EPA sets new tack on climate change The agency found that greenhouse gases are a threat to public health because they cause global warming.

WASHINGTON — In a landmark move that countered eight years of inaction by the Bush administration, the Environmental Protection Agency determined yesterday that greenhouse gases threaten public health and welfare because they contribute to climate change.

The ruling set the stage for the agency to regulate emissions from a spectrum of sources, including automobiles, ships, airplanes, power plants, oil refineries, steel mills, and more.

Supporters and critics agreed that the finding was a game-changer with potentially profound consequences, though opponents warned that implementing new rules would have devastating impact on the economy.

The finding, which includes carbon dioxide and five other greenhouse gases, is subject to a period of public comment, after which the agency has no timetable and broad leeway in how to proceed.

"This finding confirms that greenhouse-gas pollution is a serious problem now and for future generations," EPA Administrator Lisa Jackson said yesterday.

She said the solution would "create millions of green jobs and end our country's dependence on foreign oil."

Environmentalists said the decision, though long overdue, was the only logical course of action the government could take.

" 'Duh' may not be a scientific term, but it applies here," said Emily Figdor, global-warming director of Environment America. "Today, common sense prevailed over pressure from big oil and other big polluters."

Sen. Tom Carper (D., Del.), chairman of the subcommittee on clean air and nuclear safety, said: "The science about global warming is clear. The need to act is urgent. This announcement is further proof that the Obama-Biden administration is serious about addressing global warming."

Opponents have said the finding will prompt an economic train wreck and a constitutional crisis.

Sen. James Inhofe (R, Okla.), the ranking Republican on the Environment and Public Works Committee and a leading skeptic on global warming, said the decision would "unleash a torrent of regulations that will destroy jobs, harm consumers, and extend the agency's reach into every corner of American life."

The petroleum industry called the action "the EPA's single largest and potentially most complex assertion of authority over the U.S. economy and Americans' lifestyle."

The manufacturing industry said the ruling would "burden an ailing economy while doing little or nothing to improve the environment."