1. School of International and Public Affairs and Earth Institute, Columbia University, New York, New York 10025, USA;
2. Department of Human Ecology and Rutgers Energy Institute, Rutgers University, New Brunswick, New Jersey 08901, USA;
3. Department of Environmental Conservation, University of Massachusetts Amherst, Amherst, Massachusetts 01002, USA;
4. Department of Geography and Atmospheric Science, University of Kansas, Lawrence, Kansas 66045, USA;