Suggested Citation:
Handy, Susan L. and Kevin J. Krizek (2009) The Role of Travel Behavior Research in Reducing the Carbon Footprint: From the U.S. Perspective. Institute of Transportation Studies, University of California, Davis, Research Report UCD-ITS-RR-09-63

As we prepare this paper for the IATBR conference, leaders across the globe are preparing for the United Nations Climate Change Conference in Copenhagen. It appears unlikely that any sort of treaty will emerge from this gathering, in part because of the vast disparity between global greenhouse gas (GHG) emissions from developed and developing countries, and to the position of the United States at the top of the GHG-emissions list. Largely responsible for putting the U.S. in this position is the transportation sector: CO2 emissions from fossil fuel combustion in the transportation sector accounted for 26.4 percent of all GHG emissions in the U.S. in 2007, second only to electricity generation as a GHG source (U.S. Environmental Protection Agency 2009). While the U.S. makes up only about 5 percent of the world’s population, it produces over 20 percent of the world’s GHG emissions (U.S. Environmental Protection Agency 2006).

The transportation sector is large and diverse, encompassing travel by air, land, and water, and the movement of both passengers and freight. But passenger vehicles, used for the daily travel of households, are the primary source of CO2 emissions within the transportation sector. Household travel accounts for over 80 percent of VMT and three-quarters of CO2 emissions from “on-road sources” in the U.S. (Federal Highway Administration 2009). In the U.S., 88.2 percent of person miles of travel in 2001 were by passenger car, and the average American household made nearly 6 vehicle trips per day, totaling over 58 vehicle miles of travel (Hu and Reuscher 2004). Reducing GHG emissions in the U.S. means doing something to reduce CO2 emissions from passenger vehicles used for daily travel.