The Himalayan Warning: Why Nepal’s Disaster Is India’s Wake-Up Call

Nepal’s catastrophe highlights growing Himalayan risks for India and millions downstream

When the flood struck Nepal’s Trishuli valley on August 26, the world stopped and watched in horror and disbelief. Videos showed a wall of water, mud and rock tearing through the mountain corridor. Homes, vehicles and bridges were swept away within minutes. For families living downstream, there was little time to understand what was happening, let alone escape. The US Geological Survey said it was likely triggered by a rapid slope failure involving a glacier near the Nepal-China border, sending ice, rock and debris almost 100 kilometres downstream.

For India, the larger warning is clear: glacier retreat, unstable slopes, changing precipitation and poorly planned infrastructure can interact, allowing one event high in the Himalaya to trigger another downstream.

A Himalaya Under Stress

As the Nepal disaster unfolds, a lesser-known term, GLOF, comes to our drawing-room discussions. As glaciers retreat, meltwater can collect in lakes held back by moraine, loose rock and sediment deposited by glaciers. Falling ice, avalanches, landslides, heavy rain or weakening moraine can breach these natural barriers, causing a glacial lake outburst flood, or GLOF.

A 2020 IIT Indore study assessed 329 Indian Himalayan glacial lakes and classified 23 as very high risk and 50 as high risk. A separate inventory published in 2024 identified more than 1,200 glacial lakes in the Indian Himalaya. Researchers have documented at least 16 GLOF events in the Indian Himalaya since 1980, although the true number is likely higher because smaller floods in remote valleys often go unrecorded. In October 2023, South Lhonak Lake in Sikkim burst into the Teesta system, damaging settlements, roads and hydropower infrastructure.

Flood risk also travels far beyond the mountains. In the Western Himalaya, rivers draining Ladakh, Himachal Pradesh and Uttarakhand feed the Indus, Yamuna and upper Ganga systems, carrying extreme rainfall and mountain runoff towards the plains.

The Central Himalaya, including Nepal, feeds the Ghaghara, Gandak, Kosi and Bagmati, which flow into Uttar Pradesh and Bihar. This downstream connection is visible again this monsoon: heavy rainfall in Nepal and adjoining catchments has contributed to rising river levels in Bihar, where the Kosi, Gandak, Bagmati and other rivers have crossed danger levels in several places, while the Ghaghara has flooded parts of eastern Uttar Pradesh.

In the Eastern Himalaya, the Teesta and the great Brahmaputra tributaries carry water from Sikkim, Arunachal Pradesh and neighbouring Himalayan regions into Assam. What begins as extreme rainfall, a landslide or a sudden release of water high in the Himalaya can therefore become a major flood hundreds of kilometres downstream, making basin-wide monitoring, early warning and cross-border cooperation essential.

Faster melting can initially increase river flows, but it also steadily reduces the ice stored in the mountains. Scientists describe the point when glacier meltwater reaches its maximum contribution as “peak water”. After that, meltwater begins to decline as glaciers shrink.

The impact will vary between river basins. The Indus is particularly dependent on snow and glacier melt, while the Ganga and Brahmaputra depend more heavily on monsoon rainfall. But across the Himalaya, shrinking glaciers will reduce an important source of dry-season water.

The Himalaya is often called Asia’s water tower. Climate change is slowly reducing the amount of water stored inside that tower. The immediate danger may be too much meltwater and destructive floods; the longer-term danger is having less ice left to provide water when it is most needed.

Glacier loss is only one sign of a changing Himalaya. Rising temperatures are also altering rainfall and snowfall, increasing fire-conducive conditions, shifting vegetation uphill and changing what farmers can grow at different elevations. Climate stress may amplify Himalayan migration, food insecurity and human-wildlife conflict.

Precipitation is becoming harder to predict. The concern is not simply receiving less precipitation, but receiving it at different times and in more damaging bursts, increasing the possibility of floods and landslides while leaving longer dry periods between events.

Drier pre-monsoon conditions can also make Himalayan forests more vulnerable to fire. A peer-reviewed study of Uttarakhand using nearly two decades of satellite records found that higher pre-monsoon temperatures and lower winter and pre-monsoon rainfall were strongly associated with greater fire incidence, particularly in chir pine forests. Warmer, drier conditions can make forests easier to burn and fires harder to control.

