Last glacial inception trajectories for the Northern Hemisphere from coupled ice and climate modelling
We present an ensemble of last glacial inception (LGI) simulations for the Northern Hemisphere that captures a significant fraction of inferred ice volume changes within proxy uncertainties. This ensemble was performed with LCice 1.0, a coupled ice sheet and climate model, varying parameters of both...
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ftcopernicus:oai:publications.copernicus.org:cp82805 2023-05-15T16:00:14+02:00 Last glacial inception trajectories for the Northern Hemisphere from coupled ice and climate modelling Bahadory, Taimaz Tarasov, Lev Andres, Heather 2021-02-15 application/pdf https://doi.org/10.5194/cp-17-397-2021 https://cp.copernicus.org/articles/17/397/2021/ eng eng doi:10.5194/cp-17-397-2021 https://cp.copernicus.org/articles/17/397/2021/ eISSN: 1814-9332 Text 2021 ftcopernicus https://doi.org/10.5194/cp-17-397-2021 2021-02-22T17:22:15Z We present an ensemble of last glacial inception (LGI) simulations for the Northern Hemisphere that captures a significant fraction of inferred ice volume changes within proxy uncertainties. This ensemble was performed with LCice 1.0, a coupled ice sheet and climate model, varying parameters of both climate and ice sheet components, as well as the coupling between them. Certain characteristics of the spatiotemporal pattern of ice growth and subsequent retreat in both North America (NA) and Eurasia (EA) are sensitive to parameter changes while others are not. We find that the initial inception of ice over NA and EA is best characterized by the nucleation of ice at high-latitude and high-elevation sites. Subsequent spreading and merger along with large-scale conversion of snowfields dominate in different sectors. The latter plays an important role in the merging of eastern and western ice regions in NA. The inception peak ice volume in the ensemble occurs approximately at 111 ka and therefore lags the summer 60 ∘ N insolation minimum by more than 3 kyr. Ice volumes consistently peak earlier over EA than NA. The inception peak in North America is characterized by a merged Laurentide and Cordilleran ice sheet, with the Davis Strait covered in ice in ∼80 % of simulations. Ice also bridges Greenland and Iceland in all runs by 114 ka and therefore blocks the Denmark Strait. This latter feature would thereby divert the East Greenland Current and Denmark Strait overflow with a potentially significant impact on ocean circulation. The Eurasian ice sheet at its inception peak varies across ensemble runs between a continuous ice sheet and multiple smaller ice caps. In both continents, the colder high latitudes (i.e. Ellesmere and Svalbard) tend to grow ice through the entire simulation (to 102 ka), while lower latitudes lose ice after ∼110 ka. We find temperature decreases over the initial phases of the inception lead to the expansion of NA ice sheet area and that subsequent precipitation increases contribute to its thickening. EA ice sheet area also expands with decreasing temperatures, but sea ice limits any increases in precipitation, leading to an earlier retreat away from the EA maximum ice sheet volume. We also examine the extent to which the capture of both LGI ice growth and retreat constrains the coupled ice–climate model sensitivity to changing atmospheric p CO 2 . The 55-member sub-ensemble that meets our criteria for “acceptable” ice growth and retreat has an equilibrium climate sensitivity lower bound that is 0.3 ∘ C higher than that of the full ensemble. This suggests some potential value of fully coupled ice–climate modelling of the last glacial inception to constrain future climate change. Text Davis Strait Denmark Strait East Greenland east greenland current Greenland Ice Sheet Iceland Sea ice Svalbard Copernicus Publications: E-Journals Greenland Svalbard Climate of the Past 17 1 397 418 |
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Copernicus Publications: E-Journals |
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ftcopernicus |
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English |
description |
