Tailpipe GHG emissions at 29% in the US (plus another 6% for fuel mining and refining, manufacture, infrastructure)

The magnitude of climate change beyond the next few decades depends primarily on the quantity of greenhouse gas (GHG) emissions humans produce globally. Achieving substantial reductions in GHG emissions is possible, but will require widespread utilization of low-carbon energy, improvements in energy efficiency, and conservation measures that reduce demand for energy. Transportation agencies can help develop climate solutions by implementing measures to limit growth in vehicle miles traveled, improving the efficiency of operations and promoting infrastructure to support low carbon vehicles and fuels.

The U.S. has pledged to reduce GHG emissions 26-28 percent by 2025 and 80 percent or more by 2050. These emissions reductions are consistent with scientific targets for stabilizing atmospheric concentrations of CO2 at 450 parts per million. The transportation sector is a significant source of U.S. GHG emissions, and will need to achieve major reductions to support national climate commitments.

Tailpipe GHG emissions from transportation sources accounted for 29 percent of total U.S. GHG emissions in 2012, and almost 4 percent of global GHG emissions. Including other life cycle processes-such as the extraction and refining of fuel, the manufacture of vehicles and the construction and maintenance of infrastructure-the U.S. transportation sector accounts for roughly 5 percent of global GHGs.

Line graph shows annual global greenhouse gas emissions growing under business as usual scenario.  Under policy scenarios, emissions level off at  differing years and then decline to near zero by 2100.Under a business-as-usual emissions scenario, global GHG emissions produced each year are expected to nearly triple. Demand for energy is expected to increase along with a growing global economy that continues to derive most of its energy from fossil fuels.
Line graph shows global average temperature increasing rapidly under business as usual scenario to 8 degrees Fahrenheit by 2100 and increasing slowly and then leveling off at 2 degrees Fahrenheit under substantial greenhouse gas reductions scenario.Based on the business-as-usual scenario mentioned above, surface temperatures are expected to increase 8 degrees or more by the end-ofcentury, with further increases very likely thereafter. This level of warming will lead to high to very high risk of severe, widespread, and irreversible impacts globally — including heat waves, sea level rise, and changes in precipitation patterns — threatening human health, infrastructure, agriculture, and livelihoods. Future warming and associated impacts can be much less severe, but will require significant reductions in GHGs below current annual levels.


Line graph shows daily greenhouse gas emissions from transportation for Washington State under business as usual (BAU) and policy scenarios.  Policies modeled include transportation demand management, pricing, technology, system optimization, and truck fuel economy.

Daily CO2 GHG Emissions for Washington State

Washington State DOT modeled GHG reduction strategies using the Energy and Emissions Reduction Policy Analysis Tool (EERPAT), an integrated, state-level modeling system designed specifically to evaluate strategies for reducing surface transportation GHG emissions. It is sensitive to a number of strategies that are difficult to analyze using travel demand models, especially at the state level, which can be used to evaluate the contribution of policy scenarios to GHG reduction goals.  EERPAT and found that a combination of aggressive strategies came close to meeting the state’s target for transportation GHG reductions.

Southern California Association of Governments analyzed GHG emissions from multimodal public transportation trips, including car, bus, bike, and walking trips to and from rail stations. The findings will be used to prioritize the most effective transportation and land-use planning strategies for optimizing GHG reductions achieved from public transit investments.

Transit passengers and bus in Santa Clara, CA.

The MPO for the greater Albuquerque, NM area used scenario planning to analyze strategies to reduce greenhouse gas emissions and adapt to climate change impacts, alongside other community goals. The project demonstrated how climate change considerations can be incorporated into transportation and land use scenario planning and provided analysis that was incorporated into the region’s long range transportation plan.

Map showing difference between trend and preferred scenarios for number of households in the year 2040. Preferred scenario shows more growth in housing downtown.   Children bicycling in Vermont.

Vermont Agency of Transportation used FHWA’s EERPAT to analyze the effectiveness of strategies in meeting the state’s GHG reduction target for transportation of 75% below 1990 levels by 2050. Vermont analyzed a combination of policies: travel demand management, parking pricing, increased biking and walking, and alternatives fuels for heavy duty vehicles.

Delaware Valley Regional Planning Council is developing a spreadsheet tool to determine the changes in energy use and GHG emissions associated with different electric vehicle and compressed natural gas vehicle deployment scenarios in the region. The tool can be used by other transportation agencies around the country.

Electric vehicle charging in Durham, NC.   Bar chart of greenhouse gas emission reduction potential of policies analyzed by the Maryland Department of Transportation, including "cash for clunkers", transportation demand management, pricing, electric vehicles, alternative fuels, transit, car sharing, and land use.

Maryland’s Greenhouse Gas Reduction Act of 2009 requires the state to reduce statewide GHG emissions by 25% from 2006 levels by 2020. Maryland DOT used FHWA’s EERPAT tool to model strategies and combinations of strategies for meeting the target.

East-West Gateway Council of Governments estimated GHG emissions from on-road vehicles at the regional and sub-regional scales, and analyzed future emissions for multiple policy and land use scenarios.

Colorado DOT conducted a pilot of FHWA’s policy analysis tool, EERPAT, to analyze the effectiveness of Colorado’s Energy Smart Transportation Initiative in reducing GHG emissions.  Massachusetts DOT used FHWA’s policy analysis tool, EERPAT, to analyze and quantify GHG benefits from current activities, as well as estimate the impact of a set of potential future strategies to help the State meet its GHG targets.

Strategic Highway Research Program 2 Sites

Under the Strategic Highway Research Program, Washington State DOT is conducting GHG analysis at a corridor level and enhancing the agency’s efforts to link the environmental review process with the system planning process. The study focuses on the I-5 corridor in the Seattle area, where light rail expansion is planned. Communities there have started to identify the decisions and actions needed to support ridership and improve multimodal connections.

Under the Strategic Highway Research Program, the Denver Region Council of Governments (DRCOG) is exploring land use and transportation scenarios and their impacts on GHG emissions.

Under the Strategic Highway Research Program, Massachusetts DOT is working with MPOs in the state on GHG analysis in the project development and selection processes as well as incorporating GHG considerations into freight planning.

Alternative fuels pooled fund study

Oregon DOT, in coordination with FHWA and other state DOTs, initiated a pooled fund study to assist transportation agencies interested in promoting the use of alternative vehicle and fuel technologies at a state, regional, or corridor scale and provide tools, information, and knowledge to do so. http://altfueltoolkit.org/.