Antarctic ice shelves rapidly melting

Antarctica’s ice shelves are shrinking at an accelerating rate, one of the longest satellite records of ice thickness reveals. Researchers report online March 26 in Science that several West Antarctic ice shelves are now on pace to disappear completely within 100 years.

Floating ice shelves mark the outermost edges of an ice sheet and line nearly half the Antarctic coastline. Using ice thickness measurements collected by satellites from 1994 to 2012, glaciologist Fernando Paolo of the Scripps Institution of Oceanography in La Jolla, Calif., and colleagues analyzed how recent warming has impacted Antarctica’s ice. The researchers discovered that Antarctic ice shelves shrank on average 25 cubic kilometers per year from 1994 to 2003. The melting then accelerated to 310 cubic kilometers — roughly twice the volume of Lake Tahoe — on average per year from 2003 to 2012.

While scientists have known that the West Antarctic ice shelves are thinning, the research also shows that the East Antarctic ice shelves, which expanded between 1994 and 2003, are thinning now as well.

The shelves serve as doorstops for glaciers. As the bottom of an ice shelf grinds over the seabed, it stems the flow of the land-based ice queued up behind it. Because ice shelves float, their melt water does not directly contribute to sea level rise. Their disappearance, however, speeds the loss of glacial ice, which does raise sea levels.