Gangotri recedes as globe warms

The Tribune , Monday, March 26, 2007
Correspondent : Vibha Sharma
New Delhi, March 25

The Gangotri glacier receded at the rate of 17.15 metres per year between 1971 and 2004, says a study conducted by the Department of Science and Technology. One more study has estimated that the glacier retreated 12.10 metres during 2004-05, another clear example of global warming and climate change in the region.

Regular monitoring of several glaciers during the past 100 years in major basins of the Himalayas from Shyok in the West to Changme Khangpu (Tista) in the East has revealed that a majority of the glaciers in the Himalayan region are passing through a phase of recession.

The DST started an all-India coordinated programme on Himalayan glaciers in 1988 to study glaciers of the western and central Himalayas, Gangotri and its tributary glaciers and Chhota Sigri glaciers in the central Himalayas.

While the glacier recession rate varies from glacier to glacier, preliminary analysis suggests that the recession rate was of the order of about 10 to 15 metres per year for some glaciers. Recession has also been observed in the case of the Pindari glacier, which went back by 9.41 metres during 1958-2001.

While recession may cause a marginal rise in the discharge of Himalayan rivers due to enhanced melting because of global warming, in the long term it spells disaster, particularly for areas dependent on perennial rivers like the Ganga.

In fact, a recently-released WWF report, “World’s top 10 rivers at risk”, also points out that the world’s top 10 rivers, including the Ganga and the Indus, are dying. Citing over-extraction of water for agriculture, pollution and climate change as the main reasons, the report says that these top 10 rivers are in the clear danger zone. A recent report by the Inter-Governmental Panel on Climate Change (IPCC) also warns that India should gear up to face challenges of rising sea level, melting glaciers, vanishing mangroves and more severe droughts and floods.

All this will be caused by a rise in global temperature between 1.8 and 4.0 degrees Celsius due to increasing human-induced concentration of greenhouse gases into the atmosphere. Temperatures rose about 0.7 degrees Celsius in the 20th century. In India, observations have revealed that during the past 100 years, mean temperatures increased by 0.5 Celsius.

Global atmospheric concentrations of carbon dioxide, methane and nitrous oxide have increased markedly as a result of human activities since 1750 and far exceed pre-industrial values determined from ice cores spanning many thousands of years.

The global increases in carbon dioxide concentration are primarily due to fossil fuel, land-use change, while methane and nitrous oxide are primarily due to agriculture, says the IPCC panel report.

 
SOURCE : The Tribune, Monday, March 26, 2007
 


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