U.S. Carbon Emissions Fall to an 18-Year Low – But Will Likely Rise Again

Warmer weather helped keep CO2 emissions down in 2012 According to a recent report by the Energy Information Administration (EIA), U.S. carbon emissions in 2012 were 3.8 percent lower than in 2011, representing the lowest level of energy-related carbon emissions since 1994. Unlike in 2009, when carbon emissions dropped due to the recession, the reduction in 2012 was paired with a 2.8 percent growth in GDP, making it the largest emissions drop in a year with positive GDP growth. Indeed, despite growth in population and per capita output, carbon and energy intensity fell.

The decline in carbon intensity is largely due to the increase in natural gas usage over coal to produce electricity, as burning natural gas releases less carbon.

The decline in electricity consumption brought additional reductions in total carbon output. Half of the overall decline in energy consumption came from the residential sector, and can largely be attributed to warmer weather in 2012. “By the end of March, cumulative heating degree days (HDD) were about 19 percent below the 10-year normal and 22 percent below 2011”. In other words, less space heating, which uses more energy than air-conditioning, was required. Another significant reduction in energy intensity came from the transportation sector, which accounted for 22 percent of the total decline in energy consumption. Vehicle miles traveled were 3.3 percent lower and fleet efficiency improved 16 percent in 2012 as compared to 2007.

When combined, decreased energy consumption, increased efficiency, and the use of natural gas instead of coal, led to an overall decline of carbon intensity of 6.5 percent. This is “the largest drop in the overall carbon intensity of the economy since records were kept beginning in 1949” according to the EIA.

Unfortunately, worldwide carbon emissions rose 1.4 percent in 2012, to an all-time record of 31.6 billion tons, according to the Paris-based International Energy Agency. Higher emissions in China, now the world's leading CO2 emitter, more than offset falls in Europe and the United States. In addition, despite the sharp decrease in 2012, evidence suggests U.S. carbon emissions will soon be back on the rise. According to preliminary data, "carbon-dioxide emissions for energy have already risen 2.6 percent in the first half of 2013." This is likely due to the rise in natural gas prices, which have allowed coal to regain some market share in electricity production.

Following the development of shale gas and continued improvements in efficiency, U.S. carbon emissions from energy are expected to remain below their 2005 level until 2040 at least. But in order to meet the White House's climate goal of a 17 percent cut in emissions by 2020, more will need to be done.

Author: Gabrielle Tilley

For more information:

• "U.S. Energy-Related Carbon Dioxide Emissions, 2012," U.S. Energy Information Administration
• "Warm winters, more efficient cars, less coal use combine for big drop in US carbon pollution," Star Tribune
• "U.S. Energy-Related Carbon Emissions Fall to 18-Year Low," National Geographic
• "U.S. carbon emissions fell sharply in 2012. But don’t expect that to last," Washington Post
• "Global carbon emissions hit record high in 2012," Reuters