executive summary overview us emissions of greenhouse gases in 2002 totaled 6 862 0 million metric tons carbon dioxide equivalent 5 percent more than 2001 828 9 although car bon and hydrofluorocarbons perfluorocarbons sulfur hexafluoride grew by 8 2 respectively those increases were moderated reductions methane 7 nitrous oxide 1 resulting a relatively low growth total gas have aver aged annual since 1990 even though the economy 4 slightly less its trend for period was restrained somewhat due to reduction output from energy intensive manu facturing sector consequently intensity per unit real economic lower has declined 21 or an average
