A melting glacier in the Himalayas. Although the outsides of the ice cap is getting smaller, the thickness near the top is growing (Photo: GettyImages)A new study led by a research team from the University of Colorado Boulder shows that glaciers and ice caps in the world, outside Greenland and Antarctica, are shedding roughly 150 billion tons of ice annually.

This is the first comprehensive satellite study of the contribution of the world's melting glaciers and ice caps to global sea level rise. The result indicates they are adding roughly 0.4 millimeters annually according to physics Professor John Wahr who led the study. Melting sea ice contributes to global rise in sea levels, which could lead to significant threats in the future.

The team used satellite images to conduct the study and the annual shed between the years 2003-2010 was enormous. The total does not count the mass from individual glacier and ice caps on the fringes of the Greenland and Antarctic ice sheets -- roughly an additional 80 billion tons.

Launched in 2002, two GRACE satellites whip around Earth in tandem 16 times a day at an altitude of about 300 miles, sensing subtle variations in Earth's mass and gravitational pull. Separated by roughly 135 miles, the satellites measure changes in Earth's gravity field caused by regional changes in the planet's mass, including ice sheets, oceans and water stored in the soil and in underground aquifers.

One unexpected study result from GRACE was that the estimated ice loss from high Asia Mountains -- including ranges like the Himalaya, the Pamir and the Tien Shan -- was only about 4 billion tons of ice annually. Some previous ground-based estimates of ice loss in the high Asia Mountains have ranged up to 50 billion tons annually, Wahr said.

A leading glacier expert in Iceland, confirms that the melt in the Himalayas is not as great as many have thought. He says that it is a misunderstanding that millions of people will be without water if the glaciers melt. Even if they melt, it would continue to snow in the Himalayas and it would be sufficient for the water supply.

He also concluded that the total loss in the Himalayas was not sufficient, as the cap near the top in the Himalayas was getting thicker, while the outsides were shrinking.

Tómas also point out that the great gap in between studies of the Himalayas shows that the measurements are not as accurate as many think. A study from a few years back showed great melt in the Himalayas, much greater then this study.


Colorado Boulder