The United States on March 27 set the first national standards on carbon emissions from power plants, taking aim at the burning of coal, which is considered a top culprit in climate change.
After more than a year of deliberations on the politically charged proposal, President Barack Obama's administration said it would only apply the rules to future sites and paved the way for more coal-fired plants if they are upgraded.
Lisa Jackson, head of the Environmental Protection Agency, said she was approving the regulations in a hope to "enhance the lives of our children and our children's children" and to spur U.S. global leadership in clean energy.
"We know that the potential impact of climate change touches everything from tourism to agriculture and will have an extraordinary environmental and economic footprint if allowed to proceed unchecked," she told reporters on a conference call.
Jackson said that after a 12-year grace period for sites under construction, the agency would not allow power plants to emit more than 1,000 pounds of carbon pollution per megawatt hour.
Natural gas generates slightly less than that, but standard coal plants emit nearly 1,800 pounds an hour. Renewable energy such as solar and wind -- along with nuclear power -- produces far less.
Electricity generation in the world's largest economy emits 41 percent of the country's carbon emissions, which scientists blame for the planet's rising temperatures and increasingly severe weather.
The Obama administration has vowed to reduce U.S. carbon emissions, but its efforts face strong opposition from industry and the rival Republican Party, many of whose members question the science behind climate change.
Proposals by Obama's allies to set up a nationwide system to curb carbon emissions have died in Congress. UN-led negotiations on a new climate treaty have also made little concrete progress, with China -- which has surpassed the United States as the top carbon emitter -- demanding greater U.S. commitment.
Republicans have been sharply critical of the EPA since it first announced in December 2010 that it would move to regulate power plants, with some lawmakers seeking ways to strip its authority.
The Supreme Court ruled in 2007 that the agency holds the authority to regulate carbon dioxide and other greenhouse gases under existing legislation.
Coal is among the most politically sensitive areas due to its impact on domestic employment. Coal accounts for about half of U.S. power -- more than any other source -- but 81 percent of carbon emissions from the electricity sector, according to government data.
Jackson was quick to say that the Obama administration saw a future for coal, saying that it "will remain an important part of America's electricity generation mix."
She said that the agency will still allow new coal plants to maintain emissions above the limits if the operators agree that the level will average below the 1,000-pound threshold over a 30-year period.
The Obama administration has supported research in so-called carbon capture, which would hold back emissions from the burning of coal. Some environmentalists have criticized such efforts as costly but unproven.
Supporters of efforts to fight climate change largely welcomed the administration's new rules but said that regulations would eventually have to encompass existing plants.
"Existing plants represent a significant opportunity to improve efficiency and reduce U.S. greenhouse gas emissions," said Kevin Kennedy, U.S. climate director at the World Resources Institute.
Copyright Agence France-Presse, 2012
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