Cars, Trucks, and Climate: EPA Regulation of Greenhouse Gases from Mobile Sources

James E. McCarthy
Specialist in Environmental Policy

As Congress and the Administration consider new legislation to reduce the greenhouse gas (GHG) emissions that contribute to climate change, the Environmental Protection Agency has simultaneously begun to exercise its existing authority under the Clean Air Act to set standards for GHG emissions. The Administration has made clear that its preference would be for Congress to address the climate issue through new legislation. Nevertheless, it is moving forward on several fronts to define how the Clean Air Act will be used and to promulgate regulations. 

On April 1, 2010, EPA used existing authority under Section 202 of the act to set the first national GHG emission standards: the standards will control emissions from new cars and light trucks beginning in model year 2012. The standards will require cars, SUVs, minivans, and other light trucks to meet combined emissions levels that the agency estimates will average 250 grams/mile of carbon dioxide (CO2) in model year 2016, about a 30% reduction in emissions compared to current levels. The standards will be gradually phased in, with the first reduction targets set for model year 2012. As part of an agreement brokered by the White House, EPA's standards were issued jointly with fuel economy (CAFE) standards developed by the National Highway Traffic Safety Administration, and the state of California agreed to harmonize state-level GHG emission standards, so that the auto industry would have a single national set of standards to meet. 

The key to using the Clean Air Act's authority to control greenhouse gases was for the EPA Administrator to find that GHG emissions are air pollutants that endanger public health or welfare. Administrator Jackson promulgated such an endangerment finding in December 2009. With the endangerment finding finalized, the agency can proceed to regulate emissions from motor vehicles of all kinds. Medium- and heavy-duty trucks are next in line: EPA expects to propose GHG emission standards for them in the summer of 2010. 

EPA has received 10 petitions asking that it make endangerment findings and proceed to regulate emissions of greenhouse gases. Nine of the 10 petitions address mobile sources: besides motor vehicles, the petitions cover aircraft, ships, nonroad vehicles and engines, and fuels, all of which are covered by Title II of the Clean Air Act. In addition to describing the motor vehicle regulations, this report discusses the range of EPA's authority under Title II and provides information regarding other mobile sources that might be regulated under this authority. 

Regulation of GHGs from mobile sources will lead the agency to establish controls for stationary sources, such as electric power plants, as well. Stationary source options, the authority for which comes from different parts of the Clean Air Act, are addressed in CRS Report R40585, Climate Change: Potential Regulation of Stationary Greenhouse Gas Sources Under the Clean Air Act and CRS Report R41212, EPA Regulation of Greenhouse Gases: Congressional Responses and Options. .


Date of Report: May 4, 2010
Number of Pages: 20
Order Number: R40506
Price: $29.95

Document available via e-mail as a pdf file or in paper form.
To order, e-mail Penny Hill Press or call us at 301-253-0881. Provide a Visa, MasterCard, American Express, or Discover card number, expiration date, and name on the card. Indicate whether you want e-mail or postal delivery. Phone orders are preferred and receive priority processing.