Recent climate and ice-sheet changes in West Antarctica compared with the past 2,000 years

Journal name:
Nature Geoscience
Volume:
6,
Pages:
372–375
Year published:
DOI:
doi:10.1038/ngeo1778
Received
Accepted
Published online

Changes in atmospheric circulation over the past five decades have enhanced the wind-driven inflow of warm ocean water onto the Antarctic continental shelf, where it melts ice shelves from below1, 2, 3. Atmospheric circulation changes have also caused rapid warming4 over the West Antarctic Ice Sheet, and contributed to declining sea-ice cover in the adjacent Amundsen–Bellingshausen seas5. It is unknown whether these changes are part of a longer-term trend. Here, we use water-isotope (δ18O) data from an array of ice-core records to place recent West Antarctic climate changes in the context of the past two millennia. We find that the δ18O of West Antarctic precipitation has increased significantly in the past 50 years, in parallel with the trend in temperature, and was probably more elevated during the 1990s than at any other time during the past 200 years. However, δ18O anomalies comparable to those of recent decades occur about 1% of the time over the past 2,000 years. General circulation model simulations suggest that recent trends in δ18O and climate in West Antarctica cannot be distinguished from decadal variability that originates in the tropics. We conclude that the uncertain trajectory of tropical climate variability represents a significant source of uncertainty in projections of West Antarctic climate and ice-sheet change.

At a glance

Figures

  1. Map of West Antarctica.
    Figure 1: Map of West Antarctica.

    Ice-core locations are shown by filled circles. Blue shading shows the main Siple Coast and Amundsen Sea ice streams. Ice shelves are shaded grey. The inset map shows the locations of well-dated, annually resolved ice cores for which there are δ18O data available to at least 1994. WD, WAIS Divide ice core (white-edged circle). PIG, Pine Island Glacier. The location of the Byrd weather station is shown by an open circle.

  2. West Antarctic temperature and
[delta]18O.
    Figure 2: West Antarctic temperature and δ18O.

    a, Temperature 7 at Byrd Station (80°S, 120°W) (upper) and composite of annual mean δ18O anomalies from ice cores in West Antarctica (lower). The two time series are correlated at r=0.48, p=0.01. Grey shading shows the running decadal mean of temperature and the standard error of the running decadal mean of δ18O. b, Probability from a one-tailed t-test that decadal mean West Antarctic δ18O centred on any given year is as elevated as the decade of the 1990s (1991–2000). The dashed line shows the number of records contributing to each decadal mean.

  3. Decade-average
[delta]18O from the WAIS Divide ice core for the past 2,000 years.
    Figure 3: Decade-average δ18O from the WAIS Divide ice core for the past 2,000 years.

    Grey shading shows 2 s.d. about the decadal mean, based on the upper 100 years of the multi-core δ18O composite, providing an estimate of the 95% confidence range. The dashed line shows the 97.5 percentile value relative to the average linear trend.

  4. Modelled versus observed West Antarctic
[delta]18O and tropical SSTs.
    Figure 4: Modelled versus observed West Antarctic δ18O and tropical SSTs.

    a, Difference in mean simulated decadal-mean δ18O in Antarctic precipitation between 1991 and 2000 and the three preceding decades. b, Model range (2 s.d., grey shading) of simulated annual mean δ18O in precipitation averaged over West Antarctica compared with observed δ18O anomalies (black line). In both a and b, the model simulations are from 10-member ensembles of ECHAM4.6 simulations forced by global tropical SST with a slab ocean in the extratropics. c, SST anomalies26 averaged over the central tropical Pacific Niño4 region (thin solid line) and over the entire tropics (thick line), 1880–2009.

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Author information

Affiliations

  1. Quaternary Research Center and Department of Earth and Space Sciences, University of Washington, Seattle, Washington 98195, USA

    • Eric J. Steig,
    • Qinghua Ding,
    • Marcel Küttel,
    • Peter D. Neff,
    • Ailie J. E. Gallant,
    • Spruce W. Schoenemann,
    • Bradley R. Markle,
    • Tyler J. Fudge,
    • Andrew J. Schauer &
    • Rebecca P. Teel
  2. Institute of Arctic and Alpine Research, University of Colorado, Boulder, Colorado 80303, USA

    • James W. C. White &
    • Bruce H. Vaughn
  3. Department of Geological Sciences, Brigham Young University, Provo, Utah 84602, USA

    • Summer B. Rupper,
    • Landon Burgener &
    • Jessica Williams
  4. NASA Goddard Space Flight Center, Code 615, Greenbelt, Maryland 20770, USA

    • Thomas A. Neumann
  5. Climate Change Institute and School of Earth and Climate Sciences, University of Maine, Orono, Maine 04469, USA

    • Paul A. Mayewski,
    • Daniel A. Dixon &
    • Elena Korotkikh
  6. Desert Research Institute, Reno, Nevada 89512, USA

    • Kendrick C. Taylor
  7. Laboratoire des Sciences du Climat et de l’Environnement, Centre d’Etudes de Saclay, Gif-sur-Yvette 91191, France

    • Georg Hoffmann
  8. Institute for Marine and Atmospheric Research, Utrecht University, Utrecht 3508 TC, Netherlands

    • Georg Hoffmann
  9. National Center for Atmospheric Research, Boulder, Colorado 80305, USA

    • David P. Schneider
  10. Present address: Antarctic Research Centre, Victoria University of Wellington, Wellington 6140, New Zealand

    • Peter D. Neff
  11. Present address: School of Geography and Environmental Science, Monash University, Clayton, Victoria 3800, Australia

    • Ailie J. E. Gallant

Contributions

E.J.S., J.W.C.W., S.B.R., P.D.N., B.R.M., B.H.V., D.P.S., S.W.S., T.A.N., P.A.M., K.C.T., T.J.F., D.A.D. and E.K. conducted fieldwork and sample collection. P.D.N., A.J.S., R.P.T., B.H.V., E.K., E.J.S., D.P.S., J.W.C.W., S.B.R., L.B. and J.W. obtained the ice-core water-isotope data. G.H. provided code and assistance with the modelling. E.J.S. and Q.D. compiled the data, conducted the model experiments and calculations and wrote the paper. All authors contributed to the final manuscript text.

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The authors declare no competing financial interests.

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