As climate change intensifies, glaciers worldwide are melting \u2013 even in high regions such as the Himalayas<\/a>. The Himalayas are especially vulnerable, because the steep slopes of many of these very tall mountains are made of permafrost \u2013 rock and soil frozen for centuries. As temperatures rise, these slopes are beginning to melt or destabilise. If an earthquake or slope failure occurs, it can trigger a sudden and devastating debris flow. <\/p>\n It\u2019s too early to say this was the exact cause. But we know that the great ice stores of the Himalayas \u2013 known as the world\u2019s \u201cthird pole<\/a>\u201d because it contains the largest amount of snow and ice after the Arctic and Antarctic \u2013 are no longer safe. <\/p>\n What do we know about this disaster?<\/p>\n What happened in Nepal is likely due to an enormous ice-and-rock landslide<\/a> sweeping down a mountain pass and gathering up ice, water, rock, trees and dirt. <\/p>\n The landslide was so large it was originally thought to be an earthquake, as the seismic energy registered as a 4.4 magnitude quake<\/a> on seismographs. <\/p>\n By the time it reached Gyirong Port \u2013 a China-Nepal border crossing \u2013 the wall of debris resembled a tsunami of dirt. Early estimates suggest the wave may have been 30 metres high<\/a>. <\/p>\n A flood-damaged section of a highway in Nuwakot, central Nepal, following the flooding. What are the likely causes?<\/p>\n Sometimes, disasters like these can be caused when glacial meltwater trapped in a lake by a landslide breaks free. One of these events \u2013 known as a glacial lake outburst flood \u2013 hit Nepal<\/a> in 2024. <\/p>\n But early analysis<\/a> suggests this isn\u2019t the case here. Satellite imagery suggests<\/a> the landslide may have carved away large parts of a glacier, triggering its collapse<\/a>. <\/p>\n<\/p>\n We don\u2019t know yet what caused the glacier to collapse. But glaciers worldwide are broadly in retreat<\/a> \u2013 and flood and debris flow disasters can follow. <\/p>\n A smaller flood hit the same district in Nepal last year, killing nine people<\/a>. Also last year, a melting glacier in Switzerland triggered a huge debris flow that destroyed the village<\/a> of Blatten. In 2023, a landslide and subsequent flood in my home country of Georgia killed 33 people<\/a> at a mountain resort. <\/p>\n But this disaster is one of the largest so far. <\/p>\n<\/p>\n Permafrost is vulnerable<\/p>\n The high-elevation glaciers of the Himalayas can respond differently to climate change than glaciers at lower elevations or in relatively warmer regions. Thawing and degrading permafrost can also contribute by making steep Himalayan slopes less stable.<\/p>\n Permafrost is ground containing rock, soil and ice that has remained at or below 0\u00b0C for many years. As the climate warms, the ground can thaw, weakening the ice that helps bind rock and soil together.<\/p>\n On steep mountain slopes, this loss of frozen ground can make slopes less stable and make rockfalls, landslides and other forms of ground movement more likely. An earthquake, rockfall or other disturbance can then trigger a rapid downslope movement of rock, soil and debris. <\/p>\n Can these disasters be prevented?<\/p>\n No one died when the Swiss glacier collapsed. That\u2019s because early warning systems were in place<\/a>. Authorities evacuated residents before it fell. <\/p>\n As temperatures rise and climate-related disasters become more frequent or severe in some regions, early warning systems will become increasingly important<\/a> for villages and towns located near glaciers or thawing permafrost. <\/p>\n These systems can monitor rapidly rising river levels, intense rainfall and seismic waves to alert authorities before disaster strikes. <\/p>\n However, installing and maintaining effective early warning systems can require significant investment. That\u2019s a challenge for lower-income and developing countries. In good news, the Green Climate Fund last year announced funding<\/a> for better monitoring systems in Nepal. <\/p>\n![\"People](\"https:\/\/www.newsbeep.com\/uk\/wp-content\/uploads\/2026\/08\/file-20260827-60-p2a42g.jpg\")
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\n Subaas Shrestha\/Getty Images<\/a><\/p>\n