In the soaring heights of High Mountain Asia, a region often hailed as the “Third Pole,” the glaciers are vanishing at an alarming pace. This vast expanse, which contains the largest repository of glacier ice outside the polar regions, has been losing over 22 gigatons of ice annually. To contextualize, this loss equates to nearly nine million Olympic-sized swimming pools emptied each year, presenting a stark illustration of the scale of change. Recent findings by researchers from the University of Utah and Virginia Tech reveal not only the undeniable role of rising temperatures but also a less examined but critical dynamic: the shifting patterns of seasonal rainfall and snowfall driven by the South Asian monsoons.
Glaciers in High Mountain Asia serve as vital freshwater reservoirs, feeding lakes and river systems that nourish more than 1.4 billion people downstream. These water sources sustain agriculture, hydropower generation, and drinking water supplies, underpinning regional economies and human livelihoods. The urgency to understand the mechanisms behind glacier mass loss grows as stakeholders grapple with water security challenges across South and Central Asia. Until now, the narrative had focused primarily on atmospheric warming and its direct effects, but this latest study delves deeper into how alterations in monsoon dynamics exacerbate glacier retreat.
Unlike many glacial systems worldwide that accumulate ice primarily during colder winter months, glaciers in the southern reaches of the Central Himalayas display a different behavior. They build up mass chiefly during the summer monsoon season. At elevated altitudes, monsoon precipitation transforms into substantial snowfall due to frigid temperatures, directly replenishing glacier ice. However, increasing global temperatures disrupt this delicate balance, resulting in variations not only in the amount of precipitation but also in its form—shifting from snow to rain. Such shifts lead to less ice accumulation on glaciers, accelerating their decline beyond what temperature rise alone would dictate.
This nuanced understanding stems from utilizing advanced remote sensing data from NASA’s Gravity Recovery and Climate Experiment (GRACE). The GRACE mission provides unparalleled sensitivity to changes in ice mass, offering a comprehensive view of glacier dynamics over regional scales. Coupled with extensive hydrological and meteorological datasets, researchers could isolate the intricate relationship between climate seasonality and glacier mass variations. Their observations indicate that in the Central and Western Himalayas, where glaciers typically grow during warmer months, increased rainfall rather than snowfall drives mass losses, revealing a counterintuitive but crucial feedback mechanism in glacier hydrology.
In the Eastern Himalayas, a contrasting pattern emerges, where diminishing snowfall emerges as a prime contributor to ice retreat. Reduced snowfall not only limits ice accumulation but also exposes glacier surfaces to enhanced melting by lowering the surface albedo—the reflectivity that helps glaciers resist solar heating. These findings hold profound implications, as they link regional climatic idiosyncrasies with disparate glacier behaviors, underscoring the need for location-specific climate and glacier models.
Moreover, this study unveiled repeating cycles in glacier retreat occurring within 3 to 4.5 years and 5 to 8 years, cycles that concord with known natural variabilities in monsoon patterns. This periodicity raises critical concerns regarding the future trajectory of glacier health as climate change potentially alters the timing, intensity, and variability of monsoon rains and snows. The interplay between climatological seasonality and glacier mass is intricate, where shifts in precipitation season length, volume, and type compound the warming effects, leading to accelerated glacier degradation.
Beyond the long-term threat to water resources, the rapid loss of glacial ice portends immediate hazards. One such risk is posed by glacial lake outburst floods (GLOFs), increasingly frequent and volatile phenomena triggered by unstable moraine dams succumbing to rising water volumes behind retreating glaciers. These sudden floods unleash catastrophic downstream impacts, including landslides and flash floods, imperiling communities, infrastructure, and ecosystems. The confluence of accelerated melt rates and seasonal monsoon shifts heightens the unpredictability and intensity of these geohazards, underscoring the urgent need for improved monitoring and early warning systems.
Lead author Sonam Sherpa, an assistant professor at the University of Utah specializing in glaciology, emphasizes that the ramifications extend beyond gradual environmental changes. “This risk is not only about long-term water shortages but also about immediate threats to lives and infrastructure,” Sherpa notes. The scientific community must prioritize developing adaptive strategies that encompass both mitigation of glacier retreat drivers and resilience building in vulnerable downstream populations.
Looking forward, the study projects that as glaciers recede, the main contributors to river flows will increasingly come from rainfall rather than glacier melt. This hydrological shift has complex consequences. Initially, river flows may surge due to enhanced melting; however, over extended periods, declining glacier volumes reduce base flows, particularly during dry seasons. The transition amplifies drought risk, challenging water management frameworks across the region. Anticipating these changes necessitates integrating glacial mass balance dynamics with hydro-climate models, particularly considering monsoon variability.
The methodology behind these revelations involved leveraging the unique capabilities of the GRACE satellite mission, which tracks variations in Earth’s gravitational field to infer mass changes on the planet’s surface. This observational approach, combined with ground-based climate records, allowed the researchers to unravel seasonal and interannual fluctuations in glacier mass and link them to monsoon precipitation patterns. This synthesis of satellite data and hydrometeorological analysis represents a significant advancement in unraveling the complex drivers influencing the cryosphere in High Mountain Asia.
Furthermore, this research underscores the pressing need for enhancing observational networks across the region. Current deficiencies in monitoring rainfall, snowfall, and glacier changes create substantial uncertainties in predicting glacier responses to evolving climate regimes. Denser, high-resolution data streams would enable more precise modeling and forecasting, facilitating the development of targeted policies to safeguard water resources and mitigate disaster risks. The researchers call for international collaboration to expand monitoring infrastructure and data-sharing frameworks.
Funded by prominent institutions including the U.S. National Science Foundation, NASA, the Intergovernmental Panel on Climate Change Fellowship, and the Prince Albert II de Monaco Foundation, the study pushes the frontiers of our understanding of climate-glacier interactions. Its publication in the IEEE Journal of Selected Topics on Applied Earth Observations and Remote Sensing marks a milestone in applied Earth science, highlighting the transformational role of remote sensing technologies in addressing complex environmental challenges.
Ultimately, these findings intimate a future where the stability of High Mountain Asia’s glaciers—and by extension, the regional water security and ecological integrity they support—rests precariously on the intertwined threads of climate warming and monsoon variability. As the region contends with unprecedented glacier retreat, integrating climatological seasonality into models and adaptation frameworks will be pivotal. Timely action, informed by cutting-edge science and bolstered by international partnerships, offers the best hope for mitigating the cascading impacts of this unfolding cryospheric crisis.
Subject of Research:
Article Title: Investigating the Influence of Climate Seasonality on Glacier Mass Changes in High Mountain Asia via GRACE Observations
News Publication Date: 1-Aug-2025
Web References: https://ieeexplore.ieee.org/abstract/document/11107312/authors#authors
References:
Sherpa, S., Werth, S., et al. (2025). Investigating the Influence of Climate Seasonality on Glacier Mass Changes in High Mountain Asia via GRACE Observations. IEEE Journal of Selected Topics on Applied Earth Observations and Remote Sensing. DOI: 10.1109/JSTARS.2025.3595165
Image Credits: Sonam Sherpa
