WASHINGTON -- The Obama administration today will announce one of the strongest actions ever taken by the U.S. government to fight climate change, a proposed Environmental Protection Agency regulation to cut carbon pollution from the nation's power plants 30 percent from 2005 levels by 2030, according to people briefed on the plan.
The regulation takes aim at the largest source of carbon pollution in the United States, the nation's more than 600 coal-fired power plants. If it withstands an expected onslaught of legal and legislative attacks, experts say that it could shutter hundreds of the plants and also lead, over the course of decades, to systemic changes in the American electricity industry, including transformations in how power is generated and used.
It is also likely to stand as President Barack Obama's last chance to substantially shape domestic policy and as a defining element of his legacy. The president, who failed to push a sweeping climate change bill through Congress in his first term, is now acting on his own by using his executive authority under the 1970 Clean Air Act to issue the regulation.
Under the rule, states will be given a wide menu of policy options to achieve the pollution cuts. Rather than immediately shutting down coal plants, states would be allowed to reduce emissions by making changes across their electricity systems -- by installing new wind and solar generation or energy-efficiency technology, and by starting or joining state and regional "cap and trade" programs, in which states agree to cap carbon pollution and buy and sell permits to pollute.
EPA officials have said they hope the flexible approach will allow states to comply with the regulation more easily and cost-effectively, by adopting policies best tailored to regional economies and energy mixes. But industry groups planning to sue to block or delay the rule have said that approach makes the rule more legally vulnerable.
Lawmakers in several states already are trying to blunt the impact on aging coal-fired power plants that feed electricity to millions of consumers.
Without waiting to see Mr. Obama's proposal, the governors of Kansas, Kentucky, Virginia and West Virginia signed laws directing their environmental agencies to develop their own carbon emission plans that consider the costs of compliance at individual power plants. Similar measures recently passed in Missouri and are pending in the Louisiana and Ohio legislatures.
Missouri lawmakers went even further in their defense of the coal industry. When activists proposed a ballot initiative barring local tax breaks for St. Louis-based Peabody Energy, state lawmakers quickly passed a measure banning such moves.
Eighty-three percent of Missouri's electricity comes from coal-fired power plants, the fifth-highest percentage nationally behind West Virginia, Kentucky, Wyoming and Indiana.
Federal emission regulations already allow flexibility for states if they can demonstrate costs would be unreasonable for particular facilities. But a spokesman for the EPA's Midwestern region, which oversees several states that rely predominantly on coal for their electricity, said he's unaware of that provision ever being used.
It's unlikely that the Obama administration would essentially undercut its new carbon emission standards by granting widespread exceptions, said Bill Becker, executive director of the National Association of Clean Air Agencies, which represents air pollution control agencies in 42 states and 116 metropolitan areas. If a state doesn't comply with EPA guidelines, the federal agency can create its own plan for the state.
"This is not a standard that a state then can willy-nilly ignore," Mr. Becker said. "It's going to have to achieve at least that standard or more. Period."
The details of the proposed regulation were first reported Sunday afternoon by The Wall Street Journal online.
Because burning coal is the largest source of the greenhouse gas emissions that scientists blame for trapping heat in the atmosphere and dangerously warming the planet, the rule is expected to have a powerful environmental impact. It comes on top of a regulation Mr. Obama issued in his first term that sharply increased the required fuel economy of vehicles, the second-largest source of carbon pollution in the United States.
Experts said that the new regulation would set the country on track to meet its target set forth in a U.N. accord in 2009, when Mr. Obama pledged that the United States would cut its greenhouse gas pollution 17 percent from 2005 levels by 2020, and 83 percent by 2050.
On Sunday, environmental advocates praised the proposed rule for its breadth and reach while the coal industry attacked it as a symbol of executive overreach that could wreak economic havoc. Republican campaigns plan to use the rule to attack incumbent Democrats in this fall's midterm elections.
"This momentous announcement raises the bar for controlling carbon emissions in the United States," said Andrew Steer, president of the World Resources Institute, a Washington research organization.
Scott Segal, a lawyer with the firm Bracewell & Giuliani, which represents coal companies and plans to sue over the rule, wrote in an email, "Clearly, it is designed to materially damage the ability of conventional energy sources to provide reliable and affordable power, which in turn can inflict serious damage on everything from household budgets to industrial jobs."
Associated Press contributed.