| In order to evaluate the effect and mechanism of energy saving and carbon reduction of the Air Pollution Prevention and Control Action Plan (the Policy), on the basis of measuring the energy consumption and CO2 emissions of GDP per unit area in 281 prefecture-level cities and above from 2003 to 2017, the influence, intermediary effect of innovation, and urban heterogeneity of the Policy on energy saving and carbon reduction were explored by using a difference-in-difference model. The results showed that:① the Policy promoted a significant reduction of 17.60% in the energy consumption intensity and 19.99% in the carbon emission intensity in the whole sample city. Based on a series of robustness tests, such as the parallel trend test, overcomed endogenous and placebo, dynamic time window and counterfactual, difference-in-difference-in-differences, and PSM-DID estimation, the above conclusions were still valid. ② Mechanism analysis showed that the Policy achieved energy saving and carbon reduction through the direct innovation intermediary effect of green invention patents as the carrier, and the indirect innovation mediation effect of the industrial structure upgrading effect caused by innovation achieved an energy-saving effect. ③ Heterogeneity analysis showed that the energy saving and carbon reduction rate of the Policy for coal-consuming provinces was 0.86% and 3.25% higher than that of non-coal-consuming provinces. The carbon reduction in the old industrial base city was 36.43% higher than that in the non-old industrial base, but the energy saving effect was 8.93% lower than that of the non-old industrial base. The range of energy saving and carbon reduction in non-resource-based cities was 31.30% and 74.95% higher than that in resource-based cities, respectively. ④ The results showed that it was necessary to strengthen the innovation investment and industrial structure upgrading in key areas such as big coal-consumption provinces, old industrial base cities, and resource-based cities, so as to give full play to the energy saving and carbon reduction effect of the Policy. |
