Significant portions of a large Antarctic ice shelf just south of one that suddenly broke apart in February 2002 are rapidly thinning and may suffer a similar, catastrophic demise in less than a century, scientists say.
Satellite observations collected between 1992 and 2001 suggest that the upper surface of the Larsen C ice shelf dropped as much as 27 centimeters per year during the period. About a quarter of that shrinkage, or 7 cm, may have resulted from snow packing down into denser material called firn, says Andrew Shepherd, a glaciologist at the University of Cambridge in England. Uncertainties about such factors as the height of ocean tides and the temperature and the salinity of water beneath the ice shelf would account for no more than a small fraction of the remaining loss in height above water, says Shepherd.
Therefore, he notes, as much as 20 cm per year of the upper surface's drop stems from melting. About nine-tenths of any mass of floating ice lies below t