Exploring the impact of atmospheric forcing and basal drag on the Antarctic Ice Sheet under Last Glacial Maximum conditions
<p>Little is known about the distribution of ice in the Antarctic Ice Sheet (AIS) during the Last Glacial Maximum (LGM). Whereas marine and terrestrial geological data indicate that the grounded ice advanced to a position close to the continental-shelf break, the total ice volume is unclear. G...
| Main Authors: | , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2021-01-01
|
| Series: | The Cryosphere |
| Online Access: | https://tc.copernicus.org/articles/15/215/2021/tc-15-215-2021.pdf |
| _version_ | 1818607002043023360 |
|---|---|
| author | J. Blasco J. Blasco J. Alvarez-Solas J. Alvarez-Solas A. Robinson A. Robinson A. Robinson M. Montoya M. Montoya |
| author_facet | J. Blasco J. Blasco J. Alvarez-Solas J. Alvarez-Solas A. Robinson A. Robinson A. Robinson M. Montoya M. Montoya |
| author_sort | J. Blasco |
| collection | DOAJ |
| description | <p>Little is known about the distribution of ice in the Antarctic Ice Sheet (AIS) during the Last Glacial Maximum (LGM). Whereas marine and terrestrial geological data indicate that the grounded ice advanced to a position close to the continental-shelf break, the total ice volume is unclear. Glacial boundary conditions are potentially important sources of uncertainty, in particular basal friction and climatic boundary conditions. Basal friction exerts a strong control on the large-scale dynamics of the ice sheet and thus affects its size and is not well constrained. Glacial climatic boundary conditions determine the net accumulation and ice temperature and are also poorly known. Here we explore the effect of the uncertainty in both features on the total simulated ice storage of the AIS at the LGM. For this purpose we use a hybrid ice sheet shelf model that is forced with different basal drag choices and glacial background climatic conditions obtained from the LGM ensemble climate simulations of the third phase of the Paleoclimate Modelling Intercomparison Project (PMIP3). Overall, we find that the spread in the simulated ice volume for the tested basal drag parameterizations is about the same range as for the different general circulation model (GCM) forcings (4 to 6 m sea level equivalent). For a wide range of plausible basal friction configurations, the simulated ice dynamics vary widely but all simulations produce fully extended ice sheets towards the continental-shelf break. More dynamically active ice sheets correspond to lower ice volumes, while they remain consistent with the available constraints on ice extent. Thus, this work points to the possibility of an AIS with very active ice streams during the LGM. In addition, we find that the surface boundary temperature field plays a crucial role in determining the ice extent through its effect on viscosity. For ice sheets of a similar extent and comparable dynamics, we find that the precipitation field determines the total AIS volume. However, precipitation is highly uncertain. Climatic fields simulated by climate models show more precipitation in coastal regions than a spatially uniform anomaly, which can lead to larger ice volumes. Our results strongly support using these paleoclimatic fields to simulate and study the LGM and potentially other time periods like the last interglacial. However, their accuracy must be assessed as well, as differences between climate model forcing lead to a large spread in the simulated ice volume and extension.</p> |
| first_indexed | 2024-12-16T14:19:49Z |
| format | Article |
| id | doaj.art-99dabf8568e9425f956e254f8de011a8 |
| institution | Directory Open Access Journal |
| issn | 1994-0416 1994-0424 |
| language | English |
| last_indexed | 2024-12-16T14:19:49Z |
| publishDate | 2021-01-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | The Cryosphere |
| spelling | doaj.art-99dabf8568e9425f956e254f8de011a82022-12-21T22:28:31ZengCopernicus PublicationsThe Cryosphere1994-04161994-04242021-01-011521523110.5194/tc-15-215-2021Exploring the impact of atmospheric forcing and basal drag on the Antarctic Ice Sheet under Last Glacial Maximum conditionsJ. Blasco0J. Blasco1J. Alvarez-Solas2J. Alvarez-Solas3A. Robinson4A. Robinson5A. Robinson6M. Montoya7M. Montoya8Departamento de Física de la Tierra y Astrofísica, Universidad Complutense de Madrid, Facultad de Ciencias Físicas, 28040 Madrid, SpainInstituto de Geociencias, Consejo Superior de Investigaciones Cientifícas-Universidad Complutense de Madrid, 28040 Madrid, SpainDepartamento de Física de la Tierra y Astrofísica, Universidad Complutense de Madrid, Facultad de Ciencias Físicas, 28040 Madrid, SpainInstituto de Geociencias, Consejo Superior de Investigaciones Cientifícas-Universidad Complutense de Madrid, 28040 Madrid, SpainDepartamento de Física de la Tierra y Astrofísica, Universidad Complutense de Madrid, Facultad de Ciencias Físicas, 28040 Madrid, SpainInstituto de Geociencias, Consejo Superior de Investigaciones Cientifícas-Universidad Complutense de Madrid, 28040 Madrid, SpainPotsdam Institute for Climate Impact Research, 14473 Potsdam, GermanyDepartamento