Onset of Antarctic Circumpolar Current 30 million years ago as Tasmanian Gateway aligned with westerlies
Earth’s mightiest ocean current, the Antarctic Circumpolar Current (ACC), regulates the exchange of heat and carbon between the ocean and the atmosphere, and influences vertical ocean structure, deep-water production and the global distribution of nutrients and chemical tracers. The eastward-flowing...
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ftsouthampton:oai:eprints.soton.ac.uk:383697 2023-07-30T03:57:59+02:00 Onset of Antarctic Circumpolar Current 30 million years ago as Tasmanian Gateway aligned with westerlies Scher, Howie D. Whittaker, Joanne M. Williams, Simon E. Latimer, Jennifer C. Kordesch, Wendy E.C. Delaney, Margaret L. 2015-07-30 https://eprints.soton.ac.uk/383697/ English eng Scher, Howie D., Whittaker, Joanne M., Williams, Simon E., Latimer, Jennifer C., Kordesch, Wendy E.C. and Delaney, Margaret L. (2015) Onset of Antarctic Circumpolar Current 30 million years ago as Tasmanian Gateway aligned with westerlies. Nature, 523 (7562), 580-583. (doi:10.1038/nature14598 <http://dx.doi.org/10.1038/nature14598>). Article PeerReviewed 2015 ftsouthampton https://doi.org/10.1038/nature14598 2023-07-09T22:02:43Z Earth’s mightiest ocean current, the Antarctic Circumpolar Current (ACC), regulates the exchange of heat and carbon between the ocean and the atmosphere, and influences vertical ocean structure, deep-water production and the global distribution of nutrients and chemical tracers. The eastward-flowing ACC occupies a unique circumglobal pathway in the Southern Ocean that was enabled by the tectonic opening of key oceanic gateways during the break-up of Gondwana (for example, by the opening of the Tasmanian Gateway, which connects the Indian and Pacific oceans). Although the ACC is a key component of Earth’s present and past climate system1, the timing of the appearance of diagnostic features of the ACC (for example, low zonal gradients in water-mass tracer fields) is poorly known and represents a fundamental gap in our understanding of Earth history. Here we show, using geophysically determined positions of continent–ocean boundaries, that the deep Tasmanian Gateway opened 33.5 ± 1.5 million years ago (the errors indicate uncertainty in the boundary positions). Following this opening, sediments from Indian and Pacific cores recorded Pacific-type neodymium isotope ratios, revealing deep westward flow equivalent to the present-day Antarctic Slope Current. We observe onset of the ACC at around 30 million years ago, when Southern Ocean neodymium isotopes record a permanent shift to modern Indian–Atlantic ratios. Our reconstructions of ocean circulation show that massive reorganization and homogenization of Southern Ocean water masses coincided with migration of the northern margin of the Tasmanian Gateway into the mid-latitude westerly wind band, which we reconstruct at 64° S, near to the northern margin. Onset of the ACC about 30 million years ago coincided with major changes in global ocean circulation and probably contributed to the lower atmospheric carbon dioxide levels that appear after this time. Article in Journal/Newspaper Antarc* Antarctic Southern Ocean University of Southampton: e-Prints Soton Antarctic Southern Ocean The Antarctic Pacific Indian Nature 523 7562 580 583 |
institution |
Open Polar |
collection |
University of Southampton: e-Prints Soton |
op_collection_id |
ftsouthampton |
language |
English |
description |
Earth’s mightiest ocean current, the Antarctic Circumpolar Current (ACC), regulates the exchange of heat and carbon between the ocean and the atmosphere, and influences vertical ocean structure, deep-water production and the global distribution of nutrients and chemical tracers. The eastward-flowing ACC occupies a unique circumglobal pathway in the Southern Ocean that was enabled by the tectonic opening of key oceanic gateways during the break-up of Gondwana (for example, by the opening of the Tasmanian Gateway, which connects the Indian and Pacific oceans). Although the ACC is a key component of Earth’s present and past climate system1, the timing of the appearance of diagnostic features of the ACC (for example, low zonal gradients in water-mass tracer fields) is poorly known and represents a fundamental gap in our understanding of Earth history. Here we show, using geophysically determined positions of continent–ocean boundaries, that the deep Tasmanian Gateway opened 33.5 ± 1.5 million years ago (the errors indicate uncertainty in the boundary positions). Following this opening, sediments from Indian and Pacific cores recorded Pacific-type neodymium isotope ratios, revealing deep westward flow equivalent to the present-day Antarctic Slope Current. We observe onset of the ACC at around 30 million years ago, when Southern Ocean neodymium isotopes record a permanent shift to modern Indian–Atlantic ratios. Our reconstructions of ocean circulation show that massive reorganization and homogenization of Southern Ocean water masses coincided with migration of the northern margin of the Tasmanian Gateway into the mid-latitude westerly wind band, which we reconstruct at 64° S, near to the northern margin. Onset of the ACC about 30 million years ago coincided with major changes in global ocean circulation and probably contributed to the lower atmospheric carbon dioxide levels that appear after this time. |
format |
Article in Journal/Newspaper |
author |
Scher, Howie D. Whittaker, Joanne M. Williams, Simon E. Latimer, Jennifer C. Kordesch, Wendy E.C. Delaney, Margaret L. |
spellingShingle |
Scher, Howie D. Whittaker, Joanne M. Williams, Simon E. Latimer, Jennifer C. Kordesch, Wendy E.C. Delaney, Margaret L. Onset of Antarctic Circumpolar Current 30 million years ago as Tasmanian Gateway aligned with westerlies |
author_facet |
Scher, Howie D. Whittaker, Joanne M. Williams, Simon E. Latimer, Jennifer C. Kordesch, Wendy E.C. Delaney, Margaret L. |
author_sort |
Scher, Howie D. |
title |
Onset of Antarctic Circumpolar Current 30 million years ago as Tasmanian Gateway aligned with westerlies |
title_short |
Onset of Antarctic Circumpolar Current 30 million years ago as Tasmanian Gateway aligned with westerlies |
title_full |
Onset of Antarctic Circumpolar Current 30 million years ago as Tasmanian Gateway aligned with westerlies |
title_fullStr |
Onset of Antarctic Circumpolar Current 30 million years ago as Tasmanian Gateway aligned with westerlies |
title_full_unstemmed |
Onset of Antarctic Circumpolar Current 30 million years ago as Tasmanian Gateway aligned with westerlies |
title_sort |
onset of antarctic circumpolar current 30 million years ago as tasmanian gateway aligned with westerlies |
publishDate |
2015 |
url |
https://eprints.soton.ac.uk/383697/ |
geographic |
Antarctic Southern Ocean The Antarctic Pacific Indian |
geographic_facet |
Antarctic Southern Ocean The Antarctic Pacific Indian |
genre |
Antarc* Antarctic Southern Ocean |
genre_facet |
Antarc* Antarctic Southern Ocean |
op_relation |
Scher, Howie D., Whittaker, Joanne M., Williams, Simon E., Latimer, Jennifer C., Kordesch, Wendy E.C. and Delaney, Margaret L. (2015) Onset of Antarctic Circumpolar Current 30 million years ago as Tasmanian Gateway aligned with westerlies. Nature, 523 (7562), 580-583. (doi:10.1038/nature14598 <http://dx.doi.org/10.1038/nature14598>). |
op_doi |
https://doi.org/10.1038/nature14598 |
container_title |
Nature |
container_volume |
523 |
container_issue |
7562 |
container_start_page |
580 |
op_container_end_page |
583 |
_version_ |
1772820596819755008 |