What’s going on: Scientists piecing together satellite images and seismic data believe a devastating landslide and glacial collapse in the Himalayas likely unleashed the floods on Wednesday in Nepal and Tibet. New satellite images show a huge section of mountainside gave way beneath a glacier just as a massive chunk of the glacier itself broke off. Together, researchers estimate the two collapses sent nearly 400 million metric tons of rock and ice crashing into the valley (roughly the weight of 1,000 Empire State Buildings) — and generated the equivalent of a 5.2-magnitude earthquake. Scientists say the debris picked up water and sediment as it tore downhill, creating an enormous wall of mud, ice, and water that traveled for dozens of miles. The catastrophe wiped out entire towns, roads, and bridges, killing at least 469 people in Nepal. More than 1,500 people remain missing across the disaster zone, including hundreds of tourists. US officials say about 90 Americans remain unaccounted for.
The bigger red flag: What happened in Nepal may be an extreme example of a risk scientists expect to grow as the planet warms. Rising temperatures are shrinking glaciers and thawing permafrost — think of it as the frozen glue that has helped hold mountain rock and ice together for thousands of years. As that grip weakens, some slopes can become more vulnerable to collapse. And that concern is growing as glaciers disappear faster. That instability has already led to devastation around the world. In recent years, glacier collapses have buried a Swiss village, killed 11 mountaineers in Italy, and contributed to floods that killed at least 200 people in India. Yet scientists still can’t reliably predict which glacier or mountainside could give way next. That makes Nepal’s timeline especially chilling: The torrent reached a busy border crossing just 10 minutes after the initial collapse — too fast for even the warning system to go off.
