DEHRADUN: Uttarakhand authorities and scientists have stepped up glacier monitoring after the recent Nepal tragedy, as a five-decade study has revealed accelerating ice loss in the Bhilangana Valley and the rapid formation of a potentially dangerous glacial lake.
The research, published in the journal Regional Environmental Change on August 28, found that six major glaciers in Tehri district consistently lost ice, mass and surface area between 1973 and 2025. The decline has accelerated sharply over the past decade.
The study, titled 'Accelerating Glacier Mass Loss in Bhilangana Valley Since the 1970s', was conducted by Dr Rakesh Bhambri and Senior Research Fellow Sharmistha Halder of Dehradun’s Wadia Institute of Himalayan Geology.
“The findings point to a significant acceleration in glacier thinning and mass loss, particularly after 2014,” the study said, underlining the need for sustained monitoring of the Himalayan cryosphere.
Researchers examined the Khatling, Phating, Doodhganga, Ratangarian, Jogin and an unnamed glacier. Together, they account for nearly 75 per cent of the Bhilangana Valley’s total glacier-covered area.
Using satellite imagery and digital elevation models from different periods, scientists measured changes in glacier elevation, ice mass, surface area and the retreat of glacier snouts between 1973 and 2025.
The most dramatic change was recorded at Khatling, the valley’s largest glacier. It retreated by around 5.33 kilometres between 1973 and 2024. The glacier was approximately 10 kilometres long in 2024.
The sustained retreat also caused the Khatling and Phating glaciers, which were once connected, to separate around 2000. Phating retreated by nearly 1,825 metres between 1973 and 2024.
Researchers divided the observation period into three phases — 1973-2000, 2000-2014 and 2014-2025. They found that mass loss at Khatling and the unnamed glacier during 2014-2025 was four to five times higher than during 1973-2000.
Adding to the concern is a lake rapidly developing in front of one of the glaciers. Scientists fear its continued expansion could increase the risk of a glacial lake outburst flood, or GLOF, threatening downstream settlements and infrastructure.
“The emerging lake and the rapid retreat of the glaciers require regular field assessment, satellite surveillance and an effective early-warning mechanism,” researchers cautioned.
The Bhilangana is a major tributary of the Bhagirathi and an important source of water for the Tehri reservoir. Glacier melt supports hydropower generation, agriculture and large downstream populations.
Scientists warned that while increased melting may temporarily raise river discharge, prolonged glacier decline could eventually reduce water availability, with serious consequences for water security, farming and energy production across the region.