The EPA has released its 15th 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 CO₂ 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.

The Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2008 is the latest annual report that the United States has submitted to the Secretariat of the United Nations Framework Convention on Climate Change. The convention sets an overall framework for intergovernmental efforts to tackle the challenge posed by climate change.