Header image: Sagarmatha National Park, Nepal. Photo credit: Peter Prokosch
Glaciers across High Mountain Asia are losing more than 22 gigatons of ice per year-the equivalent to nearly 9 million Olympic swimming pools, according to research from the University of Utah and Virginia Tech. The impact of a warming climate on glacial loss is undisputed-this new study provides the first evidence that seasonal shifts in rainfall and snowfall patterns, particularly of the South Asian monsoons, are also exacerbating glacier melting across the region.
"These findings highlight that glaciers dominated by the South Asian monsoons, such as the Central Himalaya, Western Himalaya and Eastern Himalaya, are especially vulnerable," said Sonam Sherpa, assistant professor at the University of Utah and lead author of the study. "If the timing and intensity of the monsoon continues to alter, it could accelerate ice loss and threaten water availability for millions downstream."
High Mountain Asia is known as the "Third Pole" because it holds the world's largest reserve of glacier ice outside the Arctic and Antarctic. The region's glaciers feed lakes and rivers that supply freshwater to more than 1.4 billion people across South and Central Asia, sustaining agriculture, hydropower and drinking water.
"Looking ahead, a faster retreat of mountain glaciers will shift the main source of river flow from glacier melt to rainfall, thereby heightening the risk of droughts in downstream regions for future generations," said Susanna Werth, assistant professor at Virginia Tech and co-author of the study.
High-lying glaciers in the southern parts of the Central Himalayas accumulate during the summer, rather than in the winter. At higher elevations, cold temperatures turn annual monsoon precipitation into intense snowfall that feeds the glaciers. Glaciers retreat because they either receive less snowfall or experience more melting than usual. While warming itself drives melting, it also alters rain and snowfall patterns. This can shorten the precipitation season, reduce precipitation amount or cause a shift from snow to rainfall on the glaciers, driving even more melting due to less accumulation on glaciers.
Accelerated glacier-melt patterns also carry significant risks. Faster melting can increase the likelihood of glacial lake outburst floods, a growing threat in mountain regions worldwide as receding glaciers retreat in response to climate change. Together with follow-up cascading hazards, including landslides and river flooding, unstable glaciers can devastate vulnerable communities.
"This risk is not only about long-term water shortages but also about immediate threats to lives and infrastructure," said Sherpa.
The study was published in the IEEE Journal of Selected Topics on Applied Earth Observations and Remote Sensing on Aug. 1, 2025.
Monsoon-driven melt: A widespread phenomenon
The authors used satellite data from NASA's GRACE mission sensitive to ice mass losses, combined with hydrological and meteorological records, to assess the effects of a warming climate, changing precipitation seasonality and evolving monsoon patterns on glacier melt and the hydrological cycle in High Mountain Asia.
The key findings of the analysis are:
- In the central and western Himalayan regions where glaciers typically grow during the summer, ice losses are associated with increased rainfall.
- In eastern regions of the Himalaya, ice dynamics could be associated with reduced snowfall.
- Repeating patterns in glacier retreat occur at 3-4.5-year and 5-8-year cycles, aligning with natural variability in monsoon patterns. This raises urgent questions about how future climate-driven monsoon shifts will impact long-term glacier health.
The researchers emphasize the urgent need for denser and more accurate monitoring networks of rainfall, snowfall and related climate variables. Improved observation systems, they argue, are critical for predicting the impacts of monsoon alterations and guiding adaptation strategies.
