School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA

now at: Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA

School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA

School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA

Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA

Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA, USA

School of Earth & Atmospheric Sciences and School of Chemical & Biological Engineering, Georgia Institute of Technology, Atlanta, GA, USA

Department of Civil & Environmental Engineering and Department of Engineering & Public Policy, Carnegie Mellon University, Pittsburgh, PA, USA

Argonne National Laboratory, Argonne, IL, USA

Electric Power Research Institute, Palo Alto, CA, USA

NASA Goddard Institute for Space Studies, New York, NY, USA