1. School of Economics and Trade, Hunan University, Changsha, China
2. School of Applied Economics, Renmin University of China, Beijing, China
3. Department of Economics, Uppsala University, Uppsala, Sweden
4. Center for Environmental Management, Resources and Energy, Ruhr-Universität Bochum, Bochum, Germany
5. School of Environment, Tsinghua University, Beijing, China
6. School of Economics, Zhejiang University, Hangzhou, China