Spatial heterogeneity in air pollution-carbon synergies: Global evidence of decoupled development and disordered coordination

• Decoupling between GDP and PM 2.5 , O 3 , and CO 2 is more prevalent in developed nations. • Countries with higher energy consumption generally show higher coupling coordination levels. • The driving mechanisms of O 3 -CO 2 and PM 2.5 -CO 2 coupling coordination present similarities. A comprehensive understanding of the synergies between air pollutants and carbon emissions is crucial for achieving co-benefits in air quality improvement and climate change mitigation. This study investigated the global spatiotemporal dynamics of PM 2.5 concentrations, O 3 concentrations, and CO 2 emissions from 1990 to 2020. And then the coupling coordination degree (CCD) model and the geographically and temporally weighted regression (GTWR) model were applied to quantify their synergies and uncover the underlying driving mechanisms. The results indicate that PM 2.5 pollution declined substantially over the study period, with 112 countries experiencing notable reductions and 120 countries exhibiting strong decoupling between PM 2.5 and economic growth. In contrast, O 3 concentrations increased in 107 countries, 86.9% of which showed significant upward trends, and the O 3 –GDP relationship was predominantly characterized by weak decoupling. CO 2 emissions also rose in 145 countries, with 102 countries displaying weak decoupling from GDP. Regarding the coupling coordination between air pollutants and CO 2 emissions, countries with high energy consumption generally had higher CCD values (above 0.5), particularly developing Asian countries undergoing rapid economic growth and urbanization. The GTWR results further indicated that carbon intensity, industrial development, fossil fuel consumption, economic growth, and R&D investment positively influenced coupling coordination, whereas population density negatively influenced it. Overall, this study elucidates the intrinsic linkages between air pollutants and CO 2 emissions and provides scientific insights for promoting synergistic air pollution control and carbon reduction globally.