1. K. Hayhoe, A. Jain, and D. Wuebbles are in the Department of Atmospheric Sciences, University of Illinois, Urbana, IL 61801, USA.
2. H. Pitcher and C. MacCracken are at the U.S. Department of Energy Pacific Northwest National Laboratory, Washington, DC 20024-2115, USA.
3. M. Gibbs is in the ICF Kaiser Consulting, Sherman Oaks, CA, 91403, USA.
4. R. Harvey and D. Kruger are in the Office of Air and Radiation, Climate Protection Division, Methane Energy Branch, U.S. Environmental Protection Agency, Washington, DC 20460, USA.