Letter

Lower satellite-gravimetry estimates of Antarctic sea-level contribution

  • Nature volume 491, pages 586589 (22 November 2012)
  • doi:10.1038/nature11621
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Abstract

Recent estimates of Antarctica’s present-day rate of ice-mass contribution to changes in sea level range from 31 gigatonnes a year (Gt yr−1; ref. 1) to 246 Gt yr−1 (ref. 2), a range that cannot be reconciled within formal errors3. Time-varying rates of mass loss2,4,5,6 contribute to this, but substantial technique-specific systematic errors also exist3. In particular, estimates of secular ice-mass change derived from Gravity Recovery and Climate Experiment (GRACE) satellite data are dominated by significant uncertainty in the accuracy of models of mass change due to glacial isostatic adjustment7,8 (GIA). Here we adopt a new model of GIA, developed from geological constraints, which produces GIA rates systematically lower than those of previous models, and an improved fit to independent uplift data9. After applying the model to 99 months (from August 2002 to December 2010) of GRACE data, we estimate a continent-wide ice-mass change of −69 ± 18 Gt yr−1 (+0.19 ± 0.05 mm yr−1 sea-level equivalent). This is about a third to a half of the most recently published GRACE estimates2,5, which cover a similar time period but are based on older GIA models. Plausible GIA model uncertainties, and errors relating to removing longitudinal GRACE artefacts (‘destriping’), confine our estimate to the range −126 Gt yr−1 to −29 Gt yr−1 (0.08–0.35 mm yr−1 sea-level equivalent). We resolve 26 independent drainage basins and find that Antarctic mass loss, and its acceleration, is concentrated in basins along the Amundsen Sea coast. Outside this region, we find that West Antarctica is nearly in balance and that East Antarctica is gaining substantial mass.

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Acknowledgements

This work was funded by NERC, and an RCUK Academic Fellowship to M.A.K., and partially supported by COST Action ES0701. G.A.M. acknowledges support from the Natural Sciences and Engineering Research Council of Canada and the Canada Research Chairs programme. We thank E. Ivins for discussions.

Author information

Affiliations

  1. School of Civil Engineering and Geosciences, Newcastle University, Newcastle upon Tyne NE1 7RU, UK

    • Matt A. King
    • , Rory J. Bingham
    •  & Phil Moore
  2. School of Geography and Environmental Studies, University of Tasmania, Hobart 7001, Australia

    • Matt A. King
  3. Department of Geography, Durham University, Durham DH1 3LE, UK

    • Pippa L. Whitehouse
    •  & Michael J. Bentley
  4. Department of Earth Sciences, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada

    • Glenn A. Milne

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Contributions

M.A.K. and G.A.M. conceived the study. M.A.K. oversaw the work and wrote the paper. P.M. did the GRACE processing and R.J.B. did the forward modelling. R.J.B. and M.A.K. did the leakage analysis. P.L.W., M.J.B. and G.A.M. developed the GIA model. All authors commented on the paper.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Matt A. King.

Supplementary information

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  1. 1.

    Supplementary Information

    This file contains Supplementary Text 1-5, which includes Supplementary Figures 1-4, Supplementary Tables 1-2 and Supplementary References.

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