Washington, D.C., USA (GLOBE-Net) – Greenhouse gas emissions in the United States rose by 0.8 percent from 2004 to 2005, as economic growth and hot summer weather offset a continuing shift towards a less carbon-intensive, service-based economy, according to the United States Environmental Protection Agency (EPA).

The EPA prepares an annual Inventory of Greenhouse Gas Emissions and Sinks to comply with existing commitments under the United Nations Framework Convention on Climate Change (UNFCCC), as do Canada and other parties to the agreement.

In 2005, total anthropogenic U.S. greenhouse gas emissions were 7,260.4 million metric tonnes of carbon dioxide equivalent (CO2e). (Emissions of methane, nitrous oxides and other greenhouse gases are benchmarked against CO2 according to their global warming potential, or ability to trap heat in the earth’s atmosphere.)

According to the EPA, the primary causes for increased emissions were strong economic growth leading to increased demand for electricity and an increase in the demand for electricity due to warmer summer conditions. These factors were moderated by decreasing demand for heating fuels due to warmer winter conditions and higher fuel prices.

Energy consumption, primarily the combustion of fossil fuels, accounted for 85 percent of total U.S. greenhouse gas (GHG) emissions in 2005. Approximately 86 percent of the energy consumed that year in the United States (on a Btu basis) was produced through the combustion of fossil fuels.

GHG emissions from fossil fuel consumption were also separated according to end-user sectors, revealing that transportation, industrial, residential and commercial were the largest consumers of electricity and energy, in that order.

CO2 represented approximately 83.9 percent of total greenhouse gas emissions, primarily from fossil fuel combustion. Methane emissions, which have steadily declined since 1990, resulted primarily from decomposition of wastes in landfills, natural gas systems, and enteric fermentation associated with domestic livestock. Agricultural soil management and mobile source fossil fuel combustion were the major sources of nitrous oxide emissions.

Electrical transmission and distribution systems accounted for most sulphur hexafluoride (SF6) emissions, while perfluorocarbons (PFCs) emissions resulted from semiconductor manufacturing and as a by-product of primary aluminum production.

Approximately 11.4% of total emissions in 2005 were ‘offset’ by carbon sequestration in forests, trees in urban areas, agricultural soils, and landfilled yard trimmings and food scraps. The ability of such changes to offset GHG emissions by increasing natural carbon storage is calculated according to methodology set forth by the UNFCCC.

Since 1990, U.S. GHG emissions have risen by 16.3 percent since 1990. The economy, as measured by Gross Domestic Product (GDP), has grown by 55% over that period. As a result, the ‘emissions intensity’ of the U.S. economy has decreased over time, despite the gross rise in GHG output.

One of the reasons for the decrease in intensity is a general shift from a manufacturing-based economy to a service-based economy, as well as overall increases in energy efficiency.

Canada’s GHG inventory for 2005 has yet to be released. In 2004, total domestic GHG emissions were 758 million tonnes, 26.6 percent above 1990 levels and 34.6 percent above the country’s Kyoto Protocol target.

On a per capita basis, Canada is one of the world’s highest per capita emitters, behind only Australia and slightly higher than the United States, producing approximately 2% of global greenhouse gases with only 0.5% of the world’s population.

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For More Information: Environmental Protection Agency - US