Total U.S. greenhouse gas (GHG) emissions were 7,282 million metric tons carbon dioxide equivalent (MMTCO 2e) in 2007 – an increase of 1.4% from the 2006 level, according to ‘Emissions of Greenhouse Gases in the United States 2007,’ a report released by the Energy Information Administration. Since 1990, U.S. GHG emissions have grown at an average annual rate of 0.9%.
U.S. GHG emissions per unit of gross domestic product (GDP) fell from 636 metric tons per million 2000 constant dollars of GDP (MMTCO 2e/million dollars GDP) in 2006 to 632 MMTCO 2e /million dollars GDP in 2007 – a decline of 0.6%. Since 1990, the annual average decline in GHG intensity has been 1.9%.
Total estimated U.S. GHG emissions in 2007 consisted of 6,022 million metric tons of CO2 (82.6% of total emissions); 700 MMTCO 2e of methane (9.6% of total emissions); 384 MMTCO 2e of nitrous oxide (5.3% of total emissions); and 177 MMTCO 2e of hydrofluorocarbons (HFCs), perfluorocarbons (PFCs) and sulfur hexafluoride (SF6) (2.4% of total emissions).
CO2 emissions from energy consumption and industrial processes, which had risen at an average annual rate of 1.1% per year from 1990 to 2006, increased by 1.3% in 2007.
Unfavorable weather patterns – where both heating and cooling degree-days were higher in 2007 than 2006 – and an increase in the carbon intensity of electricity generation – driven by decreased availability of hydropower – both contributed to higher energy-related CO2 emissions in 2007.
Methane emissions increased by 1.9%, while nitrous oxide emissions rose by 2.2%. Emissions of HFCs, PFCs and SF6 – a group labeled collectively as high-GWP gases because of their high heat-trapping capabilities – increased by 3.3%.
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SOURCE: Energy Information Administration