Thermokarst disturbance responses to climate change across the circumpolar permafrost regions from 1990 to 2023
Ya Liu, Haijun Qiu, Ninglian Wang, Dongdong Yang, Kailiang Zhao, Guoqing Yang, Wenchao Huangfu, Wanqi Luo
Abstract
• Spectral indices can monitor long-term thermokarst disturbance. • The disturbance year of thermokarst events is determined. • Thermokarst disturbance is connected with climate warming. Warming climate drives permafrost degradation and forms serious thermokarst disturbances, with significant impacts on geomorphology, hydrology, and ecological processes. However, the long-term monitoring of thermokarst disturbances and their next development remains a challenge across the circumpolar permafrost regions. Here, we calculate six spectral indices from Landsat images to represent greenness, wetness, and brightness, quantifying the spatiotemporal characteristics of thermokarst landscape dynamics and further revealing their development with a warming climate. Additionally, DNMI, NDWI, and NDVI are selected to verify the occurrence and severity of retrogressive thaw slumps, thermokarst lake expansion, and drainage by the LandTrendr algorithm on the Google Earth Engine platform. Three major types of thermokarst events show a consistent disturbance year, correlating with the summer temperature increase point around 2000. Their correlation analysis also reveals that the subsequent landscape development of thermokarst disturbances is related to the warming context, showing vegetation greening and soil wetting trends. These findings highlight the dynamic characteristics of thermokarst disturbances from 1990 to 2023, providing a comprehensive understanding of thermokarst development under a changing climate.