Late Miocene onset of the modern Antarctic Circumpolar Current

• Published in: Nature Geoscience
• Main Authors: Evangelinos, Dimitris, Etourneau, Johan, van de Flierdt, Tina, Crosta, Xavier, Jeandel, Catherine, Flores, José Abel, Harwood, David M., Valero, Luis, Ducassou, Emmanuelle, Sauermilch, Isabel, Klocker, Andreas, Cacho, Isabel, Pena, Leopoldo D., Kreissig, Katharina, Benoit, Mathie, Paredes, Eduardo, García-Solsona, Ester, López-Quirós, Adrián, Escutia, Carlota
• Other Authors: Australian Research Council, Ministère de l'Europe et des Affaires étrangères (France), Generalitat de Catalunya, International Ocean Discovery Program, Ministerio de Economía, Industria y Competitividad (España), UK Research and Innovation
• Format: Article in Journal/Newspaper
• Language: English
• Published: Nature Publishing Group 2024
• Subjects: Antarctic Circumpolar Current; Antarctic Ice Sheet; Antarctica; Southern Ocean; Cenozoic; Circumpolar current; Global climate; Miocene; Neodymium isotope; Sea ice; Silt; Antarc*; Antarctic; Ice Sheet
• Online Access: http://hdl.handle.net/10261/354812; https://doi.org/10.1038/s41561-023-01356-3

The Antarctic Circumpolar Current plays a pivotal role in global climate through its strong influence on the global overturning circulation, ocean heat and CO uptake. However, when and how the Antarctic Circumpolar Current reached its modern-like characteristics remains disputed. Here we present neodymium isotope and sortable silt records from sediment cores in the Southwest Pacific and South Indian oceans spanning the past 31 million years. Our data indicate that a circumpolar current like that of today did not exist before the late Miocene cooling. These findings suggest that the emergence of a homogeneous and deep-reaching strong Antarctic Circumpolar Current was not linked solely to the opening and deepening of Southern Ocean Gateways triggering continental-scale Antarctic Ice Sheet expansion during the Eocene–Oligocene Transition (∼34 Ma). Instead, we find that besides tectonic pre-conditioning, the expansion of the Antarctic Ice Sheet and sea ice since the middle Miocene Climate Transition (∼14 Ma) played a crucial role. This led to stronger density contrast and intensified Southern Westerly Winds across the Southern Ocean, establishing a vigorous deep-reaching circumpolar flow and an enhanced global overturning circulation, which amplified the late Cenozoic global cooling. This research used samples provided by the International Ocean Discovery Program (IODP). We acknowledge the staff and shipboard party from Leg 28 and Leg 119. We thank the staff at the Gulf Coast core repository (GCR) for curating these cores and for assistance in core handling and shipping. Funding for this research is provided by the Spanish Ministry of Economy, Industry and Competitivity (grant CTM2017-89711-C2-1/2-P; PID2021-126495NB-C31), co-funded by the European Union through FEDER funds. D.E. was funded by the Alexander S. Onassis Public Benefit Foundation PhD research grant (F ZL 016-1/2015-2016), by MOPGA postdoctoral visiting fellowship programme funded by the French Ministry of Europe and Foreign Affairs (grant MOPGA ...