The U.S. Environmental Protection Agency (EPA) has released the15th annual U.S. greenhouse gas inventory report, which shows a drop in overall emissions of 2.9 percent from 2007 to 2008. The downward trend is attributed to a decrease in carbon dioxide emissions associated with fuel and electricity consumption. Total emissions of the six main greenhouse gases in 2008 were equivalent to 6,957 million metric tons of carbon dioxide. The gases include carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons and sulfur hexafluoride. Though overall emissions dropped in 2008, emissions are still 13.5 percent higher than they were in 1990. http://www.epa.gov/climatechange/emissions/usinventoryreport.html
