The EPA said it found that "greenhouse gases in the atmosphere endanger the public health and welfare of current and future generations" as part of a scientific finding it was given the green light to pursue by President Barack Obama.

Regulation is not automatically triggered by the finding, the agency said, and there will be a 60-day public comment period.

But the ruling represents a major victory for environmentalists who had fought to have a 2007 US Supreme Court decision that the EPA rule on whether greenhouse gas emissions be considered a pollutant, and thus subject to regulation.

The EPA ruling also puts the United States on much firmer footing going into climate talks in Copenhagen in December, where it is hoped that a larger internationally binding replacements for the Kyoto protocol can be negotiated.

“It is obvious that carbon dioxide and other greenhouse gases threaten public health and welfare by triggering global warming, so the EPA finding simply confirms that the US is ‘back in reality,’” said Eivind Hoff, Director of Bellona Europa.

Bellona’s Hoff is working actively to establish an emissions cap for European Union nations. He says that an “emissions performance standard” (EPS) will be a golden effort for the climate battle since is will for all practical purposes impose CCS.

Now that the EPA has recognised greenhouse gasses as pollutants, it will be on the same page as many of its European Union counterparts at a time when many are looking to the United States to take a leading role.

"The Obama administration now has the legal equivalent of a .44 Magnum" to fight global warming, said Frank O’Donnell, president of the environmental group Clean Air Watch. "The bullets aren’t loaded yet, but they could be."

O’Donnell called the move "a landmark moment in environmental history."

The Bush Administration stalled the EPA in its efforts to make its court ordered determination. Obama’s EPA chief Lisa Jackson said in February that her agency would make a scientific determination on whether greenhouse gasses like carbon dioxide are pollutants.

Friday’s move by the EPA could trigger a series of federal regulations affecting polluters from vehicles to coal-fired power plants. It also marks a radical shift in the US Government’s position toward global warming.

The Bush administration opposed putting mandatory limits on carbon dioxide and other greenhouse gases, on the grounds that such limits would hurt business, and the EPA had resisted identifying such emissions as pollutants under the 1963 US Clean Air Act.

In a statement accompanying the release of its finding, the EPA declared that carbon dioxide and five other greenhouse gases endanger public health.

"In both magnitude and probability, climate change is an enormous problem," the agency said in it’s report. "The greenhouse gases that are responsible for it endanger public health and welfare within the meaning of the Clean Air Act."

In the EPA statement that accompanied the release of the finding, Jackson said that while global warming pollution is "a serious problem now and for future generations," the United States can combat it without making major economic sacrifices.

"This pollution problem has a solution – one that will create millions of green jobs and end our country’s dependence on foreign oil," Jackson said, according to the Washington

The finding includes a lengthy summation of scientific warnings about human contributions to climate change, and of the potentially devastating impacts that could result.

Although the next steps remain unclear, the EPA’s designation of greenhouse gasses as a pollutant means that either the agency or Congress will have to act soon.

“This is a big chance for congress to put forth a bill to introduce a quota system, but the question is when,” said Belllona USA Director Jonathan Temple. “The EPA’s finding can put extra wind in the sails of the representatives who support a quote system, but this will meet plenty of opposition, chiefly from the business sector.”

The Obama administration already is developing a plan to make the US auto fleet cleaner by regulating carbon dioxide emissions from tailpipes.

But the move Friday also gives the EPA the capacity to either regulate larger emissions producers such as power plants or prod Congress to set limits. The EPA was established in 1974 under President Richard Nixon and is part of the administration, not Congress.

“If I were the EPAs chief, I would put regulations in place immediately,” said Temple.

However, the Administration, many lawmakers and US industry, however, would prefer to see Congress act, administration officials told Bellona Web.

Congress therefore is likely to be the scene of a tough battle: Cap-and-trade legislation, which would limit emissions and allow emitters to trade pollution allowances, is fiercely opposed by a coalition of Republicans and Democrats from fossil-fuel-dependent Midwestern states who fear that such a system would raise energy prices and hurt the nation’s economy.

Yet, if Congress doesn’t act, the Obama administration is now within its rights to press ahead with at least some curbs on carbon dioxide and other pollutants blamed for global warming.

"It is now no longer a choice between doing a bill or doing nothing," Democratic Representative Edward Markey of Massachusetts, and co-author of the main House bill establishing federal limits on greenhouse gases, was quoted as saying by the Washington Post.

"It is now a choice between legislation and regulation. The EPA will have to act if Congress does not act."

Markey’s panel will begin hearings on climate legislation next week, and House Energy and Commerce Committee Chairman  Henry A. Waxman, a California Democrat, has pledged to pass the bill, which he co-authored with Markey, by May 25th.

Bellona’s Hoff, referring to the European experience, said, “In the past, we have dealt quite successfully with classic pollutants like sulphur dioxide or nitrogen oxides by setting regulatory ceilings for the concentrations of these gases in the flue gases,” adding that, “Given the scale and urgency of tackling climate change, why don’t we impose a similar ceiling for carbon dioxide – so as to rule out the dirtiest technologies such as coal-fired power plants without carbon dioxide capture and storage?”

California Representative Darell Issa, the top Republican on the House Committee on Oversight and Government Reform, opposed the EPA finding on his website.

"This administration is playing a game of chicken with Congress over regulations and our economy: Either pass legislation or force economically damaging new regulations on businesses," he said.

But even Issa has indicated he is behind the development of “zero emissions clean energy generation (…) which can meet our energy needs now and replace older and dirtier fossil fuel generation,” he said in remarks on his website.

White House spokesman Ben LaBolt, speaking  to the Washington Post, said that, “the president has made clear his strong preference that Congress act to pass comprehensive legislation."

But he went on to emphasise that the new scientific finding by the EPA may leave the regulatory agency little choice.

While the Senate has not released a timeline for passing a cap-and-trade bill, a senior Senate aide told the Washington post the Senate would move soon after the House began to act.

California Democratic Senator Barbara Boxer, who handles climate legislation as chair of the Environment and Public Works Committee was quoted as saying that, "If Congress does not act to pass legislation, then I will call on EPA to take all steps authorized by law to protect our families."

Ola Innset contributed to this report.