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 below. Atmospheric circulation changes have also caused rapid warming over the West Antarctic Ice Sheet, and contributed to declining sea-ice cover in the adjacent Amundsen-Bellingshausen seas. It is unknown whether these changes are part of a longer-term trend. Here, we use water-isotope (δ 18 O) 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 δ 18 O 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, δ 18 O 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 δ 18 O 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.
Quaternary Research Center, Department of Earth and Space Sciences, University of Washington, Seattle, WA 98195, United States; Institute of Arctic and Alpine Research, University of Colorado, Boulder, CO 80303, United States; Department of Geological Sciences, Brigham Young University, Provo, UT 84602, United States; NASA Goddard Space Flight Center, Code 615, Greenbelt, MD 20770, United States; Climate Change Institute, School of Earth and Climate Sciences, University of Maine, Orono, ME 04469, United States; Desert Research Institute, Reno, NV 89512, United States; Laboratoire des Sciences du Climat et de l'Environnement, Centre d'Etudes de Saclay, Gif-sur-Yvette 91191, France; Institute for Marine and Atmospheric Research, Utrecht University, Utrecht 3508 TC, Netherlands; National Center for Atmospheric Research, Boulder, CO 80305, United States; Antarctic Research Centre, Victoria University of Wellington, Wellington 6140, New Zealand; School of Geography and Environmental Science, Monash University, Clayton, VIC 3800, Australia
Recommended Citation:
Steig E.J.,Ding Q.,White J.W.C.,et al. Recent climate and ice-sheet changes in West Antarctica compared with the past 2,000 years[J]. Nature Geoscience,2013-01-01,6(5)