Spatial structure and carbon emission of urban agglomerations: Spatiotemporal characteristics and driving forces

To highlight the impact mechanism of spatial structure on carbon emission, this study calculates the spatial structure index of six urban agglomerations in China from the perspective of population and economy by using the rank-size rule. The Geographically and Temporally Weighted Regression (GTWR) model is used to analyze the spatial and temporal differences of the impact of spatial structure on carbon emissions in different urban agglomerations. The research results reveal that the carbon emissions of Yangtze River Delta (YRD), Beijing-Tianjin-Hebei (BTH) and Central Plains (CP) are much higher than that of the other three urban agglomerations. Chengdu-Chongqing (CY) and Pearl River Delta (PRD) show the characteristics of single-center structure, while the other four urban agglomerations show the characteristics of multi-center structure in 2019. The impact of spatial structures on carbon emissions of Yangtze River Delta and Pearl River Delta have experienced the process from positive impact to negative impact. The findings show that the multi-center structure of some urban agglomerations does not achieve the effect of carbon emission reduction to a certain extent, but promotes carbon emission. Therefore, it is not advisable to set the spatial structure of urban agglomeration as a unified model. The government should optimize the spatial structure of urban agglomerations according to the time evolution and internal characteristics of urban agglomerations.