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Ice patches on melting glaciers greater threat than thought: ISRO scientists

March 15, 2026 5 min read Science & Technology Environment & Ecology Geography GS Paper 1 (Geography Disaster) GS Paper 3 (Disaster Management Environment)
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What Happened

  • Researchers from ISRO have published a peer-reviewed study in the journal npj Natural Hazards establishing that the August 2025 flash flood at Dharali village in Uttarkashi district, Uttarakhand, was triggered by the collapse of a large exposed ice patch on the Srikanta Glacier — not a cloudburst, GLOF, or landslide as initially assumed.
  • The ice patch weighed approximately 69 million kilograms (69,000 tonnes), spanning 0.25 square kilometres, and had never been visible in satellite imagery from 15 previous summers — indicating it was newly exposed by accelerating snow-melt driven by climate warming.
  • Warming stripped away the protective snow cover by June–July 2025, exposing the structurally weakened ice patch, which subsequently collapsed and descended the steep valley slope into the Dharali area.
  • The study introduces "ice-patch collapse" as a distinct and under-recognised category of cryo-hydrological hazard in the Central Himalaya, separate from the more commonly studied Glacial Lake Outburst Flood (GLOF) paradigm.
  • The findings have significant implications for early warning systems, which currently focus on glacial lake monitoring but may miss smaller, hidden cryospheric instabilities.

Static Topic Bridges

Glacial Lake Outburst Floods (GLOFs) and the Spectrum of Cryospheric Hazards

A Glacial Lake Outburst Flood (GLOF) occurs when water impounded by a glacial dam — either ice or moraine — is suddenly released. GLOFs are the best-studied glacier-related hazard in the Himalayas and have been the primary focus of early-warning systems. However, the Dharali event expands the recognised spectrum to include "cryo-hydrological disasters" — broader failures of the cryosphere that do not involve a glacial lake at all.

  • India has over 7,500 glacial lakes within its territory (out of ~28,000 in the broader Hindu Kush-Himalaya region); 190 are classified as "very high risk" for GLOFs by national authorities
  • NDMA has classified 13 glacial lakes in Uttarakhand as "high risk"; the 2013 Kedarnath tragedy involved a glacial lake failure
  • The National Disaster Management Authority's USD 20 million programme targets 195 high-risk lakes using bathymetry surveys, Electrical Resistivity Tomography (ERT), UAVs, and slope stability mapping
  • Ice-patch collapses do not require a lake: they represent direct gravitational failure of destabilised ice bodies on steep terrain — making them invisible to lake-monitoring systems

Connection to this news: The Dharali study shows that hazard monitoring frameworks built around GLOFs are incomplete. Ice-patch collapses represent a category of threat that existing early warning infrastructure — designed for lake-level monitoring — cannot detect or predict.

Himalayan Glacier Retreat and Deglaciation Under Climate Change

The Himalayas contain the largest concentration of glaciers outside the polar regions, often called the "Third Pole." Under current warming trajectories, Himalayan glaciers are retreating faster than in any other mountain region. ISRO and other agencies use multi-temporal satellite imagery (from Resourcesat, Landsat, Sentinel series) to track changes in glacier extent, snow cover, and surface features.

  • The Srikanta Glacier is located in the Garhwal Himalaya in Uttarakhand; the broader region feeds the Ganges and Yamuna river systems
  • The exposed ice patch on Srikanta was unprecedented in 15 years of satellite observation, consistent with a long-term trend of accelerating deglaciation
  • IPCC Sixth Assessment Report (AR6): Himalayan glaciers are projected to lose 40–70% of their mass by 2100 under high-emission scenarios
  • More than 10% of Himalayan glacial lakes have grown over the past decade due to glacier melt, increasing downstream hazard
  • The Intergovernmental Panel on Climate Change (IPCC) 2022 report on impacts specifically flagged Himalayan cryosphere changes as a Category 1 risk for South Asia

Connection to this news: The ice patch that caused the Dharali flood was a direct product of long-term deglaciation — the snow that previously stabilised and concealed it had vanished. This is a concrete, locally documented consequence of the broader Himalayan glacier retreat trend.

India's Disaster Management Framework and Mountain Hazards

Under the Disaster Management Act, 2005, the NDMA sets national policies, while State Disaster Management Authorities (SDMAs) implement them. For Himalayan hazards, the key institutions include ISRO's National Remote Sensing Centre (NRSC), Wadia Institute of Himalayan Geology, Geological Survey of India (GSI), and the Central Water Commission (CWC) which operates flood early warning systems.

  • The Dharali/Uttarkashi event (August 2025) killed several people; initial response attributed it to cloudburst — a misclassification that highlights how response protocols can be misdirected
  • Correct hazard classification affects disaster preparedness, insurance, infrastructure design (road, bridge, dam), and land-use planning in mountain districts
  • India's National Action Plan on Climate Change (NAPCC) includes the National Mission for Sustaining the Himalayan Ecosystem (NMSHE) — but early warning for non-GLOF cryospheric failures has not been systematically addressed
  • The study recommends expanding hazard monitoring beyond glacial lake area to include: (a) ice-patch extent mapping, (b) snow-cover trend analysis in late summer, (c) slope-stability modelling on steep deglaciating terrain

Connection to this news: The Dharali finding is both a scientific advance and a policy call to action — existing disaster risk frameworks must be updated to incorporate newly identified cryospheric hazard types that climate change is making more frequent.

Key Facts & Data

  • Glacier studied: Srikanta Glacier, Garhwal Himalaya, Uttarakhand
  • Ice patch weight: ~69 million kg (69,000 tonnes); area: 0.25 sq km
  • First visible in 15 years of satellite record — newly exposed by accelerating deglaciation
  • Trigger mechanism: Snow-cover stripped away by June–July 2025 warming, exposing ice patch; structural failure followed
  • Flash flood date: August 2025, Dharali village, Uttarkashi district
  • Initial (incorrect) hypotheses: cloudburst, GLOF, landslide — all ruled out by ISRO analysis
  • Study published in: npj Natural Hazards (Nature Publishing Group)
  • India has 7,500 glacial lakes; 190 classified "very high risk" for GLOF
  • NDMA has classified 13 glacial lakes in Uttarakhand as high risk
  • IPCC AR6 projects 40–70% Himalayan glacier mass loss by 2100 under high emissions
  • Term coined: "cryo-hydrological disaster" — hazard triggered by cryospheric element failure without glacial lake involvement