Fifteen states that have taken steps to reduce greenhouse gas emissions are seeking assurances that their efforts will be recognized when the U.S. Environmental Protection agency issues new rules governing pollution from power plants.

In a petition delivered to the EPA Monday, officials from states including California, New York and Colorado say they want to make sure the agency recognizes their efforts as it crafts the federal rules, set to be released in June. The rules could force companies such as Southern Co., American Electric Power Co. and Duke Energy Corp. to shutter or idle aging coal plants.

“Our states are already achieving significant carbon pollution reductions from the power sector and are demonstrating a variety of ways in which such reductions can be achieved,” officials from the states said in the letter. “We encourage EPA to develop a stringent but flexible framework that equitably achieves meaningful reductions in carbon.”

Carbon-dioxide emissions since the Industrial Revolution have led to a warming of the Earth’s temperature in the past 50 years, worsening forest fires, drought and coastal flooding, according to the U.S. Global Change Research Program.

President Barack Obama directed the EPA to cap carbon dioxide from power plants, which account for 40 percent of U.S. emissions, as part of the effort to reach his goal of cutting overall greenhouse-gas emissions 17 percent by 2020 from 2005 levels.

New Steps

Without additional actions, U.S. emissions will fall short of that goal, as the drop in coal use is accompanied by a drop in nuclear generation, which has zero carbon emissions, the Energy Information Administration said in a report Monday.

Obama’s first step to improve the outlook was to issue rules for new plants in September. More contentious rules for existing plants are scheduled to be announced in 2014.

In their filing, the 15 states said that by 2011, they had cut emissions 20 percent from 2005 levels.

“Our state programs are delivering major economic and health benefits by reducing carbon pollution and traditional pollutants while driving investments in energy efficiency and renewable energy,” the letter said.

The states called on the EPA to issue a cap that would cut power-plant emissions by more than 17 percent, because finding reductions elsewhere “will be more difficult to achieve.” The EPA should then give states “flexibility” to achieve that reduction and minimize cost and burden, the filing said.

The other states that filed the petition are Connecticut, Delaware, Illinois, Maine, Maryland, Massachusetts, Minnesota, New Hampshire, Oregon, Rhode Island, Vermont and Washington.

(Editors: David Ellis, Jon Morgan)