1. University of Osnabrück, Institute of Environmental Systems Research, Barbarastrasse 12, 49069 Osnabrück, Germany
2. World Bank, 1850 I Street Northwest, Washington, D.C. 20433-0001, United States
3. Department of Sustainable Development, Environmental Science and Engineering, KTH Royal Institute of Technology, Teknikringen 10B, SE-10044 Stockholm, Sweden
4. Faculty of Technology, Policy, Management, Delft University of Technology, P.O. Box 5015, 2600 GA Delft, The Netherlands