On Tuesday, the U.S. Environmental Protection Agency (“EPA”) granted a petition from the Sierra Club and others to reconsider former EPA Administrator Stephen Johnson’s December 18, 2008 memorandum interpreting the federal Clean Air Act as not requiring regulation of carbon dioxide emissions from new coal-fired power plants. The reconsideration comes as no surprise in light of recently confirmed EPA Administrator Lisa Jackson’s calls for immediate steps towards what she describes as a carbon-constrained future.

Johnson’s 2008 memo followed a November 13, 2008 decision by EPA’s Environmental Appeals Board that the statutory provision defining the scope of the Clean Air Act’s Prevention of Significant Deterioration (“PSD”) program was ambiguous and encouraged the EPA to further explain why the program did not apply to carbon dioxide. Under Title I, Part C of the Clean Air Act, the PSD program requires new or modified major stationary sources of regulated air pollutants located in certain areas to obtain preconstruction permits. The PSD program also requires newly constructed or modified major sources of one or more “regulated NSR pollutants” to install best available control technology. In his memo, Johnson clarified the scope of the PSD program by interpreting “regulated NSR pollutants” to exclude pollutants for which EPA regulations require only monitoring or reporting, including carbon dioxide. Industry groups praised Johnson’s memo as precluding widespread regulation of even small sources of greenhouse gases, such as hospitals and schools. Environmental groups, however, claimed that the memo unlawfully tried to establish a new, binding interpretation of the Clean Air Act.

The Sierra Club and others in January sued the EPA in the U.S. Circuit Court of Appeals for the District of Columbia Circuit, asking the court to overturn the Johnson memo. On Tuesday’s deadline for Petitioners to file a motion to stay the memo, the EPA granted reconsideration but declined to grant a stay while reconsideration was ongoing. The agency cautioned that “permitting authorities should not assume that the memorandum is the final word on the appropriate interpretation of Clean Air Act requirements.” It said it will soon publish a notice of proposed rulemaking in the Federal Register.

Comments by Administrator Jackson suggest that the EPA is steadily moving toward regulation of greenhouse gases under the Clean Air Act and reconsideration of the Johnson memo is a step towards such regulation. “It is clear that the Clean Air Act has a mechanism in it for other pollutants to be addressed,” she said. EPA additionally promised this week to re-address the issue of coal ash regulation as a solid or hazardous waste and to reach a decision by the end of the year. President Obama likewise immediately indicated a shift in federal policy towards additional regulation of greenhouse gases when, during his first week in office, he directed the EPA to review a decision by the Bush administration denying states the right to independently regulate greenhouse gas emissions from automobiles. The Administration’s actions come amidst increasing international pressure to take action on global warming in advance of the world climate conference in Copenhagen later this year.