Unraveling daily dynamics of supraglacial lakes in response to hydrological pulses and anomalous climate signals

Mass loss from debris-covered glaciers in High Mountain Asia drives the expansion of small supraglacial lakes (SGLs) and changes the occurrence patterns of hazardous processes including glacial lake outburst floods. Here, we analyse surface area changes of small SGLs ( > 0.045×104 m2) in the Sagarmatha region, Eastern Himalaya, integrating data with daily resolution from 2016 to 2024. The results show SGLs expanded at a mean rate of 5.90 ± 1.49×104 m2·yr⁻¹. Starting from October 2022, SGLs in the study area have exhibited anomalous expansion, with the total lake area reached its maximum during this period, 67.35% higher than during the second peak (2020). The seasonal fluctuations of SGLs are synchronous with short-term variations in global temperature. By mid-century, SGL expansion in High Mountain Asia is expected to continue. Given their rapid response to climate change, small SGLs could support the development of early-warning frameworks for hydrological pulses and extreme climate events. This study shows that small supraglacial lakes not only reflect the increasingly frequent hazards associated with small-lake outburst events, but also indicate that their seasonal dynamics serve as a precursor signal of global warming.