The EPA’s proposal is the first time the federal government is seeking to regulate carbon emissions blamed for climate change. It calls on states to craft their own plans to cut carbon dioxide by dispatching more natural gas power, expanding efficiency programs, boosting renewables and shutting down coal plants or making them more efficient.

In Missouri, the EPA figured the state can cut carbon emissions 21 percent from 2012 levels by 2030. With the state’s reliance on carbon-heavy coal — 80 percent of Missouri’s electricity comes from it — the feds called for a smaller percentage cut than states less reliant on the black rock.

While Nixon didn’t dispute that the state could reach 21 percent reduction by 2030, the criticism of the interim targets was similar to the position taken by the state’s largest utility, Ameren Missouri.

Ameren has called for an implementation schedule that stretches to 2035 and warned the interim targets could require it to build a new natural gas plant just to meet the rules. Environmental groups argue the utility can meet the targets with a heavier emphasis on energy efficiency.