Simulating the Holocene deglaciation across a marine-terminating portion of southwestern Greenland in response to marine and atmospheric forcings
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Published:2022-06-17
Issue:6
Volume:16
Page:2355-2372
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ISSN:1994-0424
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Container-title:The Cryosphere
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language:en
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Short-container-title:The Cryosphere
Author:
Cuzzone Joshua K., Young Nicolás E.ORCID, Morlighem MathieuORCID, Briner Jason P., Schlegel Nicole-JeanneORCID
Abstract
Abstract. Numerical simulations of the Greenland Ice Sheet (GrIS) over geologic
timescales can greatly improve our knowledge of the critical factors driving
GrIS demise during climatically warm periods, which has clear relevance for
better predicting GrIS behavior over the upcoming centuries. To assess the
fidelity of these modeling efforts, however, observational constraints of
past ice sheet change are needed. Across southwestern Greenland, geologic
records detail Holocene ice retreat across both terrestrial-based and marine-terminating environments, providing an ideal opportunity to rigorously
benchmark model simulations against geologic reconstructions of ice sheet
change. Here, we present regional ice sheet modeling results using the
Ice-sheet and Sea-level System Model (ISSM) of Holocene ice sheet history
across an extensive fjord region in southwestern Greenland covering the
landscape around the Kangiata Nunaata Sermia (KNS) glacier and extending
outward along the 200 km Nuup Kangerula (Godthåbsfjord). Our
simulations, forced by reconstructions of Holocene climate and recently
implemented calving laws, assess the sensitivity of ice retreat across the
KNS region to atmospheric and oceanic forcing. Our simulations reveal that
the geologically reconstructed ice retreat across the terrestrial landscape
in the study area was likely driven by fluctuations in surface mass balance
in response to Early Holocene warming – and was likely not influenced
significantly by the response of adjacent outlet glaciers to calving and
ocean-induced melting. The impact of ice calving within fjords, however,
plays a significant role by enhancing ice discharge at the terminus, leading
to interior thinning up to the ice divide that is consistent with
reconstructed magnitudes of Early Holocene ice thinning. Our results,
benchmarked against geologic constraints of past ice-margin change, suggest
that while calving did not strongly influence Holocene ice-margin migration
across terrestrial portions of the KNS forefield, it strongly impacted
regional mass loss. While these results imply that the implementation and
resolution of ice calving in paleo-ice-flow models is important towards
making more robust estimations of past ice mass change, they also illustrate
the importance these processes have on contemporary and future long-term ice
mass change across similar fjord-dominated regions of the GrIS.
Funder
Division of Arctic Sciences
Publisher
Copernicus GmbH
Subject
Earth-Surface Processes,Water Science and Technology
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