Nepal floods: Warning from the Himalayas

The devastating flash flood in Nepal is the latest stark warning about the vulnerability of the Himalayas to glacial lake outburst floods and other extreme weather events.

Over the past 15 years, India has witnessed similar disasters – Kedarnath in 2013, Chamoli in 2021, both in Uttarakhand, the South Lhonak glacial lake outburst in Sikkim in 2023, and Dharali in Uttarakhand last year.

The Himalayas are often called the world's third Pole after the North and South Poles because the mountain range hosts numerous glaciers and extensive snow cover. These are highly sensitive to changes in the global climate, with significant implications for both the physical environment and human societies.

Long-term satellite imagery of the catchments of Indian Himalayan river basins from 1984 to 2023 shows significant changes in glacial lakes, according to a 2024 report by the Indian Space Research Organisation (Isro).

Of the 2,431 lakes larger than 10 hectares identified in 2016-17, 676 glacial lakes have expanded significantly since 1984. At least 130 of these are located in India, including 65 in the Indus, seven in the Ganges and 58 in the Brahmaputra river basins.

Of the 676 lakes, 601, or 89%, have more than doubled in size, while 10 have grown between 1.5 and two times and 65 by 1.5 times, the space agency said.

Scientists say the increasing frequency of floods, landslides, glacial melting and extreme rainfall events in the Hindu Kush-Himalaya region indicates that the region is experiencing severe impacts of climate change.

A study by YP Sundriyal, senior scientist at the Department of Geology at Himalayan Research and Study Institute at Doon University; Dr Nityanand of the same institute; Dr SP Sati of the Department of Basic and Social Sciences at Veer Chandra Singh Garhwali Uttarakhand University of Horticulture and Forestry, Bharsar; and retired Isro scientist Naveen Juyal found that the frequency and intensity of extreme weather events during the summer monsoon are increasing in the Hindu Kush-Himalayas.

In a written reply to the Lok Sabha on 29 July this year, Science and Technology Minister Jitendra Singh said accelerated glacier melting would have several noticeable impacts.

These include shifts in the seasonality and greater year-to-year variation of runoff, potentially affecting water supplies from local to regional and continental scales, including surrounding lowlands; the formation and expansion of new and existing lakes, increasing the frequency of glacial lake outburst floods (GLOFs) and flash floods; and rising global sea levels.

Jitendra Singh said the Indian government is using satellite and geospatial technologies to monitor glaciers, glacial lakes, snowfall, water resources and landslides in Ladakh.

Isro is also conducting advanced research and development activities to strengthen space-based early warning systems for GLOFs, extreme weather events and landslides.

How is India monitoring Himalayan glaciers and glacial lakes?

In a written reply to the Rajya Sabha on 31 July 2025, Jitendra Singh, who is also India's Space Minister, said several Indian institutes, universities and government-funded organisations monitor Himalayan glaciers for scientific studies, including glacier melting.

These studies have reported accelerated and varying rates of mass loss among Himalayan glaciers.

The mean retreat rate of glaciers in the Hindu Kush-Himalayas is about 14.9 to 15.1 metres per year.

This varies from nearly 12.7 to 13.2 metres per year in the Indus basin, 15.5 to 14.4 metres per year in the Ganges basin and 20.2 to 19.7 metres per year in the Brahmaputra basin, he said.

However, glaciers in the Karakoram region have shown comparatively minor changes in length, ranging from less than 1.37 to 22.8 metres per year.

Based on field measurements of glaciers from 1975 to 2023, the cumulative mass loss of Indian Himalayan glaciers is estimated at less than 26 metres.