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Greenhouse-Gas Emissions from Transportation and Other Mobile Sources
Basic Information
Based on current greenhouse-gas (GHG) emission reporting guidelines, the transportation sector directly accounted for about 27 percent of total U.S. GHG emissions in 2003. Transportation is the fastest-growing source of U.S. GHGs and the largest end-use source of CO2, which is the most prevalent greenhouse gas. Estimates of GHG emissions do not include additional "lifecycle" emissions related to transportation, 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.
EPA promotes strategies to reduce transportation greenhouse-gas emissions and save fuel. This effort includes EPA's Clean Automotive Technology research and a range of voluntary programs to encourage efficient freight transport and alternatives to single-occupancy travel. The 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.
The California Greenhouse-Gas Waiver
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.
Documents
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.
- Report: A Wedge Analysis of the U.S. Transportation Sector (PDF) (23 pp, 535K, EPA420-R-07-007, April 2007)
- Greenhouse-gas Emissions from the U.S. Transportation Sector:1990-2003 (EPA420-R-06-003, March 2006)
- Executive Summary
- Full report (PDF) (68 pp, 1.2MB)
- Fact Sheet: A Wedge Analysis of the U.S. Transportation Sector | PDF Version (6 pp, 1.6M, EPA420-F-07-049, October 2007)
- Fact Sheet: Emission Facts: Average Carbon Dioxide Emissions Resulting from Gasoline and Diesel Fuel | PDF Version (3 pp, 29K, EPA420-F-05-001, February 2005)
- Fact Sheet: Emission Facts: Metrics for Expressing greenhouse-gas Emissions: Carbon Equivalents and Carbon Dioxide Equivalents | PDF Version (3 pp, 35K, EPA420-F-05-002, February 2005)
- Fact Sheet: Emission Facts: Calculating Emissions of Greenhouse Gases: Key Facts and Figures | PDF Version (5 pp, 45K, EPA420-F-05-003, February 2005)
- Fact Sheet: Emission Facts: Greenhouse-gas Emissions from a Typical Passenger Vehicle | PDF Version (6 pp, 54K, EPA420-F-05-004, February 2005)
- Report: Update of Methane and Nitrous Oxide Emission Factors for On-Highway Vehicles (PDF) (39 pp, 683K, EPA420-P-04-016, November 2004)
- Report: Light-Duty Automotive Technology and Fuel Economy Trends: 1975 Through Present
- Report: Emissions of Nitrous Oxide from Highway Mobile Sources: Comments on the Draft Inventory of U.S. Greenhouse-gas Emissions and Sinks, 1990-1996 (March 1998) (PDF) (38 pp, 139K, EPA420-R-98-009, August 1998)
- Fact Sheet: Plug-In Hybrid Electric Vehicles | PDF Version (2 pp, 89K, EPA420-F-07-048, October 2007)
- Report: A Study of Potential Effectiveness of Carbon Dioxide Reducing Vehicle Technologies. This report, prepared for EPA by the engineering firm Ricardo under subcontract to Perrin Quarles Associates, Inc., provides a detailed assessment of the carbon dioxide emissions reduction potential of a large number of conventional vehicle technology packages. Also included is a peer review of the report, as well as a presentation given by EPA to the National Research Council's Committee on Fuel Economy of Light-duty Vehicles, which provides contextual background for this report.
- Full Report (PDF) (124 pp, 4.6M, EPA420-R-08-004, January 2008)
- Peer Review (PDF) (34 pp, 317K, EPA420-S-08-002, January 2008)
- Presentation to NRC Committee regarding the Report (PDF) (13 pp, 54K)
Related Links
Other EPA Links
- EPA Climate Change Web site
EPA's main Climate Change site presents accurate information on the very broad issue of climate change in a way that is accessible and meaningful to all parts of society – communities, individuals, business, public officials and governments. Topics covered include: why climate change is a problem; greenhouse-gas emissions; potential impacts; and actions being taken.
- Climate Protection Partnerships
Information on EPA's partnerships with businesses, organizations, governments, and consumers to reduce emissions of the greenhouse gases that contribute to global climate change by promoting greater use of energy efficient and other cost-effective technologies.
- EPA's Climate Change Kids Site
Basic information on climate change and fun online games.
External Links 
- Intergovernmental Panel on Climate Change
The Intergovernmental Panel on Climate Change (IPCC) was established by the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP) to assess scientific, technical, and socio-economic information relevant for the understanding of climate change, its potential impacts, and options for adaptation and mitigation.
- About Transportation and Climate Change
Center for Climate Change and Environmental Forecasting, U.S. Department of Transportation, provides basic information on the science of climate change and emissions inventories.
- Energy Information Administration, U.S. Department of Energy
Environment: provides greenhouse-gas emissions data, analyses, and forecasts.
Transportation Sector Information: provides analysis reports and papers related to environmental effects of the transportation sector.
- Transportation Energy Data Book Center for Transportation Analysis, Oak Ridge National Laboratory, U.S. Department of Energy
The Transportation Energy Data Book is a statistical compendium published annually by the Center for Transportation Analysis (CTA). Designed for use as a desk-top reference, the data book represents an assembly and display of statistics and information that characterize transportation activity, and presents data on other factors that influence transportation energy use. Previous versions of the data book can be found on the CTA Publications Web page.
- Alternative Fuels and Advanced Vehicles Data Center
Energy Efficiency and Renewable Energy, U.S. Department of Energy
The Alternative Fuels and Advanced Vehicles Data Center provides a wide range of information and resources to enable the use of alternative fuels, in addition to other petroleum reduction options such as advanced vehicles, fuel blends, idle reduction, and fuel economy.
For more information, contact: Lisa Snapp 734-214-4282 or email: Lisa Snapp (snapp.lisa@epa.gov).