Lonely Planet Writer

Glacial lake drained to keep Mt Everest trek routes safe in Nepal

Climate change might not seem an obvious problem when trekking in the rain shadow of the Himalaya, but rising temperatures are swelling the glacial lakes that dot the high valleys of the world’s highest mountains.

Mt Everest and glacial lake, Nepal.
Mt Everest and glacial lake, Nepal. Image by Getty Images

Nepal Army engineers are now heading to the trekking trails around Mt Everest to drain the Imja Tsho – the most swollen and dangerous of these glacial lakes – before it bursts its banks and washes away some of the most popular trekking routes in the world.

Khumbu Glacier, Everest.
Khumbu Glacier, Everest. Image by Rick McCharles / CC BY 2.0

Nepal’s glaciers are highly vulnerable to rising temperatures, and meltwater is flowing into the lakes at the end of these enormous tongues of ice at an unprecedented rate. In places, the surface level of glaciers has fallen by several metres in just a few years – translating to millions of gallons of water, flowing into already swollen lakes. Held at bay only by a bank of moraine gravel, Imja Tsho now holds 20 billion gallons of meltwater, more than enough to wash away villages and bridges all along the Khumbu valley.

Over the coming week, engineers hope to release enough water in controlled bursts to lower the level of the lake by up to three metres, significantly reducing the risk of glacial lake outburst floods. The lesson of history is that people ignore glacial lakes at their peril; when the nearby Dig Tsho burst its moraine in 1985, the floodwaters destroyed 14 bridges and a hydroelectric power station, killing five villagers and destroying acres of farmland and trekking trails.


A photo posted by Tom Naumann (@tom_blom) on Jul 30, 2015 at 12:56am PDT