executive summary overview us emissions of greenhouse gases in 2003 totaled 6 935 7 million metric tons carbon dioxide equivalent 0 percent more than 2002 890 9 although car bon and methane grew by 8 per cent 5 respectively those increases were partially balanced reductions nitrous oxide hydrofluorocarbons perfluoro carbons sulfur hexafluoride 3 gas have averaged 1 annual growth since 1990 the economy which is to average rate that has prevailed during period consequently intensity emis sions unit real economic output was 2 lower from declined 22 or an year 13 4 higher 115 increase
