The catastrophic rock and ice collapse on the northern Nepalese border that swept away
entire communities was influenced by a range of climatic and geological factors, most of
which are worsened by the impacts of climate change on the high altitude landscape, according to a rapid scientific analysis by an international team of glaciologists and climate scientists, including Walter Immerzeel, Professor in Mountain Hydrology at Utrecht University and Chief Science Officer at hydrominds.
Over 1,300 people were killed – and more than 5,000 remain missing – after a massive section of overhanging glacier and rock fell from Langtang Lirung mountain on 26 August. The collapse caused an enormous water, ice and debris flood that swept downstream resulting in catastrophic damage.
Rather than a single extreme weather event, scientists found that the disaster happened as a compound crisis. Decades of atmospheric warming – caused primarily by the burning of fossil fuels – have melted the glacier and pushed the freezing threshold line (0°C isotherm) upward by around 100 metres of altitude per decade. This has resulted in glacier recession and thawing occurring in permafrost within rock fractures that historically hold high mountain walls together, rendering them unstable. A massive 2015 earthquake is likely to have also further preconditioned the slope for collapse.
Walter’s view on the event: “We are witnessing fundamental, irreversible shifts in Himalayan mountain environments. Climate change from the burning of fossil fuels is pushing the freezing line – the zero-degree isotherm – upward by roughly 100 metres per decade, exposing perennially frozen ground and bedrock to thaw conditions that are longer and warmer than before. When you combine high-elevation permafrost degradation with glacier retreat and record summer heat, the structural integrity of these mountain walls is compromised. The catastrophic impacts of what can then happen are clear for all to see.”
The attribution study is done by World Weather Attribution, an international scientific collaboration that analyses and communicates the possible influence of climate change on extreme weather events. To learn more about this specific event, you can download the full report, or the summary of findings.
