1. Department of Earth and Space Sciences and Quaternary Research Center, University of Washington, Seattle, Washington 98195, USA
2. National Center for Atmospheric Research, Boulder, Colorado 80307, USA
3. Department of Environmental Science, Roger Williams University, Bristol, Rhode Island, USA
4. Department of Meteorology, and Earth and Environmental Systems Institute, Pennsylvania State University, University Park, Pennsylvania 16802, USA
5. NASA Laboratory for Hydrospheric and Biospheric Sciences, NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
6. NASA Goddard Institute for Space Studies and Center for Climate Systems Research, Columbia University, New York, New York 10025, USA

Correspondence to: Eric J. Steig¹ Correspondence and requests for materials should be addressed to E.J.S. (Email: steig@ess.washington.edu).

Abstract

Assessments of Antarctic temperature change have emphasized the contrast between strong warming of the Antarctic Peninsula and slight cooling of the Antarctic continental interior in recent decades¹. This pattern of temperature change has been attributed to the increased strength of the circumpolar westerlies, largely in response to changes in stratospheric ozone². This picture, however, is substantially incomplete owing to the sparseness and short duration of the observations. Here we show that significant warming extends well beyond the Antarctic Peninsula to cover most of West Antarctica, an area of warming much larger than previously reported. West Antarctic warming exceeds 0.1 °C per decade over the past 50 years, and is strongest in winter and spring. Although this is partly offset by autumn cooling in East Antarctica, the continent-wide average near-surface temperature trend is positive. Simulations using a general circulation model reproduce the essential features of the spatial pattern and the long-term trend, and we suggest that neither can be attributed directly to increases in the strength of the westerlies. Instead, regional changes in atmospheric circulation and associated changes in sea surface temperature and sea ice are required to explain the enhanced warming in West Antarctica.