Holocene Glacier Fluctuations and Quaternary Ice Sheet Evolution on Cumberland Peninsula, Baffin Island

Arctic temperatures are increasing faster than the Northern Hemisphere average due to strong positive feedbacks unique to polar regions. However, the degree to which recent Arctic warming is unprecedented remains a topic of debate. Because Arctic glacier dimensions are dominantly controlled by summe...

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Main Author: Pendleton, Simon Lewis
Format: Text
Language:unknown
Published: CU Scholar 2019
Subjects:
Online Access:https://scholar.colorado.edu/geol_gradetds/164
https://scholar.colorado.edu/cgi/viewcontent.cgi?article=1168&context=geol_gradetds
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spelling ftunicolboulder:oai:scholar.colorado.edu:geol_gradetds-1168 2023-05-15T14:52:26+02:00 Holocene Glacier Fluctuations and Quaternary Ice Sheet Evolution on Cumberland Peninsula, Baffin Island Pendleton, Simon Lewis 2019-01-01T08:00:00Z application/pdf https://scholar.colorado.edu/geol_gradetds/164 https://scholar.colorado.edu/cgi/viewcontent.cgi?article=1168&context=geol_gradetds unknown CU Scholar https://scholar.colorado.edu/geol_gradetds/164 https://scholar.colorado.edu/cgi/viewcontent.cgi?article=1168&context=geol_gradetds Geological Sciences Graduate Theses & Dissertations arctic cosmogenic exposure dating paleoclimate radiocarbon dating Geology text 2019 ftunicolboulder 2019-07-12T23:30:07Z Arctic temperatures are increasing faster than the Northern Hemisphere average due to strong positive feedbacks unique to polar regions. However, the degree to which recent Arctic warming is unprecedented remains a topic of debate. Because Arctic glacier dimensions are dominantly controlled by summer temperature, records of past glacier activity can provide context for the magnitude of modern warming. The modern-day east coast of Baffin Island, Arctic Canada, is characterized by deep fiords separated by low-relief, high elevation uplands that support numerous thin, cold-based ice caps that are frozen to the underlying surface and thus minimally erosive. As these ice caps retreat under a warming climate, they reveal dead tundra plants, still in their growth position, that have been entombed by ice since the time ice expanded over that site. Radiocarbon dates from such plants thus constrain the timing of ice cap growth. Additionally, recently exposed uneroded rock surfaces contain a long-term record of ice cover in their cosmogenic radionuclide inventoies. In this dissertation, I have incorporated radiocarbon ages of preserved plants and cosmogenic nuclide inventories of adjacent rock surfaces into 1D and 2D numerical models to constrain ice cover histories over the Quaternary. This approach reveals that Baffin Island ice caps grew gradually over the past ~2000 years, prior to rapid retreat during the last century. These data-constrained models also suggest that peak warmth during the Holocene occurred ~2000-5000 years earlier than the 8 to 5 ka suggested by biologic records, and that modern warming exceeds that early Holocene warmth, despite present-day Northern Hemisphere summer solar insolation being ~9% lower. Furthermore, some settings yielded plant ages and cosmogenic nuclide inventories indicative of ice cover for >40,000 years; these sites have likely been continuously ice-covered since the Last Interglacial period. The implication of this continuous cover is that summer temperatures on Baffin Island are now, on average, warmer than they have been for the past ~115,000 years. Finally, measurement and inversion modelling of longer-lived cosmogenic radionuclides from the same preserved landscapes indicate that the Laurentide Ice Sheet transitioned from more uniformly erosive to selectively erosive as fiord systems became more mature through successive Quaternary glacial cycles. Text Arctic Baffin Island Baffin Cumberland Peninsula glacier* Ice Sheet Tundra University of Colorado, Boulder: CU Scholar Arctic Baffin Island Canada Cumberland Peninsula ENVELOPE(-64.497,-64.497,66.501,66.501)
institution Open Polar
collection University of Colorado, Boulder: CU Scholar
op_collection_id ftunicolboulder
language unknown
topic arctic
cosmogenic exposure dating
paleoclimate
radiocarbon dating
Geology
