Rising Risk of Thermokarst Lake Drainage on the Mongolian Plateau Under Future Warming

Permafrost warming is reshaping cold region surface water systems, where thermokarst lake drainage can abruptly alter lake abundance, hydrological connectivity and exposed thaw terrain. Yet future drainage risk trajectories remain poorly constrained for thermokarst lakes on the Mongolian Plateau (MP), a mid-latitude permafrost region undergoing strong climatic and cryospheric change. Here, we developed a future-compatible drainage risk assessment framework that combines Landsat-derived drainage mapping, environmental predictors, eXtreme Gradient Boosting (XGBoost) modelling, and fixed 2020 baseline risk thresholds with climate projections. The model was trained with 2003–2020 annual lake observations and applied to 31,786 undrained candidate lakes. Independent validation using 2021–2025 drainage events showed that 987 of 1188 events (83.1%) exceeded the fixed 2020 top 10% risk threshold, corresponding to an enrichment ratio of 8.31. Future projections showed a substantial upward shift in drainage risk levels relative to the 2020 baseline. These outputs represent relative risk levels referenced to the fixed 2020 distribution rather than calibrated probabilities of drainage within a specified future period. Under the Shared Socioeconomic Pathway 5-8.5 (SSP5-8.5) scenario, 12,448 lakes (39.16%) exceeded the fixed top 10% threshold by 2081–2100, while 17,980 lakes (56.57%) exceeded the fixed top 25% threshold. Among the top 10% high-risk lakes, 9597 were consistently identified by all six global climate models (GCMs), indicating strong cross-model agreement. These GCM-supported high-risk lakes formed spatially coherent clusters in the northern, western and northeastern MP. The Stefan-type active layer sensitivity test retained high spatial overlap with the main projection (Jaccard = 0.917). Environmental association analysis showed that mean annual ground temperature (MAGT) was the most closely related factor, with consistently negative Spearman correlations across scenarios and projection periods (−0.45 to −0.43), followed by thawing degree days (TDD), freezing degree days (FDD), June–September precipitation and river network distance. These findings identify areas with elevated relative drainage risk levels as warming continues.