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. March 13, 2014.

“By issuing endangerment findings similar to the one it issued for motor vehicles, EPA could move forward to control GHG emissions from other categories of mobile sources and/or their fuels. On the other hand, by focusing on the setting of emission standards for passenger cars, light duty trucks, and medium- and heavy-duty trucks, EPA will have addressed the categories responsible for more than three-fourths of all mobile source GHG emissions. The next largest category, aircraft, has rarely been the subject of EPA regulation unless the International Civil Aviation Organization (ICAO) has first agreed on standards. Other mobile source categories are less significant: each accounted for less than 1% of total U.S. emissions in 2007. Thus, besides strengthening its car and truck standards, EPA is expanding its focus to stationary sources. Stationary sources account for about 70% of the nation’s GHG emissions; within that group electric power plants account for about one-third of all U.S. GHG emissions, a higher percentage of the nation’s total than all mobile sources combined. New and modified power plants (as well as other major stationary sources) have been subject to permit requirements and the imposition of Best Available Control Technology for newly constructed facilities since January 2, 2011, under EPA’s interpretation of Section 165 of the Clean Air Act (CAA).”