The fourth Khangri Glacier expedition has delivered a series of landmark scientific achievements in Arunachal Pradesh’s Tawang district, including the first-ever reconnaissance of Dharkha Tso glacial lake and the detection of aquatic life 20 metres below Rani Lake’s surface.
The week-long mission, held from 8 to 14 November, is a joint effort by the Centre for Earth Sciences and Himalayan Studies (CESHS) and the National Centre for Polar and Ocean Research (NCPOR), under the Union Ministry of Earth Sciences. The annual expedition, launched in 2023, focuses on glacier monitoring, climate-linked changes, and water security in the Eastern Himalayas.
CESHS Director Tana Tage emphasised that the initiative “aims to build deeper scientific insight into glacier behaviour, climate-linked changes and long-term water security in the Eastern Himalayas.”
Led by senior glaciologist Dr Parmanand Sharma and coordinated by Nyelam Sunil, the 2025 team comprised 11 scientists and engineers from CESHS, NCPOR Goa, Nagaland University and NERIST. Despite heavy snowfall limiting direct glacier access for summer mass balance studies, the team employed advanced drones to carry out high-resolution aerial surveys of Khangri Glacier and Rani Lake.
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A major highlight was a sonar-enabled bathymetric survey of Rani Lake, which revealed aquatic life thriving at 20 metres depth, a rare discovery in high-altitude Himalayan ecosystems. The expedition also retrieved data from an automatic weather station and water-level recorder, and conducted round-the-clock measurements of stream discharge to assess meltwater dynamics.
Equally significant was the first scientific scaling and reconnaissance of Dharkha Tso, one of 29 glacial lakes identified by the NDMA as prone to glacial lake outburst floods (GLOFs). Situated at 16,145 ft in the remote Mirathang Valley, the lake required a 3.8-km ascent over deep snow, steep ridges, and low-oxygen terrain. Scientists completed drone mapping and collected water and sediment samples for GLOF risk analysis.
CESHS said the expedition represents “a crucial advancement in India’s efforts to understand glacier health, meltwater contribution, hydrometeorological shifts and evolving GLOF risks across the Eastern Himalayas,” strengthening the nation’s cryospheric and hydrological datasets.
The 2025 mission builds on the previous expeditions’ findings, reinforcing India’s strategic scientific approach to high-altitude glacial ecosystems and climate change impacts.
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