Cars, power plants and factories could all soon face much tougher pollution limits after a government declaration Friday setting the stage for the first federal regulation of gases blamed for global warming.
The Environmental Protection Agency took a big step in that direction, concluding that carbon dioxide and five other greenhouse gases are a major hazard to Americans' health. That was a reversal from the Bush administration, which resisted such a conclusion and said it would be costly for companies to meet new emission limits and therefore could harm the national economy.
"In both magnitude and probability, climate change is an enormous problem (and) the greenhouse gases that are responsible for it endanger public health and welfare," said the EPA, concluding the dangers warrant action under federal air pollution laws.
It was the first time the federal government had said it was ready to use the Clean Air Act to require power plants, cars and trucks to curtail their release of climate-changing pollution, especially carbon dioxide from the burning of fossil fuels.
The agency said the science pointing to man-made pollution as a cause of global warming is "compelling and overwhelming." It also said tailpipe emissions from motor vehicles contribute.
EPA Administrator Lisa Jackson cautioned that regulations are not imminent and made clear that the Obama administration would prefer that Congress address the climate issue through a broader "cap-and-trade" program that would limit heat-trapping pollution.
But she said it was clear from the EPA analysis "that greenhouse gas pollution is a serious problem now and for future generations" and steps are needed to curtail the impact.
Even if actual regulations are not imminent, the EPA action was seen as likely to encourage action on Capitol Hill.
It's "a wake-up call for Congress" -- deal with it directly through legislation or let the EPA regulate, said Sen. Barbara Boxer, D-Calif., who chairs the Senate committee dealing with climate legislation. If Congress doesn't move, Boxer said she would press EPA to taker swift action.
Rep. Ed Markey, D-Mass., whose House Energy and Commerce subcommittee hopes to craft legislation in the coming weeks, called the EPA action "a game changer."
"It now changes the playing field with respect to legislation. It's now no longer doing a bill or doing nothing. It is now a choice between regulation and legislation," said Markey.
Republicans and some centrist Democrats have been critical of proposed cap-and-trade climate legislation, arguing it would lead to much higher energy prices. Such a measure could impose an economy-wide limit on greenhouse gas emissions but let individual companies or plants trade emission allowances among each other to mitigate costs.
House Republican leader John Boehner of Ohio called EPA's move toward regulation "a backdoor attempt to enact a national energy tax that will have a crushing impact on consumers, jobs and our economy."
But environmentalists called the EPA action a watershed in addressing climate change.
"It's momentous. This has enormous legal significance. It is the first time the federal government has said officially the science is real, the danger is real and in this case that pollution from cars contributes to it," said David Doniger, climate policy director for the Natural Resources Defense Council, an advocacy group.
Reaction from energy intensive industries was quick and critical.
"The proposed endangerment finding poses an endangerment to the American economy and every American family," declared Jack Gerard, president of the American Petroleum Institute.
A spokesman for the Edison Electric Institute, Dan Riedinger, said under the EPA approach "the process won't be pretty ... fraught with uncertainty." The group, which represents investor-owned electric utilities, prefers action by Congress rather than federal regulators.
The Bush administration strongly opposed using the Clean Air Act to address climate change and stalled on producing the so-called "endangerment finding" that had been ordered by the Supreme Court two years ago when it declared greenhouse gases pollutants under the Clean Air Act.
The court case, brought by Massachusetts, focused only on emissions from automobiles. But it is widely assumed that if the EPA must regulate emissions from cars and trucks, it will have no choice but to control similar pollution from power plants and industrial sources.
The EPA wants to unleash a "regulatory barrage that will destroy jobs, raise energy prices for consumers, and undermine America's global competitiveness," complained Sen. James Inhofe, R-Okla., one of Congress' most vocal skeptics of global warming.
In addition to carbon dioxide, a product of burning fossil fuels, the EPA finding covers five other emissions that scientists believe are warming the earth when they concentrate in the atmosphere: Methane (CH4), nitrous oxide (N2O), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6).