When the Himalayas Cracked: How Warming Temperatures Helped Trigger the Devastating Nepal‑Tibet Glacier Collapse

In late August, a massive chunk of rock and ice tore away from the Langtang Lirung mountain, flooding valleys in Nepal and Tibet. The blast claimed roughly 1,400 lives and left thousands still unaccounted for – a tragedy that still haunts the region.

Researchers from the World Weather Attribution (WWA) team have now pieced together a picture of why the slope gave way when it did. Their conclusion? Human‑driven climate change didn’t cause the collapse outright, but it certainly made it far more likely.

First, the Himalayas were unusually hot that month. Average temperatures were about five degrees Celsius (nine °F) above the norm, with roughly 1.5 °C of that excess directly linked to anthropogenic warming. That extra heat may sound modest, but up there, even a degree or two can set off a chain reaction.

Glaciers in the area have been losing thickness at a steady pace – roughly half a metre per year since the turn of the millennium. As the ice thins, the pressure it exerts on the underlying rock eases, subtly shifting stress patterns. At the same time, permafrost – the once‑frozen ground that glues the mountain together – is thawing. When that icy cement melts, it leaves the bedrock unstable, like a wall losing its mortar.

Adding fuel to the fire was an unusually heavy snowfall in October and November of the previous year. The extra snow became meltwater once temperatures rose again, swelling streams and rivers that cut into the glacier’s base. The surge of water acted like a hydraulic jack, prying the already weakened slope apart.

There’s also a lingering scar from the 7.8‑magnitude earthquake that rocked the same mountain in 2015. While scientists can’t pin down exactly how much the quake contributed, it likely cracked the rock and left hidden faults that made the later collapse easier.

“There’s absolutely no doubt that human‑induced climate change played a role here in the pre‑conditioning of the disaster,” said Friederike Otto, a climatologist at Imperial College London. “Permafrost thawing, glacier thinning, and more rain instead of snow—all these pieces fit together.”

Walter Immerzeel, a mountain hydrologist at Utrecht University, summed it up: the slope was already geologically vulnerable, possibly weakened by the 2015 quake, but the “excessive meltwater and exceptional warmth” in the weeks before the event pushed it over the edge.

The WWA’s assessment follows its usual protocol of using peer‑reviewed methods to attribute extreme weather events to climate change. While no single factor can claim sole responsibility, the consensus is clear: a warming climate set the stage, and the drama unfolded with tragic consequences.

For the communities still coping with loss and displacement, the scientific nuances offer little comfort. What matters now is rebuilding, providing aid to the missing families, and, perhaps, taking this stark warning as a cue to address the broader climate challenge before another mountain gives way.