The Obama administration will propose sweeping new environmental rules on Monday, cutting carbon pollution from existing power plants by 30% over 2005 levels by 2030, according to people briefed on the plan.
The new power plant rules – which will be formally announced by the Environmental Protection Agency on Monday morning – represent the most ambitious effort by Barack Obama or any other president to deal with climate change.
The regulations could lead to a sweeping transformation of America's energy economy, if they survive an onslaught from business and conservative groups, and Republicans in Congress.
The rules could also break open negotiations for a global climate change deal, the United Nations climate chief, Christiana Figueres, said.
The 30% target, first reported by the Wall Street Journal, represents the first attempt by any president to regulate carbon pollution from power plants.
Obama had initially sought to deal with climate change through Congress. But after that effort collapse, and with Republicans in Congress uniformly opposed to cutting carbon emissions – or even denying climate change was occuring – Obama decided last year to use his executive authority to cut carbon pollution.
The White House and the EPA would not comment on the report.
Power plants are the largest single source of carbon pollution, accounting for nearly 40% of the emissions that cause climate change.
Obama, in his weekly radio address on Saturday, said it was past time to set national limits on carbon dioxide emissions – just as the EPA has done for years with arsenic, mercury and other toxins.
“Right now there are no national limits to the amount of carbon pollution that existing plants can pump into the air we breathe. None,” he said. “They can dump unlimited amounts of carbon pollution into the air. It's not smart, it's not safe, and it doesn't make sense.”
Carbon dioxide emissions from power plants had been falling since 2005, because of the economic downturn and because of the switch from coal to cheaper natural gas.
Ethan Zindler of Bloomberg New Energy Finance said the power industry was already about a third of the way towards the 30% goal.
But emissions crept up last year and again in the first months of 2014, and the regulations would put America on course for long term and lasting cuts to carbon pollution.
Andrew Steer, the chief executive of the World Resources Institute, said it was a “momentous development” for America's efforts to deal with climate change.
“It's the most important action available to cut US emissions – and the Obama administration has seized the opportunity,” he said. “These new standards send a powerful message around the world that it's time to face the global threat of climate change.”
The rules could affect some 1,600 power plants. About 600 of these operate on coal, including many that are nearly 50 years old and will have the most difficulty meeting the new standards.
Under the rule, states and power companies will have a range of options to meet the new standards: switching from coal to cleaner-burning natural gas; forming cap-and-trade markets; expanding renewables such as wind and solar power; or encouraging customers to use less energy by moving to more efficient heating and cooling systems and appliances.
That's a departure for the EPA, which generally has focused on curbing emissions from specific smoke stacks.
But the Natural Resources Defense Council, which produced models that helped guide the EPA, said a system-wide approach would make it easier and cheaper for power companies to reach the new standard.
The 30% national target will not be applied uniformly across the country. The EPA will set individual reductions targets for each state, taking into account their energy mix, according to those briefed on the plan.
States have until 2016 to come up with a strategy for meeting the targets. However, the EPA rules will not come into force in all states until 2020, according to one individual briefed on the plan.
“They are not going to spread it out smoothly all over the place like creamy peanut butter,” said Vicky Arroyo, who heads the climate centre at the George University law school. “It's going to be more lumpy than that. Some states will have less ambitious targets, and some states will have more.”
The idea is to take account of the available energy sources in each state, as well as the measures some states have already undertaken to cut carbon pollution. North-eastern states have already cut their power plant emissions by 40% compared with 2005.
Arroyo said it was possible the rule could bring about the same level of reductions in carbon pollution as a climate change bill that was defeated by Congress five years ago.
The new EPA rule bypasses Congress, relying on Obama's executive authority and Supreme Court decisions, to propose new rules under the Clean Air Act.
The Chamber of Commerce, the country's biggest business lobby, said last week the new rules would cost the economy $51bn and put 224,000 people out of work.
Coal-mining companies, some power companies and Republican state officials have accused the EPA of overstepping its authority, and will be studying the bill closely for possible legal challenges.
In their rebuttal to Obama's radio address, the Republicans said the new standards would "kill coal" and lead to power outages.
"We'll all be paying a lot more money for electricity – if we can get it," said Wyoming senator Mike Enzi.
But Obama has been marshalling his own supporters. Environmental and public health groups have been pushing hard for the new rules.
Researchers from Harvard and Syracuse universities put out a study last week saying that curbs on carbon pollution would also reduce smog and soot, avoiding premature deaths from heart attacks and lung disease.
That campaign effort is due to pick up again on Monday. Obama is scheduled to hold a conference call with the American Lung Association and other public health groups on Monday afternoon.
White House officials spent Sunday briefing governors and business leaders about the new rule.
