Emission Mitigation and Climate Warming Increase China’s Ozone Responsiveness to Soil NO x Relative to Biogenic VOCs

Surface ozone (O3) remains a major air quality challenge in China despite recent reductions in anthropogenic emissions. Here, we use regional photochemical modeling to quantify changes in summertime O3 responses to relative perturbations in biogenic volatile organic compounds (BVOCs) and soil nitrogen oxides (NOx) under historical emission conditions and future mitigation and climate scenarios through 2060. Declining anthropogenic emissions increase ozone production efficiency and produce divergent response patterns: the modeled O3 response magnitude to BVOCs perturbations generally decreases, whereas the response magnitude to soil NOx perturbations increases. Under the 2060 net-zero scenario, the O3 response to an equivalent relative perturbation in soil NOx exceeds that to BVOCs in several regions. Projected climate warming further enhances O3 responsiveness to soil NOx, particularly in agriculturally intensive regions. These results indicate a scenario-dependent shift in the relative O3-response magnitude to natural precursor emissions, rather than a direct change in their source contributions. The increasing responsiveness to soil NOx suggests that agricultural nitrogen management should be evaluated as a potential complement to conventional industrial and transportation emission controls in future ozone mitigation strategies.