The EPA released its 19th annual report of overall U.S. greenhouse gas (GHG) emissions, showing a 3.4% decrease in 2012 from 2011. The report, Inventory of U.S. Greenhouse Gas Emissions and Sinks, presents a national-level overview of annual greenhouse gas emissions since 1990.
Major contributors to the decrease include the fall in energy consumption across all sectors in the U.S. economy; the decrease in carbon intensity for electricity generation, due to fuel switching from coal to natural gas; and a decrease in transportation sector emissions, attributed to an increase in fuel efficiency across different transportation modes and limited new demand for passenger transportation.
According to the report, GHG emissions in 2012 showed a 10% drop below 2005 levels. Total emissions of the six main greenhouse gases in 2012 were equivalent to 6,526 million metric tons of CO2. These gases include carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride.
EPA prepares the annual report in collaboration with other federal agencies and after gathering comments from stakeholders across the country. In addition to tracking U.S. GHG emissions, the inventory also calculates carbon dioxide emissions that are removed from the atmosphere through the uptake of carbon in forests, vegetation, soils, and other natural processes (called carbon “sinks”).