Cynthia D Nevison, INSTAAR/University of Colorado, Boulder, CO, United States, David R Munro, University of Colorado, Department of Atmospheric and Oceanic Sciences and Institute for Arctic and Alpine Research, Boulder, CO, United States, Nicole S Lovenduski, University of Colorado, Department of Atmospheric and Oceanic Sciences, Boulder, CO, United States, Ralph F Keeling, Univ California San Diego, La Jolla, CA, United States, Manfredi Manizza, Univ of California--SIO, Geosciences Research Division, La Jolla, CA, United States, Eric James Morgan, Scripps Institution of Oceanography, La Jolla, CA, United States and Christian Rödenbeck, Max Planck Institute for Biogeochemistry, Jena, Germany