Call it the effect of global warming or increasing climatic variation, the Himalayan glaciers in Himachal Pradesh falling in three important basins of Satluj, Chenab and Beas have shown overall reduction in their area from 2,077 sq/km area to 1,628 sq/km since 1962 and large scale fragmentation of small and medium sized glaciers.
According to the study, carried out by State Council for Science Technology and Environment, Himachal Pradesh and the Space Application Centre, Ahmedabad, the startling revelation about Himalayan glaciers falling in Himachal Pradesh have been made.
Keeping in mind the changing nature of glaciers due to climatic conditions, Space Applications Centre had initiated a programme for the mapping of glaciers and permanent snowfields in the Satluj and other important basins of Himachal Pradesh.
Using IRS satellite data, inventory was completed for the Satluj basin right from its origin in Tibet catchment. In this programme, mainly three agencies were involved which include SAC Ahmedabad, WIHG Dehradun and HPRSC Shimla.
The comparison of 2001 and 2007 glacier layers reveal that a loss of 11.04 per cent of the total glacier area has been lost due to deglaciation in the basin between 2001 and 2007, which varies in different proportions, when compared based on their glacier size.
Maximum deglaciation of about 21 per cent area loss has been observed in the large sized glaciers, where glacier area is more than 10 sq/km and about 18 per cent occurred in the 1-3 sq.km glacier size range.
The small sized glaciers with glacier area less than 1 sq/km shows an increase in the numbers as well as total area indicating that small sized glaciers have been increased due to the fragmentation of large and medium sized glaciers during this period.
This further reflects that large and medium sized glaciers have been affected by the climatic variations over a period of time as a result of which fragmentation of these glaciers has taken place, thereby increasing the small sized glaciers in 2001.
While comparing the glaciers based on their aerial size, it was found that maximum retreat of about 65 per cent has taken place in case of glaciers, where area is more than 10 sq/km between 1962-2001 followed by about 38 per cent area loss in 5-10 sq/km glacier size range and 30 per cent in case of 3-5 sq/km glacier size.
About 13 per cent glacier area has been lost amongst the glaciers where glacier size is in between 1-3 sq/km. When compared with 2001 glacier layer, it was found that total glacier area for those 188 glaciers (taken for study) have been reduced to 230.84 sq/km in 2001 from 311.13 sq/km area in 1962 indicating an overall reduction of 25.80 per cent glacier area within 1962 to 2001.
Common glaciers from the interpreted layers were taken in order to estimate the retreat in terms of loss of area for the year 1962, 1993, 2001 and 2007. On comparing 250 glaciers during these monitoring years, it was found that about 5 percent area as a whole has been lost between 1962-93 which also includes some glaciers which indicates gain in the area and about 2 percent area loss in between 1993-2001 followed by about 12 per cent loss between 2001 and 2007.
On comparing, it was found that about 13 per cent deglaciation occurred between 2001 and 2007 and a marginal loss of area about 0.44 per cent between 1993 to 2001
Geological Survey of India had estimated retreat in three glaciers in Satluj basin, six glaciers in Chenab and five glaciers in Beas and two glaciers in Ravi basin. Prominent glaciers like Chota Sigri shows 6.81 m/y retreat between 1962-95, Bara Sigri 29.78 m/y between 1906-1957, Trilokinath as 17.86 m/y between 1968-1996, Beas Kund as 18.8 m/y between 1963-2003 and Manimahesh as 29.1 between 1968-2005.
To discuss the findings, the state centre for climate change as part of initiative under the National mission for sustaining Himalayan ecosystem is organising a brainstorming session at Shimla on Snow and glaciers and the Himalayan river system on May 29-30.