Decadal-scale thermal memory of permafrost and climatic and topographic modulation on the Tibetan Plateau

Permafrost on the Tibetan Plateau (TP) exhibits a pronounced temporal offset between atmospheric warming and subsurface thermal changes, yet its characteristic timescales, spatial patterns, and environmental drivers remain poorly quantified. This complicates the interpretation of climate forcing and ground temperature relationships, increasing uncertainty in projections of permafrost degradation and carbon feedbacks. Here, we combine in-situ records from 54 boreholes (2001–2020) with a high-resolution meteorological forcing dataset (TPMFD) to characterize the apparent timescale of permafrost thermal memory on the TP. Analyses reveal a median multi-year to decadal offset of approximately 8–11 years for active layer thickness and temperatures at the permafrost table and at 10–15 m depth. This timescale shortens to 6–8 years in warm, humid southeastern margins and lengthens to 12–15 years in cold, arid northwestern interiors. Climatic factors explain 31–51% of its spatial variance, with air pressure and precipitation serving as dominant statistical contributors, reflecting large-scale climatic background conditions, while topography and soil moisture exert local controls. These offsets represent an emergent statistical timescale associated with cumulative thermal memory and energy integration in the permafrost system, indicating that ongoing permafrost degradation may continue even if near‑surface warming moderates.