Himalayan glaciers shrinking at alarming pace, ice loss doubled in 21st C, says ICIMOD

DEHRADUN: A recent report by International Centre for Integrated Mountain Development (ICIMOD) has painted an alarming picture on the state of glaciers in the Hindu Kush Himalaya (HKH) -- which have shrunk faster than previously estimated -- with new data pointing to a sharp acceleration in ice loss in the last decade.Data revealed that the region lost 12% of its total glacier area and 9% of its ice reserves between 1990 and 2020, with the pace of loss accelerating sharply.Prepared by Sudan Bikash Maharjan and Tenzing Chogyal Sherpa, the report points out that the glacier decline is not only ongoing but intensifying. It notes that while glaciers have been losing ice over several decades, the rate of ice loss has increased significantly in recent years, "with the average rate in the 21st century roughly twice that observed at the end of the 20th century".The ICIMOD study, which maps over 63,000 glaciers in the region, finds that glacier retreat is no longer gradual but accelerating, particularly after 2010, and most prominently in the eastern and central HKH. Smaller glaciers have been the most vulnerable, shrinking rapidly and, in some cases, fragmenting or disappearing altogether."The pace of glacier loss has accelerated sharply since 2010, especially in the eastern and central HKH, where smaller glaciers are most vulnerable. Though located in high mountains, these glaciers are deeply connected to rivers, economies and communities downstream. Their retreat is increasing uncertainty over water availability and heightening risks from hazards such as glacial lake outburst floods, landslides and avalanches," said Pema Gyamtsho, DG ICIMOD.The findings highlight stark regional contrasts. While parts of the Karakoram range showed relative stability, with the glacier area declining by 0.9%, other regions experienced dramatic losses. The Ganges and Brahmaputra river basins, home to the largest glacier areas outside the Indus basin, experienced the greatest total area loss over the past three decades, with reductions of approximately 21% and 16%, respectively.The HKH region, often referred to as "Water Tower of Asia", hosts the largest concentration of ice outside the polar regions and supports nearly two billion people through its major river systems. Glaciers play a crucial role in regulating river flows, particularly during dry seasons, acting as natural reservoirs that sustain agriculture, ecosystems and livelihoods downstream.According to the report, the region contained 63,761 glaciers in 2020, covering about 55,782 sq km and holding an estimated 5,735 cubic km of ice reserves. However, the distribution of this ice is highly uneven. Large glaciers, those exceeding 10 sq km, make up just 1% of total glacier numbers but account for nearly 39% of the glacier area and 40% of ice reserves, underscoring their disproportionate importance in regional water systems.The report further attributes the accelerating glacier loss to rising temperatures and changing precipitation patterns. Glaciers located below 5,500 metres above sea level have shown the most significant retreat, as they are closer to the equilibrium line altitude and thus more sensitive to warming. In contrast, glaciers at higher elevations have experienced relatively slower decline due to colder conditions.Topography also plays a critical role in determining glacier behaviour. Glaciers facing south, southeast and east, receiving greater solar radiation, have retreated faster than those oriented towards the north. Similarly, smaller and steeper glaciers are more prone to rapid ice loss due to lower snow accumulation and thinner ice cover.One of the most concerning trends identified in the report is the fragmentation of glaciers. As larger glaciers shrink, they break into smaller units, increasing the number of small glaciers even as total glacier area declines. These smaller glaciers are more vulnerable to climatic changes and are disappearing at faster rates, further accelerating overall ice loss.The implications of these changes are far-reaching. The report warns that glacier retreat is directly linked to increasing risks of hazards such as glacial lake outburst floods (GLOFs), avalanches, landslides and debris flows. These risks are no longer theoretical. In 2023, a devastating GLOF from South Lhonak Lake in Sikkim triggered catastrophic flooding in Teesta basin, while more recent flash floods in Dharali in Uttarakhand and last year's J&K floods highlight the growing frequency and intensity of such events.At the same time, the long-term decline in glacier mass threatens to reduce water availability during dry seasons, intensifying water stress across South Asia.The findings further accentuate the growing uncertainty surrounding future water resources in the region. As glaciers continue to shrink, their ability to buffer seasonal water variability diminishes, posing challenges for agriculture, energy production and food security.By providing a high-resolution, multi-decadal dataset, the ICIMOD report offers a critical evidence base for policymakers and scientists. It highlights the urgent need for climate adaptation strategies, improved monitoring and regional cooperation to manage shared water resources in a rapidly changing environment.As the report makes clear, the fate of the HKH glaciers is closely tied to the future of millions who depend on them, making their rapid decline not just an environmental concern, but a pressing socio-economic challenge for the region as well.