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Bengaluru: Brown debris-ridden, unstoppable waves lashed the banks of Nepal’s Bhotekoshi river on August 26. It left behind a wide, empty grey trail, as mud settled over all the things it had swept away: homes, schools, buildings, dams. Twelve days later, nearly 1,350 people are dead. Almost 5,000 are still missing. 

The trigger, based on later satellite and photographic evidence, was an ice-rock avalanche high up in Rasuwa district on the Nepal-China border: a portion of a mountain had collapsed, falling thousands of feet. The impact shook the earth: scientists recorded an earthquake measuring 5.2 on the Richter Scale. 

Though the role of climate change in this incident is still being debated, the science is clear: signs of climate change have been showing up across the Himalaya, from shrinking glaciers to thawing permafrost. Scientists and activists have also flagged the need for better development models across the range, as well as the importance of sharing data not only between countries but also research teams, agencies and departments within India too. With Nepal losing US $ 2.56 billion worth of property, housing and infrastructure, rebuilding is the priority now – a feature that all countries have to grapple with once disasters like these strike. This is where climate funds have to come in, experts say.

Role of climate change?

While scientists initially thought that a 4.4 magnitude earthquake in Rasuwa district on the Nepal-China border triggered the floods downstream in the Bhotekoshi and Trishuli rivers, the US Geological Survey later said that the earthquake (a magnitude of 5.2 on the Richter Scale) was in fact triggered by a glacier collapse at the Lantang Lirung (a peak in Nepal on the China border). A few days later as more satellite data emerged, it became apparent that an ice-rock avalanche had occurred. Bedrock failure had caused a part of the mountain to collapse and it fell thousands of feet below, say scientists. It pulverised ice, and collected debris and momentum as it rushed downstream. 

Did melting glaciers caused by climate change trigger the slope failure or ice-rock avalanche? It’s hard to pinpoint climate change as the prime reason for this incident, a geospatial scientist recently told The Wire. Others, like Farooq Azam, senior cryosphere specialist and intervention manager at the Kathmandu-based International Centre for Integrated Mountain Development (ICIMOD) say that it could have been a combination of climate and geological factors at play.

“This is one of the biggest disasters in Nepalese history…Glaciers are receding and exposing rock surfaces underneath which absorb heat because their albedo is less and when the glaciers are receding there is always some loose bore and debris left behind. So, it seems like a combination of both climate treatment as well as the geologic process,” he said, commenting on the incident on September 4 in an online discussion.

The science is clear: climate change is already at work across the Himalaya. India is feeling the pinch too. 

Permafrost is thawing. This is a layer of soil or rock that remains at or below 0°C for at least two consecutive years, and traps vast amounts of carbon. A study published in Scientific Reports in 2025 that investigated the first case of permafrost-degraded subsidence in Lindur village in Lahaul and Spiti district in Himachal Pradesh found significant land subsidence rates ranging from 7.9 to−6.8 cm per year. Data from 1950 to 2024 from the area showed a rise in temperature at a rate of 0.02°C/year and a shift in the precipitation pattern over the village. Local geology and existing rock glaciers exacerbated the rate of subsidence leading to the development of cracks in the region, the study noted.

Glaciers are shrinking. Satellite images of 77 glaciers in the Drass basin in Ladakh from 2000 to 2020 show that the total glacier cover here has shrunk by 5.31 ± 0.33 km2. As glaciers retreat in the Himalaya, the number and size of glacial lakes have increased. According to the ISRO, of the 2,431 lakes larger than 10 hectares identified during 2016-17 covering the catchments of Indian Himalayan river basins across the mountain range, 676 glacial lakes have “notably expanded” since........

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