Climate Change Is Reshaping Disaster Risk Across the Himalayas

The catastrophic floods that struck Nepal on August 26 were a stark reminder that disasters in the Himalayas are becoming increasingly complex and potentially more devastating.

The 2,500 km long mountain range is one of the youngest and most tectonically active mountain systems on Earth. Its steep slopes, highly fractured and weathered rocks, active faults, frequent earthquakes and intense monsoon rainfall make it inherently vulnerable to natural hazards. Climate change is now adding another layer of instability.

In Nepal, this disaster was not triggered by an earthquake. Available evidence suggests that it originated high in the Himalayas, near the Nepal–China border. A huge mass of glacier ice and rock, estimated to have been between 1 and 1.3 km wide, detached from a high-altitude slope and plunged into the Lhende Khola, a tributary of the Bhote Koshi.

The flood was a cascading event involving glacier ice, rock, debris, temporary river blockage and an exceptionally rapid flood wave. The human toll has exceeded 1,350.

As global temperatures are going to cross the 1.5 C rise threshold, outlined in a recent UN report, the impact on the Himalayas will only exacerbate. 

Fragile mountain system

The Himalayas is undergoing profound and measurable climatic and environmental change. Temperatures are rising across the Hindu Kush–Himalaya, with evidence of elevation-dependent warming. The warming can cause precipitation at high elevations to fall increasingly as rain rather than snow, while also destabilising frozen slopes. 

At high elevations, soil and rock can remain frozen for years or even centuries. This frozen ground, known as permafrost, helps to hold mountain slopes together. As temperatures rise and permafrost thaws, slopes can become increasingly unstable, increasing the potential for rockfalls, landslides, avalanches and debris flows.

As glaciers shrink, they can leave behind depressions that gradually fill with meltwater, creating or enlarging glacial lakes. The growth of such lakes increases the potential risk of glacial lake outburst floods (GLOFs), in which large volumes of water are suddenly released downstream. There is also increasing evidence of more intense monsoon precipitation events in many parts of the region. 

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This raises an important question: How can we reduce the risks of such disasters?

Adapting

First, India, Nepal and China need to move towards a genuinely integrated, multi-hazard Himalayan monitoring system with meteorological, hydrological, geological, seismic and cryospheric observations. Modern satellite technology provides an unprecedented opportunity. High-risk glaciers, glacial lakes and unstable slopes should be monitored continuously using optical satellite imagery and synthetic-aperture radar (SAR). Radar observations can detect ground deformation even when clouds obscure the surface. 

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Second, transboundary data sharing must become an essential part of Himalayan disaster management. Real-time sharing of rainfall, river discharge, satellite, glacier and other relevant observations among China, Nepal and India could substantially improve early warning. In the Himalayas, national boundaries do not coincide with the boundaries of natural hazards.

Third, forecasting must evolve from simply predicting hazards to impact-based early warning. It is not enough to say that a flood, landslide or debris flow is likely. This is where advances in artificial intelligence and high-resolution numerical modelling could become particularly valuable. 

Finally, technology alone will not save lives. Community-based warning systems are indispensable. The evacuation of hundreds of schoolchildren following rapid warnings during this disaster demonstrated an important principle: even a very short warning can save lives if people understand the warning and know exactly what action to take.

Increasing exposure

There is also a larger lesson from Nepal. The Himalayas is becoming more hazardous because a naturally fragile mountain system is undergoing rapid climatic and environmental change, while we are simultaneously placing more people, roads, dams, tunnels, hydropower projects and other economic assets in precisely the locations where these hazards occur.

Climate change is altering the hazard environment; infrastructure development is increasing exposure. If these two trends continue without a fundamental change in Himalayan planning and infrastructure design, we can expect more events in which several hazards interact to produce disasters far greater than any single hazard alone could generate.

The future of Himalayan disaster management therefore lies in building an integrated system that combines satellites, weather prediction, hydrology, glaciology, seismology, artificial intelligence, real-time transboundary data sharing and community preparedness.

The Himalayan challenge is no longer simply about predicting the next flood or landslide. It is about understanding a rapidly changing mountain system—and ensuring that development does not outpace our ability to understand and manage its risks.

Madhavan Rajeevan is currently the Vice Chancellor of Atria University, Bengaluru. Prior to this, he worked as a Distinguished Scientist at the Ministry of Earth Sciences. Views expressed are personal