1. Department of Biological Sciences, Stanford University, Stanford, CA, USA.
2. Faculty of Economics and Politics, University of Cambridge, Austin Robinson Building, Sidgwick Avenue, Cambridge CB3 9DD, UK (E-mail: ); at the Beijer International Institute of Ecological Economics, Stockholm, Sweden; and at Resources for the Future, Washington, DC, USA.
3. Department of Meteorology, University of Stockholm.
4. Resources for the Future.
5. Food and Agriculture Organization, Rome, Italy.
6. Department of Systems Ecology, University of Stockholm, and the Beijer International Institute of Ecological Economics, Stockholm.
7. Department of Systems Ecology, University of Stockholm.
8. Princeton Environmental Institute, Princeton University, Princeton, NJ, USA.
9. Department of Ecology and Evolutionary Biology, Princeton University.
10. Beijer International Institute of Ecological Economics, Stockholm, and the Stockholm School of Economics, Stockholm.
11. International Food Policy Research Institute, Washington, DC. D. Siniscalco is at the Fondazione Eni Enrico Mattei, Milan, Italy.
12. CSIRO, Lyneham, ACT, Australia.