Responses of thermokarst lake dynamics to permafrost degradation on the central Tibetan Plateau

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As a common landscape feature of permafrost degradation, the formation and evolution/expansion of thermokarst lakes have strong impacts on hydrology, ecosystem, and biogeochemical cycle. Characterizing the dynamics of thermokarst lakes and quantifying its links to permafrost degradation on the Tibetan Plateau (TP) are essential but lacking. Here, we investigated three representative areas of permafrost degradation on the central TP, where extensive small thermokarst lakes (<0.1 km2) were found to develop rapidly. We reconstructed spatial-temporal changes of thermokarst lakes using Google Earth Engine (GEE) and ground deformation derived from Interferometric Synthetic Aperture Radar (InSAR) during 2016–2020. We found that permafrost degradation extensively accelerated surrounding the evolved thermokarst lakes. The thermokarst lake dynamics had significant correlations with peripheral ground deformation. We infer that hydrological connectivity is the main driving factor for promoting permafrost degradation and facilitating the development of thermokarst lakes on the central TP. Moreover, the impact of the recently-constructed Qinghai-Tibet railway on accelerating permafrost degradation may be overestimated. Our results suggest that thermokarst lake change is an important indicator of climate change on the central TP and thus deserves long-term monitoring.