Fire can then feed back into warming. Burning forests release carbon and black carbon, or soot. When black carbon settles on snow and glaciers, it darkens the surface, allowing it to absorb more sunlight and melt faster. As snow and ice disappear, darker land underneath absorbs still more heat. Research in the Journal of Climate has identified this snow-and-ice albedo feedback as an important contributor to amplified Himalayan warming.

The biological landscape is shifting as well. Research published in Nature Ecology & Evolution projects that trees in the Eastern Himalaya could move around 140 metres higher by the end of the century under continued warming, potentially removing at least 20 per cent of the present habitat available to endemic alpine plants. Species already restricted to mountaintops have nowhere further uphill to retreat.

One of the most visible changes can already be seen in Himachal Pradesh’s apple belt. A 2020 PLOS One study found that areas suitable for apple cultivation have progressively moved higher as winters become warmer and the chilling hours apple trees need decline. Orchards commonly found around 1,200–1,500 metres in the 1980s had shifted largely towards 1,500–2,500 metres by the 2000s, with apple cultivation later appearing above 2,500 metres in places such as Kinnaur and Lahaul-Spiti. Lower-elevation farmers, meanwhile, have increasingly had to consider other crops.

Shifting wildlife ecosystem

As temperature, rainfall and water availability change, wildlife may shift ranges and seasonal movements, increasing pressure on already fragmented habitats and potentially bringing animals into greater conflict with people. In Uttarakhand, unusually warm, low-snow winters are already disrupting Himalayan black bear hibernation and food availability, with bears remaining active longer and moving into farms and villages, adding to a sharp rise in human-bear conflict.

“Climate change is already altering ecosystems around us. Wildlife may shift ranges, alter seasonal movements or seek new refuges. If those landscapes are fragmented, animals may have nowhere to go,” said Jose Louies, Chief Executive Officer of the Wildlife Trust of India (WTI). “This makes wildlife corridors and ecological connectivity increasingly important, not only for conservation but as part of climate adaptation,” he said.

WTI’s Vice President and Chief of Conservation, Dr Sandeep Kumar Tiwari, said community-led restoration has covered more than 650 hectares of degraded forest in Meghalaya’s Garo Hills since 2010 and around 200 hectares in the D’Ering-Dibru Saikhowa elephant corridor in Arunachal Pradesh and Assam over the past five years. “Restoring the forest not only revives the ecological system of the landscape but is an excellent means to address the impact of climate change, increase productivity of the soil and help in food security,” Tiwari said.

The projects show why adaptation increasingly requires landscape-level planning, connecting forests, farms, settlements, wildlife corridors and infrastructure rather than treating protected areas as ecological islands.

India’s development goals

“Climate change presents a challenge for conventional economic analysis because its impacts involve long time horizons, uncertainty, and potentially irreversible damage,” said Dr Gurudas Nulkar, Professor and Director of the Centre for Sustainable Development at the Gokhale Institute of Politics and Economics, Pune.

Nulkar argued that cost-benefit analysis should be complemented by risk assessment and the precautionary principle. In simple terms, we should not wait for complete certainty before acting to prevent potentially serious or irreversible harm. He also points to the limits of GDP, which measures economic activity but does not adequately capture the natural wealth supporting it. Forests, rivers, wetlands and soils, he said, should be recognised as economic assets, and climate risk must therefore be assessed across entire landscapes, not project by project.

India’s development goals depend not only on built infrastructure, but also on the natural systems that protect people and economies. Wetlands hold floodwater, floodplains give rivers room to spread, forests stabilise watersheds, soils hold carbon, mangroves buffer coasts and wildlife corridors help species move as habitats change. These are not merely biodiversity assets. They are India’s natural climate infrastructure.

The Centre’s Rs 150-crore National GLOF Risk Mitigation Project for Arunachal Pradesh, Himachal Pradesh, Sikkim and Uttarakhand includes hazard assessment, monitoring, early warning, mitigation and community preparedness. But early warnings alone cannot make communities safe. Land-use planning, climate-resilient infrastructure, ecosystem restoration and stringent regulation of construction in flood-prone areas, unstable slopes and coastal zones must be placed at the heart of development planning.

Nepal’s disaster is a warning that climate risks move through rivers, food systems, economies and communities. One of India’s greatest strengths is our natural capital, and millions of livelihoods depend directly on it. Protecting this natural wealth should therefore not be seen as being against development. It should be recognised as fundamental to our economic security and our ability to withstand climate change.

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India’s GLOF Exposure