1. a Department of Earth and Planetary Sciences, The Johns Hopkins University, Baltimore, Maryland
2. b Geosciences and Environmental Change Science Center, U.S. Geological Survey, Denver, Colorado
3. c Department of Botany and Plant Sciences, University of California, Riverside, Riverside, California
4. d SkyTruth, Santa Fe, New Mexico
5. e Nelson Institute Center for Sustainability and the Global Environment, University of Wisconsin–Madison, Madison, Wisconsin
6. f Department of Agronomy, University of Wisconsin–Madison, Madison, Wisconsin