The impact of low-carbon city construction on ecological efficiency: Empirical evidence from quasi-natural experiments

Building a low-carbon city is an important guarantee to optimize the ecological environment and the key to improving ecological efficiency. This study conducts a quasi-natural experiment using panel data of China's 286 prefecture-level cities from 2003 to 2016. It evaluates the influence of low-carbon city construction on urban ecological efficiency using the difference-in-difference (DID) method and tests the robustness of the empirical results. In addition, it explores the influence mechanism on urban ecological efficiency and further investigates the differential influence based on heterogeneous resource dependence and urban scale. The results show that: (1) China's low-carbon city pilot (LCCP) policy has significantly improved urban ecological efficiency, as confirmed through a series of robustness tests. (2) In terms of action mechanisms, the LCCP policy in 2012 improved urban ecological efficiency only through the technological innovation path and not through industrial structure advancement or energy utilization efficiency; there is room to expand the scope and enhance the effectiveness of the LCCP policy. (3) Regarding urban heterogeneity, resource-based cities are constrained by the dilemma of resource dependence and the construction of low-carbon cities has a weak effect on improving ecological efficiency. Similarly, the economic agglomeration effect of megacities can further strengthen the role of low-carbon city construction in improving ecological efficiency, while the effect is weak in small and medium-sized cities. This study's conclusions reliably evaluate the results of the current low-carbon city construction and suggest a feasible path for further implementation of the related policy.