A new scientific study has found that the Gangotri Glacier, one of the most important Himalayan glaciers that sustains the Ganga River, has been witnessing a steady decline in snowmelt contribution over the past four decades due to the impacts of climate change.
The research, jointly conducted by the Indian Institute of Technology (IIT) Indore, the International Centre for Integrated Mountain Development (ICIMOD), and several U.S.-based universities, examined the glacier system’s hydrology between 1980 and 2020.
According to the study, Gangotri’s annual water discharge has averaged 28 cubic metres per second over the past four decades. Snowmelt continues to be the primary contributor, accounting for 64% of the total flow, followed by glacier melt (21%), rainfall runoff (11%), and base flow (4%).
However, the share of snowmelt has shown a clear declining trend — dropping from 73% in the 1980s to 63% in the 2010s. During 2000–2010, the contribution dipped to a low of 52%, before recovering slightly in the following decade. Researchers attribute the rebound to colder winter temperatures and increased precipitation, which led to higher seasonal snow accumulation that later melted in summer.
“The long-term trend indicates a shrinking snow-covered area due to rising temperatures, which has reduced snowmelt volumes. This is a direct impact of climate change on the glacier system,” experts involved in the study told Down To Earth.
The findings also reveal that the peak water discharge period has shifted from August to July since the 1990s, a result of earlier melting triggered by warmer summers and reduced winter precipitation. Scientists warn that such shifts could have serious implications for hydropower generation, irrigation, and water security, especially in Himalayan states that rely heavily on glacial meltwater.
The study concludes that while snowmelt remains the dominant source of discharge from the Gangotri Glacier, its declining contribution, alongside increasing rainfall-runoff and base flow trends, highlights the significant hydrological changes being driven by a warming climate.