US PRESIDENT Barack Obama unveiled a plan today to cut carbon dioxide emissions from power plants by nearly a third over the next 15 years.

But the path to implementation is unlikely to be smooth, given political and industrial opposition to his plan.

Under the presidential plan, carbon emissions would be reduced by 30 per cent by 2030, compared to 2005 levels, putting in motion one of the most significant actions ever on global warming.

All 50 US states will determine separately how to meet customised targets set by the Environmental Protection Agency, which has given them up to 2017 to submit plans.

This means that transformation will not begin in earnest until after Mr Obama’s second term in office ends, leaving open the possibility of his plan being further amended.

It has already drawn hostility from Republicans and even some Democrats facing difficult campaigns this year in energy-producing states.