Urban shrinkage impedes carbon scale but increases carbon intensity in China

The pursuit of carbon neutrality in urban environments constitutes a multifaceted challenge, particularly within the framework of China's Dual Carbon Strategy that mandates coordinated reductions in both total carbon emissions and intensity (carbon emissions per unit of GDP). However, existing research predominantly focuses on the impact of urban shrinkage on carbon scale, often overlooking its association with carbon intensity. This study addresses this research gap by systematically examining the dual impacts of urban shrinkage on emission scale and intensity. Using econometric models, we analyze panel data from 288 prefecture-level and higher-tier cities in China, covering the period from 2005 to 2020. Our findings show that the number of high-carbon-emission cities increased over the study period, with a gradual westward shift toward central and western regions. Shrinking cities exhibited significantly lower carbon scale but notably higher carbon intensity compared to non-shrinking cities. In shrinking cities, each 1% decline in population corresponds to a 0.495% decrease in carbon scale, but a 0.629% increase in carbon intensity. The dual effect of shrinkage was most pronounced in central China and among medium-sized cities, large cities, and supercities. Crucially, we identify energy efficiency as the critical mediating mechanism through which urban shrinkage influences both emission scale and intensity.