Hydrological impact of Middle Miocene Antarctic ice-free areas coupled to deep ocean temperatures
Oxygen isotopes from ocean sediments (δ 18 O) used to reconstruct past continental ice volumes additionally record deep water temperatures (DWTs). Traditionally, these are assumed to be coupled (ice-volume changes cause DWT changes). However, δ 18 O records during peak Middle Miocene warmth (~16–15...
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Online Access: | https://hdl.handle.net/1983/e6f36b78-4536-4911-8f86-395627d920b8 https://research-information.bris.ac.uk/en/publications/e6f36b78-4536-4911-8f86-395627d920b8 https://doi.org/10.1038/s41561-021-00745-w http://www.scopus.com/inward/record.url?scp=85105825922&partnerID=8YFLogxK |
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ftubristolcris:oai:research-information.bris.ac.uk:publications/e6f36b78-4536-4911-8f86-395627d920b8 2024-02-11T09:57:30+01:00 Hydrological impact of Middle Miocene Antarctic ice-free areas coupled to deep ocean temperatures Bradshaw, Catherine D. Langebroek, Petra M. Lear, Caroline H. Lunt, Daniel J. Coxall, Helen K. Sosdian, Sindia M. de Boer, Agatha M. 2021-06 https://hdl.handle.net/1983/e6f36b78-4536-4911-8f86-395627d920b8 https://research-information.bris.ac.uk/en/publications/e6f36b78-4536-4911-8f86-395627d920b8 https://doi.org/10.1038/s41561-021-00745-w http://www.scopus.com/inward/record.url?scp=85105825922&partnerID=8YFLogxK eng eng info:eu-repo/semantics/restrictedAccess Bradshaw , C D , Langebroek , P M , Lear , C H , Lunt , D J , Coxall , H K , Sosdian , S M & de Boer , A M 2021 , ' Hydrological impact of Middle Miocene Antarctic ice-free areas coupled to deep ocean temperatures ' , Nature Geoscience , vol. 14 , no. 6 , pp. 429-436 . https://doi.org/10.1038/s41561-021-00745-w article 2021 ftubristolcris https://doi.org/10.1038/s41561-021-00745-w 2024-01-18T23:32:13Z Oxygen isotopes from ocean sediments (δ 18 O) used to reconstruct past continental ice volumes additionally record deep water temperatures (DWTs). Traditionally, these are assumed to be coupled (ice-volume changes cause DWT changes). However, δ 18 O records during peak Middle Miocene warmth (~16–15 million years ago) document large rapid fluctuations (~1–1.5‰) difficult to explain as huge Antarctic ice sheet (AIS) volume changes. Here, using climate modelling and data comparisons, we show DWTs are coupled to AIS spatial extent, not volume, because Antarctic albedo changes modify the hydrological cycle, affecting Antarctic deep water production regions. We suggest the Middle Miocene AIS had retreated substantially from previous Oligocene maxima. The residual ice sheet varied spatially more rapidly on orbital timescales than previously thought, enabling large DWT swings (up to 4 °C). When Middle Miocene warmth terminated (~13 million years ago) and a continent-scale AIS had stabilized, further ice-volume changes were predominantly in height rather than extent, with little impact on DWT. Our findings imply a shift in ocean sensitivity to ice-sheet changes occurs when AIS retreat exposes previously ice-covered land; associated feedbacks could reduce the Earth system’s ability to maintain a large AIS. This demonstrates ice-sheet changes should be characterized not only by ice volume but also by spatial extent. Article in Journal/Newspaper Antarc* Antarctic Ice Sheet University of Bristol: Bristol Research Antarctic Nature Geoscience 14 6 429 436 |
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Open Polar |
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University of Bristol: Bristol Research |
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ftubristolcris |
language |
English |
description |
