According to a February 15, 2011 U.S. EPA draft Inventory of U.S. Greenhouse Gas Emissions and Sinks, 2009 greenhouse gas emissions in the United States dropped six percent from 2008 levels. This reduction is significant when compared to the 2.9 percent reduction achieved between 2007 and 2008. In 2009, the United States emitted 6,639 million tons of carbon dioxide equivalent emissions which is the lowest level of greenhouse gas emissions since 1995. According to U.S. EPA, the decrease was primarily due to (1) a decrease in economic output resulting in a decrease in energy consumption across all sectors; and (2) a decrease in the carbon intensity of fuels used to generate electricity due to fuel switching as the price of coal increased, and the price of natural gas decreased significantly.
Although greenhouse gas emissions as a whole decreased, methane emissions increased. U.S. EPA attributes this increase in part to the switch from coal to natural gas which resulted in lower carbon dioxide emissions but an increase in methane emissions. There was also an observed increase in methane emissions from manure management.
U.S. EPA will accept comments on the draft inventory for a period of 30 days.