Study finds glacial lake flood risks in the Himalaya-Karakoram region remain poorly assessed and weakly monitored
Rapid warming has driven a sharp rise in the number, size and volume of glacial lakes since 1990
Nearly one million people living downstream of glacial lakes face potential Glacial Lake Outburst Floods
Researchers warn gaps in data, field studies and early-warning systems are hindering adaptation
The growing number, size, and volume of glacial lakes across the Himalaya-Karakoram ranges have not been adequately assessed for risk, despite the increasing likelihood of catastrophic flooding events, according to a new study. A paper published in the journal npj Natural Hazards on January 22, 2026, has warned that lack of enough research is making it harder for nearly one million people living within 10 kilometres of glacial lakes to prepare for sudden and potentially devastating floods.
A Glacial Lake Outburst Flood, or GLOF, occurs when a natural dam holding back water in a glacial lake collapses, releasing a sudden surge of water downstream in a large flash flood. These floods often gather debris from the surrounding mountains like rocks, soil, and trees, intensifying their destructive force.
Natural dams can be formed in two main ways. Moraine-dammed lakes are held back by loose rock and soil left behind by retreating glaciers, while ice-dammed lakes are restrained mainly by ice.
India has experienced some of the most severe GLOF disasters in recent years. In June 2013, a GLOF event in the Uttarkashi area of Uttarakhand killed an estimated 5,000 people, with thousands more reported missing. The disaster was triggered when a moraine dam at the upstream Chorabari glacial lake failed after an ice avalanche, which was set off by extreme rainfall.
More recently, in October 2023, a GLOF in Sikkim killed 55 people, injured many more and caused widespread damage to homes and infrastructure. The flood followed the sudden collapse of part of the lake’s north-western wall, which broke the large ice blocks and released floodwaters downstream.
The study documented 388 GLOF events across the Himalaya-Karakoram region to date. The highest number, 196, occurred in the Karakoram, despite it having fewer glacial lakes than other sub-regions. The central Himalayas recorded 99 events, the eastern Himalayas 72, and the western Himalayas 21.
Moraine-dammed lakes accounted for the largest share of GLOF events, with 163 incidents, followed by ice-dammed lakes with 144. Around 50 floods were linked to supraglacial lakes, where sudden surface warming and melting can rapidly destabilise stored water. Supraglacial lakes form on the surface of glaciers and can drain suddenly when surface ice melts rapidly.
By countries in the region, Pakistan recorded the highest number of GLOF events at 131, followed by China with 123. India experienced 59 such events, while Nepal recorded 54.
Several glaciers in the Karakoram, including Khurdopin and Kyagar, have experienced repeated GLOF events in recent decades, mostly involving ice-dammed or supraglacial lakes.
Climate change is intensifying GLOF risks. Rising rates and intensity of warming in the Himalaya-Karakoram region, especially at higher elevations because of a phenomenon called elevation-dependent warming, are driving a steady increase in the number, area, and volume of glacial lakes.
Since 1990, the number of glacial lakes in the region has risen by 53 per cent, their total area by 51 per cent, and their volume by 48 per cent. Glaciers that end in lakes are also retreating faster than those that terminate on land, creating a feedback loop that further accelerates lake expansion and glacier loss.
Despite these trends, the authors say research has not kept pace with the growing threat, pointing to limited assessments of social vulnerability among downstream communities. Generally “the analysis revealed significant gaps in GLOF research, including limited social vulnerability assessments for populations near glacial lakes, insufficient studies on the impacts of climate change on GLOF frequency, and inadequate focus on mitigation measures like early warning systems (EWSs) in the region”, the scientists wrote in the paper.
The study also points to major inconsistencies across existing GLOF datasets, making comparisons difficult, along with a lack of ground-based observations, particularly in the Himalaya-Karakoram region. “Discrepancies in glacial lake definitions and varying size thresholds have resulted in significant inconsistencies among independently created datasets for the H-K region and the broader Third Pole region,” the paper stated.
While glacial lake datasets now cover most regions of the world, the study noted that the Himalayas remain particularly difficult to assess because of their challenging terrain and harsh climate, which limit field-based glacier and glacial lake research. “Consequently, most studies in this region rely heavily on remotely-sensed data, which often suffer from limitations such as coarse spatial and temporal resolution, introducing ambiguities in understanding ground-level processes”, according to the paper.
Other issues are a lack of standardised mapping thresholds, varying definitions of what constitutes a glacial lake — including whether supraglacial and ice-contact lakes are included — and differing classification methods introduce significant uncertainty when inventories are compared across regions or over time.
“Furthermore, most inventories are static snapshots in time and do not adequately capture seasonal variability, rapid lake evolution, or short-lived lakes that may still pose substantial GLOF hazards,” the authors wrote in the study. “These findings underscore the need for more integrated and region-specific research to address the growing risks of GLOFs effectively,” they added.