Research Scientist, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, Calif. (2012-Present)
Chief Science Officer and Principal Investigator, NEON. (2011-2012)
CEO, and Principal Investigator National Ecological Observatory, Inc. (2007-2011)
Senior Scientist, National Center for Atmospheric Research (1995-2009)
Professor and Director, Max-Planck Institute for Biogeochemistry (1997-2002)
Senior Research Scientist, NREL, Colorado State University (Affiliate) (1995-present)
National Center for Atmospheric Research (NCAR)
Section Head, Climate and Global Dynamics Division, (1992-1997)
Scientist, (1992-1995)
Project Scientist, Climate System Modeling Program, UCAR (1990-1995)
Associate Professor, Department of Forest & Wood Science, Colorado State University (1989-1995)
National Research Council Senior Fellow, NASA/Ames Research Center (1988-1989)
Colorado State University
Research Associate, NREL, Colorado State University (1983-1986)
Postdoctoral Fellow, NREL, Colorado State University (1982-1983)
Graduate Research Assistant, NREL, Colorado State University (1979-1982)
Research Associate, The Marine Biological Laboratory, Ecosystems Center, Woods Hole, Massachusetts (1977-1979)
Statistical Consultant, University of Massachusetts, Research Computing Center, Amherst, Massachusetts (1976-1977)
