Climate change likely contributed to Nepal-Tibet glacier collapse, scientists say

Scientists have concluded that climate change likely played a significant role in triggering the massive glacier collapse in Nepal that occurred in late August, resulting in widespread flooding and the tragic loss of around 1,400 lives. Rapidly rising temperatures in the region have caused glaciers to thin, leading to the melting of ice and permafrost buried deep within the Himalayas' bedrock, according to the World Weather Attribution (WWA) group of researchers.

While it is challenging to determine the exact extent to which climate change contributed to the collapse of approximately 2 square kilometers of rock wall and glacier ice on the Langtang Lirung mountain, soaring temperatures undoubtedly created the preconditions that made such an event more likely, researchers say. Climatologist Friederike Otto of Imperial College London emphasizes that there is no doubt that human-induced climate change played a role in preconditioning the disaster by causing permafrost thawing, thinning glaciers, and bringing about more rainfall rather than snow.

WWA utilizes peer-reviewed methods to evaluate the role of global warming in extreme weather events. The study reveals that mean temperatures were around 5 degrees Celsius (9 degrees Fahrenheit) higher than normal in the Himalayan region during August, with 1.5 degrees Celsius of the increase attributed to climate change. Unusually high levels of snowfall in October and November of the previous year also added to the volume of meltwater once temperatures started to rise, potentially contributing to the glacier collapse.

Glaciers in the region have been thinning by approximately half a meter per year (about 1.6 feet) since 2000, altering the stresses placed on the rock. The melting permafrost is further suspected to have weakened the rock wall, according to the study. A 7.8 magnitude earthquake that struck the same mountain in 2015 might have played a role in weakening the underlying bedrock as well, but its precise impact remains unclear.

Researchers conclude that the mountain slope was geologically vulnerable and that its destabilization was further exacerbated by glacier and permafrost retreat, along with the excessive meltwater and exceptional warmth in the final period leading up to the collapse, according to mountain hydrologist Walter Immerzeel from Utrecht University.