The Obama administration announced plans Monday to cut harmful emissions at existing power plant by 30 percent on 2005 figures, a significant move against climate change that may nonetheless disappoint some environmentalists and be bitterly fought by business interests.

The new rule on carbon dioxide emissions, which is set to finalized next year after an extended comment period, is intended to form the centerpiece of President Barack Obama's plans to reduce pollution linked to global warming.

Announcing the plan, Environmental Protection Agency (EPA) administrator Gina McCarthy, said the cuts would “clean the air we breathe while helping slow climate change.”

She added that global warming, fueled by carbon pollution “supercharges risks to our health, our economy, and our way of life."

But even before being announced, the proposal came under attack from industry groups and Republican lawmakers, as well as some Democrats representing coal-heavy states like West Virginia. Meanwhile potential delays to when states will be required to put forward their individual plans, and a retrospective start date to the benchmark for cuts may disappoint environmentalists.

Details of the plan to counter climate change causing pollution — including the topline 30 percent cut by 2013 figure — are less restrictive than some had suggested.

By using the 2005 starting point, the EPA has made the target easier to hit, since emissions by 2013 were already more than 10 percent lower than eight years previous.

Additionally, the proposals allow for states to delay putting forward their plan to reach the goals.

Obama initially wanted plans to be submitted by mid-2016. But details of the proposal show that states could have until 2017 to submit a complete plan. If they join with other states, they could put it back further, to 2018.

That means the rules won't full take effect until long after Obama leaves office. The delay raises questions about the fate of the landmark rules in the event that Republicans form the next administration.

In addition, the statistical slight of hand — backdating the benchmark to 2005, when emissions were higher — may disappoint many green energy activists who had hoped that Obama might have gone further in what is being touted as a legacy issue for his presidency, and one he has repeatedly fell short on, in the opinion of some.

Nonetheless most welcomed Monday's announcement as a clear step in the right direction.

Greenpeace said it sent a “clear signal” to power firms that they need to move from outdated models that fuel global warming.

“The new rule shows that the Obama administration is serious about taking action on climate change, but the Administration could and should strengthen it considerably,” said Greenpeace director Gabe Wisniewski.

Likewise Amanda Starbuck, director of the Rainforest Action Network said the proposal does not go far enough.

"The proposed rule is not yet enough to slow global warming and not yet enough to inspire the world to make the necessary deep cuts in climate pollution,” she said.

McCarthy acknowledged that more needed to be done to reduce carbon emissions, but added that she is hopeful that the planned cut would have an effect.

"America has always turned small steps into giant leaps,” she said in a speech soon after the rule was released. "Given the astronomical price we pay for climate inaction, the most costly thing we can do is nothing."

Power plants are the largest source of greenhouse gases in the U.S., accounting for about a third of the annual emissions that make the U.S. the second largest contributor to global warming on the planet.

Despite concluding as far back as 2009 that greenhouse gases endanger human health and welfare — a finding that triggered their regulation under the 1970 Clean Air Act — it has taken years for the administration to take on the nation's fleet of power plants.

In December 2010, the Obama administration announced a "modest pace" for setting greenhouse gas standards for power plants, setting a May 2012 deadline.

Obama put them on the fast track last summer when he announced his climate action plan and a renewed commitment to climate change after the issue went dormant during his re-election campaign.

Yet the rule carries significant political and legal risks, by further diminishing coal's role in producing U.S. electricity and offering options for pollution reductions far afield from the power plant, such as increased efficiency. Once the dominant source of energy in the U.S., coal now supplies just under 40 percent of the nation's electricity, as it has been replaced by booming supplies of natural gas and renewable sources such as wind and solar. But others have predicted a boom in the renewables sector as a result of Monday’s announcement.

Senate Minority Leader Mitch McConnell, was among senior Republicans blasting the plan Monday. Casting it as “draconian”, he said it amounted to a “dagger in the heart of the American middle class.”

"The impact on individuals and families and entire regions of the country will be catastrophic, as a proud domestic industry is decimated,” he added.

House Speaker John Boehner, R-Ohio weighed in, saying, "The president's plan is nuts. There's really no more succinct way to describe it."

Meanwhile, the U.S. Chamber of Commerce suggested that the cuts would cost the U.S. economy more than $50 billion a year between now and 2030.

But an economic impact study by the EPA concluded that the health and environmental benefits of the plan outweighed costs anywhere from $8 to $1 to $12 to $1 over the same timeframe.

And Obama pre-empted and countered criticism of the rules in his weekly radio address on Saturday.

"Special interests and their allies in Congress will claim that these guidelines will kill jobs and crush the economy. Let's face it, that's what they always say," Obama said.

Sources briefed on the proposal were told that an economic impact study by the EPA concluded that the health and environmental benefits of the plan outweighed costs anywhere from $8 to $1 to $12 to $1 by 2030.

EPA data shows that the nation's power plants have reduced carbon dioxide emissions by nearly 13 percent since 2005, or about halfway to the goal the administration set Monday. The agency is aiming to have about 26 percent cut by 2020.