The Keeling Curve is a daily record of global atmospheric carbon dioxide concentration maintained by Scripps Institution of Oceanography at UC San Diego. Scripps CO2 measurements at Mauna Loa have been supported for many years by the U.S. Department of Energy (DOE), and have more recently been supplemented by Earth Networks, a technology company collaborating with Scripps to expand the global GHG monitoring network. Support for website development was provided in part by the National Science Foundation (NSF). Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of NSF.