We present an ensemble of last glacial inception (LGI) simulations for the Northern Hemisphere that captures a significant fraction of inferred ice volume changes within proxy uncertainties. This ensemble was performed with LCice 1.0, a coupled ice sheet and climate model, varying parameters of both climate and ice sheet components, as well as the coupling between them. Certain characteristics of the spatiotemporal pattern of ice growth and subsequent retreat in both North America (NA) and Eurasia (EA) are sensitive to parameter changes while others are not. We find that the initial inception of ice over NA and EA is best characterized by the nucleation of ice at high-latitude and high-elevation sites. Subsequent spreading and merger along with large-scale conversion of snowfields dominate in different sectors. The latter plays an important role in the merging of eastern and western ice regions in NA. The inception peak ice volume in the ensemble occurs approximately at 111 ka and therefore lags the summer 60 ∘ N insolation minimum by more than 3 kyr. Ice volumes consistently peak earlier over EA than NA. The inception peak in North America is characterized by a merged Laurentide and Cordilleran ice sheet, with the Davis Strait covered in ice in ∼80 % of simulations. Ice also bridges Greenland and Iceland in all runs by 114 ka and therefore blocks the Denmark Strait. This latter feature would thereby divert the East Greenland Current and Denmark Strait overflow with a potentially significant impact on ocean circulation. The Eurasian ice sheet at its inception peak varies across ensemble runs between a continuous ice sheet and multiple smaller ice caps. In both continents, the colder high latitudes (i.e. Ellesmere and Svalbard) tend to grow ice through the entire simulation (to 102 ka), while lower latitudes lose ice after ∼110 ka. We find temperature decreases over the initial phases of the inception lead to the expansion of NA ice sheet area and that subsequent precipitation increases contribute to its thickening. EA ice sheet area also expands with decreasing temperatures, but sea ice limits any increases in precipitation, leading to an earlier retreat away from the EA maximum ice sheet volume. We also examine the extent to which the capture of both LGI ice growth and retreat constrains the coupled ice–climate model sensitivity to changing atmospheric p CO 2 . The 55-member sub-ensemble that meets our criteria for “acceptable” ice growth and retreat has an equilibrium climate sensitivity lower bound that is 0.3 ∘ C higher than that of the full ensemble. This suggests some potential value of fully coupled ice–climate modelling of the last glacial inception to constrain future climate change. |
format |
Text |
author |
Bahadory, Taimaz Tarasov, Lev Andres, Heather |
spellingShingle |
Bahadory, Taimaz Tarasov, Lev Andres, Heather Last glacial inception trajectories for the Northern Hemisphere from coupled ice and climate modelling |
author_facet |
Bahadory, Taimaz Tarasov, Lev Andres, Heather |
author_sort |
Bahadory, Taimaz |
title |
Last glacial inception trajectories for the Northern Hemisphere from coupled ice and climate modelling |
title_short |
Last glacial inception trajectories for the Northern Hemisphere from coupled ice and climate modelling |
title_full |
Last glacial inception trajectories for the Northern Hemisphere from coupled ice and climate modelling |
title_fullStr |
Last glacial inception trajectories for the Northern Hemisphere from coupled ice and climate modelling |
title_full_unstemmed |
Last glacial inception trajectories for the Northern Hemisphere from coupled ice and climate modelling |
title_sort |
last glacial inception trajectories for the northern hemisphere from coupled ice and climate modelling |
publishDate |
2021 |
url |
https://doi.org/10.5194/cp-17-397-2021 https://cp.copernicus.org/articles/17/397/2021/ |
geographic |
Greenland Svalbard |
geographic_facet |
Greenland Svalbard |
genre |
Davis Strait Denmark Strait East Greenland east greenland current Greenland Ice Sheet Iceland Sea ice Svalbard |
genre_facet |
Davis Strait Denmark Strait East Greenland east greenland current Greenland Ice Sheet Iceland Sea ice Svalbard |
op_source |
eISSN: 1814-9332 |
op_relation |
doi:10.5194/cp-17-397-2021 https://cp.copernicus.org/articles/17/397/2021/ |
op_doi |
https://doi.org/10.5194/cp-17-397-2021 |
container_title |
Climate of the Past |
container_volume |
17 |
container_issue |
1 |
container_start_page |
397 |
op_container_end_page |
418 |
_version_ |
1766396128501170176 |