E.P.A. Sets Carbon Crackdown

The Environmental Protection Agency on Monday will complete its determination that greenhouse gases pose a danger to human health and the environment, paving the way for regulation of carbon dioxide emissions from vehicles, power plants, factories refineries and other major sources.

The agency finding also will allow Mr. Obama to tell delegates at the United Nations climate change conference that began today in Copenhagen that the United States is moving aggressively to address the problem.

The E.P.A. administrator, Lisa P. Jackson, is expected to announce the step at a news conference this afternoon in Washington.

The move gives President Obama a significant tool to combat the gases blamed for the heating of the planet even while Congress remains stalled on economy-wide global warming legislation.

The Obama administration has signaled its intent to issue a so-called endangerment finding for carbon dioxide and five other greenhouse gases since taking office in January. Ms. Jackson announced a proposed finding in April and has taken steps to implement the rules that would be needed to back it up.

The administration has wielded the finding as a prod to Congress to act on legislation, saying in effect that if lawmakers do not act to control greenhouse gas pollution they will use their rule-making power to do so. At the same time, the president and his top environmental aides have frequently said that they prefer such a major step be taken through the give-and-take of the legislative process.

The administration struck a deal with automakers in the spring to set stricter tailpipe emissions and higher fuel economy standards as part of the greenhouse gas regulation efforts. The E.P.A. has also announced rules requiring all major emitters to report an annual inventory of emissions.

In late September, the agency announced a proposed “tailoring rule,” that limits regulation of climate-altering gases to large stationary sources such as coal-burning power plants and cements kilns that produce 25,000 or more tons a year of carbon emissions.

Industry groups and the United States Chamber of Commerce have objected to the proposed regulations, saying they would damage the economy and drive jobs overseas. Some groups are likely to file lawsuits challenging the new regulations, which could delay their effective date for years.

Thomas J. Donohue, the president of the Chamber of Commerce, said that the endangerment finding “could result in a top-down command-and-control regime that will choke off growth by adding new mandates to virtually every major construction and renovation project.” He said that his group supports “rational” federal legislation and an international agreement to control global carbon emissions.

“The devil will be in the details, and we look forward to working with the government to ensure we don’t stifle our economic recovery,” Mr. Donohue said.