Report: U.S. Greenhouse Gas Emissions Increased Last Year

Overall greenhouse gas emissions during 2004 increased by 1.7 percent from the previous year, and this rise was due primarily to an increase in carbon dioxide emissions associated with fuel and electricity consumption, according to an EPA report announced on Feb. 28.

Total emissions of the six main greenhouse gases in 2004 were equivalent to 7,075 million metric tons of carbon dioxide. Fossil fuel combustion was the largest source of emissions, accounting for 80 percent of the total. Overall, emissions have grown by 15.8 percent from 1990 to 2004, while the U.S. economy has grown by 51 percent over the same period.

The inventory contains estimates of carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), hydrofluorocarbons (HFC), perfluorocarbons (PFC) and sulfur hexafluoride (SF6) emissions. Overall, from 1990 to 2004, total emissions of CO2 increased by 20 percent, while CH4 and N2O emissions decreased by 10 percent and 2 percent, respectively. During the same period, aggregate weighted emissions of HFCs, PFCs and SF6 rose by 58 percent (see page 25 of the report for details). Despite being emitted in smaller quantities relative to the other principal greenhouse gases, emissions of HFCs, PFCs, and SF6 are significant because many of them have extremely high global warming potentials and, in the cases of PFCs and SF6, long atmospheric lifetimes, according to the report.

The inventory also includes estimates of carbon sequestration in U.S. forests. The technical approach used in this report to estimate emissions and sinks for greenhouse gases is consistent with the methodologies recommended by the Intergovernmental Panel on Climate Change (IPCC) and reported in a format consistent with the United Nations Framework Convention on Climate Change (UNFCCC) reporting guidelines, the agency stated.

A Federal Register notice announcing a 30-day public comment period on the report was published on Feb. 27 and can be accessed at http://www.epa.gov/fedrgstr/index.html.

The report is available at http://yosemite.epa.gov/oar/globalwarming.nsf/content/ResourceCenterPublicationsGHGEmissions.html.

This article originally appeared in the 02/01/2006 issue of Environmental Protection.

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