Glaciers are among the most visible indicators of climate change, and their rapid melting poses a severe threat to ecosystems, infrastructure, and communities worldwide. Recognizing this crisis, the United Nations has declared 2025 as the International Year of Glaciers' Preservation and designated March 21st as World Day for Glaciers. This initiative underscores the urgency of safeguarding glaciers, particularly in high-altitude regions like the Hindu Kush Himalayas, including Nepal, where glacial retreat, glacial lake outburst floods (GLOFs), permafrost degradation, landslides, flooding, sedimentation, and freshwater depletion present growing risks.
Hindu Kush Himalayas, home to some of the world's largest ice reserves outside the polar regions, are experiencing unprecedented cryosphere changes.
Recent studies indicate that Himalayan glaciers have been losing over eight billion tons of ice annually in the last two decades, almost double the rate observed in the preceding 25 years. The region's temperature has already risen by 1.5°C over the past century and is projected to increase by another 1.8°C to 2.2°C by 2050. If global emissions remain unchecked, up to 75% of glacier volume in the Eastern Himalayas could vanish by the end of the century.
Additionally, permafrost degradation is expected to reduce the permafrost extent by 20–30% by 2030 and by up to 50% by 2050, thereby exacerbating landslide and debris risks, as well as infrastructure instability. Glaciers and snow-capped mountains are a major attraction for tourism in Nepal. Melting glaciers threaten popular trekking routes, mountaineering activities, and overall tourism revenue.
One of the most immediate and devastating consequences of glacier melt in Nepal is the increasing frequency of GLOFs. These sudden discharges of water from glacial lakes can cause severe destruction to downstream communities, infrastructures, and farmlands. Nepal has thousands of glacial lakes, with more than 47 identified as potentially hazardous. The number and size of glacial lakes have been increasing rapidly every year; therefore, the actual number of glacial lakes and the potential dangers associated with them are higher than the reported numbers. A recent GLOF at Birendra Lake in Gorkha underscored the cascading risks of glacier ice collapsing into lakes, triggering devastating overflows. Similarly, the Thame GLOF on August 16, 2024, destroyed several structures, including homes, a school, guesthouses, and a hydropower project, displacing over a hundred people. The glacial lake that caused a devasted flood in Thame was not documented or listed in the glacial lake inventory because its size fell below the minimum threshold for classification as a glacial lake. This event underscores a critical gap in existing glacial lake inventories. Despite its small size, the resulting flood caused extensive downstream damage, destroying homes and infrastructure. This highlights the significant risks posed by smaller, undocumented glacial lakes, emphasizing the potential for widespread destruction given the presence of thousands of such lakes across the region.
Permafrost, the permanently frozen ground that supports mountain slopes and infrastructure, is another hidden hazard rapidly degrading across the Himalayas. Glacier melt contributes to permafrost degradation in several interconnected ways, primarily through increased heat transfer, changes in water flow, and loss of protective ice cover. Thawing permafrost weakens moraine dams, increasing the likelihood of GLOFs and triggering landslides that endanger roads, bridges, and settlements. Permafrost-driven debris flows have been observed in several valleys located in the Himalayas, which are considered high-risk due to thawing ice. Permafrost degradation in Nepal remains largely unstudied, despite its increasing contribution to landslides, rising sedimentation in rivers, and infrastructure instability. Increased sedimentation in rivers reduces the efficiency of hydropower reservoirs and increases flood risks, underscoring the broader implications of these changes. Climate change-induced heavy rainfall events exacerbate landslide risks even further. The 2021 Melamchi disaster, caused by excessive monsoon rain coupled with glacial melt, is a stark reminder of these interconnected hazards. Similarly, the 2012 Seti River flash flood in Pokhara highlighted the compound risks posed by glacial melt and moraine instability. These events underscore the urgent need for comprehensive hazard assessments, multi-hazard early warning systems, disaster financing policies, and climate-resilient infrastructure.
The Himalayas serve as a critical source of freshwater for nearly 2 billion people across Asia. The region's glaciers, snowmelt, and rivers provide essential water resources for drinking, agriculture, and hydropower, particularly during the dry season. Nepal's hydropower sector, a critical energy source, faces mounting challenges due to glacial retreat and extreme hydrological variability. As glaciers shrink, reduced water availability could jeopardize drinking energy production, water supplies, and irrigation. HKH-fed river systems support irrigation across millions of hectares of farmland, sustaining food production in some of the world's most densely populated regions. Additionally, GLOFs and increased sedimentation pose severe threats to existing and planned hydropower projects. The Lhonak GLOF in Sikkim (2023) caused extensive damage to critical infrastructure, including the Teesta III hydropower project.
