Exploring differentiated impacts of socioeconomic factors and urban forms on city-level CO2 emissions in China: Spatial heterogeneity and varying importance levels

Abstract

Excessive anthropogenic carbon emissions due to rapid socioeconomic development and urban expansion have resulted in significant climate change. Different levels of socioeconomic development and urban forms combinedly affecting CO2 emissions at city level is still unclear, specifically considering the temporal and spatial heterogeneity. This study investigated the varying importance, spatial multiscale variation, and spatial heterogeneity of socioeconomic and urban form drivers on CO2 emissions of 275 cities in China for the years 2005, 2012, and 2015, using the eXtreme Gradient Boosting and multiscale geographically weighted regression models. Results showed that while socioeconomic factors (i.e., per capita GDP) had more significant impacts on CO2 emissions than that of urban forms (i.e., urban shape), the contribution from urban forms presented a rapid increase. Technological innovation and high population density reduced CO2 emissions at the national level in China, with accentuated effects in the southeastern coastal region; urban expansion, fragmentation, and shape complexity of urban forms increased CO2 emissions. While urban compactness initially curbed CO2 emissions, beyond a point, it promoted the growth of CO2 emissions. A compact but polycentric urban structure is therefore suggested for cities to achieve emission reduction targets. Results could provide a basis for decision-making on localized and targeted carbon emission reduction at city-level. Based on the analysis of global and local effects, inhibitory drivers should be better considered in policy formulation to provide novel insights for sustainable cities and low-carbon growth in China and other developing countries with similar rapid urban expansion, from the perspective of socioeconomic development and effective urban spatial planning.