The Important Greenhouse Gases (except water vapor)
U.S. Department of Energy, (October, 2000) (1)
(all concentrations expressed in parts per billion) Pre-industrial baseline Natural additions Man-made additions Total (ppb) Concentration Percent of Total Carbon Dioxide (CO2) 288,000 68,520 11,880 368,400 99.438% Methane (CH4) 848 577 320 1,745 0.471% Nitrous Oxide (N2O) 285 12 15 312 0.084% Misc. gases ( CFC's, etc.) 25 0 2 27 0.007% Total 289,158 69,109 12,217 370,484 100.00%