U.S. emissions of greenhouse gases in 2004 totaled 7,122.1 million metric tons carbon dioxide equivalent (MMTCO2e), 2.0 percent more than in 2003 (6,983.2 MMTCO2e), according to a report by the Energy Information Administration (EAI, www.eia.doe.gov) titled Emissions of Greenhouse Gases in the United States 2004. The report attributes the growth primarily to a 1.7-percent increase in emissions of carbon dioxide, along with increases in emissions of nitrous oxide (5.5 percent) and methane (0.9 percent). Emissions of engineered gases — hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6) — also increased, by 9.6 percent.

According to the administration, emissions are on the rise in part by an upswing in the U.S. economy, which grew by 4.2 percent in 2004, the highest rate of growth since 1999. The report shows U.S. greenhouse gas emissions in 2004 were 16 percent higher than the 1990 emissions level of 6,148.8 MMTCO2e — an average annual increase of 1.1 percent over the period. The report notes, since 1990 U.S. emissions have increased more slowly than the average annual growth in population (1.2 percent), primary energy consumption (1.2 percent), electric power generation (1.9 percent), or gross domestic product (3.0 percent). This is largely attributed to falling emissions levels for methane and nitrous oxide, as carbon dioxide emissions since 1990 (1.3 percent) have closely tracked annual growth in population and energy consumption. However, in 2004 emissions from methane and nitrous oxide were both up. Methane and nitrous oxide emissions are generally caused by the biological decomposition of various waste streams and fertilizer, fugitive emissions from chemical processes, and fossil fuel production, transmission, and combustion.

Also of note, the report shows emissions in the industrial sector rose for the second straight year after steadily declining from 1997-2002. Still, of the four sectors examined in the report — Commercial, Residential, and Transportation being the other three — Industrial remained by far the lowest producer of emissions.

To view Emissions of Greenhouse Gases in the United States 2004 in its entirety, visit ftp://ftp.eia.doe.gov/pub/oiaf/1605/cdrom/pdf/ggrpt/057304.pdf.

— Flow Control Staff