Up until a disastrous day earlier this month, more than 150 trucks crossed daily over a border bridge between Nepal and China. Known by locals as the Miteri Pul (Friendship Bridge), the Rasuwagadhi crossing served as the main trade route between the two countries, with over $50m of goods passing over it last year alone.

But on the 8 July, floodwaters tore through northern Nepal’s Rasuwa district, sweeping away parts of this critical border highway. According to the National Disaster Risk Reduction & Management Authority, seven people lost their lives, and 20 were missing, including six Chinese nationals.

The Chinese nationals were working on a 200 megawatt hydro project in the Tirsuli River, which was also damaged by the floods. Initial estimates suggest Nepal has sustained losses of over $100m in the incident as a whole.

Scientists have determined that the cause was an outburst from a glacial lake. According to Jakob Steiner, a postdoctoral fellow at the University of Graz (Austria), and Amrit Thapa, a PhD student at the University of Alaska Fairbanks, the glacial lake had formed in March, approximately 35km upstream from the border inside Chinese territory.

Glacial lake outburst floods (GLOFs) have become increasingly common in Nepal, driven by rapid warming in the Himalayas. Nepal's Department of Hydrology and Meteorology reports that temperatures in the Himalayan region have increased by 0.42C per decade between 2008 and 2018 – nearly double the global average.

Nepal lost 24 per cent of its glaciers due to global warming between 1977 and 2010, the most recent data available, contributing to a substantial decline in freshwater reserves in the Himalayas. In the Himalayan region, the number of glacial lakes and their area are rapidly increasing.