Greenhouse-gas emissions have dropped dramatically in the United States since 2005, and the nation now appears on track to achieve the 17 percent reduction sought by President Obama by 2020, thanks to a trend toward increased fuel efficiency for vehicles and a switch by power companies from coal to cleaner-burning natural gas made possible by the shale gas revolution.
The conservation trend, which began before Mr. Obama took office in response to $4 a gallon gasoline prices, accelerated as a result of the stringent environmental regulations the administration imposed on power plants, cars and trucks in Mr. Obama's first term, and is likely to gain further momentum as Mr. Obama ratchets up environmental mandates in his second term, climate activists say.
While the U.S. was once vilified by other nations as the world's biggest source of greenhouse-gas emissions, those days are over, with U.S. emissions falling by 10 percent in the past seven years. At a United Nations conference on climate change in Doha, Qatar, late last year, the United States was the star performer, having achieved a bigger emissions drop than most European and developing-world countries at the event, participants said.
China came more sharply into focus as the biggest and fastest-growing source of emissions as it relies increasingly on coal -- the biggest source of CO2 emissions -- to generate electricity.
"The U.S. was in a much stronger position going into the Doha talks, despite the failure of Congress to pass comprehensive climate legislation" during Mr. Obama's first term, because market and regulatory pressures were already reducing emissions, said Trevor Houser, a former U.S. climate negotiator who attended the Doha talks. "For countries like China that were able to hide behind a perception of U.S. inaction, the fact that U.S. emissions are falling helps increase pressure. It takes away the excuse that action is stalled because of the U.S."
A combination of Factors
While idled workers and plants during the Great Recession account for some of the decline in U.S. emissions since 2005, analysts think that trends toward increased conservation and cleaner energy sources are well-established and will continue for years even as the economy picks up.
The trends are the result of a combination of factors, including high gasoline prices since the late-2000s, which have prompted Americans to buy more fuel-efficient cars and use their cars less, along with increasingly strict fuel-economy regulations, which started with the government takeover of General Motors and Chrysler in 2009. Those regulations will double the fuel efficiency of cars to more than 54.5 miles per gallon on average by 2025.
Add to that an unexpected boost from the shale revolution, which is unlocking huge volumes of inexpensive natural gas and making that an irresistible alternative for power plants that are under the gun from the administration to cut their use of coal. About half of the nation's power previously was generated by coal, but new regulations raising standards for new power plants have pushed many utilities to build new gas-fired plants or consider renewables such as wind while retiring an army of coal-fired plants that are more than a half-century old.
In addition to regulations limiting carbon-dioxide emissions from new power plants, the old coal-fired plants have been targeted for extinction by a raft of other environmental rules restricting mercury, lead, ozone and other pollutants, what critics have dubbed a "war on coal." As a result, U.S. power generators plan to retire 170 coal-fired plants by 2020, according to SNL Energy research.
