The evolving instability of the remnant Larsen B Ice Shelf and its tributary glaciers
Following the 2002 disintegration of the northern and central parts of the Larsen B Ice Shelf, the tributary glaciers of the southern surviving part initially appeared relatively unchanged and hence assumed to be buttressed sufficiently by the remnant ice shelf. Here, we modify this perception with...
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ftcdlib:oai:escholarship.org:ark:/13030/qt7m1405b0 2023-10-25T01:32:10+02:00 The evolving instability of the remnant Larsen B Ice Shelf and its tributary glaciers Khazendar, Ala Borstad, Christopher P Scheuchl, Bernd Rignot, Eric Seroussi, Helene 2015-01-01 application/pdf https://escholarship.org/uc/item/7m1405b0 unknown eScholarship, University of California qt7m1405b0 https://escholarship.org/uc/item/7m1405b0 CC-BY Antarctica Larsen Ice Shelf ice-shelf instability laser altimetry InSAR ice flow speeds numerical ice modeling Physical Sciences Earth Sciences Geochemistry & Geophysics article 2015 ftcdlib 2023-09-25T18:02:55Z Following the 2002 disintegration of the northern and central parts of the Larsen B Ice Shelf, the tributary glaciers of the southern surviving part initially appeared relatively unchanged and hence assumed to be buttressed sufficiently by the remnant ice shelf. Here, we modify this perception with observations from IceBridge altimetry and InSAR-inferred ice flow speeds. Our analyses show that the surfaces of Leppard and Flask glaciers directly upstream from their grounding lines lowered by 15 to 20 m in the period 2002-2011. The thinning appears to be dynamic as the flow of both glaciers and the remnant ice shelf accelerated in the same period. Flask Glacier started accelerating even before the 2002 disintegration, increasing its flow speed by ~55% between 1997 and 2012. Starbuck Glacier meanwhile did not change much. We hypothesize that the different evolutions of the three glaciers are related to their dissimilar bed topographies and degrees of grounding. We apply numerical modeling and data assimilation that show these changes to be accompanied by a reduction in the buttressing afforded by the remnant ice shelf, a weakening of the shear zones between its flow units and an increase in its fracture. The fast flowing northwestern part of the remnant ice shelf exhibits increasing fragmentation, while the stagnant southeastern part seems to be prone to the formation of large rifts, some of which we show have delimited successive calving events. A large rift only 12 km downstream from the grounding line is currently traversing the stagnant part of the ice shelf, defining the likely front of the next large calving event. We propose that the flow acceleration, ice front retreat and enhanced fracture of the remnant Larsen B Ice Shelf presage its approaching demise. Article in Journal/Newspaper Antarc* Antarctica Flask Glacier Ice Shelf Larsen Ice Shelf University of California: eScholarship Flask Glacier ENVELOPE(-62.792,-62.792,-65.762,-65.762) Larsen Ice Shelf ENVELOPE(-62.500,-62.500,-67.500,-67.500) Starbuck Glacier ENVELOPE(-62.416,-62.416,-65.616,-65.616) |
institution |
Open Polar |
collection |
University of California: eScholarship |
op_collection_id |
ftcdlib |
language |
unknown |
topic |
Antarctica Larsen Ice Shelf ice-shelf instability laser altimetry InSAR ice flow speeds numerical ice modeling Physical Sciences Earth Sciences Geochemistry & Geophysics |
spellingShingle |
Antarctica Larsen Ice Shelf ice-shelf instability laser altimetry InSAR ice flow speeds numerical ice modeling Physical Sciences Earth Sciences Geochemistry & Geophysics Khazendar, Ala Borstad, Christopher P Scheuchl, Bernd Rignot, Eric Seroussi, Helene The evolving instability of the remnant Larsen B Ice Shelf and its tributary glaciers |
topic_facet |
Antarctica Larsen Ice Shelf ice-shelf instability laser altimetry InSAR ice flow speeds numerical ice modeling Physical Sciences Earth Sciences Geochemistry & Geophysics |
description |
Following the 2002 disintegration of the northern and central parts of the Larsen B Ice Shelf, the tributary glaciers of the southern surviving part initially appeared relatively unchanged and hence assumed to be buttressed sufficiently by the remnant ice shelf. Here, we modify this perception with observations from IceBridge altimetry and InSAR-inferred ice flow speeds. Our analyses show that the surfaces of Leppard and Flask glaciers directly upstream from their grounding lines lowered by 15 to 20 m in the period 2002-2011. The thinning appears to be dynamic as the flow of both glaciers and the remnant ice shelf accelerated in the same period. Flask Glacier started accelerating even before the 2002 disintegration, increasing its flow speed by ~55% between 1997 and 2012. Starbuck Glacier meanwhile did not change much. We hypothesize that the different evolutions of the three glaciers are related to their dissimilar bed topographies and degrees of grounding. We apply numerical modeling and data assimilation that show these changes to be accompanied by a reduction in the buttressing afforded by the remnant ice shelf, a weakening of the shear zones between its flow units and an increase in its fracture. The fast flowing northwestern part of the remnant ice shelf exhibits increasing fragmentation, while the stagnant southeastern part seems to be prone to the formation of large rifts, some of which we show have delimited successive calving events. A large rift only 12 km downstream from the grounding line is currently traversing the stagnant part of the ice shelf, defining the likely front of the next large calving event. We propose that the flow acceleration, ice front retreat and enhanced fracture of the remnant Larsen B Ice Shelf presage its approaching demise. |
format |
Article in Journal/Newspaper |
author |
Khazendar, Ala Borstad, Christopher P Scheuchl, Bernd Rignot, Eric Seroussi, Helene |
author_facet |
Khazendar, Ala Borstad, Christopher P Scheuchl, Bernd Rignot, Eric Seroussi, Helene |
author_sort |
Khazendar, Ala |
title |
The evolving instability of the remnant Larsen B Ice Shelf and its tributary glaciers |
title_short |
The evolving instability of the remnant Larsen B Ice Shelf and its tributary glaciers |
title_full |
The evolving instability of the remnant Larsen B Ice Shelf and its tributary glaciers |
title_fullStr |
The evolving instability of the remnant Larsen B Ice Shelf and its tributary glaciers |
title_full_unstemmed |
The evolving instability of the remnant Larsen B Ice Shelf and its tributary glaciers |
title_sort |
evolving instability of the remnant larsen b ice shelf and its tributary glaciers |
publisher |
eScholarship, University of California |
publishDate |
2015 |
url |
https://escholarship.org/uc/item/7m1405b0 |
long_lat |
ENVELOPE(-62.792,-62.792,-65.762,-65.762) ENVELOPE(-62.500,-62.500,-67.500,-67.500) ENVELOPE(-62.416,-62.416,-65.616,-65.616) |
geographic |
Flask Glacier Larsen Ice Shelf Starbuck Glacier |
geographic_facet |
Flask Glacier Larsen Ice Shelf Starbuck Glacier |
genre |
Antarc* Antarctica Flask Glacier Ice Shelf Larsen Ice Shelf |
genre_facet |
Antarc* Antarctica Flask Glacier Ice Shelf Larsen Ice Shelf |
op_relation |
qt7m1405b0 https://escholarship.org/uc/item/7m1405b0 |
op_rights |
CC-BY |
_version_ |
1780727761607852032 |