The surface temperature record from Byrd Station on the West Antarctic Ice Sheet (WAIS), demonstrates a marked increase of 2.4 degrees Celsius in average annual temperature since 1958, which is three times faster than the average temperature rise around the globe. The warming trends during the summer months of the Southern Hemisphere (December through February) indicate that the temperature increase is nearly double of what has been previously documented. This could upset the surface mass balance of the ice sheet, which could make the WAIS even bigger contributor to sea level rise than it already does. The Gravity Recovery and Climate Experiment (GRACE) satellite provides observations of gravity change which gives direct mass-change estimates at monthly intervals and with a spatial resolution of better than a few hundred kilometers. Using these observations from 1992 to 2011, a significant ice loss was estimated as –65 ± 26 Gt/yr for West Antarctic Ice Sheet and 14 ± 43 Gt/yr for East Antarctic Ice Sheet (Shepherd et al., 2012).

Enhanced surface melting contributed to the breakup of the Antarctic's Larsen B Ice Shelf, where glaciers at the edge discharged massive chunks of ice into the ocean that contributed to sea level rise. Since the base of WAIS rests below sea level, it is vulnerable to direct contact with warm ocean water. It’s melting currently contributes 0.3 mm to sea level rise each year – second to Greenland, whose contribution to sea level rise has been estimated as high as 0.7 mm per year. So if this trend continues, melting will become more extensive in the region in the future. This work appeared in Nature Geosciences (Bromwich et al., 2012).

References:

Bromwich, D. H., Nicolas, J. P., Monaghan, A. J., Lazzara, M. A., Keller, L. M., Weidner, G. A., and Wilson, A. B. (2012). Central West Antarctica among the most rapidly warming regions on Earth. Nature Geoscience. DOI: 10.1038/ngeo1671.

Shepherd and 47 scientists from EU (2012). A Reconciled Estimate of Ice-Sheet Mass Balance, Science. 10.1126/science.1228102.