Obama to unveil 'biggest step ever' in climate fight

Washington - President Barack Obama will on Monday unveil what he called the "biggest, more important step we've ever taken" to fight climate change, an issue central to his legacy.

The White House will release the final version of America's Clean Power Plan, a set of environmental rules and regulations that will home in on the pollution from the nation's power plants, according to a video released early on Sunday.

"Power plants are the single biggest source of harmful carbon pollution that contributes to climate change," Obama said in the video.

"But until now there have been no federal limits to the amount of that pollution that those plants can dump into the air."