Integrated assessment of climate–vegetation trade-offs between carbon sequestration and ozone air quality in China

Vegetation plays a dual role in enhancing carbon sequestration while influencing ozone (O3) formation through biogenic volatile organic compounds (BVOCs). Yet, the relative contributions of these processes and their spatial coupling remain poorly quantified, limiting our understanding of the co-benefits and trade-offs between air quality improvement and carbon mitigation. In this study, we established an integrated modeling framework that couples land-use, vegetation dynamics, and atmospheric chemistry to quantify the co-effects of vegetation on air quality and carbon sequestration. The results show that vegetation dynamics enhanced China’s terrestrial carbon sink by 73.7–151.9 Tg C yr–1 and increased BVOC emissions by 13.6–17.5 Tg, leading to 9.1–10.5 μg m–3 increases in surface O3 concentrations. Both O3 and carbon sinks exhibited pronounced spatial heterogeneity. Regions where enhanced carbon sinks coincided with elevated O3 were mainly located in Northeast China, the North China Plain, and Central China. In contrast, co-beneficial regions, characterized by simultaneous increases in carbon sinks and decreases in O3, were concentrated in southeastern China. These findings provide the first spatially explicit evidence of heterogeneous trade-offs and synergies between air-quality improvement and carbon sequestration, offering scientific guidance for coordinated land-use planning and vegetation management under future climate scenarios.