Rapid warming of the region leads to not only melting of glaciers but also fragmentation, says the area’s first-ever assessment
The number of glaciers in the Himalayan area has increased in the last five decades and this is an indicator of how severe glacier melting has been due to global warming, says the first-ever assessment of climate change impacts on the Hindu Kush Himalayan (HKH) region.
This assessment, done by the International Centre for Integrated Mountain Development (ICIMOD), a regional intergovernmental body, has synthesised numerous earlier studies due to the non-availability of regional studies. It has brought out a scary picture of the landscape that is yet to be studied well from this perspective.
The increase in the number of glaciers is primarily due to glacier fragmentation — that big ones are splitting into smaller ones. And this is happening due to consistent loss in areas the glaciers occupy. “Since the 1950s, only reductions have been observed in glacier area (or shrinkage). Based on a compilation of area change studies, eastern Himalayan glaciers have tended to shrink faster than glaciers in the central or western Himalayas,” finds the assessment.
In the northern slopes of the Himalayas, glaciers are clearly receding. Glacier area change ranges between −0.1 per cent/year for the Chandra-Bhaga basin (northwestern Indian Himalayan region) between 1980 and 2010 to more than −1 per cent/year for the Poiqu basin (on the northern slopes of central Himalaya) between 1986 and 2001.
Smaller glaciers are shrinking faster than larger ones, although the smaller glaciers of Ladakh show a lower rate of retreat than other Himalayan glaciers. However, the assessment makes clear that despite the surety of glaciers in the Hindu Kush mountains losing length since 1973, no studies have been done to examine area change in this region.
Studies on various glaciers in the Khumbu Himalayan region reports rates of area change varied between −0.12 ± 0.05 per cent/year in the period 1962–2005 and −0.27 ± 0.06 per cent/year in 1962–2011.
Known as Asia’s water tower with the maximum snow storage after the poles, the HKH region sustains over two billion people directly and indirectly.
According to ICIMOD’s assessment, in a 1.5 degree Celsius world, about a third of glaciers in HKH region will disappear by 2100, and under the current emission scenario the region will lose two-third of glacier volumes.
“Mountains are warming up faster than the global averages. Even if we could limit global warming to 1.5 degrees Celsius, mountain temperatures would rise above 2 degrees Celsius, and if current trends continue temperatures could go up by 4 to 6 degrees Celsius. This has dire consequences not only on glaciers, but on food, energy and ecosystems, and the people who rely on them in terms of ecosystem change, changing water flow patterns, and increased hazards of disasters,” says David James Molden, director general of ICIMOD.
Overall, snow fall and accumulation has been coming down in this region. Since 2000, snow-covered area of HKH has reported a decline. Since 1960s, an analysis of ice cores on the Tibetan Plateau shows, snow accumulation has been decreasing at high altitudes.
At the river basin scale, snow-covered area increased in the Indus basin, but decreased in Ganga and Brahmaputra basins between 2000 and 2011. Similarly in Himachal Pradesh, end-of-summer snowline elevation has risen by approximately 400 metres between 1980 and 2007, or at a rate of 14.8 m/year and it lowered by 20 metre/year between 2000 and 2011.
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