- Glaciers in the Hindu Kush Himalaya have lost up to 27 metres of ice since 1975
- Between 1990 and 2020, HKH glaciers lost about 12% of area and 9% of ice reserves
- Glacial ice loss rates doubled since 2000, nearing irreversible retreat in some areas
Five months ago, two reports by an intergovernmental knowledge and learning centre working on behalf of the people of the Hindu Kush Himalaya (HKH) had said that glaciers across the HKH have been melting faster and faster with ice loss rates doubling since the turn of the millennium.
The International Centre for Integrated Mountain Development (ICIMOD) based in Kathmandu, whose regional members include India, Nepal, Bhutan and China, among others, in the two reports said up to 27 metres of glacial ice thickness had been lost since 1975.
The reports indicated an alarming scenario in the future for the "nearly two billion people downstream who depend on meltwater from the 'Water Towers of Asia'."
What exactly caused the Nepal flash floods that killed over 270 just days ago is under investigation by scientists and researchers. However, many of them are inclined towards a combination of factors, one of which is the most concerning - it is raining at an altitude of 4,000 metres and above instead of snowing.
A scientist at the central government's Dehradun-based Wadia Institute of Himalayan Geology told NDTV on Thursday that warming may explain why it has been raining in those altitudes that once received snowfall, and why glaciers have been receding very fast.
Separately, the two ICIMOD reports published in March this year had said that "between 1990 and 2020, HKH glaciers lost about 12 per cent of their total area and 9 per cent of their estimated ice reserves."
One of the two ICIMOD reports, the HKH Glacier Outlook 2026, which analysed data from 38 monitored glaciers, found that glacial wastage had doubled since the year 2000 in a strong indication that "parts of the Himalayan cryosphere may be nearing critical tipping points toward irreversible retreat."
It, however, noted a data gap that only seven of those 38 monitored glaciers met the global benchmark monitoring standards of the World Glacier Monitoring Service (WGMS). It said regions with massive glacier presence including the Karakoram, Sikkim, Zanskar and Bhutan remained largely unmonitored.
ICIMOD researchers are now investigating whether an ice-rock avalanche originating from a high-altitude location may have triggered the floods. A large volume of ice and rock debris may have entered Lende Khola, a tributary of the Bhote Koshi River, and generated a sudden surge carrying water, sediment and boulders downstream.
"It is related to climate change because the snow covers are reducing, the glaciers are receding, more rocky or barren areas are exposed - they absorb more heat which makes the slopes more vulnerable," Mohd Farooq Azam, senior cryosphere specialist at ICIMOD and associate professor at the Indian Institute of Technology Indore, told news agency PTI on Thursday.
He added that though the exact cause is yet to be ascertained, it increasingly pointed at less snow cover due to receding glaciers and permafrost degradation.
The largest volume of ice outside the poles is in the Hindu Kush Himalaya, with over 63,700 glaciers covering over 55,000 sqkm, according to ICIMOD. They are the sources of 10 major river systems in Asia and support food, water, energy and livelihood security of billions. At least 78 per cent of this glacier area located between 4,500 and 6,000 metres is highly exposed to elevation-dependent warming, ICIMOD said in the March reports titled 'Changing Dynamics of Glaciers in the Hindu Kush Himalaya Region from 1990 to 2020', and 'HKH Glacier Outlook 2026: Insights from 50 Years of Himalayan Glacier Monitoring'.
While announcing the publication of the reports, ICIMOD had said they highlighted that glacier losses were spatially skewed with the highest percentage of area loss in the eastern Hengduan Shan mountains, where some areas lost up to 33 per cent of their glacier area in just three decades.
However, the largest absolute area losses were concentrated in the Indus, Ganges and Brahmaputra basins where over 74 per cent of the region's glaciers are found, underlining their critical vulnerability, ICIMOD had said.
