U.S. carbon emissions hit lowest level since 1994

Wendy Koch

USA TODAY

Water vapor streams away from a coal fire electric plant over the ice-covered St. Croix River as seen from the interstate bridge separating Wisconsin and Minnesota at Hudson, Wis., on Jan. 9, 2010.

U.S. carbon dioxide emissions continue their downward trend since peaking in 2007
Decline due to greater efficiency%2C warmer weather%2C switch from coal to gas
Global emissions%2C however%2C continue to rise because of China and India%27s fuel use

In a bit of encouraging climate news, the U.S. government reported Monday that U.S. emissions of heat-trapping greenhouse gases from the burning of fossil fuels were lower last year than at any time since 1994.

Driven by efficiency gains, an unusually warm winter and a switch from coal to natural gas, energy-related carbon dioxide emissions actually declined 3.8% in 2012 even though the U.S. economy grew 2.8% that year, according to new data by the U.S. Energy Information Administration, the statistical arm of the Department of Energy.

This emissions decline was the largest in any year that had positive growth in per capita gross domestic product (GDP) — its economic output — and the only drop when GDP rose at least 2%. It reflects a generally downward U.S. trend, in which the nation's CO2 emissions have fallen five out of the last seven years — and are now 12% below the 2007 peak.

Worldwide, the concentration of heat-trapping carbon dioxide in the atmosphere -- a key driver of global warming -- has risen from about 315 parts per million in 1960 to 393 ppm last month, according to the Scripps Institution of Oceanography, a private research center based in LaJolla, Calif.

Despite U.S. progress, global emissions continue to rise as major developing countries including China and India use more oil and coal to fuel their economic growth. Worldwide, the concentration of CO2 in the atmosphere — a major cause of global warming — has risen from about 315 parts per million (ppm) in 1960 to 393 last month, according to the Scripps Institution of Oceanography, a private research center based in LaJolla, Calif.

In the United States, though, only the recession year of 2009 had a larger emissions decline than 2012. The EIA reports that energy consumption fell 2.4% last year, helped partly by a very warm first quarter that lowered heating demand, while energy intensity (energy use per dollar of GDP) rose 5.1%, spurred partly by more fuel-efficient vehicles. It also attributed the emissions decline to a greater substitution in power generation from coal to natural gas, which emits much less carbon dioxide, and greater use of renewable energy such as solar and wind.

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