The Ganga and Brahmaputra basins have experienced a record low in snow persistence — the fraction of time snow is on the ground after snowfall – over the past 23 years, raising alarms about an impending water crisis that could affect over 650 million people. This decline has been consistently observed for three consecutive years. Experts attribute it to climate change.
Seasonal snowmelt is crucial for regional and local water availability. It contributes around 23% of annual river flow, especially in the early summer, and nourishes rivers for agriculture, hydropower and several ecosystem services.
According to the latest Snow Update report of the Hindu Kush Himalaya (HKH) region, released by the International Centre for Integrated Mountain Development (ICIMOD), a regional intergovernmental organisation, HKH experienced its third consecutive below-normal snow year in 2025, with snow persistence hitting a vicennial record low of -23.6%.
Lesser snow persistence is worrying for the water security of nearly two billion people across 12 major river basins that originate in the HKH.
In the Ganga basin, the snow persistence this year has been 24.1% below normal, the lowest in the past 23 years. The current snowmelt deficit may lead to reduced flows in early summer. In contrast, the basin recorded its highest snow persistence in 2015, which was 30.2% above normal.
The basin had a deficit of -13.6% and -20.4% snow persistence between November and March in 2023 and 2024, respectively. This year, the deficit increased to -24.1%. In the past six years, four witnessed snow persistence deficit. However, in 2020 and 2022, the basin had snow surplus.
The consistent decline of snow for three years has put the lives of India’s 43% population who reside in the Ganga basin at risk.
Similarly, in the Brahmaputra basin, snow persistence declined to its lowest of -27.9% below normal in 2025. The basin had a deficit of -10.7% and -15.7% snow persistence between November and March in 2023 and 2024, respectively.
A continued decline in snow persistence is likely to adversely impact approximately 130 million people in the riparian state. It will negatively impact hydropower generation and agriculture, especially in early summer, underscoring the need for integrated drought risk planning. Warmer winter and late snowfall trend is due to feeble large-scale atmospheric circulations. “Normally, winter season snowfalls start normally in October/November but this year, winter remained quite dry and snowfall only started late in January,” said Sher Mohammad, Remote sensing (cryosphere) specialist at ICIMOD. Mohammad further points out that climate change has weakened other atmospheric circulations also, which contributed to lesser snow persistence. “Due to the changing climate, jet stream and other large-scale atmospheric circulations are weakening, which can disrupt the usual patterns of snowfall and snow season,” he explained.
According to the report, snow persistence has been below normal across all 12 major river basins, with the most alarming decline observed in the Mekong (-51.9%) and Salween (-48.3%) basins, followed by Tibetan Plateau (-29.1%), Brahmaputra (-27.9%), Yangtze (-26.3%), and Ganges (-24.1%). Even snow-dominant basins such as the Amu Darya (-18.8%) and Indus (16.0%) also continued experiencing a reduction in snow persistence.
The steadily declining seasonal snow and below-normal precipitation in spring may lead to reduced runoff, which may cascade into major environmental disasters. Lesser river runoffs lead to intensive groundwater extraction and drought across the region.
The report stressed the level of deficit in snow persistence in the western river basins is comparatively low. However, it doesn’t provide respite from the existing water stress in these areas. In contrast, eastern river basins face deficits up to 50% below normal. Mohammad attributes it to the weakening of western disturbances and Siberian winds.