Miocene Antarctic Ice Sheet area adapts significantly faster than volume to CO2-induced climate change
The strongly varying benthic δ 18 O levels of the early and mid-Miocene (23 to 14 Myr ago) are primarily caused by a combination of changes in Antarctic Ice Sheet (AIS) volume and deep-ocean temperatures. These factors are coupled since AIS changes affect deep-ocean temperatures. It has recently bee...
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Online Access: | https://doi.org/10.5194/cp-20-257-2024 https://cp.copernicus.org/articles/20/257/2024/ |
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ftcopernicus:oai:publications.copernicus.org:cp110174 2024-09-15T17:47:04+00:00 Miocene Antarctic Ice Sheet area adapts significantly faster than volume to CO2-induced climate change Stap, Lennert B. Berends, Constantijn J. Wal, Roderik S. W. 2024-01-30 application/pdf https://doi.org/10.5194/cp-20-257-2024 https://cp.copernicus.org/articles/20/257/2024/ eng eng doi:10.5194/cp-20-257-2024 https://cp.copernicus.org/articles/20/257/2024/ eISSN: 1814-9332 Text 2024 ftcopernicus https://doi.org/10.5194/cp-20-257-2024 2024-08-28T05:24:15Z The strongly varying benthic δ 18 O levels of the early and mid-Miocene (23 to 14 Myr ago) are primarily caused by a combination of changes in Antarctic Ice Sheet (AIS) volume and deep-ocean temperatures. These factors are coupled since AIS changes affect deep-ocean temperatures. It has recently been argued that this is due to changes in ice sheet area rather than volume because area changes affect the surface albedo. This finding would be important when the transient AIS grows relatively faster in extent than in thickness, which we test here. We analyse simulations of Miocene AIS variability carried out using the three-dimensional ice sheet model IMAU-ICE forced by warm (high CO 2 , no ice) and cold (low CO 2 , large East AIS) climate snapshots. These simulations comprise equilibrium and idealized quasi-orbital transient runs with strongly varying CO 2 levels (280 to 840 ppm). Our simulations show a limited direct effect of East AIS changes on Miocene orbital-timescale benthic δ 18 O variability because of the slow build-up of volume. However, we find that relative to the equilibrium ice sheet size, the AIS area adapts significantly faster and more strongly than volume to the applied forcing variability. Consequently, during certain intervals the ice sheet is receding at the margins, while ice is still building up in the interior. That means the AIS does not adapt to a changing equilibrium size at the same rate or with the same sign everywhere. Our results indicate that the Miocene Antarctic Ice Sheet affects deep-ocean temperatures more than its volume suggests. Text Antarc* Antarctic Ice Sheet Copernicus Publications: E-Journals Climate of the Past 20 1 257 266 |
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Open Polar |
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Copernicus Publications: E-Journals |
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ftcopernicus |
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English |
description |
The strongly varying benthic δ 18 O levels of the early and mid-Miocene (23 to 14 Myr ago) are primarily caused by a combination of changes in Antarctic Ice Sheet (AIS) volume and deep-ocean temperatures. These factors are coupled since AIS changes affect deep-ocean temperatures. It has recently been argued that this is due to changes in ice sheet area rather than volume because area changes affect the surface albedo. This finding would be important when the transient AIS grows relatively faster in extent than in thickness, which we test here. We analyse simulations of Miocene AIS variability carried out using the three-dimensional ice sheet model IMAU-ICE forced by warm (high CO 2 , no ice) and cold (low CO 2 , large East AIS) climate snapshots. These simulations comprise equilibrium and idealized quasi-orbital transient runs with strongly varying CO 2 levels (280 to 840 ppm). Our simulations show a limited direct effect of East AIS changes on Miocene orbital-timescale benthic δ 18 O variability because of the slow build-up of volume. However, we find that relative to the equilibrium ice sheet size, the AIS area adapts significantly faster and more strongly than volume to the applied forcing variability. Consequently, during certain intervals the ice sheet is receding at the margins, while ice is still building up in the interior. That means the AIS does not adapt to a changing equilibrium size at the same rate or with the same sign everywhere. Our results indicate that the Miocene Antarctic Ice Sheet affects deep-ocean temperatures more than its volume suggests. |
format |
Text |
author |
Stap, Lennert B. Berends, Constantijn J. Wal, Roderik S. W. |
spellingShingle |
Stap, Lennert B. Berends, Constantijn J. Wal, Roderik S. W. Miocene Antarctic Ice Sheet area adapts significantly faster than volume to CO2-induced climate change |
author_facet |
Stap, Lennert B. Berends, Constantijn J. Wal, Roderik S. W. |
author_sort |
Stap, Lennert B. |
title |
Miocene Antarctic Ice Sheet area adapts significantly faster than volume to CO2-induced climate change |
title_short |
Miocene Antarctic Ice Sheet area adapts significantly faster than volume to CO2-induced climate change |
title_full |
Miocene Antarctic Ice Sheet area adapts significantly faster than volume to CO2-induced climate change |
title_fullStr |
Miocene Antarctic Ice Sheet area adapts significantly faster than volume to CO2-induced climate change |
title_full_unstemmed |
Miocene Antarctic Ice Sheet area adapts significantly faster than volume to CO2-induced climate change |
title_sort |
miocene antarctic ice sheet area adapts significantly faster than volume to co2-induced climate change |
publishDate |
2024 |
url |
https://doi.org/10.5194/cp-20-257-2024 https://cp.copernicus.org/articles/20/257/2024/ |
genre |
Antarc* Antarctic Ice Sheet |
genre_facet |
Antarc* Antarctic Ice Sheet |
op_source |
eISSN: 1814-9332 |
op_relation |
doi:10.5194/cp-20-257-2024 https://cp.copernicus.org/articles/20/257/2024/ |
op_doi |
https://doi.org/10.5194/cp-20-257-2024 |
container_title |
Climate of the Past |
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20 |
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1 |
container_start_page |
257 |
op_container_end_page |
266 |
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1810495608741429248 |