An Emerging Cryospheric Threat in the Himalaya
Context:
A recent study by scientists from the Indian Space Research Organisation, published in the journal NPJ Natural Hazards, has revealed that exposed ice patches on melting Himalayan glaciers may pose a greater disaster risk than previously understood.
About the study:
The study examined the August 5, 2025 flash flood in Dharali village in Uttarakhand, which caused severe destruction and loss of lives, and identified the collapse of an ice patch on the Srikanta Glacier as the primary trigger of the event.
The Dharali Flash Flood and Its Cause:
-
- Initially, the disaster in Dharali was attributed to a cloudburst or heavy rainfall. However, satellite data and terrain analysis revealed that the flood was triggered when a large exposed ice patch collapsed in the nivation zone of the glacier, releasing ice, meltwater and debris into the Khir Gad stream, which flows into the Bhagirathi River.
- The collapsing ice mass, estimated at around 69 million kilograms descended rapidly from an altitude above 5,000 metres, generating a high-velocity debris flow that devastated downstream settlements.
- Initially, the disaster in Dharali was attributed to a cloudburst or heavy rainfall. However, satellite data and terrain analysis revealed that the flood was triggered when a large exposed ice patch collapsed in the nivation zone of the glacier, releasing ice, meltwater and debris into the Khir Gad stream, which flows into the Bhagirathi River.
About Ice Patches:
-
- Ice patches are masses of glacial ice that remain preserved beneath layers of seasonal snow and firn (partially compacted snow). Normally, this snow cover acts as an insulating layer that stabilizes the ice.
- However, due to rising temperatures and glacier retreat (deglaciation), these protective layers are thinning, exposing underlying ice patches. Once exposed, the ice becomes more sensitive to temperature fluctuations, rainfall and freeze-thaw cycles. This makes it prone to melting, fragmentation or sudden collapse, which can release water and debris and trigger flash floods.
- Ice patches are masses of glacial ice that remain preserved beneath layers of seasonal snow and firn (partially compacted snow). Normally, this snow cover acts as an insulating layer that stabilizes the ice.
Significance of Satellite Monitoring:
A major implication of the research is the importance of satellite-based glacier monitoring. Scientists used multi-temporal satellite imagery, digital elevation models and field observations to detect exposed ice patches weeks before the flood occurred. Such observations can act as early warning signals for potential disasters in remote Himalayan regions.
Broader Implications:
-
- The findings highlight a broader challenge associated with climate change and glacier retreat. Traditionally, glacial hazards in the Himalaya have focused on Glacial Lake Outburst Floods (GLOFs). However, the Dharali event demonstrates that smaller and less visible instabilities, such as collapsing ice patches can also trigger catastrophic floods.
- As glaciers continue to shrink due to global warming, such cryo-hydrological hazards may become more frequent across the Himalayan region.
- The findings highlight a broader challenge associated with climate change and glacier retreat. Traditionally, glacial hazards in the Himalaya have focused on Glacial Lake Outburst Floods (GLOFs). However, the Dharali event demonstrates that smaller and less visible instabilities, such as collapsing ice patches can also trigger catastrophic floods.
Way Forward:
To reduce future disaster risks, experts recommend:
-
- Continuous satellite monitoring of glaciers and nivation zones
- Development of early-warning systems for cryospheric hazards
- Integrated glacier hazard mapping in the Himalayan region
- Strengthening disaster preparedness in vulnerable mountain communities
- Continuous satellite monitoring of glaciers and nivation zones
Conclusion:
The Dharali flash flood illustrates how subtle changes in the cryosphere can trigger major downstream disasters. The identification of exposed ice patches as a new hazard indicator underscores the need for improved glacier monitoring and climate-resilient disaster management strategies in the fragile Himalayan ecosystem.
