Energy-related carbon dioxide (CO2) emissions in 2012 were the lowest in the United States since 1994, and are continuing to decline according to the U.S. Energy Information Administration. After 1990, only the recession year of 2009 saw a larger percentage emissions decrease than 2012.
A large drop in energy intensity (energy measured in Btu per dollar of gross domestic product [GDP] ) assisted the 2012 decline in energy-related carbon dioxide emissions despite economic growth.
- Although GDP increased by 2.8 percent in 20121, energy consumption fell by 2.4 percent (2.4 quadrillion Btu) in that same year—the result was a 5.1 percent decline in energy use per dollar of GDP and this meant emissions were about 282 million metric tons CO2 (MMTCO2) lower.
- The decline in carbon intensity reduced emissions by about 75 MMTCO2.
- With population growth of about 0.7 percent, per capita output rose by about 2 percent in 2012. The emissions decline was the largest in a year with positive growth in per capita output and the only year to show a decline where per capita output increased 2 percent or more. However, emissions would have increased by about 143 MMTCO2 if the energy and carbon intensities had not decreased at the rates they did.
Percent changes in emissions drivers that led to a decline in energy-related carbon dioxide in 2012. (Credit: U.S. Energy Information Administration)
The combined reduction in energy use per dollar of GDP and the carbon intensity of the energy supply meant that the overall carbon intensity of the economy (carbon dioxide per GDP) declined 6.5 percent in 2012.
- The largest drop in the overall carbon intensity of the economy since records were kept beginning in 1949. Only two other years, 1952 and 1981 had declines greater than 5 percent.
- There was decreased consumption of heating fuels because of a warm first quarter in 2012.
- Natural gas competed favorably with coal, and electric power producers consumed (dispatched) the lower-priced natural gas in place of coal, which has higher carbon content than natural gas.
Carbon intensity of the U.S. economy, 1949-2012. (Credit: U.S. Energy Information Administration)
Because the generation of electricity, which is widely used in all sectors except transportation, is an important source of emissions, declines in the carbon intensity of electricity generation lowers emissions throughout the economy.
- The increase in natural gas-fired generation, while coal-fired generation decreased, substantially reduced the carbon intensity of electricity generation in 2012.
- While there was an increase in wind generation, hydropower generation declined from 2011 by over twice the increase in wind generation.
- Despite the overall decline in renewables, the carbon intensity of power generation still fell by 3.5 percent, due largely to the transition from coal to natural gas.
Annual change in generation by fuel type in 2012. (Credit: U.S. Energy Information Administration)