The Environmental Protection Agency released its Clean Power Plan in August, designed to control carbon dioxide emissions from coal-fired power plants, which scientists say are a major contributor to climate change. Some utility companies and lawmakers from coal-producing states immediately condemned the plan — which aims to reduce power-sector carbon emissions by 32 percent from 2005 levels by 2030 — and are challenging it in court. The plan is part of U.S. preparations for a November international conference on climate change in Paris. In the run-up to the conference, the United States also has forged carbon-control agreements with China and Brazil. Questions remain, however, about China’s commitment to the agreement and what heavy polluters India and Russia will do to control carbon emissions. Pope Francis also has weighed in, calling climate change one of the principal challenges facing humanity.

President Obama announces a major anti-climate change plan on Aug. 3, 2015, aimed at reducing carbon dioxide emissions from the nation’s coal-fired power plants. Under the plan, states would have until 2030 to reduce carbon emissions from the electric power sector by 32 percent from 2005 levels. Opponents, including coal and some utility companies and lawmakers from coal-producing states, have vowed to wage a legal and political battle against the plan. (Getty Images/Mark Wilson)

In early August, the Environmental Protection Agency (EPA) unveiled the final version of the Obama administration’s Clean Power Plan, which will establish carbon dioxide (CO₂) emission limits for fossil fuel-fired power plants. When fully implemented, the limits will reduce emissions from the electricity sector by 32 percent from 2005 levels by 2030. 1 Under the plan, each state must devise by Sept. 6, 2016, a customized program for cutting CO₂ — one of the so-called greenhouse gases that scientists say contribute to climate change. 2 States can achieve this goal by phasing out older, high-polluting coal-fired power plants, adding renewable energy power sources or trading emission credits in carbon markets, a market-based solution some Chinese cities already are testing in pilot programs. 3

Supporters praised the plan’s flexibility. “It’s really historic. The U.S. is stepping up and providing states with a lot of flexibility as we start to accelerate toward the increased use of renewables,” says Rachel Cleetus, an economist and climate change policy expert at the Union of Concerned Scientists, a national environmental advocacy group.