Surface Elevation Dynamics of Lake Karakul from 1991 to 2020 Inversed by ICESat, CryoSat-2 and ERS-1/2

High-altitude lakes are sensitive indicators of climate change, reflecting the hydrological impacts of global warming in alpine regions. This study investigates the long-term dynamics of the water level and surface area of Lake Karakul on the eastern Pamir Plateau from 1991 to 2020 using integrated satellite altimetry data from ERS-1/2, ICESat, and CryoSat-2. A multi-source fusion approach was applied to generate a continuous time series, overcoming the temporal limitations of individual missions. The results show a significant upward trend in both water level and area, with an average lake level rise of 8 cm per year and a surface area increase of approximately 13.2 km2 per decade. The two variables exhibit a strong positive correlation (r = 0.84), and the Mann–Kendall test confirms the significance of the trends at the 95% confidence level. The satellite-derived water levels show high reliability, with an RMSE of 0.15 m when compared to reference data. These changes are primarily attributed to increased glacial meltwater inflow, driven by regional warming and accelerated glacier retreat, with glacier area shrinking by over 10% from 1978 to 2001 in the eastern Pamir. This study highlights the value of integrating multi-sensor satellite data for monitoring inland waters and provides critical insights into the climatic drivers of hydrological change in high-altitude endorheic basins.