While glaciers globally are shedding billions of tons of ice each year, the Himalayas aren't, a study shows.
A University of Colorado Boulder study shows that the Earth's glaciers and ice caps outside Greenland and Antarctica are shedding roughly 150 billion tons of ice, and adding roughly 0.4 millimeters to sea levels, each year.
Total sea level rise from all land-based ice on Earth, including Greenland and Antarctica, was roughly 1.5 millimeters per year annually or about one-half inch from 2003 to 2010. This figure includes the expansion of water due to warming.
"This is the first time anyone has looked at all of the mass loss from all of Earth's glaciers and ice caps with GRACE," says CU-Boulder physics professor John Wahr.
"The Earth is losing an incredible amount of ice to the oceans annually, and these new results will help us answer important questions in terms of both sea rise and how the planet's cold regions are responding to global change."
The team used GRACE data to calculate that the ice loss from both Greenland and Antarctica, including their peripheral ice caps and glaciers, was roughly 385 billion tons of ice each year. The total mass ice loss from Greenland, Antarctica and all Earth's glaciers and ice caps from 2003 to 2010 was about 1,000 cubic miles.
One unexpected resultwas that the estimated ice loss from high Asia mountains - including ranges like the Himalaya, the Pamir and the Tien Shan - was only about four billion tons of ice per year - less than a tenth of some previous estimates.
"The GRACE results in this region really were a surprise," says Wahr.
"One possible explanation is that previous estimates were based on measurements taken primarily from some of the lower, more accessible glaciers in Asia and were extrapolated to infer the behavior of higher glaciers. But unlike the lower glaciers, many of the high glaciers would still be too cold to lose mass even in the presence of atmospheric warming."