WASHINGTON (AP) - President Barack Obama is planning a major push against the pollution blamed for global warming in an effort to follow promises he made at the start of his second term.
"This is the global threat of our time," Mr Obama said in a speech on Wednesday in Berlin.
The plan is to use Mr Obama's executive powers - which don't require Congress approval - to expand renewable energy and boost the energy efficiency of appliances and buildings, said Mr Obama's senior energy and climate adviser, Heather Zichal.
She said the Environmental Protection Agency was preparing to use its authority under the Clean Air Act to regulate heat-trapping pollution from coal-fired power plants. Ms Zichal spoke at a forum in Washington.
The plan comes as Mr Obama has been under increasing pressure from environmental groups and lawmakers from Northeast states harmed by last year's Superstorm Sandy to cut pollution from existing power plants, the largest source of climate-altering gases.
Several major environmental groups and states have threatened to sue the administration to force cuts. And last week, former Vice President Al Gore, a prominent climate activist and fellow Democrat, called on Mr Obama to go beyond "great words" to "great actions."
It was unclear whether the White House plans would include controls on existing power plants. An administration official, who wasn't authorized to comment on the plan by name, said the White House was still weighing it. But since the administration has already proposed action on future power plants, the law likely would compel it to eventually tackle the remaining plants, or it would be forced to through litigation.
Mr Obama's remarks on Wednesday echoed comments he made in his State of the Union and inaugural speeches this year.
"For the sake of future generations, our generation must move toward a global compact to confront a changing climate before it is too late," Mr Obama said.
Some environmentalists urged the president to take action.
"President Obama deserves praise for including climate change among the long-term threats facing us all," said Ned Helme, president of the Center for Clear Air Policy, an environmentally friendly think tank.
"But he should do more than talk about the problem. The president needs to put the full force of his office behind new regulations that will truly curb greenhouse gas emissions."
One hot issue in among environmentalists is the proposed Keystone XL oil pipeline, which would carry oil extracted from tar sands in western Canada to refineries along the Texas Gulf Coast.
Canada's prime minister has pushed for the pipeline, but opponents call the US$7 billion (S$8.82 billion) project a "carbon bomb" that would carry "dirty oil" and exacerbate global warming.
The State Department, which must approve the project because it crosses an international border, has concluded in an environmental evaluation that other means of transporting the oil would be worse from a climate perspective.