Reducing Greenhouse Gas Emissions From U.S. Transportation

Transportation accounts for nearly a third of our nation’s greenhouse gas emissions, and its emissions are growing more rapidly than other sectors. In this report, authors David Greene and Andreas Schafer find that numerous opportunities are available now and in the future to reduce the transportation sector’s impact on climate. Many of these same actions would also address other national priorities, including reducing U.S. dependence on oil imports.

This latest Pew Center report is the first building block in our effort to examine key sectors, technologies, and policy options to construct the “10-50 Solution” to climate change. The idea is that we need to tackle climate change over the next fifty years, one decade at a time. This report points to the following key elements of the 10-50 Solution to transportation.

  • We can start now, and we must start now. Fuel economy for cars and trucks could be increased by 25-33 percent over the next 10 to 15 years using market-ready technology at a net savings, if fuel savings are taken into account. Increasing efficiency of vehicles (aircraft, car, trucks and trains) takes time because fleet turnover typically takes 15 years or more.
  • We will need a sustained effort over many decades. Technologies on the horizon are likely to enable fuel economy improvements in cars and light trucks of 50 to 100 percent by 2030. Transforming land-use patterns to enable more efficient travel, or transitioning to a hydrogen based transportation system, will require decades of incremental change.
  • R&D and voluntary efforts are necessary but not sufficient; mandatory policies are essential. Since fuel economy is undervalued in the marketplace, policies such as mandatory standards and public information are needed to pull technological improvements into the market. Fuel economy has gotten worse recently not because of lack of technology, but because of lack of policy. Hydrogen holds out the tantalizing promise of near-zero greenhouse gas emissions, but government must provide clear policy direction to drive massive private investment by the fuel and vehicle industries.
  • We need a mix of policies, and there are many to choose from. Opportunities for significant emission reductions include implementing a carbon constraint, raising efficiency standards for automobiles, blending low-carbon fuels with gasoline, and changing land-use patterns through urban design and planning. Each of these measures could contribute to reducing GHG emissions, but none is sufficient alone. The authors estimate that a combination of reasonable measures would reduce carbon emissions by about 20 percent by 2015, and almost 50 percent by 2030, compared to “business as usual.”