1. Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, Colorado, USA
2. Institute of Arctic and Alpine Research, University of Colorado, Boulder, Colorado, USA
3. Department of Environmental Science, Policy, and Management, University of California, Berkeley, California, USA
4. Department of Earth Science and Geography, Vassar College, Poughkeepsie, New York, USA
5. Department of Geography, University of Colorado, Boulder, Colorado, USA
6. Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA