A huge wall of water and debris swept down the Teesta valley in the eastern Himalayas on October 3 2023, causing widespread devastation and the tragic loss of over 50 people. This powerful flood in India was the result of a landslide which caused a glacial lake higher up the valley to spill over. This phenomenon is known as a glacial lake outburst flood, or GLOF.
In a 2025 study of glacial lakes across the Bolivian Andes, my colleagues and I found that 11 are highly susceptible to producing potentially hazardous GLOFs. Such lakes are increasing in size and number as glaciers retreat around the world. In Bolivia, we saw 60 new lakes form in just six years.
