Controls on interior West Antarctic Ice Sheet Elevations: inferences from geologic constraints and ice sheet modeling
Knowledge of the West Antarctic Ice Sheet (WAIS) response to past sea level and climate forcing is necessary to predict its response to warmer temperatures in the future. The timing and extent of past interior WAIS elevation changes provides insight to WAIS behavior and constraints for ice sheet mod...
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ftcolumbiauniv:oai:academiccommons.columbia.edu:10.7916/D8CG010P 2023-05-15T13:50:01+02:00 Controls on interior West Antarctic Ice Sheet Elevations: inferences from geologic constraints and ice sheet modeling Ackert Jr., Robert P. Putnam, Aaron Ervin Mukhopadhyay, Sujoy Pollard, David DeConto, Robert M. Kurz, Mark D. Borns Jr., Harold W. 2013 https://doi.org/10.7916/D8CG010P English eng https://doi.org/10.7916/D8CG010P Climatic changes Geology Geophysics Articles 2013 ftcolumbiauniv https://doi.org/10.7916/D8CG010P 2019-04-04T08:08:58Z Knowledge of the West Antarctic Ice Sheet (WAIS) response to past sea level and climate forcing is necessary to predict its response to warmer temperatures in the future. The timing and extent of past interior WAIS elevation changes provides insight to WAIS behavior and constraints for ice sheet models. Constraints prior to the Last Glacial Maximum (LGM) however, are rare. Surface exposure ages of glacial erratics near the WAIS divide at Mt. Waesche in Marie Byrd Land, and at the Ohio Range in the Transantarctic Mountains, range from ∼10 ka to >500 ka without a dependence on elevation. The probability distribution functions (PDF) of the exposure ages at both locations, are remarkably similar. During the last glaciation, maximum interior ice elevations as recorded by moraines and erratics were reached between 10 ka and 12 ka. However, most exposure ages are older than the LGM and cluster around ∼40 ka and ∼80 ka. The peak in the exposure age distributions at ∼40 ka includes ages of alpine moraine boulders at Mercer Ridge in the Ohio Range. Comparison of the PDF of exposures ages from the Ohio Range and Mt. Waesche with the temperature record from the Fuji Dome ice core indicates that the youngest peak in the exposure age distributions corresponds to the abrupt warming during the Last Glacial termination. A prominent peak in the Ohio Range PDF corresponds to the penultimate termination (stage 5e). During the intervening glacial period, there is not a consistent relationship between the peaks in the PDF at each location and temperature. A combined ice sheet/ice shelf model with forcing scaled to marine δ18O predicts that interior WAIS elevations near the ice divide have varied ∼300 m over the Last Glacial cycle. Peaks in the PDF correspond to model highstands over the last 200 ka. In the simulated elevation history, maximum ice elevations at Ohio Range (+100 m) and Mt. Waesche (+60 m) occur at ∼10 ka, in agreement with observations from these sites. During collapse of the marine portion of the WAIS, ice elevations at Ohio Range and Mt. Waesche are drawn down at least 200 m below the present ice elevation. The good correspondence between the model results and observations at both the Ohio Range and Mt. Waesche supports the conclusion that interior WAIS highstands do not occur during glacial maximums. Rather, the highstands are controlled primarily by increased accumulation during temperature maximums that occur early in the interglacials. Interior down-draw events follow highstands, resulting from the arrival of a wave of thinning triggered by retreat of the WAIS grounding line coupled with decreasing accumulation rates. Article in Journal/Newspaper Antarc* Antarctic ice core Ice Sheet Ice Shelf Marie Byrd Land Columbia University: Academic Commons Antarctic Byrd Marie Byrd Land ENVELOPE(-130.000,-130.000,-78.000,-78.000) Mercer ENVELOPE(65.647,65.647,-70.227,-70.227) Mercer Ridge ENVELOPE(-113.750,-113.750,-84.833,-84.833) Ohio Range ENVELOPE(-114.000,-114.000,-84.750,-84.750) Transantarctic Mountains West Antarctic Ice Sheet |
institution |
Open Polar |
collection |
Columbia University: Academic Commons |
op_collection_id |
ftcolumbiauniv |
language |
English |
topic |
Climatic changes Geology Geophysics |
spellingShingle |
Climatic changes Geology Geophysics Ackert Jr., Robert P. Putnam, Aaron Ervin Mukhopadhyay, Sujoy Pollard, David DeConto, Robert M. Kurz, Mark D. Borns Jr., Harold W. Controls on interior West Antarctic Ice Sheet Elevations: inferences from geologic constraints and ice sheet modeling |
topic_facet |
Climatic changes Geology Geophysics |
