Establishing a robust area-to-volume scaling for Qinghai-Tibetan Plateau Retrogressive Thaw Slumps: A key tool for quantifying mass wasting and carbon release induced by permafrost degradation

Quantifying soil erosion and associated carbon release from Retrogressive Thaw Slumps (RTSs) across the vast Qinghai-Tibetan Plateau (QTP) remains challenging due to the difficulty in obtaining large-scale volumetric data. This knowledge gap hinders accurate assessments of permafrost degradation impacts. Here, we developed a regionally specific area-to-volume scaling relationship using multi-source high-resolution Digital Elevation Model (DEM) data. Based on the regression of 1,443 slumps, we found that RTS volume (V) scales with area (A) following the power law V=0.18±0.04·A1.20±0.02,R2=0.88p<0.001. This distinct scaling relationship reflects the relatively smaller area and shallower slump floor depth of RTSs on the QTP compared to those in Arctic regions. By integrating this scaling with an estimation model accounting for RTS geometry and the spatial heterogeneity of soil and ground-ice content, we reconstructed RTS volumetric changes (1989–2022), revealing a total mass wasting of 0.87 × 108 t (95 % CI: 0.54× 108–1.44× 108 t) in the past 3 decades. Associated carbon release peaked at 0.16 Tg·C·yr−1 (95 % CI: 0.13–0.20 Tg·C·yr−1) in 2016, offsetting ∼3.1 % of the total permafrost carbon sink. Although current impacts remain moderate, the observed non-linear response of RTS activity to warming and wetting—where ∼20 % higher temperatures and 12 % more precipitation in summer months have driven nearly a tenfold increase in activity—suggests future risks could escalate. Our findings close a critical gap in RTS volume monitoring across the QTP and provide a quantitative framework for evaluating permafrost degradation and its carbon feedback under a warming climate.