EXPLAINER: How glaciers can burst and send floods downstream

The floods that slammed into two hydroelectric plants and damaged villages in northern India were set off by a break on a Himalayan glacier upstream. Glaciers advance and retreat with cycles of snowfall and melting, and can form glacial lakes behind them. This pattern builds up water, as well as a risk the water will break free and flood areas downstream. Similar glacial flooding disasters have happened in Peru and Nepal. Monitoring for such risks is possible, but many of the world’s glaci