Overview and evaluation of the mitigation efficiency for China's seven pilot ETS

China's pilot emission trading schemes (CP-ETS) have been operating for five years since the first pilot ETS launched its carbon market in 2013. The seven pilots have a common framework but different details. In this study, an assessment model which is used to evaluate mitigation efficiency, is constructed by combining the DID method and an evaluation matrix. Results show that the five CP-ETS have been effective in promoting emission reduction, whereas the pilot ETS of Shanghai and Chongqing have failed to drive the covered enterprises to reduce their GHG emission directly. Our findings reveal that at least three key elements, namely, allowance cap, the covered enterprises' potential emission reduction capacity, and economic structure stability, affect the mitigation efficiency of the CP-ETS. The mitigation efficiency of the CP-ETS may be enhanced by conducting a pre-evaluation of the potential mitigation capacity of the covered enterprises, setting a mechanism for the evaluation and adjustment of the allowance cap, and employing financial tools to maintain the carbon price within a reasonable range that most covered enterprises can afford.