University of Minnesota researchers reveal that states must use comprehensive approach to reduce greenhouse gases

Individual states within the United States can have an impact on reducing greenhouse gas emissions from motor vehicles, but only if they use a comprehensive approach that includes improved vehicle efficiency, lower carbon fuels and reduced distances traveled, say researchers at the University of Minnesota. The new research on reducing motor vehicle greenhouse gas emissions is published in the current issue of Environmental Science and Technology, an environmental journal published by the American Chemical Society.

Transportation is the largest end-use source of greenhouse gas emissions in the country. Using Minnesota as a case study, the new research focuses on state efforts to reduce emissions. Approximately 18 U.S. states would rank in the top 50 greenhouse gas emitting nations if they were considered as independent countries.

As of mid-2009, approximately 33 states have a climate change action plan and about 15 states have adopted California's vehicle greenhouse gas emission standards. California also has enacted a low-carbon fuel standard.

While California is well--studied, the researchers decided to study Minnesota because it is more representative of a typical state in relation to several factors affecting greenhouse gas emissions including population, registered vehicles, typical distances traveled, and gasoline consumption. Minnesota also recently enacted legislation in 2007 regarding emissions. The greenhouse gas emission reduction targets in Minnesota are 15 percent by 2015 and 30 percent by 2025, relative to 2005.

In their research, the team modeled several technology and policy options for reducing Minnesota's emissions. They studied a wide range of scenarios, from doing nothing, to adopting strict standards for fuels and vehicle efficiency, to increasing mass transit.

The University of Minnesota researchers concluded that Minnesota has a viable approach to meeting these goals only if advancements are made in all three areas--vehicle efficiency, decreased carbon content of fuels, and reduction of distances traveled by car. If the approach is not comprehensive and policies focus on only one or two areas, potential improvements may be negated by backsliding in another area, the report stated.

"States can play an important and unique role in environmental policy," said Julian Marshall, a lead researcher on the study and a civil engineering assistant professor in the University of Minnesota's Institute of Technology. "States have different legal constraints and opportunities compared to the federal government. With their diversity of political views, states often can serve as policy laboratories on issues like this."

In addition to Marshall, other University of Minnesota members of the interdisciplinary research team include Adam Boies (graduate student, mechanical engineering, Institute of Technology), Steve Hankey (graduate student, civil engineering, Institute of Technology), David Kittelson (professor, mechanical engineering, Institute of Technology), Peter Nussbaum (graduate student, Humphrey Institute of Public Affairs), Winthrop Watts (research associate, mechanical engineering, Institute of Technology), and Elizabeth Wilson (assistant professor, Humphrey Institute of Public Affairs).

View the full research report.

December 15, 2009