Nepal glacier experienced exceptional heat before collapse triggered deadly floods: Researcher

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Nayapage

2026-09-08 23:17

Kathmandu : The mountain section whose collapse triggered deadly floods in Nepal and China on August 26 experienced unprecedented heat for that time of year, according to meteorological data analysed by a researcher.

Average temperatures at the glacier, located at an altitude of 5,200 metres (17,060 feet), were estimated at around 5 degrees Celsius between August 21 and 26. Such temperatures are exceptionally high for the region and time of year.

Temperatures had never exceeded 4.0 degrees Celsius during the same period in more than 55 years of recorded data, although no direct link between the extreme heat and the collapse has so far been established.

The highly localised temperature data were reconstructed by Robert Rohde, chief scientist at the independent Berkeley Earth organisation in California.

At the site of the collapse, the average temperature recorded during the six-day period has risen by about 1.8 degrees Celsius since the mid-20th century.

Without the additional heat associated with climate change, a comparable temperature pattern would probably occur only once every few thousand years, Rohde calculated for AFP.

The collapse occurred during the Langtang region's fourth-hottest summer on record, according to an AFP analysis of data from Europe's Copernicus climate observatory dating back to 1970.

Tipping point

“These hot conditions can also explain permafrost thaw and the combined collapse of the slope and glacier,” said French climatologist Valerie Masson-Delmotte.

Permafrost acts like ice cement, helping hold rock faces together. Its degradation can make mountain slopes increasingly unstable.

Satellite images also showed significant snowmelt in the days before the disaster. This provided “a substantial source of liquid water that can infiltrate fractures in the mountain and facilitate landslides,” said Etienne Berthier, a glaciologist at France's CNRS research agency.

Experts, however, remain cautious about the precise role played by the heatwave.

“It’s not as straightforward as ‘high temperature equals collapse,’” Kristen Cook, a geomorphologist at Grenoble Alpes University in France, told AFP.

“If the temperature acted as a trigger, it seems that it needed to wait until the rock was right at the tipping point of collapse,” she added.

Researchers are now examining the small movements observed in the mountain in the years before the collapse and how they interacted with changes in temperature.

According to Rohde of Berkeley Earth, proving that the rock near the fracture plane was significantly weakened by meltwater and/or permafrost thaw would provide a “smoking gun” for the role of climate change.

His temperature analysis used data from the Copernicus programme’s ERA5 climate model, along with observations from a network of 14 high-altitude weather stations located between nine and 140 kilometres (six and 87 miles) from the collapsed glacier.