US President Barack Obama has promised to outline his plan to deal with climate change in a speech at Georgetown University on Tuesday.
He said it would include measures to reduce carbon pollution and to lead global efforts to fight climate change.
Mr Obama has said repeatedly he would tackle climate change, but has been blocked by Congress.
He is believed to be planning to pass the new measures by executive action, meaning he will bypass Congress.
"There's no single step that can reverse the effects of climate change," he said in a video message.
"But when it comes to the world we leave our children, we owe it to them to do what we can."
He made similar points earlier this year at his inauguration and in his State of the Union address.
He returned to the theme in Berlin on Wednesday: "We know we have to do more, and we will do more."
Mr Obama also promised at the beginning of his first term in office in 2009 to provide global leadership on climate change.
But his attempts to introduce a cap-and-trade scheme to reduce carbon emissions were thwarted by his opponents in Congress.
Many Republicans argue that his attempts to tackle climate change are wasteful and give too much power to the state.
US media report that Mr Obama is now intending to introduce a series of executive actions, which can be put into effect by various federal agencies without Congress approval.
The measures reportedly will include tighter regulation of coal-fired power plants and making more land available for wind farms and other renewable energy projects.
White House energy and climate adviser Heather Zichal told a forum in Washington a few days ago "we are very much focused on the power plant piece of the equation".
She said the plan would also boost energy efficiency of appliances and buildings.
Mr Obama has come under pressure to cut emissions from power plants. from prominent figures in north-eastern states hit by Super storm Sandy in October 2012.