Third pole melting away
Himalayan glaciers disappearing 65% faster since 2010. This will drastically reduce water flows in the Indus, Ganga and Brahmaputra
ALL REGIONS of the Hindu Kush Himalayas are seeing an increase in mean temperature, with an average observed trend of 0.28oC per decade from 1951 to 2020. This is likely to impact the cryosphere, and in particular glacial melt, which is a major contributor of water for Himalayan rivers like the Ganga, the Brahmaputra and the Indus, says latest assessment from the International Centre for
Integrated Mountain Development (ICIMOD), an intergovernmental institute serving the eight Himalayan countries. Already, mass loss of glaciers has accelerated in the first two decades of this century. The report, released on June 20, says that for a global warming level of 1.5-2°C, Himalayan glaciers are expected to lose 30-50 per cent of their volume by 2100. If warming exceeds 4°C, the heavily glaciercovered regions of West Kunlun and Karakoram will have their remaining glacier area reduced to about 50 per cent of their 2020 area. In all other regions, glacier-covered area will be reduced to less than 30 per cent of the 2020 area.
“As glaciers continue to melt and get smaller, the water eventually starts to decrease. We call this point peak water, when the change occurs from increasing glacier runoff to decreasing glacier runoff,” says Miriam Jackson, senior cryosphere specialist at ICIMOD. Peak water in most basins will be reached around mid century, and water availability will decline by 2100.
The Hindu Kush Himalayas will also see a decline in snowfall of 30-50 per cent in the Indus basin; 50-60 per cent in the Ganga basin; and 50-70 per cent in
the Brahmaputra basin between 2070 and 2100, as against the average from 1971 to 2000. About 83 per cent of springs, the main source of water for mountain communities, are replenished through snow and glacier melt. Decline in snow cover will impact 240 million people in the mountains and 1.65 billion people downstream.
The report notes an increase in disasters like landslides, avalanches and glacial lake outburst floods (GLOFs) in recent years. Warming may lead to an increase in snow avalanches, while glacial retreat will result in a rise in GLOFs, especially by the mid century. For biodiversity, the report highlights range shifts, ecosystem degradation, species decline and extinction. By 2100, Indian Himalayas may see nearly a quarter of its endemic species wiped out, it says with medium confidence.