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Monday, February 25, 2013

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



James E. McCarthy
Specialist in Environmental Policy

Brent D. Yacobucci
Section Research Manager


On October 15, 2012, the Obama Administration took a major step toward reducing greenhouse gas (GHG) emissions from motor vehicles when it promulgated GHG emission standards for model year 2017-2025 light duty vehicles. Under the standards, GHG emissions from new cars and light trucks will be reduced about 50% by 2025 compared to 2010, and average fuel economy standards will rise to nearly 50 miles per gallon. EPA had previously set GHG emission standards for MY2012-2016 vehicles as well as for 2014-2018 model year medium- and heavy-duty trucks.

These steps have been taken as the Congress (particularly the House) and the Administration have reached an impasse over climate issues. The Administration has made clear that its preference would be for Congress to address the climate issue through new legislation. Nevertheless, in the wake of a 2007 Supreme Court decision, it has moved forward on several fronts to define how the Clean Air Act will be used and to promulgate regulations.

The key to using the CAA’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. EPA Administrator Jackson promulgated such an endangerment finding in December 2009. With the endangerment finding finalized, the agency has proceeded to regulate emissions from motor vehicles.

In all, EPA has received 12 petitions asking that it make endangerment findings and proceed to regulate emissions of greenhouse gases. Ten of the 12 petitions addressed mobile sources: besides motor vehicles, the petitions cover aircraft, ships, nonroad vehicles and engines, locomotives, and fuels, all of which are covered by Title II of the CAA. This report discusses the full range of EPA’s authority under Title II and provides information regarding other mobile sources that might be regulated under this authority, in addition to describing the car and truck regulations.

Regulation of GHGs from mobile sources has led 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 CAA, are addressed in CRS Report R41212, EPA Regulation of Greenhouse Gases: Congressional Responses and Options.


Date of Report: February 14, 2013
Number of Pages: 22
Order Number: R40506
Price: $29.95

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