Pew study finds that changes in technology, policy and consumer behavior could combine to deliver up to 65% reduction in US transport GHG by 2050
|US transportation GHG emissions under the Base Case and three Mitigation Scenarios. Source: Greene and Plotkin (2011). Click to enlarge.
A new study published by the Pew Center on Global Climate Change finds that combined actions across three fronts—technology, policy, and consumer behavior—could deliver up to a 65% reduction in transportation emissions from current levels by 2050. The study was written by David L. Greene, Corporate Fellow of Oak Ridge National Laboratory, and Steven Plotkin, a staff scientist with Argonne National Laboratory’s Center for Transportation Research.
Currently, greenhouse gas (GHG) emissions from the US transportation sector represent 27% of the GHG emissions of the entire US economy and 30% of the world’s transportation GHG emissions. Without shifts in existing policies, the US transportation GHG emissions are expected to grow by about 10% by 2035, and will still account for a quarter of global transportation emissions at that time.
The study provides three plausible scenarios of improved transportation efficiency and reduced GHG emissions through 2050, with technology progress and policy ambition and agressiveness increasing from the first to third scenario. The scenarios show emissions reductions of 17%, 39%, and 65% below 2010 levels by 2050. The findings were based on a wide range of existing transportation literature and the authors’ own analysis.
The Base Case is the EIA’s 2010 AEO Reference Case projection, extrapolated from 2035 to 2050, and includes relatively high energy prices, the US Renewable Fuels Standard (RFS), and existing emission standards. Under the base case, transportation’s CO2 emissions increase 28% from 1.8 gigatons in 2010 to 2.3 gigatons in 2050. Heavy-duty truck emissions increase the most (0.2 gigatons) and the fastest (a 70% increase over 2010).
All three scenarios incorporate a price on carbon, obtained directly from a carbon tax or indirectly from a carbon cap-and-trade system.
The Low Mitigation Case includes post-2016 GHG emissions standards for LDVs requiring reductions of about 2% per year. The scenario includes an energy efficiency indexed highway user fee, modest improvements in energy efficiency in non-highway modes, and little additional alternative fuel use beyond the Base Case.
The Mid Mitigation Case reflects a greater public commitment to reducing GHG emissions, more rapid technological progress, and a tolerance for some additional innovative pricing policies. Emission standards are more stringent, and public commitment is reflected in greater reductions from energy-efficient driving, land use strategies, an acceptance of feebates, and minimum liability PATP (pay-at-the-pump) vehicle insurance.
The High Mitigation Case assumes rapid technological progress and aggressive emission standards. Public urgency about addressing climate change is reflected in greater effectiveness of policies such as eco-driving, land use policies, and the acceptance of congestion pricing and more comprehensive PATP insurance. In the High Mitigation Case, a transition to electric and/or hydrogen vehicles is well underway by 2050. Finally, automated highways are introduced by 2050 on major routes.
Technological improvements to vehicle energy efficiency, low-carbon energy sources, and all other strategies make roughly comparable contributions to GHG mitigation in the High Mitigation Case. No single technology, policy, or mode is able to accomplish a 65% reduction in total transportation GHG emissions. Achieving reductions of that magnitude requires a comprehensive strategy, with strong public support, sustained by rapid technological progress.
Transportation will remain a cornerstone of the US economy and a fundamental contributor to Americans’ quality of life to 2050 and beyond. The enormous value to society of the mobility of people and commodities must be preserved. Because rates of technological progress and future energy prices are uncertain, the GHG mitigation strategy for transportation must be adaptable. This can be accomplished by monitoring technological progress to insure that policies remain cost effective, taking advantage of faster progress when it occurs, and adjusting to disappointments accordingly.—Greene and Plotkin, 2011
David L. Greene and Steven E. Plotkin (2011) Reducing Greenhouse Gas Emissions from US Transportation