As the Himalayas melt, deadly floods become the new normal

A day before a wall of ice, rock and muddy water tore through Himalayan valleys along the Nepal-China border, Dipesh Chapagain was discussing with a colleague just how devastating such a disaster could be.For the 40-year-old climate researcher, who grew up in the hills of eastern Nepal and now studies mountain hazards at the United Nations University in Bonn, Germany, the subject was both professional and deeply personal.He has watched the risks facing the region change within his own lifetime.“When I was kid, it was not like that,” he told me. “Or when my parents were kids or my grandparents, that was not the major challenge [they faced].”A glacier fails, a mountain collapsesThen, on Wednesday morning at 8:37, a mountainside high in the Himalayas gave way.The collapse was so vast that seismic instruments registered it as a magnitude-5.2 event, initially mistaking it for an earthquake. Bedrock beneath a glacier failed, carrying a huge mass of ice and rock roughly 1,200 meters toward the valley floor.Water, sediment and boulders surged into the rivers below, sweeping through towns and villages along one of Nepal’s most important trade routes with China. At one monitoring station, th...