de Física de la Tierra y Astrofísica, Universidad Complutense de Madrid, Facultad de Ciencias Físicas, 28040 Madrid, SpainInstituto de Geociencias, Consejo Superior de Investigaciones Cientifícas-Universidad Complutense de Madrid, 28040 Madrid, Spain<p>Little is known about the distribution of ice in the Antarctic Ice Sheet (AIS) during the Last Glacial Maximum (LGM). Whereas marine and terrestrial geological data indicate that the grounded ice advanced to a position close to the continental-shelf break, the total ice volume is unclear. Glacial boundary conditions are potentially important sources of uncertainty, in particular basal friction and climatic boundary conditions. Basal friction exerts a strong control on the large-scale dynamics of the ice sheet and thus affects its size and is not well constrained. Glacial climatic boundary conditions determine the net accumulation and ice temperature and are also poorly known. Here we explore the effect of the uncertainty in both features on the total simulated ice storage of the AIS at the LGM. For this purpose we use a hybrid ice sheet shelf model that is forced with different basal drag choices and glacial background climatic conditions obtained from the LGM ensemble climate simulations of the third phase of the Paleoclimate Modelling Intercomparison Project (PMIP3). Overall, we find that the spread in the simulated ice volume for the tested basal drag parameterizations is about the same range as for the different general circulation model (GCM) forcings (4 to 6 m sea level equivalent). For a wide range of plausible basal friction configurations, the simulated ice dynamics vary widely but all simulations produce fully extended ice sheets towards the continental-shelf break. More dynamically active ice sheets correspond to lower ice volumes, while they remain consistent with the available constraints on ice extent. Thus, this work points to the possibility of an AIS with very active ice streams during the LGM. In addition, we find that the surface boundary temperature field plays a crucial role in determining the ice extent through its effect on viscosity. For ice sheets of a similar extent and comparable dynamics, we find that the precipitation field determines the total AIS volume. However, precipitation is highly uncertain. Climatic fields simulated by climate models show more precipitation in coastal regions than a spatially uniform anomaly, which can lead to larger ice volumes. Our results strongly support using these paleoclimatic fields to simulate and study the LGM and potentially other time periods like the last interglacial. However, their accuracy must be assessed as well, as differences between climate model forcing lead to a large spread in the simulated ice volume and extension.</p>https://tc.copernicus.org/articles/15/215/2021/tc-15-215-2021.pdf |
| spellingShingle | J. Blasco J. Blasco J. Alvarez-Solas J. Alvarez-Solas A. Robinson A. Robinson A. Robinson M. Montoya M. Montoya Exploring the impact of atmospheric forcing and basal drag on the Antarctic Ice Sheet under Last Glacial Maximum conditions The Cryosphere |
| title | Exploring the impact of atmospheric forcing and basal drag on the Antarctic Ice Sheet under Last Glacial Maximum conditions |
| title_full | Exploring the impact of atmospheric forcing and basal drag on the Antarctic Ice Sheet under Last Glacial Maximum conditions |
| title_fullStr | Exploring the impact of atmospheric forcing and basal drag on the Antarctic Ice Sheet under Last Glacial Maximum conditions |
| title_full_unstemmed | Exploring the impact of atmospheric forcing and basal drag on the Antarctic Ice Sheet under Last Glacial Maximum conditions |
| title_short | Exploring the impact of atmospheric forcing and basal drag on the Antarctic Ice Sheet under Last Glacial Maximum conditions |
| title_sort | exploring the impact of atmospheric forcing and basal drag on the antarctic ice sheet under last glacial maximum conditions |
| url | https://tc.copernicus.org/articles/15/215/2021/tc-15-215-2021.pdf |
| work_keys_str_mv | AT jblasco exploringtheimpactofatmosphericforcingandbasaldragontheantarcticicesheetunderlastglacialmaximumconditions AT jblasco exploringtheimpactofatmosphericforcingandbasaldragontheantarcticicesheetunderlastglacialmaximumconditions AT jalvarezsolas exploringtheimpactofatmosphericforcingandbasaldragontheantarcticicesheetunderlastglacialmaximumconditions AT jalvarezsolas exploringtheimpactofatmosphericforcingandbasaldragontheantarcticicesheetunderlastglacialmaximumconditions AT arobinson exploringtheimpactofatmosphericforcingandbasaldragontheantarcticicesheetunderlastglacialmaximumconditions AT arobinson exploringtheimpactofatmosphericforcingandbasaldragontheantarcticicesheetunderlastglacialmaximumconditions AT arobinson exploringtheimpactofatmosphericforcingandbasaldragontheantarcticicesheetunderlastglacialmaximumconditions AT mmontoya exploringtheimpactofatmosphericforcingandbasaldragontheantarcticicesheetunderlastglacialmaximumconditions AT mmontoya exploringtheimpactofatmosphericforcingandbasaldragontheantarcticicesheetunderlastglacialmaximumconditions |