Support for
has been provided by these organizations and individuals:

John Hennessy III,

Transportation’s Role in Reducing U.S. Greenhouse Gas Emissions

Posted by Content Coordinator on Thursday, April 29th, 2010


Executive Summary

This study evaluates potentially viable strategies to reduce transportation greenhouse gas (GHG) emissions. The study was mandated by the Energy Independence and Security Act (P.L. 110­140, December 2007). The Act directed the U.S. Department of Transportation (DOT), in coordination with the U.S. Environmental Protection Agency (EPA) and consultation with the U.S. Global Change Research Program (USGCRP), to conduct a study of the impact of the Nation’s transportation system on climate change and strategies to mitigate the effects of climate change by reducing GHG emissions from transportation. This study also examines the potential impact of these strategies on air quality, petroleum savings, transportation goals, costs, and other factors. Each GHG reduction strategy may have various positive impacts (including co­benefits) or negative impacts on these factors. Potential tradeoffs and interdependencies when reducing GHG emissions will need to be considered in order to develop balanced solutions.

This study does not take a position as to which strategy, or collection of  strategies, should be adopted to accomplish the Nation’s clean energy and GHG  reduction goals.  Rather, the study attempts to objectively examine numerous  proposed strategies and assess their potential to reduce transportation GHG  emissions.  The assessments are based on published scientific literature, current  policy studies, and best professional estimates.  Each strategy is assessed relative  to projections of future transportation GHG emissions based on U.S. Energy  Information Administration Annual Energy Outlook (AEO) estimates.

The study is presented in two parts: Volumes 1 and 2.  Volume 1:  Synthesis  Report provides an overview of the study’s findings and discusses policy options  that Congress may wish to consider to reduce transportation GHG emissions.   Volume 2:  Technical Report provides the technical details of the assessment.

The Intergovernmental Panel on Climate Change (IPCC) estimates that in the  absence of additional climate policies to reduce GHG emissions, baseline global  GHG emissions from human sources will increase between 25 percent and  90 percent between 2000 and 2030, with CO2 emissions from energy use growing  between 40 and 110 percent over the same period.  The IPCC projects that global  temperatures will rise between 2°F to 11.5°F by 2100, and global sea level will  rise between 7 to 23 inches.  More recent estimates that include the effects of  polar ice sheet melting suggest a possible 3 to 4 foot sea level rise.  According to  the Intergovernmental Panel, global GHG emissions must be reduced to 50 to  85 percent below year 2000 levels by 2050 to limit warming to 2.0°C to 2.4°C  (3.6°F to 4.3°F).  To reach this target, GHG emissions from all sectors must be reduced through a multi­generational effort.

The primary greenhouse gases produced by the transportation sector are carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and hydrofluorocarbons (HFC).  Carbon dioxide, a product of fossil fuel combustion, accounts for 95 percent of transportation GHG emissions in the United States.

Transportation GHG emissions account for 29 percent of total U.S. GHG  emissions, and over 5 percent of global GHG emissions.  Except otherwise noted, the estimates in this report account for “tailpipe” emissions from burning  fossil fuels to power vehicles and do not account for greenhouse gases emitted
through other transportation lifecycle processes, such as the manufacture of vehicles, the extraction and refining of fuels, and the construction and  maintenance of transportation infrastructure. Including these processes, U.S. transportation lifecycle greenhouse gases are estimated to account for about 8 percent of global GHG emissions. 

Transportation GHG emissions have been growing steadily in recent decades.  From 1990 to 2006 alone, transportation GHG emissions increased 27 percent, accounting for almost one­half of the increase in total U.S. GHG emissions for the period.

In 2006, emissions from on­road vehicles accounted for 79 percent of  transportation GHG emissions.  Emissions from light­duty vehicles, which include passenger cars and light duty trucks (e.g., sport utility vehicles, pickup trucks, and minivans) accounted for 59 percent of emissions.  Emissions from freight trucks accounted for 19 percent, and emissions from commercial aircraft (domestic and international) for 12 percent.  Emissions from all other modes accounted for less than 10 percent of total emissions.


Download full executive summary (PDF)

Download Volume 1 of the report (PDF)

Download Volume 2 of the report (PDF)

About the U.S. Department of Transportation
“The mission of the Department is to: Serve the United States by ensuring a fast, safe, efficient, accessible and convenient transportation system that meets our vital national interests and enhances the quality of life of the American people, today and into the future.”

Tags: , , , , , ,

Comments are closed.

Follow InfraUSA on Twitter Facebook YouTube Flickr


Show us your infra! Show us your infra!

Video, stills and tales. Share images of the Infra in your community that demands attention. Post your ideas about national Infra issues. Go ahead. Show Us Your Infra!  Upload and instantly share your message.

Polls Polls

Is the administration moving fast enough on Infra issues? Are Americans prepared to pay more taxes for repairs? Should job creation be the guiding determination? Vote now!


What do the experts think? This is where the nation's public policy organizations, trade associations and think tanks weigh in with analysis on Infra issues. Tell them what you think.  Ask questions.  Share a different view.


The Infra Blog offers cutting edge perspective on a broad spectrum of Infra topics. Frequent updates and provocative posts highlight hot button topics -- essential ingredients of a national Infra dialogue.