Millennial-scale migration of the frozen/melted basal boundary, western Greenland ice sheet

The geometry and thermal structure of western Greenland ice sheet are known to have undergone relatively substantial change over the Holocene. Evolution of the frozen and melted fractions of the bed associated with the ice-sheet retreat over this time frame remains unclear. We address this question...

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Bibliographic Details
Published in:Journal of glaciology Vol. 68; no. 270; pp. 775 - 784
Main Authors: Stansberry, Aidan, Harper, Joel, Johnson, Jesse V., Meierbachtol, Toby
Format: Journal Article
Language:English
Published: Cambridge, UK Cambridge University Press 01.08.2022
Subjects:
Basal ice
Bedrock
Fields
Flowlines
Geothermal power
Glaciation
Greenland ice sheet
Heat conductivity
Heat flux
Heat sinks
Heat transfer
Heating
Holocene
Ice
Ice ages
Ice sheets
ice temperature
ice-sheet modeling
Simulation
Thermal structure
Topography
Greenland
Basal ice
ice temperature
ice-sheet modeling
ISSN:0022-1430, 1727-5652
Online Access:Get full text
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Summary:The geometry and thermal structure of western Greenland ice sheet are known to have undergone relatively substantial change over the Holocene. Evolution of the frozen and melted fractions of the bed associated with the ice-sheet retreat over this time frame remains unclear. We address this question using a thermo-mechanically coupled flowline model to simulate a 11 ka period of ice-sheet retreat in west central Greenland. Results indicate an episode of ~100 km of terminus retreat corresponded to ~16 km of upstream frozen/melted basal boundary migration. The majority of migration of the frozen area is associated with the enhancement of the frictional and strain heating fields, which are accentuated toward the retreating ice margin. The thermally active bedrock layer acts as a heat sink, tending to slow contraction of frozen-bed conditions. Since the bedrock heat flux in our region is relatively low compared to other regions of the ice sheet, the frozen region is relatively greater and therefore more susceptible to marginward changes in the frictional and strain heating fields. Migration of melted regions thus depends on both geometric changes and the antecedent thermal state of the bedrock and ice, both of which vary considerably around the ice sheet.
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ISSN:0022-1430
1727-5652
DOI:10.1017/jog.2021.134