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Basic Information
Greenhouse Gas Emissions from Transportation
Transportation sources accounted for 29 percent of total U.S. greenhouse gas (GHG) emissions in 2006. Transportation is the fastest-growing source of GHGs in the U.S., accounting for 47 percent of the net increase in total U.S. emissions since 1990. Transportation is also the largest end-use source of CO2, which is the most prevalent greenhouse gas. These estimates of transportation GHGs do not include emissions from additional lifecycle processes, such as the extraction and refining of fuel and the manufacture of vehicles, which are also a significant source of domestic and international GHG emissions.
NOTE: You will need Adobe Acrobat Reader, available as a free download, to view some of the files on this page. See EPA's PDF page to learn more about PDF, and for a link to the free Acrobat Reader.
For more information on GHG emissions from the transportation sector, including how emissions are measured, recent inventories, and emissions trends, see Greenhouse-Gas Emissions from the U.S. Transportation Sector: 1990-2003
- Executive Summary
- Full report (PDF) (68 pp, 1.2MB, EPA420-R-06-003, March 2006)
Research and Partnerships
EPA promotes strategies to reduce transportation GHG emissions and save fuel. These strategies include EPA's Clean Automotive Technology research and a range of partnerships to encourage efficient freight transport and alternatives to single-occupancy travel, including EPA’s SmartWay Transport Partnership. EPA’s Green Vehicle Guide helps consumers do their part to reduce greenhouse-gas emissions by providing information to help in picking the cleanest, most fuel-efficient vehicle that meets their needs.
Regulations
In June 2008, EPA signed an Advance Notice of Proposed Rulemaking for the regulation of greenhouse gases. For more about those regulations, see EPA's Climate Change regulations page.
The California Air Resources Board in December 2005 requested a waiver of pre-emption for its greenhouse gas regulations for certain new motor vehicles beginning with Model Year 2009. See California’s request for a waiver, the letter to Governor Schwarzenegger from EPA, EPA’s Federal Register Notice Denying California’s request for a waiver, and other information on the California greenhouse-gas waiver page.