1. a Office of Population Research , Princeton University , 207 Wallace Hall, Princeton, New Jersey, 08544, USA
2. b Center for Sustainability and the Global Environment and the Department of Geography , University of Wisconsin-Madison , 1710 University Avenue, Madison, Wisconsin, 53726, USA
3. c Robert F. Wagner Graduate School of Public Service , New York University , 295 Lafayette Street, New York, New York, 10012, USA
4. d Department of Natural Resources and the Environment , University of Connecticut , 1376 Storrs Road, Storrs, Connecticut, 06269, USA