Will polycentric cities cause more CO emissions? A case study of 232 Chinese cities.

From 2000 to 2010 China experienced rapid economic development and urbanization. Many cities in economically developed areas have developed from a single-center status to polycentricity. In this study, we used exploratory spatial data analysis (ESDA) to identify the population centers, which identified 232 cities in China as having urban centers. COMP was used to represent urban agglomeration, and POLYD (representing how far is the city's sub-centers to the main center), POLYC (representing the number of a city's centers), and POLYP (representing the population distributed between the main center and the sub-centers) were used to indicate urban polycentricity. Night light data were used to determine the CO emissions from various cities in China. A mixed model was used to study the impact of urban aggregation and polycentric data on the CO emission efficiency in 2000 and 2010. The study found that cities with higher compactness were distributed in coastal areas, and the cities with higher multicentricity were distributed in the Yangtze River Delta and Shandong Province. The more compact the city was, the less conducive it was to improving CO emission efficiency. Polycentric development of the city was conducive to improving the CO emission efficiency, but the number of urban centers had no significant relationship with the CO emission efficiency. Our research showed that the compactness and multicentricity of the city had an impact on the CO emission efficiency and provided some planning suggestions for the low carbon development of the city.