Does Dual-Pilot Policy of Broadband China and Low-Carbon City Enhance Carbon Emission Efficiency?

As global climate change intensifies, achieving the dual goals of economic efficiency and low-carbon development has become a pressing challenge. Using panel data for 269 Chinese cities from 2010 to 2021, based on their carbon emission efficiencies (CEEs) measured using the DEA-SBM model, a staggered difference-in-differences (SDID) model is employed to identify the policy impacts, which is further extended into a triple-difference (DDD) framework to examine the causal impact of the dual-pilot policy. The results show that (1) China’s CEE has improved gradually but remains relatively low, with significant regional disparities. (2) Empirical results indicate that the dual-pilot policy leads to a significant improvement in CEE, raising it by approximately 4.06%. The positive impact is particularly pronounced in cities characterized by more advanced industrial structures and stricter environmental regulatory frameworks. (3) Industrial upgrading and green technological innovation serve as key mediating channels, contributing 2%, 7%, and 10.7% to the total mediation effect. (4) The positive impacts are particularly evident in eastern, large-scale cities. These results underscore that the integration of digitalization and low-carbon initiatives serves as an effective pathway to improving CEE. Therefore, policymakers are encouraged to further advance the dual-pilot programs, foster green technological innovation, and accelerate industrial upgrading toward a digitally empowered and low-carbon development model.