Despite record floods during monsoons, rivers like Ganges, Brahmaputra, and Teesta will experience critical water shortages in the dry season, due to rapid melting of Himalayan ice, an UN report has said.
The Hindu Kush Himalayas serve as the source of ten major Asian rivers, including the Indus, Brahmaputra, and Ganges, which supplies 60 per cent of the world's freshwater annually. More than a billion people live in mountain areas, while over two billion depend on mountain water for drinking, sanitation, and livelihoods.
The findings were published in UNESCO's "United Nations World Water Development Report 2025" on March 21, coinciding with the first-ever observance of World Glacier Day.
"The continued melting of glaciers is expected to severely disrupt river flows, particularly during the dry season. Currently, 65 per cent of the Brahmaputra's and 70 per cent of the Ganges' dry-season flow depends on Himalayan glacier meltwater," the report said.
The impacts will only get worse unless greater efforts are made to curb black carbon deposits that are accelerating melting. The mountain ranges of the Himalayas, the Hindu Kush, and the Karakoram span 2,400 kilometers across six nations and contain 60,000 km² of ice - storing more water than anywhere except the Arctic and Antarctic. Melting glaciers and loss of seasonal snow pose significant risks not just to the people who live at their foot but to the stability of water resources in the South Asia region more broadly, it reads.
"More than 750 million people depend on the glacier- and snow-fed Indus, Ganges, and Brahmaputra rivers for freshwater, and changes in the volume and timing of flows will have important economic and social implications. It was apprehended that by 2050, from 1.5 billion to 1.7 billion people in South Asia will be projected to be vulnerable to water scarcity due to rapid melting of Himalayan ice; moreover, it will also change the weather and food diversity of these region," Dr Ainun Nishat told the Daily Observer.
However, Black carbon deposits originating from factories, cooking and vehicles are compounding the effects of climate change to speed up the melting of the Himalayan glaciers.
The report cautions that without significant reductions in carbon emissions, the impact of glacier melt will be catastrophic and endanger biodiversity and food production.
"Recent devastating flash floods attributed to a collapsing glacier in the Himalayas were a sobering reminder of the future disastrous effects of climate change and the dangers we have to protect against," said Hartwig Schafer, World Bank Vice President for South Asia.
"As glaciers shrink, the lives and livelihoods of many people downstream are affected by changes in the water supply. We can slow glacier melt by collectively acting to curb the black carbon deposits that are speeding up the thinning of the ice. Regional cooperation to protect these resources will pay important dividends for the health and well-being of the people in the region."
Dr Farhina Ahmed, Secretary of the Ministry of Environment, Forest and Climate Change, said "Accumulated greenhouse gases from fossil fuels continue to heat the planet. In Bangladesh, forest coverage has declined alarmingly, and rural water bodies are disappearing as canals and ponds are filled in. This loss of natural cooling agents is exacerbating the rise in temperature, however, to address the issue, regional effort is a must, we are working on it."
Professor Ahmad Kamruzzaman Majumder, Chairman of the Centre for Atmospheric Pollution Studies (CAPS) blamed global warming, deforestation, unplanned urbanisation, and carbon emissions for causing severe disruptions. "If immediate steps aren't taken, the situation may worsen in the coming years," he warned.
"In 2017, the average temperature in areas under Dhaka South City Corporation was 33.50°C, which climbed to 36.54°C in 2024. The trend suggests a further rise by mid-2025. Dhaka North City Corporation has seen an even steeper increase - nearly 4°C. The average there jumped from 33.39°C in 2017 to 37.38°C last year, all these are the impact of climate changes," Professor Majumder said.
