1. School of the Environment, Washington State University, Vancouver, Washington, and Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York
2. Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York
3. Lamont-Doherty Earth Observatory, Columbia University, Palisades, and NASA Goddard Institute for Space Studies, New York, New York
4. University of California, Riverside, Riverside, California