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Regional-scale abrupt mid-Holocene ice sheet thinning in the western Ross Sea, Antarctica

R. S. Jones, R. J. Whitmore, A. N. Mackintosh, K. P. Norton, S. R. Eaves, J. Stutz and M. Christl
Regional-scale abrupt mid-Holocene ice sheet thinning in the western Ross Sea, Antarctica
Geology (Boulder) (October 2020) 49 (3): 278-282


Outlet glaciers drain the majority of ice flow in the Antarctic ice sheet. Theory and numerical models indicate that local bed topography can play a key role in modulating outlet glacier response to climate warming, potentially resulting in delayed, asynchronous, or enhanced retreat. However, the period of modern observations is too short to assess whether local or regional controls dominate ice sheet response on time scales that are critical for understanding ice sheet mass loss over this century and beyond. The recent geological past allows for insight into such centennial-scale ice sheet behavior. We present a cosmogenic surface-exposure chronology from Mawson Glacier, adjacent to a region of the Ross Sea that underwent dynamic marine-based ice sheet retreat following the Last Glacial Maximum. Our data record at least 220 m of abrupt ice thinning between 7.5 and 4.5 ka, followed by more gradual thinning until the last millennium. The timing, rates, and magnitudes of thinning at Mawson Glacier are remarkably similar to that documented 100 km to the south at Mackay Glacier. Together, both outlet glaciers demonstrate that abrupt deglaciation occurred across a broad region in the Mid-Holocene. This happened despite the complex bed topography of the western Ross Sea and implies an overarching external driver of retreat. When compared to regional sea-level and ocean-temperature changes, our data indicate that ocean warming most likely drove grounding-line retreat and ice drawdown, which then accelerated as a result of marine ice sheet instability.

ISSN: 0091-7613
EISSN: 1943-2682
Serial Title: Geology (Boulder)
Serial Volume: 49
Serial Issue: 3
Title: Regional-scale abrupt mid-Holocene ice sheet thinning in the western Ross Sea, Antarctica
Affiliation: Monash University, School of Earth, Atmosphere and Environment, Melbourne, Victoria, Australia
Pages: 278-282
Published: 20201021
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 32
Accession Number: 2021-003232
Categories: Quaternary geologyGeochronology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. geol. sketch map
S76°19'60" - S76°10'00", E162°00'00" - E163°00'00"
Secondary Affiliation: Victoria University of Wellington, NZL, New ZealandEidgenoessische Technische Hochschule Zuerich, CHE, Switzerland
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2021, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 202103
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