|Title:||Sensitivity of West Antarctica to climate and ice sheet variability on multiple timescales (Invited)|
|Author:||Steig, E.J., White, J.W., Fudge, T.J., Taylor, K., Markle, B.R., Schoenemann, S.W., Ding , Q., Brook, E., McConnell, J.R. and Buizert, C.|
|Periodical:||American Geophysical Union, Fall Meeting 2013, abstract #C21E-03|
West Antarctica is one of the fastest-warming locations on earth. The rising temperatures in West Antarctica have been accompanied by the loss of sea ice in the Amundsen-Bellingshausen Seas. Both the temperature and sea ice changes are connected by atmospheric and ocean circulation variability that is implicated in the thinning of ice shelves along the Amundsen Sea coast. In contrast, changes in climate, sea ice, and ice dynamics in most of East Antarctica have been relatively modest. Evidence from ice cores shows that the greater variability of West Antarctica than East Antarctic persists on multiple timescales. An array of ice cores across West Antarctica shows that the decadal variability characterized by modern observations, and linked to variability in the tropical Pacific, has been active throughout at least the last several thousand years. Results from a new deep ice core at the WAIS Divide site in central West Antarctica, published in Nature this year (WAIS Divide Project Members, 2013) shows that warming in Antarctica at the end of the last glacial period began at least 2000 years earlier than had been thought based on records from East Antarctica alone. Modeling results show that declining sea ice around Antarctica, driven by Milankovitch orbital forcing, would have had a greater influence on West Antarctica due to its lower elevation and more gentle topography. Similarly, on millennial timescales, the magnitude of climate variability in West Antarctica is greater than in East Antarctica – for example, the Antarctic Isotope Maximum (AIM 2) event, occurring about 24 ka ago, has little expression at Vostok or Dome C, yet is prominent in WAIS Divide.