WASHINGTON — The Environmental Protection Agency unveiled a detailed proposal Wednesday for using the government's regulatory powers to curb greenhouse gas emissions -- reassuring foreign allies of the U.S. commitment to fight climate change and warning Congress that the administration will act on its own if lawmakers fail to address the issue.
The proposed regulations would apply to large-scale industrial sources of heat-trapping gases, including power plants, factories and refineries, but not to smaller sources such as new schools, as some critics of EPA action had feared.
The rules would force new or substantially modified industrial plants emitting at least 25,000 tons of greenhouse gases a year to employ "best available control technologies and energy-efficiency measures" to minimize emissions. That would cover the sources responsible for 70% of greenhouse gas emissions in the U.S., the EPA said -- primarily carbon dioxide created by burning fossil fuels.
The agency unveiled its proposal hours after Senate Democrats introduced their version of the global warming bill that passed the House in June, and as international climate negotiators gathered in Bangkok, Thailand, to prepare for global warming treaty talks in Copenhagen in December.
The EPA and Senate actions stoked optimism among environmentalists and others. Some had voiced concern that reaching agreement in Copenhagen could be difficult if the Senate failed to act, because other countries might conclude that the United States was not prepared to take the steps it has urged other developed nations to take.
Both the new Senate bill and the EPA's proposed regulations address that concern.
"We are not going to continue with business as usual while we wait for Congress to act," EPA Administrator Lisa Jackson told a climate conference in Los Angeles.
She said that the proposal "allows us to do what the Clean Air Act does best: Reduce emissions for better health, drive technology innovation for a better economy, and protect the environment for a better future, all without placing an undue burden on the businesses that make up the better part of our economy."
Senators also were aware of the global implications.
"We're geared to move this and hopefully get it to the floor before" the Copenhagen summit, said Sen. John F. Kerry (D-Mass.), who co-wrote the climate bill with Sen. Barbara Boxer (D-Calif.). "I think we're going to make it."
The EPA rules would mimic how the agency forces power plants and factories to install "scrubbers" and other means of limiting many types of air pollutants. But it's unclear exactly how it would apply to greenhouse gases, which scientists blame for climate change. Researchers are still investigating commercial-scale methods to capture and store carbon emissions from coal plants, for example.
The new proposal follows one announced by President Obama and automotive executives in May to regulate greenhouse gas emissions from cars and trucks. The automotive regulations, which would take effect in 2012, stemmed from a 2007 Supreme Court decision that carbon dioxide and other greenhouse gases are pollutants subject to regulation under the Clean Air Act.
Therefore, the EPA said, it was required to control greenhouse gases from industrial sources too. Industry groups disputed that logic.
The latest proposal must move through a lengthy process of comments and reviews, and will probably encounter legal challenges.
"The real question is whether this would stand up in court," said Jeffrey Holmstead, who headed the EPA air office under former President George W. Bush and now is a partner for the law and lobbying firm of Bracewell & Giuliani in Washington.
Politically, though, the Senate bill appears headed for the same challenges that nearly toppled the House climate bill -- GOP opposition and demands from the coal and petroleum industries.