description |
Knowledge of the West Antarctic Ice Sheet (WAIS) response to past sea level and climate forcing is necessary to predict its response to warmer temperatures in the future. The timing and extent of past interior WAIS elevation changes provides insight to WAIS behavior and constraints for ice sheet models. Constraints prior to the Last Glacial Maximum (LGM) however, are rare. Surface exposure ages of glacial erratics near the WAIS divide at Mt. Waesche in Marie Byrd Land, and at the Ohio Range in the Transantarctic Mountains, range from ∼10 ka to >500 ka without a dependence on elevation. The probability distribution functions (PDF) of the exposure ages at both locations, are remarkably similar. During the last glaciation, maximum interior ice elevations as recorded by moraines and erratics were reached between 10 ka and 12 ka. However, most exposure ages are older than the LGM and cluster around ∼40 ka and ∼80 ka. The peak in the exposure age distributions at ∼40 ka includes ages of alpine moraine boulders at Mercer Ridge in the Ohio Range. Comparison of the PDF of exposures ages from the Ohio Range and Mt. Waesche with the temperature record from the Fuji Dome ice core indicates that the youngest peak in the exposure age distributions corresponds to the abrupt warming during the Last Glacial termination. A prominent peak in the Ohio Range PDF corresponds to the penultimate termination (stage 5e). During the intervening glacial period, there is not a consistent relationship between the peaks in the PDF at each location and temperature. A combined ice sheet/ice shelf model with forcing scaled to marine δ18O predicts that interior WAIS elevations near the ice divide have varied ∼300 m over the Last Glacial cycle. Peaks in the PDF correspond to model highstands over the last 200 ka. In the simulated elevation history, maximum ice elevations at Ohio Range (+100 m) and Mt. Waesche (+60 m) occur at ∼10 ka, in agreement with observations from these sites. During collapse of the marine portion of the WAIS, ice elevations at Ohio Range and Mt. Waesche are drawn down at least 200 m below the present ice elevation. The good correspondence between the model results and observations at both the Ohio Range and Mt. Waesche supports the conclusion that interior WAIS highstands do not occur during glacial maximums. Rather, the highstands are controlled primarily by increased accumulation during temperature maximums that occur early in the interglacials. Interior down-draw events follow highstands, resulting from the arrival of a wave of thinning triggered by retreat of the WAIS grounding line coupled with decreasing accumulation rates. |
format |
Article in Journal/Newspaper |
author |
Ackert Jr., Robert P. Putnam, Aaron Ervin Mukhopadhyay, Sujoy Pollard, David DeConto, Robert M. Kurz, Mark D. Borns Jr., Harold W. |
author_facet |
Ackert Jr., Robert P. Putnam, Aaron Ervin Mukhopadhyay, Sujoy Pollard, David DeConto, Robert M. Kurz, Mark D. Borns Jr., Harold W. |
author_sort |
Ackert Jr., Robert P. |
title |
Controls on interior West Antarctic Ice Sheet Elevations: inferences from geologic constraints and ice sheet modeling |
title_short |
Controls on interior West Antarctic Ice Sheet Elevations: inferences from geologic constraints and ice sheet modeling |
title_full |
Controls on interior West Antarctic Ice Sheet Elevations: inferences from geologic constraints and ice sheet modeling |
title_fullStr |
Controls on interior West Antarctic Ice Sheet Elevations: inferences from geologic constraints and ice sheet modeling |
title_full_unstemmed |
Controls on interior West Antarctic Ice Sheet Elevations: inferences from geologic constraints and ice sheet modeling |
title_sort |
controls on interior west antarctic ice sheet elevations: inferences from geologic constraints and ice sheet modeling |
publishDate |
2013 |
url |
https://doi.org/10.7916/D8CG010P |
long_lat |
ENVELOPE(-130.000,-130.000,-78.000,-78.000) ENVELOPE(65.647,65.647,-70.227,-70.227) ENVELOPE(-113.750,-113.750,-84.833,-84.833) ENVELOPE(-114.000,-114.000,-84.750,-84.750) |
geographic |
Antarctic Byrd Marie Byrd Land Mercer Mercer Ridge Ohio Range Transantarctic Mountains West Antarctic Ice Sheet |
geographic_facet |
Antarctic Byrd Marie Byrd Land Mercer Mercer Ridge Ohio Range Transantarctic Mountains West Antarctic Ice Sheet |
genre |
Antarc* Antarctic ice core Ice Sheet Ice Shelf Marie Byrd Land |
genre_facet |
Antarc* Antarctic ice core Ice Sheet Ice Shelf Marie Byrd Land |
op_relation |
https://doi.org/10.7916/D8CG010P |
op_doi |
https://doi.org/10.7916/D8CG010P |
_version_ |
1766252753240195072 |