中国二氧化硫排污权交易试点的政策效应——基于PSM-DID方法的政策效应评估

The Policy Effect of China’s Sulfur Dioxide Emission Trading System in Pilot Areas: Based on the PSM-DID Analysis

排污权交易制度在中国11个省(市)已经试行十余年,但仍未在全国范围内推广。排污权交易制度是否改善了试点地区的环境质量?其政策效应如何?能否进一步推广?本文将2007年财政部会同环境保护部、国家发展改革委批准11个省(市)为国家级排污权交易试点视作一次准自然实验,基于2001—2015年中国30个省份的面板数据,利用基于倾向得分匹配的双重差分法(PSM-DID)评估排污权交易政策对试点地区工业二氧化硫排放强度的影响。研究发现,排污权交易政策显著降低了试点地区的二氧化硫排放强度。稳健性检验证明,该政策效应并非时间趋势所导致,即使剔除2002年在市级层面试点的省份,该政策效应依旧显著,证明了排污权交易试点政策具有显著的减排效果。

The emission trading system has been carried out in Chinas 11 provinces for more than 10 years, but its still not been applied nationwide. Does the emission trading system improve the environmental quality in the pilot areas? How is its policy effect? Can it be further expanded? This paper views the nationally approved pilot project of the emission trading system in 2007 as a quasi-natural experiment. Based on a panel dataset from 2001 to 2015, this paper combines propensity score matching(PSM) and difference-in-difference(DID) method to assess the influence of emission trading policy on the emission intensity of industrial sulfur dioxide (SO2) in pilot areas. The results indicate that the emission trading policy significantly reduces the emission intensity of SO2 in the pilot areas. The robustness check proves that the findings are not driven by time trend and testifies the emission reduction even after eliminating the data of provinces which piloted this policy in 2002.