The rising temperatures driving glacier melt, and permafrost degradation is a global phenomenon, and reversing or halting these processes is beyond the practical scope of localized or national efforts. Reducing global warming or mitigating the effects of climate change is a long-term challenge, even with worldwide commitment and immediate action.
Although lowering water levels in glacial lakes offers temporary relief and is technically feasible in certain cases, it is not a sustainable solution given the thousands of existing lakes and the hundreds forming each year due to accelerating glacier melt. In this regard, it is practically impossible to mitigate glacier-related hazards caused by climate change. In many cases, mitigating debris flow or stabilizing landslides to reduce the hazards is often too costly and impractical, given the scale of the challenge in the region. Risk arises from the interaction of hazard, exposure, and vulnerability. Minimizing risk by reducing hazards is a conventional approach to risk management, but it is not practical in all cases. Therefore, we need to focus on reducing vulnerability and exposure rather than hazards. Vulnerability and exposure can be reduced through comprehensive risk assessment using cutting-edge technology, the evaluation and development of cost-effective risk mitigation measures, the design of robust, climate-resilient infrastructure, the introduction of disaster insurance and reinsurance policies, capacity building, and fostering regional cooperation.
A thorough understanding of multi-hazard risks is essential for informed decision-making. This involves collecting and analyzing topographical data, conducting hazard assessments, and using maps, satellite imagery, and local knowledge. By partnering with data providers and creating digital platforms to map safe and hazardous zones, governments and planners can improve land-use and infrastructure decisions, promoting resilience to glacial hazards.
Remote sensing technologies, such as Sentinel-2 and Landsat satellite imagery, along with high-resolution digital elevation models (DEMs) and LiDAR, enhance hazard detection by tracking glacier retreats and permafrost degradation. Integrating AI-driven analytics with remote sensing enhances hazard assessments, providing timely alerts for effective disaster mitigation. Real-time monitoring systems, including weather stations and GPS sensors, provide continuous data, while AI-driven flood modeling enhances early warning systems, enabling preemptive evacuations. Multi-hazard warning systems integrating glacial, hydrological, and meteorological data can reduce casualties and infrastructure damage. Ground-based observations complement satellite data, ensuring a comprehensive understanding of glacier-related risks.
Risk management strategies should be assessed for their cost-effectiveness, both for existing infrastructure and future development projects. Possible interventions include constructing climate-resilient infrastructure, retrofitting existing structures to meet climate-resilient compliance, implementing risk-informed land-use planning, and establishing robust early warning systems. For example, introducing a tower intake for water supply can enhance debris resilience; while incorporating cross or side water (submerge) intakes can improve climate resiliency, particularly in the Himalayas. Infrastructure planning must incorporate climate risk assessments and cost-effectiveness, ensuring that hydropower plants, roads, and settlements are built to withstand extreme weather events and shifting geological conditions
Enhancing regional collaboration is crucial to mitigate the transboundary risks posed by glacier melt. The Hindu Kush Himalayas span multiple countries, requiring cooperative efforts in data sharing, research collaboration, and coordinated response strategies. Establishing cross-border agreements for the real-time exchange of information can enhance preparedness and response capabilities in the region. Community-based disaster risk reduction plays a pivotal role in enhancing local resilience. Training programs on hazard preparedness, evacuation drills, and community-led monitoring initiatives empower people to take proactive measures. Strengthening local governance structures and ensuring that communities have access to real-time hazard information fosters a culture of preparedness and rapid response, ultimately reducing disaster-related losses.
Addressing the challenges posed by glacial melt and permafrost degradation in the Himalayas requires a paradigm shift from hazard mitigation to vulnerability and exposure reduction. Through scientific advancements, climate-resilient infrastructure, regional collaboration, and community-driven initiatives, we can build a more adaptive and resilient future. It's high time to act, before irreversible changes, to reshape the landscapes and livelihoods of millions.
Sharma holds a PhD in Geotechnical Engineering and works in Nepal and Bhutan to address climate change-induced geohazard risks.
