Total U.S. human-caused greenhouse gas emissions in 2009 were 5.8 percent below 2008 levels. The decline in total emissions—from 6,983 million metric tons carbon dioxide equivalent (MMTCO2e) in 2008 to 6,576 MMTCO2e in 2009—was the largest since 1990 when emissions were first tracked , according to a new report from the Energy Information Administration.
EIA said the drop was largely the result of a 419 MMTCO2e drop in carbon dioxide (CO2) emissions (7.1 percent). It reported an increase of 7 MMTCO2e (0.9 percent) in methane (CH4) emissions and an increase of 8 MMTCO2e (4.9 percent) based on partial data in emissions of man-made gases with high global warming potentials.
Emissions of nitrous oxide (N2O) fell by 4 MMTCO2e (1.7 percent).
The decrease in U.S. CO2 emissions in 2009 resulted primarily from three factors: an economy in recession, a particularly hard-hit energy-intensive industries sector and a large drop in the price of natural gas that caused fuel switching away from coal to natural gas in the electric power sector.
Methane emissions totaled 731 MMTCO2e in 2009, up by 7 MMTCO2e (0.9 percent) from 2008. Increases in energy-related methane emissions (largely from underground coal mining) were offset by decreases in emissions from agricultural sources. Methane emissions from waste management systems rose by 7 MMTCO2e, while industrial emissions declined by 0.4 MMTCO2e.
Emissions of nitrous oxide dropped by 4 MMTCO2e (1.7 percent) to 220 MMTCO2e. The decrease came mainly from a reduction in energy-related emissions, as well as declines in industrial-related and agricultural nitrous oxide emissions.
Based on a partial estimate, U.S. emissions of high global warming potential gases totaled 178 MMTCO2e in 2009. That was 8 MMTCO2e (4.9 percent) above the 2008 level. Emissions of hydrofluorocarbons (HFCs) rose by 7 MMTCO2e (5.4 percent) from 2008 to 2009.
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