Five million years of Antarctic Circumpolar Current strength variability

• 成果类型: Article
• 署名作者: Lamy, Frank; Winckler, Gisela; Arz, Helge W.; Farmer, Jesse R.; Gottschalk, Julia; Lembke-Jene, Lester; Middleton, Jennifer L.; van der Does, Michelle; 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
• 署名单位: Helmholtz Association; Alfred Wegener Institute, Helmholtz Centre for Polar & Marine Research; University of Bremen; Columbia University; Columbia University; Leibniz Institut fur Ostseeforschung Warnemunde; University of Massachusetts System; University of Massachusetts Boston; University of Kiel; Texas A&M University System; Texas A&M University College Station; University of Delaware; Yale University; State University of New York (SUNY) System; Stony Brook University; Japan Agency for Marine-Earth Science & Technology (JAMSTEC); Rutgers University System; Rutgers University New Brunswick; National Taiwan University; University of Milano-Bicocca; Max Planck Society; Universite Paris Saclay; Centre National de la Recherche Scientifique (CNRS); CEA; University of Otago; University of California System; University of California Santa Cruz; University of Portsmouth; Korea Institute of Ocean Science & Technology (KIOST); Indian Institute of Technology System (IIT System); Indian Institute of Technology (IIT) - Bhubaneswar; University of Massachusetts System; University of Massachusetts Amherst; Universidade Federal do Rio de Janeiro; Oregon State University; Universidade Federal Fluminense; Chinese Academy of Sciences; South China Sea Institute of Oceanology, CAS; University of Lausanne; Research Organization of Information & Systems (ROIS); National Institute of Polar Research (NIPR) - Japan
• 刊物名称: Nature
• ISSN/ISSBN: 0028-5936
• DOI: 10.1038/s41586-024-07143-3
• 发表日期: 2024-03-28
• 关键词: southern-ocean; pacific; stratification; circulation; climate; record

摘要

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 CO2 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. The strength of the Antarctic Circumpolar Current, as traced in sediment cores from the Pacific Southern Ocean, shows no linear long-term trend over the past 5.3 Myr; instead, the strongest flow occurs consistently in warmer-than-present intervals.