Variability of Thermokarst-Driven Long-term Thaw Subsidence Across the Arctic

Thermokarst is an often non-linear pulse disturbance that rapidly and irreversibly degrades ice-rich permafrost and results in the mobilization of permafrost carbon. Thermokarst landforms occur in most regions with ice-rich permafrost, including the High Arctic, and provide evidence for both past and present permafrost landscape change that can be used to better understand future potential responses. We use high- and medium-resolution optical remote sensing, high-resolution airborne and space-borne digital elevation information, and field data to capture and describe the variability of long-term thaw subsidence and ground deformation due to thermokarst processes across Arctic permafrost regions. The spatial variability of thaw subsidence associated with various thermokarst landforms provides information about potential landscape-scale thaw susceptibilities as well as ground ice volumes and distribution. Accordingly, a landscape vulnerability index based on thermokarst landform morphologies may serve as a proxy for better understanding carbon mobilization potentials. We here exemplarily analyze sites with known near-surface ice-rich deposit thicknesses and where thermokarst has occurred in the recent and distant past. We assess whether there are correlations between observed thaw subsidence magnitude and its spatial variability in a given area based on depositional environment, thermokarst age and morphology, and ground ice volume and type. While many of our sites are located in the Yedoma region of Northeast and Central Siberia and Alaska, several others are located in non-Yedoma permafrost regions, such as the Alaska North Slope. The ultimate goal of this study is an observation-based assessment of thermokarst potential on a panarctic scale as well as contributions to a new panarctic ground ice map