The US reduced its energy-related carbon dioxide (CO2) pollution by 3.8% in 2012, the second largest drop since 1990, according to the Department of Energy (DOE).
American cars and factories produced 5.83 billion t of CO2 in 2012, down from 6.06 billion t in 2011. The 3.8% downturn means that emissions are at their lowest level since 1994 and over 12% below the recent 2007 peak.
According to DOE economist Perry Lindstrom, the 2012 carbon pollution reduction is due to warm winter weather, more efficient cars due to new mileage requirements and an ongoing shift from coal-power to natural gas to produce electricity. In the past, some drops in carbon pollution have been due to economic factors, such as the 7.1% drop in 2009, during the American recession. However, while GDP increased by 2.8% in 2012, energy consumption fell by 2.4%, resulting in a 5.1% decline in energy use per dollar of GDP, resulting in a 282 million t reduction in CO2 emissions.
Half of the overall energy decline was from the residential sector, where a very warm first quarter of the year lowered energy demand and emissions. Residential sector electricity consumption was lower in 2012 than in 2011 and this also helped to lower emissions as electricity-related emissions have been the principle source of residential sector emissions since 1965.
After the residential sector, the next biggest decline in energy consumption was in the transportation sector, accounting for 22% of the total energy decline. Vehicle miles travelled in 2012 were flat compared to 2011, while more energy-efficient vehicles are continuing to enter the market.
Coal vs. natural gas
In 1994, coal provided 52% of US power, and this has fallen to 37%. The increase in natural gas-fired generation 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%, due largely to the increase in the share of natural gas generation relative to coal generation.
"This latest drop in energy-related carbon emissions is reason for cautious optimism that we're already starting to move in the right direction," said Pennsylvania State University climate scientist Michael Mann. "But this alone will not lead us toward the dramatic carbon reductions necessary to avoid dangerous climate change."
In 2011, the world CO2 emissions increased by 3%, largely due to a considerable increase in production by China, the top carbon polluting country. The US is the second largest producer of carbon emissions in the world.
Adapted from press release by Katie Woodward
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