Nepal’s catastrophic flooding is a red alert for the world’s mountain towns

In 2011, I trekked with scientists and engineers to about 17,000 feet to look at Lake Imja in Nepal’s Everest region. I thought about that expedition from the safety of my home in Peru as I watched the awful consequences of permafrost weakened by warming upon the northern district of Rasuwa, near Nepal’s border with Tibet. 

When glaciers recede, they leave an indent created by their weight. Melt from the glacier fills that bowl, growing until the pressure gets too great, or an earthquake hits. Lake Imja did not exist in 1953, when Sir Edmund Hillary conquered Everest. By 2011, it was the fastest-growing of some 1,600 glacier lakes in Nepal.

On our visit, the artificial lake stretched down from the glacier for a mile and a half, held in place by a precarious mix of debris. An earthquake or pressure on the makeshift dam could release water with disastrous consequences for vulnerable communities in Nepal. 

On Aug. 26, the world watched the consequences of a different version of what we feared. Above Rasuwa, a broken chunk of glacier, likely the size of a big New York City building, fell 4,000 feet, setting off a tsunami. Friction at that velocity melts ice. A great wave gathered ice, snow, water, rocks and mud — and then structures — to cascade down the narrow valleys, wiping out lives, communities and infrastructure. Hurricane-force winds leveled trees. 

I’m safe as I write, but some version of the same can and likely will happen in my country and other mountainous regions, and........

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