As directed by the US Supreme Court, EPA has prepared and sent to the White House for review a proposed finding as to whether man-made greenhouse-gas emissions endanger human health and welfare. If the proposal is issued, it will undergo public comment and public hearings before it becomes final. The document does not propose any requirements on any sources of greenhouse-gas emissions. The proposed finding does not impose any new regulatory burdens on any projects, let alone those funded under the American Relief and Recovery Act.

In April 2007, the Supreme Court concluded in Massachusetts v. EPA that greenhouse gases (GHGs) meet the Clean Air Act (CAA) definition of “air pollutant,” and that section 202(a)(1) of the CAA therefore authorizes regulation of GHGs subject to an Agency determination that GHG emissions from new motor vehicles cause or contribute to air pollution that may reasonably be anticipated to endanger public health or welfare.

The Court also ruled that in deciding whether to grant or deny a pending rulemaking petition regarding section 202(a)(1), EPA must decide whether new motor vehicle GHG emissions meet that endangerment test, or explain why scientific uncertainty is so profound that it prevents making a reasoned judgment on such a determination.

Should EPA find that new motor vehicle GHG emissions meet the endangerment test, section 202(a)(1) of the CAA requires the Agency to set motor vehicle standards applicable to emissions of GHGs.

Early in 2008, senior EPA officials told the House Committee on Oversight and Government Reform that, after the agency concluded in December 2007 that CO₂ emissions were a danger to the United States and proposed significant cuts in motor vehicle emissions, the agency’s regulatory efforts on this were halted. The Committee began an investigation. (Earlier post.)

In an Advanced Notice of Public Rulemaking (ANPR) subsequently issued in July 2008 (earlier post), the EPA noted that:

EPA is also faced with the broader ramifications of any regulation of motor vehicle GHG emissions under the CAA in response to the Supreme Court’s decision. Over the past several months, EPA has received seven petitions from states, localities, and environmental groups to set emission standards under Title II of Act for other types of mobile sources, including nonroad vehicles such as construction and farm equipment, ships and aircraft. The Agency has also received public comments seeking the addition of GHGs to the pollutants covered by the new source performance standard (NSPS) for several industrial sectors under section 111 of the CAA. In addition, legal challenges have been brought seeking controls for GHG emissions in preconstruction permits for several coal-fired power plants.

The interrelationship of CAA authorities and the broad array of pending and potential CAA actions concerning GHGs make it prudent to thoroughly consider how the various CAA authorities would or could work together if GHG controls were established under any provision of the Act. Since regulation of one source of GHG emissions would or could lead to regulation of other sources of GHG emissions, the Agency should be prepared to manage the consequences of CAA regulation of GHGs in the most effective and efficient manner possible under the Act.

The ANPR released for comment in July 2008 presented the endangerment analysis essentially as a work in progress; no public action was taken subsequent to that by the Bush Administration in the run-up to the November 2008 election.