Moraine

Geotechnical engineering

Geomorphology

Glacial lake

Glacier

Physical geography

Glacial period

Geology

Geography

Hydrology (agriculture)

Terminal moraine

Environmental science

Nature Climate Change

Shrinking glaciers in the Hindu Kush–Karakoram–Himalaya–Nyainqentanglha (HKKHN) region have formed several thousand moraine-dammed glacial lakes1–3, some of these having grown rapidly in past decades3,4. This growth may promote more frequent and potentially destructive glacial lake outburst floods (GLOFs)5–7. Testing this hypothesis, however, is confounded by incomplete databases of the few reliable, though selective, case studies. Here we present a consistent Himalayan GLOF inventory derived automatically from all available Landsat imagery since the late 1980s. We more than double the known GLOF count and identify the southern Himalayas as a hotspot region, compared to the more rarely affected Hindu Kush–Karakoram ranges. Nevertheless, the average annual frequency of 1.3 GLOFs has no credible posterior trend despite reported increases in glacial lake areas in most of the HKKHN3,8, so that GLOF activity per unit lake area has decreased since the late 1980s. We conclude that learning more about the frequency and magnitude of outburst triggers, rather than focusing solely on rapidly growing glacial lakes, might improve the appraisal of GLOF hazards. Melting glaciers are increasing Himalayan glacial lakes and potentially the risk of outburst floods. An advanced automated algorithm identifies glacial lake outburst floods from Landsat images since the late 1980s to improve understanding of these events and trends in their frequency.

Unchanged frequency of moraine-dammed glacial lake outburst floods in the Himalaya