Emissions of U.S. greenhouse gases in 1998 increased by 0.2 %

Emissions of U.S. greenhouse gases in 1998 increased by 0.2 % compared with 1997, the lowest annual growth rate since the recession of 1991. Total emissions (1,803 mm metric tons of carbon equivalent) were 10 % higher than in 1990 according to "Emissions of Greenhouse Gases in the United States 1998," released by the Energy Information Administration (EIA).
Carbon dioxide accounts for 83 % of U.S. greenhouse gas emissions, and 98 % of carbon dioxide emissions are attributable to the combustion of fossil fuels. Consequently, factors affecting energy consumption also affect greenhouse gas emissions.
Emissions of carbon dioxide increased by 0.3 % or 5.1 mm metric tons of carbon. Carbon dioxide emissions from all sources totalled 1,495.5 mm metric tons of carbon. Significantly warmer than usual weather in the United States reduced consumption of winter heating fuels and resulted in emissions from the residential and commercial sectors being essentially unchanged in 1998. Emissions from the industrial sector declined 1.3 %, even though the U.S. economy grew 3.9 % in 1998. Industrial energy consumption is concentrated in a few key industries, such as petroleum refining, chemicals, and primary metals, some of which had either low growth in output or a decline in output in 1998.
Transportation emissions of carbon dioxide grew by 2.4 % compared with 1997, while the carbon dioxide emissions of regulated electric utilities expanded by 3.2 %, paced by a hotter than normal summer. Emissions of greenhouse gases other than carbon dioxide, which account for 17 % of total greenhouse gas emissions, declined by 0.6 %, to 308 mm metric tons of carbon equivalent.

Following the practice of the Intergovernmental Panel on Climate Change (IPCC), EIA converts emissions of greenhouse gases other than carbon dioxide into "carbon equivalent tons" using 100-year global warming potentials (GWPs). GWPs are intended to provide a measure of the relative effect of various greenhouse gases on climate, and to facilitatecomparisons across gases.
EIA released an initial estimate of energy-related carbon dioxide emissions in June. The report updates the initial estimate and includes the first release of data on 1998 emissions of all greenhouse gases.

Detailed information for specific gases and sources:
* Emissions of methane, the second largest contributor of total greenhouse gas emissions, declined by 1.5 % in 1998. The most important cause of the 1.5 % decline in methane (accounting for 9 % of GWP-weighted emissions) was increased capture of methane from landfills, pursuant to new regulations issued by the Environmental Protection Agency. Since 1990, U.S. methane emissions have declined by about 4.5 %.
* Nitrous oxide emissions, which account for about 6 % of total greenhouse gas emissions, declined by 0.5 mm metric tons in 1998, to 103.1 mm metric tons of carbon equivalent.
* Emissions of human-made gases such as hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulphur hexafluoride account for about 2 % of total U.S. greenhouse gas emissions. Emissions of these gases grew by 1.1 mm metric tons in 1998, to 39.5 mm metric tons of carbon equivalent.

"Emissions of Greenhouse Gases in the United States 1998" was prepared by EIA, Office of Integrated Analysis and Forecasting, pursuant to section 1605(a) of the Energy Policy Act of 1992. EIA is an independent agency within the Department of Energy that is responsible for collecting, analysing, and disseminating energy information.