By Georgina Wade
Climate change poses a significant threat to Nepalese communities as it can lead to outburst floods from glacial lakes.
In the Himalayas, rising temperatures are increasingly melting the snowpack that collects on peaks. This resulting snow-melt then accumulates in dips in the mountain landscape to form high-altitude glacial lakes.
Increasing mean temperatures will cause these lakes to grow, putting pressure on the unsteady accumulations of rock and regolith typically penning in the water. The water widens the gap until the lake can drain out at a startling speed, resulting in an avalanche of water with enough force to wipe out roads, fields, and any human settlements built in the path of the flood.
The phenomenon is called a glacial lake outburst flood (GLOF) and despite being deemed a rare event, is one of increasing concern in this age of weather chaos and shifting landscapes.
Nepal’s Khumbu Valley, in the Mount Everest region, sits in the shadow of a glacial lake called Imja Tsho. Imja Tsho, which was virtually non-existent in 1960, today contains 2.6 billion cubic feet of water – a number that grows by the year despite efforts to drain the lake. For the people of Khumbu, the fear of what might happen if this water were unleashed is not wholly abstract.
In 1985 another glacial lake above the valley, Dig Tsho, burst on a sunny August afternoon destroying several villages and killing three people. Additionally, glacial flooding in Khumba accompanied the 2015 earthquake that saw the deaths of twenty-two people at the basecamp on Mount Everest.
Following these events, experts began an assessment of GLOF risks in the country and the likely cost of such disasters. The results of the study placed Imja Tsho at the top of the list, with a $11 billion potential price tag.
Despite this, survey data gathered by social scientists found that while 45 percent of the interviewed Khumbu Valley residents considered GLOF a major threat to their life, it was not enough to make them relocate. The reasons for this are manifold, social and cultural, highlighting the need to consider aspects that reach beyond physical climate-related risks when thinking about climate change adaptation, especially community-based adaptation.