Total U.S. greenhouse gas (GHG) emissions were 6,576 million metric tons carbon dioxide equivalent (MMTCO2e) in 2009, a decrease of 5.8 percent from the 2008 level, according to Emissions of Greenhouse Gases in the United States 2009, a report released by the U.S. Energy Information Administration (EIA).
Since 1990, U.S. GHG emissions have grown at an average annual rate of 0.4 percent. This is the largest percentage decline in total U.S. GHG emissions since 1990, the starting year for EIA’s data on total GHG emissions.
“The large decline in emissions in 2009 was driven by the economic downturn, combined with an ongoing trend toward a less energy-intensive economy and a decrease in the carbon-intensity of the energy supply,” said EIA Administrator Richard Newell.
Total estimated U.S. GHG emissions in 2009 consisted of 5,446.8 million metric tons of carbon dioxide (82.8 percent of total emissions); 730.9 MMTCO2e of methane (11.1 percent of total emissions); 219.6 MMTCO2e of nitrous oxide (3.3 percent of total emissions); and 178.2 MMTCO2e of hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6) (2.7 percent of total emissions).
Emissions of energy-related carbon dioxide decreased by 7.1 percent in 2009, having risen at an average annual rate of 0.8 percent per year from 1990 to 2008. Among the factors that influenced the emissions decrease was a decline in Gross Domestic Product (GDP) of 2.6 percent.
The energy intensity of the U.S. economy, measured as energy consumed per dollar of GDP (Energy/GDP), fell by 2.2 percent in 2009. Year-to-year declines in energy intensity are relatively common. There was also a decline in the carbon dioxide intensity of U.S. energy supply (CO2 per unit of energy) in 2009, caused primarily by a drop in the price of natural gas relative to coal that led to more natural gas consumed for the generation of electricity. Also contributing was an increase in renewable energy consumption, led by wind and hydropower.
Methane emissions increased by 0.9 percent, while nitrous oxide emissions fell by 1.7 percent in 2009. Based on partial data constituting about 77 percent of the category, combined emissions of HFCs, PFCs and SF6 increased by 4.9 percent.