Oxygen isotopes from ocean sediments (δ 18 O) used to reconstruct past continental ice volumes additionally record deep water temperatures (DWTs). Traditionally, these are assumed to be coupled (ice-volume changes cause DWT changes). However, δ 18 O records during peak Middle Miocene warmth (~16–15 million years ago) document large rapid fluctuations (~1–1.5‰) difficult to explain as huge Antarctic ice sheet (AIS) volume changes. Here, using climate modelling and data comparisons, we show DWTs are coupled to AIS spatial extent, not volume, because Antarctic albedo changes modify the hydrological cycle, affecting Antarctic deep water production regions. We suggest the Middle Miocene AIS had retreated substantially from previous Oligocene maxima. The residual ice sheet varied spatially more rapidly on orbital timescales than previously thought, enabling large DWT swings (up to 4 °C). When Middle Miocene warmth terminated (~13 million years ago) and a continent-scale AIS had stabilized, further ice-volume changes were predominantly in height rather than extent, with little impact on DWT. Our findings imply a shift in ocean sensitivity to ice-sheet changes occurs when AIS retreat exposes previously ice-covered land; associated feedbacks could reduce the Earth system’s ability to maintain a large AIS. This demonstrates ice-sheet changes should be characterized not only by ice volume but also by spatial extent. |
format |
Article in Journal/Newspaper |
author |
Bradshaw, Catherine D. Langebroek, Petra M. Lear, Caroline H. Lunt, Daniel J. Coxall, Helen K. Sosdian, Sindia M. de Boer, Agatha M. |
spellingShingle |
Bradshaw, Catherine D. Langebroek, Petra M. Lear, Caroline H. Lunt, Daniel J. Coxall, Helen K. Sosdian, Sindia M. de Boer, Agatha M. Hydrological impact of Middle Miocene Antarctic ice-free areas coupled to deep ocean temperatures |
author_facet |
Bradshaw, Catherine D. Langebroek, Petra M. Lear, Caroline H. Lunt, Daniel J. Coxall, Helen K. Sosdian, Sindia M. de Boer, Agatha M. |
author_sort |
Bradshaw, Catherine D. |
title |
Hydrological impact of Middle Miocene Antarctic ice-free areas coupled to deep ocean temperatures |
title_short |
Hydrological impact of Middle Miocene Antarctic ice-free areas coupled to deep ocean temperatures |
title_full |
Hydrological impact of Middle Miocene Antarctic ice-free areas coupled to deep ocean temperatures |
title_fullStr |
Hydrological impact of Middle Miocene Antarctic ice-free areas coupled to deep ocean temperatures |
title_full_unstemmed |
Hydrological impact of Middle Miocene Antarctic ice-free areas coupled to deep ocean temperatures |
title_sort |
hydrological impact of middle miocene antarctic ice-free areas coupled to deep ocean temperatures |
publishDate |
2021 |
url |
https://hdl.handle.net/1983/e6f36b78-4536-4911-8f86-395627d920b8 https://research-information.bris.ac.uk/en/publications/e6f36b78-4536-4911-8f86-395627d920b8 https://doi.org/10.1038/s41561-021-00745-w http://www.scopus.com/inward/record.url?scp=85105825922&partnerID=8YFLogxK |
geographic |
Antarctic |
geographic_facet |
Antarctic |
genre |
Antarc* Antarctic Ice Sheet |
genre_facet |
Antarc* Antarctic Ice Sheet |
op_source |
Bradshaw , C D , Langebroek , P M , Lear , C H , Lunt , D J , Coxall , H K , Sosdian , S M & de Boer , A M 2021 , ' Hydrological impact of Middle Miocene Antarctic ice-free areas coupled to deep ocean temperatures ' , Nature Geoscience , vol. 14 , no. 6 , pp. 429-436 . https://doi.org/10.1038/s41561-021-00745-w |
op_rights |
info:eu-repo/semantics/restrictedAccess |
op_doi |
https://doi.org/10.1038/s41561-021-00745-w |
container_title |
Nature Geoscience |
container_volume |
14 |
container_issue |
6 |
container_start_page |
429 |
op_container_end_page |
436 |
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1790609794541813760 |