spellingShingle arctic
cosmogenic exposure dating
paleoclimate
radiocarbon dating
Geology
Pendleton, Simon Lewis
Holocene Glacier Fluctuations and Quaternary Ice Sheet Evolution on Cumberland Peninsula, Baffin Island
topic_facet arctic
cosmogenic exposure dating
paleoclimate
radiocarbon dating
Geology
description Arctic temperatures are increasing faster than the Northern Hemisphere average due to strong positive feedbacks unique to polar regions. However, the degree to which recent Arctic warming is unprecedented remains a topic of debate. Because Arctic glacier dimensions are dominantly controlled by summer temperature, records of past glacier activity can provide context for the magnitude of modern warming. The modern-day east coast of Baffin Island, Arctic Canada, is characterized by deep fiords separated by low-relief, high elevation uplands that support numerous thin, cold-based ice caps that are frozen to the underlying surface and thus minimally erosive. As these ice caps retreat under a warming climate, they reveal dead tundra plants, still in their growth position, that have been entombed by ice since the time ice expanded over that site. Radiocarbon dates from such plants thus constrain the timing of ice cap growth. Additionally, recently exposed uneroded rock surfaces contain a long-term record of ice cover in their cosmogenic radionuclide inventoies. In this dissertation, I have incorporated radiocarbon ages of preserved plants and cosmogenic nuclide inventories of adjacent rock surfaces into 1D and 2D numerical models to constrain ice cover histories over the Quaternary. This approach reveals that Baffin Island ice caps grew gradually over the past ~2000 years, prior to rapid retreat during the last century. These data-constrained models also suggest that peak warmth during the Holocene occurred ~2000-5000 years earlier than the 8 to 5 ka suggested by biologic records, and that modern warming exceeds that early Holocene warmth, despite present-day Northern Hemisphere summer solar insolation being ~9% lower. Furthermore, some settings yielded plant ages and cosmogenic nuclide inventories indicative of ice cover for >40,000 years; these sites have likely been continuously ice-covered since the Last Interglacial period. The implication of this continuous cover is that summer temperatures on Baffin Island are now, on average, warmer than they have been for the past ~115,000 years. Finally, measurement and inversion modelling of longer-lived cosmogenic radionuclides from the same preserved landscapes indicate that the Laurentide Ice Sheet transitioned from more uniformly erosive to selectively erosive as fiord systems became more mature through successive Quaternary glacial cycles.
format Text
author Pendleton, Simon Lewis
author_facet Pendleton, Simon Lewis
author_sort Pendleton, Simon Lewis
title Holocene Glacier Fluctuations and Quaternary Ice Sheet Evolution on Cumberland Peninsula, Baffin Island
title_short Holocene Glacier Fluctuations and Quaternary Ice Sheet Evolution on Cumberland Peninsula, Baffin Island
title_full Holocene Glacier Fluctuations and Quaternary Ice Sheet Evolution on Cumberland Peninsula, Baffin Island
title_fullStr Holocene Glacier Fluctuations and Quaternary Ice Sheet Evolution on Cumberland Peninsula, Baffin Island
title_full_unstemmed Holocene Glacier Fluctuations and Quaternary Ice Sheet Evolution on Cumberland Peninsula, Baffin Island
title_sort holocene glacier fluctuations and quaternary ice sheet evolution on cumberland peninsula, baffin island
publisher CU Scholar
publishDate 2019
url https://scholar.colorado.edu/geol_gradetds/164
https://scholar.colorado.edu/cgi/viewcontent.cgi?article=1168&context=geol_gradetds
long_lat ENVELOPE(-64.497,-64.497,66.501,66.501)
geographic Arctic
Baffin Island
Canada
Cumberland Peninsula
geographic_facet Arctic
Baffin Island
Canada
Cumberland Peninsula
genre Arctic
Baffin Island
Baffin
Cumberland Peninsula
glacier*
Ice Sheet
Tundra
genre_facet Arctic
Baffin Island
Baffin
Cumberland Peninsula
glacier*
Ice Sheet
Tundra
op_source Geological Sciences Graduate Theses & Dissertations
op_relation https://scholar.colorado.edu/geol_gradetds/164
https://scholar.colorado.edu/cgi/viewcontent.cgi?article=1168&context=geol_gradetds
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