Obama to unveil 'biggest step ever'

US President Barack Obama was to unveil yesterday what he called the "biggest, most important step we've ever taken" to fight climate change, a sensitive 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 existing power plants, setting limits on power-plant carbon emissions for the first time.

The revised Clean Power Plan will seek to slash carbon emissions from the power sector 32 percent from 2005 levels in 2030, a 9 percent increase over a previous proposal.

The regulation will usher in a sweeping transformation of the US electricity sector, encouraging an aggressive shift toward more renewable energy away from coal-fired electricity.

"My administration will release the final version of America's Clean Power Plan, the biggest, most important step we have ever taken to combat climate change," Obama said in a video posted by the White House Sunday at midnight.

The plan will be central to the United States' contribution to a United Nations agreement to tackle climate change, in which the Obama administration has vowed to play a leadership role.

Each state will be required to submit a plan to the Environmental Protection Agency next year, spelling out how it will meet an emission-cutting goal assigned to it.

Five governors who have opposed the rule have already said they will not comply.