Climate change and permafrost dynamics: Impacts on lake morphometry in the semi-arid Khangay Mountains, Mongolia

This study evaluates the impacts of recent climate change and permafrost dynamics on lake morphometry in the semi-arid Khangay Mountains of central Mongolia, focusing on Telmen (TEL), Ulaagchiny Khar (UKL), and Terkhiin Tsagaan Lakes (TTL). Multi-source datasets, including Landsat and MODIS imagery, meteorological observations, and bathymetric data, were integrated to quantify changes in lake area, volume, vegetation productivity (NDVI), air temperature, and precipitation over the period 1993–2023. Results show a persistent increase in mean annual air temperature, while precipitation exhibits clear spatial variability among lake basins. Lake volumes declined by 0.062 km³ (UKL), 0.143 km³ (TEL), and 0.027 km³ (TTL), corresponding to reductions of approximately 16%, 54%, and 10%, respectively, indicating pronounced differences in hydrological sensitivity. Evaporation appears to contribute to lake-volume decline, particularly in UKL and TEL; however, lake-water balance is also influenced by precipitation variability, inflow conditions, and groundwater exchange. Vegetation productivity increased across catchments, suggesting improved growing-season conditions associated with permafrost warming. Overall, these findings highlight the sensitivity of permafrost-influenced lake systems to climate variability and emphasize the need for further process-based studies to better constrain hydrological responses.