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Unprecedented Heat Triggered Nepal Flood Collapse
8 Sep
Summary
- Mountain glacier experienced unprecedented heat of 5C in late August.
- Unusually high temperatures contributed to permafrost thaw and slope instability.
- Climate change made such heat patterns much more probable, researchers found.
A mountain glacier collapse that caused fatal floods in Nepal and China on August 26 was preceded by unprecedented heat for the season. Data analyzed by researcher Robert Rohde indicated average temperatures around five degrees Celsius at an altitude of 5,200 meters between August 21 and 26. This temperature was significantly higher than in over 55 years of recorded data for the same period. Such hot conditions can lead to permafrost thaw, which acts as a natural cement holding rock faces together, thereby increasing instability.
Further analysis revealed that this series of localized high temperatures, reconstructed by Rohde of Berkeley Earth, has risen by approximately 1.8C since the mid-20th century at the collapse site. Without the influence of climate change, a comparable temperature pattern would likely occur only once in several thousand years. The collapse occurred during the Langtang region's fourth-hottest summer on record, according to data dating back to 1970. Satellite images also showed considerable snowmelt preceding the disaster, potentially contributing meltwater that could infiltrate fractures and facilitate landslides.
