Effects of new urbanization on China's carbon emissions: A quasi-natural experiment based on the improved PSM-DID model

Examining the influence mechanisms of new urbanization on urban carbon emissions is of great practical significance to guide cities' low-carbon and sustainable development and achieve China's "dual carbon" goal. To investigate the impact of the new urbanization policy on carbon emissions, this study conducted quasi-natural experiments on 19 urban agglomerations, including 115 cities in China, from 2011 to 2018. Based on the improved propensity score matching-difference-in-differences model, the study constructed an evaluation system based on the technique for order performance by similarity to an ideal solution or the TOPSIS-entropy method for analyzing the development status of new urbanization. Finally, the influence mechanisms and regional heterogeneity of multidimensional new urbanization development on carbon emissions were examined. The results were threefold. (1) The new urbanization policy significantly inhibits carbon emissions in the pilot cities. (2) The new urbanization policy affects urban carbon emissions through economic and population urbanization, which have an inverted U-shaped relationship with carbon emissions, and public service and environmental urbanization, which inhibit carbon emissions. (3) Regional heterogeneity exists among mechanisms. For relatively developed regions, the policy significantly affects carbon emission reduction. In rapidly developing regions, the policy implementation increases carbon emissions. The policy does not significantly impact carbon emissions in remote and underdeveloped regions. This study is a significant reference for formulating a carbon emissions reduction strategy according to local conditions.