Revealing the synergy between carbon reduction and pollution control in the process of new-type urbanization: Evidence from China's five major urban agglomerations

As a sustainable transformation of urbanization, it is unclear whether China's new-type urbanization (NTU) can promote the collaborative governance of carbon reduction (CR) and pollution control (PC). Based on the data of China's five major urban agglomerations, this study constructed a systematic framework consisting of synergy measurement, relationship exploration and driver analysis to reveal the synergy between CR and PC in the process of NTU. The results indicated that with the steady growth of CR and PC, the coupling coordination degree of the two increased from 0.6457 to 0.9030 in 2014-2022, upgrading from primary synergy to excellent synergy. From the perspective of decoupling, all urban agglomerations improved the relationship between NTU and CR/ PC with 89 and 92 cities exhibiting the state of strong decoupling, respectively, but there were differences in the decoupling types of cities within each subsystem of NTU. Overall, NTU and its subsystems significantly drove the synergy between CR and PC, while the driving effects presented a spatial heterogeneity. The Yangtze River Delta was the only urban agglomeration that fulfilled the driving effects of all subsystems of NTU. These findings provide theoretical and empirical values for taking advantage of NTU to mitigate climate change and optimize air quality.