Spatial spillover effects of a carbon trading policy on green technology innovation in China

A carbon market is a widely used policy tool worldwide. This study employs a difference-in-differences (DID) model to estimate the impact of a carbon trading policy on green technology innovation and applies a spatial DID (SDID) model to investigate its spatial spillover effects. The findings suggest that China's carbon market effectively promotes green technology innovation, as green invention patent applications for listed enterprises increase by 28.8% when implementing the carbon trading policy. Moreover, implementing a carbon trading policy promotes local green technology innovation and has spatial spillover effects on neighboring cities. Furthermore, heterogeneity test results show that the spatial spillover effects differ by geographical region, economic development levels, ownership type (state-owned and non-state-owned enterprises), and degree of government intervention. Therefore, we suggest enhancing enterprises' technological innovation by providing policy support and prioritizing the development of carbon markets in regions with high economic development levels.