Climate warming weakens soil freeze-thaw erosion in the permafrost area of Northeast China

Soil freeze-thaw erosion (SFTE) changes when climate warming causes degradation of permafrost. However, the spatiotemporal changes of SFTE and its relationship with permafrost degradation remains unclear. Here we examined changes in active layer thickness (ALT) and SFTE in the Northeast China permafrost area from 1982 to 2022. We further constructed new framework integrated Geodetector, Multiscale Geographically Weighted Regression (MGWR) and Extreme Gradient Boosting-SHapley Additive exPlanations (XGBoost-SHAP) model to explore the dominant factors, spatial heterogeneity, and nonlinear threshold effects of ALT and SFTE changes. The results showed that ALT increased by 19.7 cm from 1982 to 2022; the area of micro erosion increased by 9.97 × 10⁴ km², while the area of mild erosions and above decreased by 9.36 × 10⁴ km². The factors with the greatest contribution for ALT were air temperature (AT) and soil water content, and the greatest for SFTE were annual soil temperature difference and soil water content. Both AT and soil water content showed high spatial heterogeneity on ALT, with positive AT and negative soil water content effects. Annual soil temperature difference and soil water content showed low spatial heterogeneity for SFTE and both had positive effects. XGBoost-SHAP results showed that air temperature and annual soil temperature difference had the highest feature significance and interpretability. ALT showed a complex association mechanism for SFTE intensity, which was overall negative and showed a non-linear threshold effect. Our study showed that permafrost degradation does not increase SFTE. This finding provides a reference for maintaining ecological security and SFTE management.