On August 3, 2015, President Barack Obama announced in a White House ceremony the U. S. Environmental Protection Agency’s (EPA) Clean Power Plan (CPP) for reducing carbon dioxide (CO₂) emissions from the country’s stationary fossil-fuel power plants. In the United States, CO₂ represents 82 percent of all greenhouse-gas (GHG) emissions and power plants are the single largest source of CO₂ emissions. See also: Carbon dioxide; Greenhouse effect; Power plant

The CPP rule is the most important step, to date, by the United States to deal with climate change. “There is such a thing as being too late,” said Mr. Obama in regard to climate change. We have to do something about it, he said, and if we don’t get it right we may not be able to reverse it or adapt sufficiently. See also: Climate modification; Global climate change

The legal basis of the Plan was the 2007 U. S. Supreme Court decision that the EPA can regulate GHGs as pollutants under the Clean Air Act. In 2014, the Supreme Court narrowed the ruling to mean that only sources that are already regulated for other pollutants (such as sulfur dioxide and mercury) will have to control GHG emissions. This would include power plants but not landfills, which only emit GHGs, for example. See also: Air pollution

The 1560-page CPP rule is long in form but fairly uncomplicated in substance, as the Plan’s goal is to reduce “carbon pollution” from power plants 32 percent below 2005 levels by 2030; individual states will decide for themselves how to comply. In addition to curbing carbon pollution from power plants, state compliance may be attained by generating electricity from renewable sources (such as solar, wind, etc.) and by implementing energy-efficiency policies. States have until September 2016 to submit their plans to the EPA, with the compliance period beginning in 2022. See also: Electric power generation; Energy sources; Solar energy; Wind power

At the time of its announcement, critics of the Plan said that it would hurt the economy and increase the cost of electricity. Mr. Obama countered that the same was said in the past when the EPA limited the amount of nitrogen oxides and sulfur dioxide emitted into the atmosphere by power plants to reduce acid rain. The EPA said that the Plan will not affect energy affordability or availability. This view is supported by the Georgia Tech School of Public Policy report, Low-Carbon Electricity Pathways for the U.S. and the South: An Assessment of Costs and Options, which says that CPP compliance can be achieved cost effectively. See also: Acid rain

States that do not submit plans risk increased energy costs because the EPA will create a federal plan for them. Under the Clean Air Act, the EPA has the authority to restrict emissions from power plants but it cannot order states to set up renewable energy sources or energy-efficiency policies, two important parts of the Plan for keeping costs down.