Does Administrative Division Adjustment promote low-carbon city development? Empirical evidence from the "Revoke County to Urban District" in China

The carbon emission reduction in city regions as a result of the optimization of urban spatial layout is crucial for combating global warming and has garnered widespread attention in recent years. There is little evidence, however, that a specific spatial optimization technique has a substantial effect on urban spatial layout and carbon dioxide -(CO2) emissions. As an effective tool of hierarchical network governance in China, Administrative Division Adjustment (ADA) has the potential to achieve this goal, due to its redistributive effects on urban space resources. Therefore, we utilize the "Revoke County to Urban District" (CTD)-one of the common and typical ADA policies-as a case study to examine its environmental implications, based on the mediation mechanism of urban spatial layout. The empirical results from a panel dataset of 285 prefecture-level and above cities in China indicate that the CTD will reduce urban -CO2 emissions, especially in low administrative levels (low-rank), non-resource based (RB), non-key environmental protection (KEP), midwestern and northwestern cities. And the additional mediation mechanisms demonstrate that the environmental benefits of the CTD in China are attributed to the optimization of urban spatial layout, which reduces -CO2 emissions by improving public transportation and limiting urban sprawl.