Impact of Synergistic Governance of Digital Economy and Green Finance on Urban Carbon Total Factor Productivity: A Quasi-Natural Experiment from China’s Dual Pilot Programs

The deep integration of the digital economy and green finance is a key strategic arrangement for promoting high-quality industrial development in the new stage of development. This paper uses China’s dual pilot program—comprising both Big Data Comprehensive Pilot Zones and Green Finance Reform and Innovation Pilot Zones—as a quasi-natural experiment. Based on panel data from 285 prefecture-level cities spanning 2010–2023, and employing a dual machine learning approach, the study investigates how the digital economy and green finance synergistically enhance urban carbon total factor productivity. The study finds that, compared to cities with single-policy pilot programs, the synergy of digital and green policies can promote an increase in urban carbon total factor productivity. This conclusion remains valid after a series of robustness tests, including changing the sample period, adjusting machine learning model settings, and introducing instrumental variables. Mechanism tests indicate that the synergy of digital and green policies can enhance urban carbon total factor productivity through three pathways: increasing government focus on green development, raising the level of urban green technological innovation, and expanding the scale of green investment. Heterogeneity analysis reveals that the synergistic effects vary across cities with different resource endowments and geographical locations. This study uncovers the underlying logic of how the digital economy and green finance synergistically drive urban development and transformation, providing empirical evidence from China for the formulation of sustainable development policies tailored to local conditions.