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West Antarctic Ice Sheet retreat in the Amundsen Sea driven by decadal oceanic variability

Nature Geosciencevolume 11pages733738 (2018) | Download Citation

Abstract

Mass loss from the Amundsen Sea sector of the West Antarctic Ice Sheet has increased in recent decades, suggestive of sustained ocean forcing or an ongoing, possibly unstable, response to a past climate anomaly. Lengthening satellite records appear to be incompatible with either process, however, revealing both periodic hiatuses in acceleration and intermittent episodes of thinning. Here we use ocean temperature, salinity, dissolved-oxygen and current measurements taken from 2000 to 2016 near the Dotson Ice Shelf to determine temporal changes in net basal melting. A decadal cycle dominates the ocean record, with melt changing by a factor of about four between cool and warm extremes via a nonlinear relationship with ocean temperature. A warm phase that peaked around 2009 coincided with ice-shelf thinning and retreat of the grounding line, which re-advanced during a post-2011 cool phase. These observations demonstrate how discontinuous ice retreat is linked with ocean variability, and that the strength and timing of decadal extremes is more influential than changes in the longer-term mean state. The nonlinear response of melting to temperature change heightens the sensitivity of Amundsen Sea ice shelves to such variability, possibly explaining the vulnerability of the ice sheet in that sector, where subsurface ocean temperatures are relatively high.

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Acknowledgements

We are grateful to all cruise participants who assisted in the collection of the data. A.J. and D.S. were supported by core funding from the UK Natural Environment Research Council (NERC) to the British Antarctic Survey’s Polar Oceans Program. P.D. was supported by funding from NERC’s iSTAR Programme through grant NE/J005770/11 and NSF grant 1643285. S.J.’s support included NSF grants ANT06-32282 and 16-44159. Support for S.H.L. and T.W.K. was provided by the Korea Polar Research Institute grant KOPRI PE17060. S.S. was supported by National Science Foundation Office of Polar Programs collaborative grants 0838975 and 1443569.

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Affiliations

  1. British Antarctic Survey, Natural Environment Research Council, Cambridge, UK

    • Adrian Jenkins
    •  & Deb Shoosmith
  2. Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY, USA

    • Pierre Dutrieux
    •  & Stan Jacobs
  3. Korea Polar Research Institute, Incheon, Korea

    • Tae Wan Kim
    •  & Sang Hoon Lee
  4. Department of Ocean Sciences, Inha University, Incheon, Korea

    • Ho Kyung Ha
  5. Institute of Arctic and Alpine Research, University of Colorado, Boulder, CO, USA

    • Sharon Stammerjohn

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Contributions

A.J., D.S., P.D. and S.J. conceived the study. D.S., S.J., T.W.K., S.H.L., H.K.H. and S.S. planned and led the data collection. D.S., P.D. and T.W.K. processed the data. A.J., D.S. and P.D. undertook the data analyses and derivation of the final results. A.J. prepared the manuscript. All authors discussed the results and implications and commented on the manuscript at all stages.

Competing interests

The authors declare no competing interests.

Corresponding author

Correspondence to Adrian Jenkins.

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https://doi.org/10.1038/s41561-018-0207-4