What caused last week’s catastrophe was not immediately clear: initial reports suggested the floods could have been caused by an earthquake in the area that triggered a landslide, while early satellite imagery suggested that a glacial collapse was to blame. Subsequent satellite analysis showed that bedrock underneath a glacier collapsed, with the landslide registering as a magnitude 5.2 seismic event.
“It seems that a massive rock face with the glacier on top of it has essentially gone,” says Adrian McCallum, a senior lecturer in geotechnical engineering at the University of the Sunshine Coast in Australia. One seismologist called the landslide “one of the largest in the last decade or two in the world”.
As Nepal’s Shah said in his statement, our environmental crisis cannot be separated from this disaster. The Himalayas – spanning Nepal, India, China, Bhutan and Pakistan – are warming twice as fast as the global average, putting the region at increased risk of avalanches, landslides and floods. The UN said in 2023 that Nepal’s mountains had lost close to one-third of their ice in just over 30 years due to global heating.
While scientists haven’t definitively linked the Lhende Khola landslide to the climate crisis, they have pointed out that rising temperatures mean permanently frozen mountain slopes are at risk of melting and destabilising.
“Increased temperatures result in increased melt, which results in increased water,” McCallum says. “Movement of water into voids within either soil or rock … destabilises what once may have been a more solid rock mass or soil environment.”
With global heating, mountainous areas are also at risk of permafrost degradation, “glacial lake outburst floods” (GLOFs), and increasingly erratic rainfall, raising flood and landslide risk.
Glacial lakes form behind natural dams as a result of glacier melt, and can cause catastrophic outburst floods if their natural dam walls are breached. More than 12,000 deaths have been attributed to such floods globally.
Given the risks to downstream communities in the Himalayas, scientists have pointed to the need for early warning systems, which would require coordinated international monitoring efforts.
“Wherever the glaciers are receding … you have the potential for a GLOF to occur,” McCallum says, such as in the European Alps and the South American Andes. In North America, an outburst flood causes periodic problems in Juneau, the capital of Alaska.
To be clear, there was no GLOF involved in last week’s landslide. But Nepal has more than 2,000 glacial lakes, and 21 of those, according to the UN, are considered potentially dangerous.
As climate academic Bill McGuire wrote for the Guardian this week, global heating will “leave no part of the planet untouched. As the world processes the horror of the events in Nepal and Tibet, it is a lesson that we ignore at our peril.”
Read more:
• What the floods tell us about the future of India’s Himalayas | This Is India
• Nepal’s glacial collapse foreshadowed a future of climate disaster | Michael Mann
• The Nepal floods seem a world away – but climate breakdown will affect us all | Nesrine Malik
The floods, triggered by a glacial collapse, devastated communities in Nepal and Tibet. Photograph: Skanda Gautam/Zuma Press Wire/Shutterstock
