How rising temperatures likely contributed to Nepal’s deadly flood

A flash flood on the Nepal-Tibet border this week killed roughly 160 people, with hundreds more, including international tourists, still missing. Scientists believe the disaster began when a chunk of glacier, about 2,000 feet wide, broke off and fell nearly 4,000 feet into a valley, crushing itself into water with the force of the fall. The impact was strong enough to register as a magnitude 5.2 seismic event.

Researchers point to warming temperatures as a likely factor. Glaciers in the region have been thinning and retreating for decades. Nepal's glaciers lost nearly a quarter of their area between 1970 and 2010, and more than 160 smaller glaciers have disappeared entirely. Worldwide, glaciers have lost 5 percent of their ice since 2000, and one study warns that 40 percent of the planet's glacial ice could vanish if warming isn't kept under 1.5 degrees Celsius. As glaciers shrink, they lose their grip on surrounding rock and sediment, which can trigger landslides, and thawing permafrost (ground that used to stay frozen year-round) can loosen ice and debris that used to stay put. Melting also often leaves behind dammed lakes at high elevation that can burst catastrophically if a landslide hits them, something Nepal saw twice last year.

This event happened far from most readers' homes and doesn't call for any action on your part. But it's part of a broader pattern: as the world warms, ice in mountain regions is becoming less stable, and similar glacier collapses have caused deadly incidents in Switzerland and Italy in recent years.