A federal proposal to cut carbon pollution from existing power plants is being welcomed by Georgia climate scientists and environmental groups but rejected by Georgia Power and its regulators at the Georgia Public Service Commission. The U.S. Environmental Protection Agency on Monday released its Clean Power Plan proposal, which sets a target for Georgia to reduce its carbon emission rate from its 2012 level of 1,500 pounds per megawatt hour to 834 pounds per megawatt hour by 2030. Nationwide, the proposal seeks to reduce carbon emissions from power plants by almost a third from their 2005 levels by 2030, a goal made less daunting by the fact that levels are already 13 percent below where they were nearly a decade ago.