9 March 2006

NASA Confirms Recent Ice Sheet Losses

by Kate Melville

The current issue of the Journal of Glaciology carries findings from NASA scientist Jay Zwally on the changing ice cover of Greenland and Antarctica that tallies with other recent studies indicating unprecedented thinning of the massive ice sheets. Zwally's survey, carried out using satellites and airborne mapping, confirms that climate warming is changing how much water remains locked in Earth's largest storehouses of ice and snow.

The new survey is the first to inventory the losses of ice and the addition of new snow on both continents in a consistent way throughout an entire decade.

Zwally's findings indicate that between 1992 and 2002, there was a net loss of ice from the combined Antarctic and Greenland ice shelves and a corresponding rise in sea level.

Adding up the overall gains and loses of ice from the Greenland and Antarctic ice sheets, Zwally said there was a net loss of ice to the sea of around 20 billion tons.

The survey saw large ice losses along the southeastern coast of Greenland but this was coupled with an increase in ice thickness at higher elevations in the interior due to relatively high rates of snowfall. It's possible that this might indicate a slight gain in the total mass of frozen water in the Greenland ice sheet over the decade studied, but that situation may have changed in the past few years, according to Zwally. Last month NASA scientists reported a speed up of ice flow into the sea from several Greenland glaciers and as Zwally's survey concluded with 2002 data, recent changes such as this haven't been included.

Pic courtesy NASA