From Australian Oceans Data Network
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Gateway-driven weakening of ocean gyres leads to Southern Ocean cooling

Created 23/06/2025

Updated 23/06/2025

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Declining atmospheric CO2 concentrations are considered the primary driver for the Cenozoic Greenhouse-Icehouse transition, ~34 million years ago. A role for tectonically opening Southern Ocean gateways, initiating the onset of a thermally isolating Antarctic Circumpolar Current, has been disputed as ocean models have not reproduced expected heat transport to the Antarctic coast. Here we use high-resolution ocean simulations with detailed paleobathymetry to demonstrate that tectonics did play a fundamental role in reorganising Southern Ocean circulation patterns and heat transport, consistent with available proxy data. When at least one gateway (Tasmanian or Drake) is shallow (300 m), gyres transport warm waters towards Antarctica. When the second gateway subsides below 300 m, these gyres weaken and cause a dramatic cooling (average of 2–4°C, up to 5°C) of Antarctic surface waters whilst the ACC remains weak. Our results demonstrate that tectonic changes are crucial for Southern Ocean climate change and should be carefully considered in constraining long-term climate sensitivity to CO2.

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Field Value
Title Gateway-driven weakening of ocean gyres leads to Southern Ocean cooling
Language eng
Licence Not Specified
Landing Page https://data.gov.au/data/dataset/b5298fc3-9427-4cd7-bdfd-a090f9d75157
Contact Point
Australian Ocean Data Network
Isabel.Sauermilch@utas.edu.au
Reference Period 21/04/2020 - 21/04/2030
Geospatial Coverage
Map data © OpenStreetMap contributors
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        -85.0
      ],
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      ],
      [
        -180.0,
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      ],
      [
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    ]
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  "type": "Polygon"
}
Data Portal Australian Oceans Data Network

Data Source

This dataset was originally found on Australian Oceans Data Network "Gateway-driven weakening of ocean gyres leads to Southern Ocean cooling". Please visit the source to access the original metadata of the dataset:
https://catalogue.aodn.org.au/geonetwork/srv/eng/csw/dataset/gateway-driven-weakening-of-ocean-gyres-leads-to-southern-ocean-cooling