Fuel shifts reduce most of the greenhouse gas emissions from transportation in the United States

Abstract

Decarbonizing the United States transportation sector has emerged as a critical objective to combat climate change due to its high greenhouse gas emissions, largely from light-duty vehicles. This study assesses the breakdown of life cycle emissions of various transportation options under average and maximum ridership scenarios and quantifies emissions reductions through mode shifts and technology advancements. Electrified transportation achieves half the greenhouse gas emissions of petroleum-fueled options in 2023, with projections indicating a reduction to one-fifth by 2050. Battery systems contribute up to one-fifth of lifetime emissions of electric vehicles and buses as of 2023, and this share is estimated to increase to half by 2050 as electricity emissions are greatly reduced with the decarbonization of electricity. The study concludes that shifting away from light-duty vehicles can achieve near-term greenhouse gas reductions, but these reductions are minimal in the long term when combined with transportation electrification powered by decarbonized electricity. In the United States, electrification can reduce greenhouse gas emissions from passenger transportation by half now and up to 85 percent by 2050 with a decarbonized grid, according to an analysis that uses life cycle assessment and ridership scenarios.