Volumetric quantifications and dynamics of areas undergoing retrogressive thaw slumping in the Northern Hemisphere
Chunli Dai, Melissa Ward Jones, Jurjen van der Sluijs, Nina Nesterova, Ian M. Howat, Anna Liljedahl, Bretwood Higman, Jeffrey T. Freymueller, Steven V. Kokelj, S. Sriram
Abstract
Retrogressive thaw slumping (RTS) is a mass-wasting process characterized by upslope backwasting and rapid thawing of ice-rich permafrost. High-resolution digital elevation models (DEMs) from ArcticDEM enable the volumetric and soil organic carbon quantification of medium to large disturbance areas undergoing RTS ( ≥10,000 m2) for the Northern Hemisphere. Using DEM time-series analysis and deep learning, we retrieve a total of 2747 disturbance areas undergoing active RTS with a total volume loss of (317.0 ± 0.3) × 106 m3 between 2012 and 2022. Here we show that climatic drivers of RTS activity exhibit latitudinal and regional variations, specifically, the number of precipitation-driven RTS decreases linearly as latitudes increase, whereas temperature-driven RTS increases sharply. Finally, we estimate that 96% of detected RTS thawed ~1.95 × 10–3 Pg carbon per year, equivalent to ~0.2% of annual gradual thaw emission estimates. Our results highlight the complexity of regional RTS dynamics and the importance of high resolution, long-term monitoring efforts. This study systematically mapped 2747 retrogressive thaw slumps during the past decade. It finds that higher latitude thaw slumps are mainly driven by temperature, while lower latitudes are influenced by prior-year climate and precipitation.