Himalayan glacial lakes are growing in number and size, increasing the risk of downstream flooding, according to a recent study. Over the past three decades, dozens of new glacial lakes have formed in northern India, while existing ones have expanded rapidly. This trend is linked to the melting of glaciers caused by climate change, raising concerns about more severe floods in the future. The study, titled "Alarming trends: rapidly growing and recently formed glacial lakes in the Alaknanda Basin, northern Indian Himalayas," was published in the journal Open Geosciences. It used satellite data from Landsat and Sentinel-2 to analyze changes in 74 glacial lakes in the Alaknanda Basin, located in the western Himalayas, between 1994 and 2023. The study found that the combined area of 24 glacial lakes larger than 0.01 km² grew from 0.97 km² in 1994 to 1.62 km² in 2023, a 67% increase over 30 years. Additionally, 57 new glacial lakes formed during the study period, bringing the total number of lakes in the basin to 131. Eighteen of these new lakes were larger than 0.01 km². Some lakes showed particularly rapid growth—Vasundhara Lake expanded by 261%, while Balbala Lake grew by 119%. The study also identified 27 lakes showing significant expansion, including one located upstream of the important pilgrimage site of Badrinath. Vasundhara Lake, in particular, was highlighted as needing close attention due to its rapid growth. Glacial lake outburst floods, or GLOFs, occur when water trapped by ice, rock, or sediment is suddenly released, carrying mud and debris with potentially destructive force. While the recent disaster in Nepal was not a conventional GLOF, it demonstrated how sudden high-mountain flood events can have severe consequences on communities and infrastructure. In August, floods in Nepal caused widespread damage to homes, roads, bridges, and hydropower facilities. Dr. Aayushi Pandey, the study’s author from Charles University in Prague, emphasizes the importance of continuous monitoring in high-mountain regions where various hazards—such as extreme rainfall, glacial lake expansion, slope instability, and seismic activity—can interact and amplify downstream risks. Satellite data are crucial for monitoring large, hard-to-reach areas, allowing researchers to identify new lakes, track changes in size, and prioritize lakes for further study. However, Pandey notes that satellite observations are not enough. Field measurements are essential to assess lake depth, volume, slope stability, drainage pathways, and interactions between glaciers and lakes, all of which are important for improving flood models. She also highlights the need for stronger international collaboration and data sharing, as glacial lake and flood hazards do not respect political boundaries and must be treated as a shared regional concern.