Synergistic Effects of Low-Carbon and Science and Technology Finance Policies on New-Quality Productivity

From the perspective of neoclassical economics, this study incorporates the concept of new-quality productivity to develop an evaluation indicator system. Using panel data from 139 Chinese cities between 2008 and 2021, a quasi-natural experiment is constructed to examine the combined effects of low-carbon policies and science and technology finance policies. A regression control method grounded in counterfactual thinking is employed to evaluate their influence on new-quality productivity. The analysis further investigates heterogeneity across labor force quality, financial development level, and geographic location, as well as the transmission mechanisms via technological innovation and industrial structure. The results indicate that policy synergies significantly enhance new-quality productivity, a finding that remains robust under multiple tests. These synergies drive improvement through technological innovation and industrial structure optimization. The positive effect is more pronounced in regions with higher labor force quality and financial development, and in eastern China, whereas it is negligible in other regions. This study offers theoretical support and policy guidance for fostering new-quality productivity across regions.