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Science & Technology

NASA ICESat Shows Himalayan Glaciers Have Lost Less Ice Than Worst Estimates

Lake-Imja-Tsho-1997-himalaya-melt

A 2010 examine utilizing measurements taking by the Gravity Restoration and Local weather Experiment (GRACE) satellite tv for pc reported that glaciers within the Himalayas and the Tibetan plateau have been shedding about 50 gigatonnes of ice per 12 months. These outcomes have been refuted two years later by a analysis group utilizing the identical knowledge however diverse the interpretation to indicate that the ice loss was solely a tenth of that quantity.

A brand new examine of the Himalayan glaciers utilizing NASA’s ICESat signifies that these glaciers have been shedding on common 12 gigatonnes of ice a 12 months between 2003 and 2008. The researchers revealed their findings within the journal Nature.
himalayan glaciers

This new estimate raises much more questions concerning the reliability of satellite tv for pc and subject measurements of alpine glaciers. ICESat reveals twice as a lot ice loss because the reinterpreted GRACE knowledge, this determine remains to be thrice decrease than regional losses estimated on subject research.

ICESat was launched by NASA in 2003 to trace the general modifications in polar ice sheet by measuring their floor elevation with a laser altimeter. It’s designed for clean topography on the polar areas, and can’t be simply used to map the tough terrains of the Himalayas, states Andreas Kääb, a remote-sensing knowledgeable on the College of Oslo in Norway who led the newest examine.

The staff tried to unravel this drawback by correcting the ICESat knowledge utilizing elevation measurements taking from the Shuttle Radar Topography Mission. Kääb et al. additionally checked the altitude of adjoining terrain, which shouldn’t change drastically over a brief time period, to make sure that the modifications in elevation detected by ICESat within the glaciers have been real.

As soon as these have been in place, ICESat was used to map the area at a decision of as much as 70 meters. Between 2003 and 2008, Himalayan glaciers thinned at a charge of 21 cm a 12 months on common, considerably lower than the worldwide common for glaciers and ice caps.

This common might be deceptive as a result of it conceals massive glacier losses in some elements of the Himalayas, that are balanced out by smaller beneficial properties in others. A number of discrepancies with different satellite tv for pc research and regional-scale assessments stay. Research like this don’t point out a normal local weather pattern, since to be able to make such a conclusion, knowledge would should be collected throughout a number of many years.

[via Nature]

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