Australia: The Land Where Time Began

A biography of the Australian continent 

West Antarctica - Recent Changes in Climate and Ice Sheet Compared to the Past 2000 Years

Over the past 5 decades the wind-driven inflow of warm ocean water onto the Antarctic continental shelf, that has been enhanced by atmospheric circulation changes, where the warm water melts the ice shelves from below (Rignot et al., 2008; Thoma, Jenkins & Holland, 2008; Jenkins et al., 2010). Rapid warming (Steig et al., 2009) over the West Antarctic Ice Sheet has been caused by atmospheric circulation changes and these changes have also contributed to the declining cover of sea ice in the adjacent Amundsen-Bellingshausen Seas (Comiso & Nishio, 2008). It is not known if these changes are part of a longer-term trend. In this study by the authors¹ they placed recent climate changes in West Antarctica in the context of the past 2 millennia by the use of water isotope (δ¹⁸O) data that were obtained from an array of ice-core records. Their results show that the δ¹⁸O of precipitation in West Antarctica has significantly increased over the past 50 years, paralleling the temperature trend, and was probably higher during the 1990s than at any other time in the past 200 years. Over the past 2,000 years δ¹⁸O anomalies have occurred about 1 % of the time over the last 2,000 years. It has been suggested by general circulation model simulations that it is not possible to distinguish these recent trends in δ¹⁸O and climate in West Antarctica from decadal variability originating in the tropics. The authors¹ concluded that the tropical climate variability trajectory is a significant source of uncertainty in projections of the West Antarctic changes in climate and ice sheet.

Sources & Further reading

1. Steig, Eric J., Qinghua Ding, James W. C. White, Marcel Kuttel, Summer B. Rupper, Thomas A. Neumann, Peter D. Neff, et al. "Recent Climate and Ice-Sheet Changes in West Antarctica Compared with the Past 2,000 Years." Nature Geosci 6, no. 5 (05//print 2013): 372-75.