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Deep glacial troughs and stabilizing ridges unveiled beneath the margins of the Antarctic ice sheet

Abstract

The Antarctic ice sheet has been losing mass over past decades through the accelerated flow of its glaciers, conditioned by ocean temperature and bed topography. Glaciers retreating along retrograde slopes (that is, the bed elevation drops in the inland direction) are potentially unstable, while subglacial ridges slow down the glacial retreat. Despite major advances in the mapping of subglacial bed topography, significant sectors of Antarctica remain poorly resolved and critical spatial details are missing. Here we present a novel, high-resolution and physically based description of Antarctic bed topography using mass conservation. Our results reveal previously unknown basal features with major implications for glacier response to climate change. For example, glaciers flowing across the Transantarctic Mountains are protected by broad, stabilizing ridges. Conversely, in the marine basin of Wilkes Land, East Antarctica, we find retrograde slopes along Ninnis and Denman glaciers, with stabilizing slopes beneath Moscow University, Totten and Lambert glacier system, despite corrections in bed elevation of up to 1 km for the latter. This transformative description of bed topography redefines the high- and lower-risk sectors for rapid sea level rise from Antarctica; it will also significantly impact model projections of sea level rise from Antarctica in the coming centuries.

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Fig. 1: Bed elevation of the Antarctic ice sheet colour coded between −2,000 and 1,000 m above sea level.
Fig. 2: Detailed bed topography of Antarctic outlet glaciers.
Fig. 3: Comparison with previous datasets and radar data.

Data availability

BedMachine Antarctica is publicly available at the NSIDC, Boulder, CO, as a MEaSUREs-3 product (http://nsidc.org/data/nsidc-0756).

Code availability

The algorithms used to generate the bed topography are included in the open-source Ice Sheet System Model (https://issm.jpl.nasa.gov).

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Acknowledgements

This work was performed at the University of California Irvine under a contract with the National Aeronautics and Space Administration Cryospheric Sciences Program (NNX17AI02G, NNX15AD55G and NNX14AN03G), MEaSURES-3 Program (80NSSC18M0083) and the NSF-NERC International Thwaites Glacier Collaboration (award 1739031). We acknowledge the use of data and/or data products from CReSIS generated with support from the University of Kansas, NSF grant ANT-0424589, and NASA Operation IceBridge grant NNX16AH54G, and date products collected by the ICECAP collaboration under NSF grants ANT-1043761, ANT-1543452, ANT-0733025, ANT-1443690 and ANT-1143843, NASA grants (NNG10HPO6C and NNX11AD33G), and AAD projects (3013, 4077 and 4346), the Australian Government’s Cooperative Research Centre program through the Antarctic Climate and Ecosystems Cooperative Research Centre and the Australian Research Council’s Special Research Initiative for Antarctic Gateway Partnership (Project ID SR140300001), the National Natural Science Foundation of China grant 41876227, with support by the G. Unger Vetlesen Foundation. R.D. was partially supported by the DFG Emmy Noether Grant DR 822/3-1, W.S.L. was supported by the Korean Ministry of Oceans and Fisheries (KIMST20190361; PM19020) and KOPRI (PE19110), F.F. acknowledges ESA (PolarGAP & 4D Antarctica projects) and BAS core programme support and E.C.S. was funded through the DFG Cost S2S project (EI672/10-1) in the framework of the priority programme “Antarctic Research with comparative investigations in Arctic ice areas”.

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Contributions

M.M. developed the algorithm and led the calculations. H.S. assisted in implementing the algorithm. M.M. and E.R. wrote the first draft of the manuscript. All authors contributed data and to the writing of the Article.

Corresponding author

Correspondence to Mathieu Morlighem.

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The authors declare no competing interests.

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Supplementary information

Supplementary Information

Supplementary method, Figs. 1–60, Tables 1–3 and references.

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Morlighem, M., Rignot, E., Binder, T. et al. Deep glacial troughs and stabilizing ridges unveiled beneath the margins of the Antarctic ice sheet. Nat. Geosci. 13, 132–137 (2020). https://doi.org/10.1038/s41561-019-0510-8

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