Volumetric quantifications and dynamics of areas undergoing retrogressive thaw slumping in the Northern Hemisphere.

Dai, Chunli; Ward Jones, Melissa K; van der Sluijs, Jurjen; Nesterova, Nina; Howat, Ian M; Liljedahl, Anna K; Higman, Bretwood; Freymueller, Jeffrey T et al. · Nat Commun · 2025

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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 m<sup>2</sup>) 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) × 10<sup>6 </sup>m<sup>3</sup> 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<sup>-3</sup> 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.