High frequency of moraine-dammed lake outburst floods driven by global warming.

Glacial lake outburst floods (GLOFs) represent a major hazard in mountain regions, yet considerable uncertainty persists regarding whether their frequency has increased in recent decades and to what extent this trend is linked to climate change. Here, we developed a new inventory of GLOFs from moraine-dammed lakes, analyzing 609 events worldwide between 1900 and 2020. Insights from historical reports and geomorphological evidence presented a low but fluctuating increase in the global frequency of reported GLOFs prior to the 1970s. However, a marked acceleration occurred after the 1980s, with the annual frequency increasing from 5.2 GLOFs during 1981-1990 to 15.2 GLOFs during 2011-2020. Overall, the long-term trajectory of reported GLOF frequency closely parallels variations in global air temperature, exhibiting a lag-correlated pattern on timescales of approximately 20 years. The concept of GLOF response time was employed to explain this delayed reaction, which is attributed to warming-induced glacier recession, glacial lake expansion, and slope destabilization surrounding such lakes, ultimately triggering GLOFs.