Warm Greenland during the last interglacial: the role of regional changes in sea ice cover
The last interglacial, also known as the Eemian, is characterized by warmer than present conditions at high latitudes. This is implied by various Eemian proxy records as well as by climate model simulations, though the models mostly underestimate the warming with respect to proxies. Simulations of E...
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ftcopernicus:oai:publications.copernicus.org:cp49518 2023-05-15T16:26:48+02:00 Warm Greenland during the last interglacial: the role of regional changes in sea ice cover Merz, Niklaus Born, Andreas Raible, Christoph C. Stocker, Thomas F. 2018-09-27 application/pdf https://doi.org/10.5194/cp-12-2011-2016 https://cp.copernicus.org/articles/12/2011/2016/ eng eng doi:10.5194/cp-12-2011-2016 https://cp.copernicus.org/articles/12/2011/2016/ eISSN: 1814-9332 Text 2018 ftcopernicus https://doi.org/10.5194/cp-12-2011-2016 2020-07-20T16:23:56Z The last interglacial, also known as the Eemian, is characterized by warmer than present conditions at high latitudes. This is implied by various Eemian proxy records as well as by climate model simulations, though the models mostly underestimate the warming with respect to proxies. Simulations of Eemian surface air temperatures (SAT) in the Northern Hemisphere extratropics further show large variations between different climate models, and it has been hypothesized that this model spread relates to diverse representations of the Eemian sea ice cover. Here we use versions 3 and 4 of the Community Climate System Model (CCSM3 and CCSM4) to highlight the crucial role of sea ice and sea surface temperatures changes for the Eemian climate, in particular in the North Atlantic sector and in Greenland. A substantial reduction in sea ice cover results in an amplified atmospheric warming and thus a better agreement with Eemian proxy records. Sensitivity experiments with idealized lower boundary conditions reveal that warming over Greenland is mostly due to a sea ice retreat in the Nordic Seas. In contrast, sea ice changes in the Labrador Sea have a limited local impact. Changes in sea ice cover in either region are transferred to the overlying atmosphere through anomalous surface energy fluxes. The large-scale spread of the warming resulting from a Nordic Seas sea ice retreat is mostly explained by anomalous heat advection rather than by radiation or condensation processes. In addition, the sea ice perturbations lead to changes in the hydrological cycle. Our results consequently imply that both temperature and snow accumulation records from Greenland ice cores are sensitive to sea ice changes in the Nordic Seas but insensitive to sea ice changes in the Labrador Sea. Moreover, the simulations suggest that the uncertainty in the Eemian sea ice cover accounts for 1.6 °C of the Eemian warming at the NEEM ice core site. The estimated Eemian warming of 5 °C above present day based on the NEEM δ 15 N record can be reconstructed by the CCSM4 model for the scenario of a substantial sea ice retreat in the Nordic Seas combined with a reduced Greenland ice sheet. Text Greenland Greenland ice cores ice core Ice Sheet Labrador Sea Nordic Seas North Atlantic Sea ice Copernicus Publications: E-Journals Greenland Climate of the Past 12 10 2011 2031 |
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Open Polar |
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Copernicus Publications: E-Journals |
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ftcopernicus |
language |
English |
description |
The last interglacial, also known as the Eemian, is characterized by warmer than present conditions at high latitudes. This is implied by various Eemian proxy records as well as by climate model simulations, though the models mostly underestimate the warming with respect to proxies. Simulations of Eemian surface air temperatures (SAT) in the Northern Hemisphere extratropics further show large variations between different climate models, and it has been hypothesized that this model spread relates to diverse representations of the Eemian sea ice cover. Here we use versions 3 and 4 of the Community Climate System Model (CCSM3 and CCSM4) to highlight the crucial role of sea ice and sea surface temperatures changes for the Eemian climate, in particular in the North Atlantic sector and in Greenland. A substantial reduction in sea ice cover results in an amplified atmospheric warming and thus a better agreement with Eemian proxy records. Sensitivity experiments with idealized lower boundary conditions reveal that warming over Greenland is mostly due to a sea ice retreat in the Nordic Seas. In contrast, sea ice changes in the Labrador Sea have a limited local impact. Changes in sea ice cover in either region are transferred to the overlying atmosphere through anomalous surface energy fluxes. The large-scale spread of the warming resulting from a Nordic Seas sea ice retreat is mostly explained by anomalous heat advection rather than by radiation or condensation processes. In addition, the sea ice perturbations lead to changes in the hydrological cycle. Our results consequently imply that both temperature and snow accumulation records from Greenland ice cores are sensitive to sea ice changes in the Nordic Seas but insensitive to sea ice changes in the Labrador Sea. Moreover, the simulations suggest that the uncertainty in the Eemian sea ice cover accounts for 1.6 °C of the Eemian warming at the NEEM ice core site. The estimated Eemian warming of 5 °C above present day based on the NEEM δ 15 N record can be reconstructed by the CCSM4 model for the scenario of a substantial sea ice retreat in the Nordic Seas combined with a reduced Greenland ice sheet. |
format |
Text |
author |
Merz, Niklaus Born, Andreas Raible, Christoph C. Stocker, Thomas F. |
spellingShingle |
Merz, Niklaus Born, Andreas Raible, Christoph C. Stocker, Thomas F. Warm Greenland during the last interglacial: the role of regional changes in sea ice cover |
author_facet |
Merz, Niklaus Born, Andreas Raible, Christoph C. Stocker, Thomas F. |
author_sort |
Merz, Niklaus |
title |
Warm Greenland during the last interglacial: the role of regional changes in sea ice cover |
title_short |
Warm Greenland during the last interglacial: the role of regional changes in sea ice cover |
title_full |
Warm Greenland during the last interglacial: the role of regional changes in sea ice cover |
title_fullStr |
Warm Greenland during the last interglacial: the role of regional changes in sea ice cover |
title_full_unstemmed |
Warm Greenland during the last interglacial: the role of regional changes in sea ice cover |
title_sort |
warm greenland during the last interglacial: the role of regional changes in sea ice cover |
publishDate |
2018 |
url |
https://doi.org/10.5194/cp-12-2011-2016 https://cp.copernicus.org/articles/12/2011/2016/ |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Greenland Greenland ice cores ice core Ice Sheet Labrador Sea Nordic Seas North Atlantic Sea ice |
genre_facet |
Greenland Greenland ice cores ice core Ice Sheet Labrador Sea Nordic Seas North Atlantic Sea ice |
op_source |
eISSN: 1814-9332 |
op_relation |
doi:10.5194/cp-12-2011-2016 https://cp.copernicus.org/articles/12/2011/2016/ |
op_doi |
https://doi.org/10.5194/cp-12-2011-2016 |
container_title |
Climate of the Past |
container_volume |
12 |
container_issue |
10 |
container_start_page |
2011 |
op_container_end_page |
2031 |
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1766015781455265792 |