Dumm, Levin, Esper, Oliver, M, Herbert, Lisa, C, Iwasaki, Shinya, Kreps, Gaston, Lawson, Vera, J, Lo, Li, Malinverno, Elisa, Martinez-Garcia, Alfredo, Michel, Elisabeth, Moretti, Simone, Moy, Christopher, M, Ravelo, Ana, Christina, Riesselman, Christina, R, Saavedra-Pellitero, Mariem, Sadatzki, Henrik, Seo, Inah, Singh, Raj, K, Smith, Rebecca, A, Souza, Alexandre, L, Stoner, Joseph, S, Toyos, Maria, de Oliveira, Igor, M Venancio P, Wan, Sui, Wu, Shuzhuang, Zhao, Xiangyu
• Other Authors: 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 2024
• Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces; environment; Antarctic; Pacific; Southern Ocean; The Antarctic; Antarc*; Ice Sheet
• Online Access: https://hal.science/hal-04574721; https://hal.science/hal-04574721/document; https://hal.science/hal-04574721/file/s41586-024-07143-3.pdf; https://doi.org/10.1038/s41586-024-07143-3

International audience Abstract The Antarctic Circumpolar Current (ACC) represents the world’s largest ocean-current system and affects global ocean circulation, climate and Antarctic ice-sheet stability 1–3 . Today, ACC dynamics are controlled by atmospheric forcing, oceanic density gradients and eddy activity 4 . Whereas palaeoceanographic reconstructions exhibit regional heterogeneity in ACC position and strength over Pleistocene glacial–interglacial cycles 5–8 , the long-term evolution of the ACC is poorly known. Here we document changes in ACC strength from sediment cores in the Pacific Southern Ocean. We find no linear long-term trend in ACC flow since 5.3 million years ago (Ma), in contrast to global cooling 9 and increasing global ice volume 10 . Instead, we observe a reversal on a million-year timescale, from increasing ACC strength during Pliocene global cooling to a subsequent decrease with further Early Pleistocene cooling. This shift in the ACC regime coincided with a Southern Ocean reconfiguration that altered the sensitivity of the ACC to atmospheric and oceanic forcings 11–13 . We find ACC strength changes to be closely linked to 400,000-year eccentricity cycles, probably originating from modulation of precessional changes in the South Pacific jet stream linked to tropical Pacific temperature variability 14 . A persistent link between weaker ACC flow, equatorward-shifted opal deposition and reduced atmospheric CO 2 during glacial periods first emerged during the Mid-Pleistocene Transition (MPT). The strongest ACC flow occurred during warmer-than-present intervals of the Plio-Pleistocene, providing evidence of potentially increasing ACC flow with future climate warming.