AGU member since 1979. Chief Scientist for Earth Sciences, Goddard Space Flight Center, National Aeronautics and Space Administration (NASA). Greenbelt, Maryland, USA.

Volunteer experience includes: Convenor and co-convenor of numerous AGU Fall meeting sessions; Associate Editor, JGR (1997-2004); Montreal Protocol Scientific Assessment Panel, Co-Chair (2007-present); USGCRP Strategic Plan Author (2011); Advisory committee for the General Trust Fund for Financing Activities on Research and Systematic Observations Relevant to the Vienna Convention (2015-present); International Ozone Commission member (2008-2016) and Vice President (2016-present); WCRP/SPARC co-lead on Lifetimes of ODS activity (2011-14), and carbon tetrachloride activity (2015-present).