The marine geological imprint of Antarctic ice shelves

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Abstract

Reductions in the thickness and extent of Antarctic ice shelves are triggering increased discharge of marine-terminating glaciers. While the impacts of recent changes are well documented, their role in modulating past ice-sheet dynamics remains poorly constrained. This reflects two persistent issues; first, the effective discrimination of sediments and landforms solely attributable to sub-ice-shelf deposition, and second, challenges in dating these records. Recent progress in deciphering the geological imprint of Antarctic ice shelves is summarised, including advances in dating methods and proxies to reconstruct drivers of change. Finally, we identify several challenges to overcome to fully exploit the paleo record.

Abstract

The recent collapses of ice shelves in Antarctica due to warming make it essential to understand past ice shelf conditions and mechanisms. Here Smith and colleagues review the latest progress in deciphering the geological imprint of Antarctic ice shelves via sediments, landforms and proxy indicators.

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Most cited references 122

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Antarctic ice-sheet loss driven by basal melting of ice shelves.

H. D. Pritchard, S Ligtenberg, H A Fricker … (2012)

Accurate prediction of global sea-level rise requires that we understand the cause of recent, widespread and intensifying glacier acceleration along Antarctic ice-sheet coastal margins. Atmospheric and oceanic forcing have the potential to reduce the thickness and extent of floating ice shelves, potentially limiting their ability to buttress the flow of grounded tributary glaciers. Indeed, recent ice-shelf collapse led to retreat and acceleration of several glaciers on the Antarctic Peninsula. But the extent and magnitude of ice-shelf thickness change, the underlying causes of such change, and its link to glacier flow rate are so poorly understood that its future impact on the ice sheets cannot yet be predicted. Here we use satellite laser altimetry and modelling of the surface firn layer to reveal the circum-Antarctic pattern of ice-shelf thinning through increased basal melt. We deduce that this increased melt is the primary control of Antarctic ice-sheet loss, through a reduction in buttressing of the adjacent ice sheet leading to accelerated glacier flow. The highest thinning rates occur where warm water at depth can access thick ice shelves via submarine troughs crossing the continental shelf. Wind forcing could explain the dominant patterns of both basal melting and the surface melting and collapse of Antarctic ice shelves, through ocean upwelling in the Amundsen and Bellingshausen seas, and atmospheric warming on the Antarctic Peninsula. This implies that climate forcing through changing winds influences Antarctic ice-sheet mass balance, and hence global sea level, on annual to decadal timescales.

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Marine ice sheet collapse potentially under way for the Thwaites Glacier Basin, West Antarctica.

Ian Joughin, Benjamin E Smith, Brooke Medley (2014)

Resting atop a deep marine basin, the West Antarctic Ice Sheet has long been considered prone to instability. Using a numerical model, we investigated the sensitivity of Thwaites Glacier to ocean melt and whether its unstable retreat is already under way. Our model reproduces observed losses when forced with ocean melt comparable to estimates. Simulated losses are moderate ( 1 mm per year of sea-level rise) collapse in the different simulations within the range of 200 to 900 years. Copyright © 2014, American Association for the Advancement of Science.

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Four decades of Antarctic Ice Sheet mass balance from 1979–2017

Eric Rignot, Jérémie Mouginot, Bernd Scheuchl … (2019)

Significance Statement We evaluate the state of the mass balance of the Antarctic Ice Sheet over the last four decades using a comprehensive, precise satellite record and output products from a regional atmospheric climate model to document its impact on sea-level rise. The mass loss is dominated by enhanced glacier flow in areas closest to warm, salty, subsurface circumpolar deep water, including East Antarctica, which has been a major contributor over the entire period. The same sectors are likely to dominate sea-level rise from Antarctica in decades to come as enhanced polar westerlies push more circumpolar deep water toward the glaciers.

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Author and article information

Contributors

James A. Smith:

ORCID: http://orcid.org/0000-0002-1333-2544

jaas@bas.ac.uk

Journal

Journal ID (nlm-ta): Nat Commun

Journal ID (iso-abbrev): Nat Commun

Title: Nature Communications

Publisher: Nature Publishing Group UK (London )

ISSN (Electronic): 2041-1723

Publication date (Electronic): 10 December 2019

Publication date PMC-release: 10 December 2019

Publication date Collection: 2019

Volume: 10

Electronic Location Identifier: 5635

Affiliations

[1 ]ISNI 0000 0004 0598 3800, GRID grid.478592.5, British Antarctic Survey, ; High Cross, Madingley Road, Cambridge, CB3 0ET UK

[2 ]ISNI 0000 0004 1936 8024, GRID grid.8391.3, College of Life and Environmental Sciences, , University of Exeter, ; Exeter, UK

[3 ]ISNI 0000 0004 0606 1752, GRID grid.452453.1, Geoscience Australia, ; GPO Box 378, Canberra, ACT 2601 Australia

[4 ]ISNI 0000 0001 0662 7451, GRID grid.64337.35, Louisiana State University, , Department of Geology and Geophysics, ; Baton Rouge, 70803 USA

[5 ]ISNI 0000 0000 9003 8934, GRID grid.261128.e, Department of Geology and Environmental Geosciences, , Northern Illinois University, ; DeKalb, IL USA

[6 ]ISNI 0000 0001 2353 285X, GRID grid.170693.a, Present Address: College of Marine Science, , University of South Florida, ; St Petersburg, FL 33701 USA

Author information

James A. Smith http://orcid.org/0000-0002-1333-2544

Alastair G. C. Graham http://orcid.org/0000-0002-2880-2908

Alix L. Post http://orcid.org/0000-0002-6287-3283

Claus-Dieter Hillenbrand http://orcid.org/0000-0003-0240-7317

Article

Publisher ID: 13496

DOI: 10.1038/s41467-019-13496-5

PMC ID: 6904571

PubMed ID: 31822661

SO-VID: 90015225-1871-4619-9753-618691ef500e

License:

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.

History

Date received : 18 September 2018

Date accepted : 5 November 2019

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ScienceOpen disciplines: Uncategorized

Keywords: climate sciences,environmental sciences,ocean sciences,scientific community

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ScienceOpen disciplines: Uncategorized

Keywords: climate sciences, environmental sciences, ocean sciences, scientific community

The marine geological imprint of Antarctic ice shelves

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Most cited references 122

Antarctic ice-sheet loss driven by basal melting of ice shelves.

Marine ice sheet collapse potentially under way for the Thwaites Glacier Basin, West Antarctica.

Four decades of Antarctic Ice Sheet mass balance from 1979–2017

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