The impact of urban compactness on urban carbon emissions: A study of 281 Chinese cities

While compact cities have shown strong potential in reducing emissions, they still generate significant emissions during their initial construction phase. The potential limits of emission reduction achieved by compact cities have been largely overlooked in current literature. This paper addresses this gap by assessing the level of compactness in Chinese cities and delving into the non-linear relationship between urban compactness and carbon emissions. We find that Chinese cities have a relatively low level of compactness, and there exists an inverted U-shaped relationship between urban compactness and carbon emissions. Technological innovation and industrial upgrading are two potential channels. Our findings further reveal that the effectiveness of emission reduction through compact development varies across cities, contingent upon their size, resource orientation, and geographic location. Notably, small-sized cities demonstrate a unique U-shaped relationship, currently positioned in a phase of effective emission reduction. We also find that as urban compactness reaches a certain threshold, it becomes a catalyst for encouraging low-carbon lifestyles and urban production practices, thereby facilitating the process of urban carbon reduction. The findings of this paper provide valuable theoretical insights for the development of compact urban forms and offer fresh perspectives for further research on compact cities.