Impact of warming shelf waters on ice mélange and terminus retreat at a large SE Greenland glacier

By the end of 2018 Kangerlussuaq Glacier in southeast Greenland had retreated further inland than at any time in the past 80 years and its terminus was approaching a region of retrograde bed slope from where further rapid retreat would have been inevitable. Here we show that the retreat occurred bec...

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Published in:The cryosphere Vol. 13; no. 9; pp. 2303 - 2315
Main Authors: Bevan, Suzanne L., Luckman, Adrian J., Benn, Douglas I., Cowton, Tom, Todd, Joe
Format: Journal Article
Language:English
Published: Katlenburg-Lindau Copernicus GmbH 05.09.2019
Copernicus Publications
Subjects:
Continental shelves
Digitization
Fjords
Glacier retreat
Glaciers
Ice calving
Icebergs
Ocean warming
Oceans
open climate campaign
Remote sensing
Satellites
Sea ice
Sea level
Software
Stability
Surface stability
Surface water
Tidewater
Time series
Velocity
Winter
Greenland
ISSN:1994-0424, 1994-0416, 1994-0424, 1994-0416
Online Access:Get full text
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Summary:By the end of 2018 Kangerlussuaq Glacier in southeast Greenland had retreated further inland than at any time in the past 80 years and its terminus was approaching a region of retrograde bed slope from where further rapid retreat would have been inevitable. Here we show that the retreat occurred because the glacier failed to advance during the winters of 2016/17 and 2017/18 owing to a weakened proglacial mélange. This mixture of sea ice and icebergs is normally rigid enough to inhibit calving in winter, but for 2 consecutive years it repeatedly collapsed, allowing Kangerlussuaq Glacier to continue to calve all year round. The mélange break-ups followed the establishment of anomalously warm surface water on the continental shelf during 2016, which likely penetrated the fjord. As calving continued uninterrupted from summer 2016 to the end of 2018 the glacier accelerated by 35 % and thinned by 35 m. These observations demonstrate the importance of near-surface ocean temperatures in tidewater glacier stability and show that it is not only deep-ocean warming that can lead to glacier retreat. During winter 2019 a persistent mélange reformed and the glacier readvanced by 3.5 km.
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ISSN:1994-0424
1994-0416
1994-0424
1994-0416
DOI:10.5194/tc-13-2303-2019