A deadly cascade: A catastrophic landslide in Uttarakhand state in India on February 2021 damaged two hydropower plants, and more than 200 people were killed or are missing. Shugar et al. describe the cascade of events that led to this disaster. A massive rock and ice avalanche roared down a Himalayan valley, turning into a deadly debris flow upstream from the first of the two hydropower plants. The sequence of events highlights the increasing risk in the Himalayas caused by increased warming and development. Science , abh4455, this issue p. 300

Glacial lake outburst floods (GLOFs) represent a major hazard and can result in significant loss of life. Globally, since 1990, the number and size of glacial lakes has grown rapidly along with downstream population, while socio-economic vulnerability has decreased. Nevertheless, contemporary exposure and vulnerability to GLOFs at the global scale has never been quantified. Here we show that 15 million people globally are exposed to impacts from potential GLOFs. Populations in High Mountains Asia (HMA) are the most exposed and on average live closest to glacial lakes with ~1 million people living within 10 km of a glacial lake. More than half of the globally exposed population are found in just four countries: India, Pakistan, Peru, and China. While HMA has the highest potential for GLOF impacts, we highlight the Andes as a region of concern, with similar potential for GLOF impacts to HMA but comparatively few published research studies.