President-elect Trump announced today that he will nominate Oklahoma Attorney General Scott Pruitt to lead the Environmental Protection Agency. As Oklahoma’s AG, Mr. Pruitt has been a frequent opponent of EPA initiatives, joining Oklahoma in a lawsuit with numerous other states challenging the Administration’s Clean Power Plan. Widely regarded as an ally of the energy industry and a “climate change skeptic,” Mr. Pruitt has written that “scientists continue to disagree about the degree and extent of global warming and its connections to the actions of mankind.” The announcement of his nomination has triggered predictable praise from the fossil fuel industry and criticism from environmental groups. These voices aside, Mr. Pruitt’s leadership may mean big changes for the EPA, which the president-elect repeatedly criticized during the long election campaign.