Unveiling the Soil Crisis: The economic and environmental toll of freeze-thaw cycles by century's end

This study aims to systematically reveal the spatiotemporal patterns of FTCs-driven carbon and nitrogen release in soils under future climate scenarios through a multi-scale coupled analytical framework, while innovatively establishing an interdisciplinary assessment system bridging ecological processes and economic impacts. Grid-based spatial econometric approaches translated biogeochemical perturbations into national-scale valuations of FTCs-induced human life losses and economic depreciation.Firstly, in delineating the study areas, we used 2000-2020 monthly temperature data to establish dual constraint criteria for spatial zoning: (1) mean winter temperature ≤0°C ensures surface soil freezing, and (2) mean summer temperature ≥0°C facilitates frozen layer thawing. This methodology enabled precise identification of ecologically sensitive zones with pronounced freeze-thaw alternation characteristics using global temperature thresholds (Fig. 2a).Secondly, in multi-source data integration, we pioneered a consolidated meta-analytic database spanning 96 global FTCs experiments and employed random-effects models to decode dose-response relationships between FTCs intensity and carbon-nitrogen release. A multidimensional dataset encompassing 26 moderating factors across six categories (Supplementary Table 2) was constructed, integrating critical parameters such as soil matrix characteristics and vegetation coverage dynamics. Future multi-scenario projections were implemented using CMIP6 downscaled climate projections from the WorldClim database53.Finally, in socio-ecological-economic impact assessments, machine learning models predicted global SOC and TN content dynamics from 2021 to 2100 at a 0.5° spatial resolution. Three evaluation dimensions were analyzed: health risks quantified via CO2 mortality costs, agricultural fertilization expenditures, and climate damage monetization. The complete methodological workflow is illustrated in Supplementary Fig. 1.