Spill-over effect and efficiency of seven pilot carbon emissions trading exchanges in China

With the negative impact of climate change on the environment becoming more and more obvious, countries all over the world have strengthened their attention to environmental protection, the establishment of carbon emission trading mechanism is widely regarded as the most effective way to reduce carbon emissions. The design of carbon emission trading markets (ETMs) operation mechanisms and operational efficiency directly affect whether carbon ETM can cope with climate change and achieve its environmental protection purpose. In this study, we use multiple model synthesis to comprehensively evaluate the operation of carbon ETM, determine unreasonable modes of carbon ETM operation and propose suggestions for improvement. First, we propose a methodological framework to comprehensively evaluate the operational efficiency of carbon ETMs, and use the DCC-GARCH model to analyse information exchange and interaction between domestic and international carbon ETMs. Then, from the four dimensions of trading processes, law and inspection systems, the internal operation of carbon ETMs, and the impact of carbon ETM operation on the regional economy, 13 input-output indicators are selected to establish a super-DEA model to evaluate the efficiency of seven carbon ETMs. The results show that the spillover effect among various carbon ETMs is unstable, exchange between carbon ETMs is low. The operational efficiency of China's carbon ETMs is increasing each year, but there are significant differences in the operation efficiency levels of carbon ETMs. The system in Hubei has the highest super-DEA score, followed by that in Shenzhen, and those in Chongqing and Tianjin have lower scores. From the perspective of pilot projects with good operation, strong legal system constraints and reasonable operation mechanisms are important means to ensure operational efficiency.