1 Center for Social and Environmental Futures, Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, CO 80309.
2 Department of Environmental Studies, University of Colorado Boulder, Boulder, CO 80303.
3 Department of Economics, University of Colorado Boulder, Boulder, CO 80302.
4 Institute for Resources, Environment and Sustainability, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.