Increase in US carbon dioxide emissions

After a few years of decline, U.S. energy-related emissions of carbon dioxide increased in 2013, according to a report published on Oct. 22 by the Energy Information Administration. The emissions increase of 129 million metric tons, or 2.5 percent, was the largest since 2010 and the fourth largest since 1990, the agency said. The agency has previously reported that the emissions peaked in 2007, with a sharp drop in 2009, in part attributable to the economic recession following the 2008 global financial crisis.

EIA said that the U.S. energy intensity, a measure of energy used per unit of economic activity, had been declining at a rate of 2 percent per year prior to 2013, but increased by 0.5 percent in 2013. That increase in energy intensity may reflect cold weather and the need for the increased heating of buildings. The increase added about 134 million metric tons of carbon dioxide to the atmosphere, compared with trends over the previous nine years, EIA said.

The carbon intensity, the amount of carbon emitted per unit of energy supplied, declined by 0.13 percent in 2013. But with this decline being lower than in the previous decade, emissions were above trend, EIA said. A drop in natural gas prices has tended to cause a shift in power generation from coal-fired generation to less carbon intensive natural gas generation. But, with higher gas prices in 2013, coal usage increased somewhat, EIA said. And, while U.S. population growth was relatively slow in 2013, a growth in per-capita economic output resulted in a rate of carbon dioxide emissions higher than average, EIA said.

- Alan Bailey