Oceanic and atmospheric forcing of Larsen C Ice-Shelf thinning

Holland, P.R. ORCID: https://orcid.org/0000-0001-8370-289X; Brisbourne, A. ORCID: https://orcid.org/0000-0002-9887-7120; Corr, H.F.J.; McGrath, D.; Purdon, K.; Paden, J.; Fricker, H.A.; Paolo, F.S.; Fleming, A.H. ORCID: https://orcid.org/0000-0002-0143-4527. 2015 Oceanic and atmospheric forcing of Larsen C Ice-Shelf thinning. The Cryosphere, 9. 1005-1024. https://doi.org/10.5194/tc-9-1005-2015

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Abstract/Summary

The catastrophic collapses of Larsen A and B ice shelves on the eastern Antarctic Peninsula have caused their tributary glaciers to accelerate, contributing to sea-level rise and freshening the Antarctic Bottom Water formed nearby. The surface of Larsen C Ice Shelf (LCIS), the largest ice shelf on the peninsula, is lowering. This could be caused by unbalanced ocean melting (ice loss) or enhanced firn melting and compaction (englacial air loss). Using a novel method to analyse eight radar surveys, this study derives separate estimates of ice and air thickness changes during a 15-year period. The uncertainties are considerable, but the primary estimate is that the surveyed lowering (0.066 ± 0.017 m yr−1) is caused by both ice loss (0.28 ± 0.18 m yr−1) and firn-air loss (0.037 ± 0.026 m yr−1). The ice loss is much larger than the air loss, but both contribute approximately equally to the lowering because the ice is floating. The ice loss could be explained by high basal melting and/or ice divergence, and the air loss by low surface accumulation or high surface melting and/or compaction. The primary estimate therefore requires that at least two forcings caused the surveyed lowering. Mechanisms are discussed by which LCIS stability could be compromised in the future. The most rapid pathways to collapse are offered by the ungrounding of LCIS from Bawden Ice Rise or ice-front retreat past a "compressive arch" in strain rates. Recent evidence suggests that either mechanism could pose an imminent risk.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	https://doi.org/10.5194/tc-9-1005-2015
Programmes:	BAS Programmes > Polar Science for Planet Earth (2009 - ) > Ice Sheets BAS Programmes > Polar Science for Planet Earth (2009 - ) > Polar Oceans
ISSN:	1994-0440
Date made live:	19 Jan 2015 14:14 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/509421

Item Type:

Publication - Article

Digital Object Identifier (DOI):

https://doi.org/10.5194/tc-9-1005-2015

Programmes:

BAS Programmes > Polar Science for Planet Earth (2009 - ) > Ice Sheets
BAS Programmes > Polar Science for Planet Earth (2009 - ) > Polar Oceans

ISSN:

1994-0440

Date made live:

19 Jan 2015 14:14 +0 (UTC)

URI:

https://nora.nerc.ac.uk/id/eprint/509421