1. Land, Environment, Economics and Policy Institute, Department of Economics, University of Exeter Business School, Exeter, EX4 4PU, United Kingdom
2. Center for Science, Technology and Environmental Policy, Hubert H. Humphrey School of Public Affairs, University of Minnesota, Minneapolis, MN 55455
3. Lyndon B. Johnson School of Public Affairs, The University of Texas at Austin, Austin, TX 78713-8925
4. Department of Economics, Appalachian State University, Boone, NC 28608