Featured Research

from universities, journals, and other organizations

Himalayan Glacier Melting Observed From Space

Date:
March 28, 2007
Source:
Institut de Recherche Pour le Développement
Summary:
The Himalayan glaciers are melting under the effect of global warming. However, the extent of this melting remains difficult to assess from ground surveys owing to the great number of glaciers, the difficulty of access and the vastness of the mountain chain. IRD and CNRS scientists from the research units Great Ice and Legos have overcome these difficulties by using satellite imagery. This is the first step of a much more extensive project: evaluation and surveillance of the whole system of Himalayan glaciers .

DGPS positioning of an ablation marker on the tongue of Chhota Shigri Glacier at 4400 m.
Credit: Copyright IRD/Yves Arnaud

The Himalaya, the "Roof of the World", source of the seven largest rivers of Asia are, like other mountain chains, suffering the effects of global warming. To assess the extent of melting of its 33 000 km2 of glaciers, scientists have been using a process they have been pioneering for some years.

Satellite-imagery derived glacier surface topographies obtained at intervals of a few years were adjusted and compared. Calculations indicated that 915 km2 of Himalayan glaciers of the test region, Spiti/Lahaul (Himachal Pradesh, India) thinned by an annual average of 0.85 m between 1999 and 2004. The technique is still experimental, but it has been validated in the Alps and could prove highly effective for watching over all the Himalayan glacier systems. However, the procedure for achieving a reliable estimate must overcome a number of sources of error and approximation inherent in satellite-based observations.

The researchers started by retrieving satellite data for two periods, 2000 and 2004. A digital field model was extracted for each of them, representing the topography of a ground reference point in digital form and therefore usable in computerized processing. The earliest topography of the area studied was provided by NASA which observed 80% of the Earth's surface during the Shuttle Radar Topographic Mission of February 2000. Then, in November 2004, two 2.5 m resolution images of the same area taken at two different angles were acquired especially by the French satellite Spot5 in the framework of an ISIS (CNES) project.

Comparison of these two images has helped build a field model, a Digital Elevation Model (DEM), by stereoscopic photogrammetric techniques . The DEM model reveals that NASA radar data underestimate values at high altitudes and overestimate them at lower altitudes. And the Spot satellite produces an uncertainty of +/- 25 m in the horizontal positioning of images.

Moreover, as the authorities of the major Himalayan countries (India, Pakistan, China) do not permit public access to detailed topographic maps or aerial photographs of these sensitive cross-border regions, no reference is available for satellite observation error assessment and correction. It is therefore by comparing the SRTM and SPOT5 topographies using stable non-glaciated areas around glaciers that researchers have been able to adjust for the deviations and superimpose the two digital field models. These comparisons gave the bases for a map of glacier elevation (and hence thickness) variations for altitude intervals of 100 m over the period 2000-2004.

The results show clear regression of the large glaciers whose terminal tongues reach the lowest levels (about 4000 m) with a thinning of 8 to 10 m below 4400 m. Such loss is 4 to 7 m between 4400 and 5000 m, passing to 2 m above 5000 m. The satellite image evaluation yields an average mass balance of --0.7 to --0.85 m/a water equivalent for the 915 km2 of glaciers surveyed, a total mass loss of 3.9 km3 of water in 5 years. In order to check these results and validate the procedure, the satellite-derived results were compared with the mass balance for the small glacier Chhota Shigri (15 km2) determined from the field measurements and surveys, performed between 2002 and 2004 by the Great Ice research unit and its Indian partners. The mass balance determined from these field data and that calculated from satellite data agree. For both evaluation methods, Chhota Shigri glacier appears to have lost an average of a little over 1 m of ice per year.

These results are in line with global estimates for glacier made for the period between 2001 and 2004. The approach is therefore being extended to other areas of the Himalaya in order to gain more information on the still poorly known changes taking place in the region's glaciers, which are a water resource on which tens of millions of people depend.

Reference: Berthier Etienne, Arnaud Yves, Kumar Rajesh, Ahmad Sarfaraz, Wagnon Patrick, Chevallier Pierre - Remote sensing estimates of glacier mass balances in the Himachal Pradesh (Western Himalaya, India), Remote Sensing of the Environment. DOI : 10.1016/j.rse.2006.11.017


Story Source:

The above story is based on materials provided by Institut de Recherche Pour le Développement. Note: Materials may be edited for content and length.


Cite This Page:

Institut de Recherche Pour le Développement. "Himalayan Glacier Melting Observed From Space." ScienceDaily. ScienceDaily, 28 March 2007. <www.sciencedaily.com/releases/2007/03/070327113346.htm>.
Institut de Recherche Pour le Développement. (2007, March 28). Himalayan Glacier Melting Observed From Space. ScienceDaily. Retrieved August 22, 2014 from www.sciencedaily.com/releases/2007/03/070327113346.htm
Institut de Recherche Pour le Développement. "Himalayan Glacier Melting Observed From Space." ScienceDaily. www.sciencedaily.com/releases/2007/03/070327113346.htm (accessed August 22, 2014).

Share This




More Earth & Climate News

Friday, August 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Airlines on Iceland Volcano Alert

Airlines on Iceland Volcano Alert

Reuters - Business Video Online (Aug. 22, 2014) — Iceland evacuates an area north of the country's Bardarbunga volcano, as the country's civil protection agency says it cannot rule out an eruption. Authorities have already warned airlines. As Joel Flynn reports, ash from the eruption of the Eyjafjallajokull volcano in 2010 shut down much of Europe's airspace for six days. Video provided by Reuters
Powered by NewsLook.com
Endangered Red Wolves Face Uncertain Future

Endangered Red Wolves Face Uncertain Future

AP (Aug. 22, 2014) — A federal judge temporarily banned coyote hunting to save endangered red wolves, but local hunters say that the wolf preservation program does more harm than good. Meanwhile federal officials are reviewing its wolf program in North Carolina. (Aug. 22) Video provided by AP
Powered by NewsLook.com
Coal Gas Boom in China Holds Climate Risks

Coal Gas Boom in China Holds Climate Risks

AP (Aug. 22, 2014) — China's energy revolution could do more harm than good for the environment, despite the country's commitment to reducing pollution and curbing its carbon emissions. (Aug. 22) Video provided by AP
Powered by NewsLook.com
Microbrewery Chooses Special Can for Its Beer

Microbrewery Chooses Special Can for Its Beer

AP (Aug. 22, 2014) — Aluminum giant, Novelis, has partnered with Red Hare Brewing Company to introduce the first certified high-content recycled beverage can. (Aug. 22) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins