Global transportation energy use is steeply rising, mainly as a result of increasing population and economic activity. Petroleum fuels remain the dominant energy source, reflecting advantages such as high energy density, low cost, and market availability. The movement of people and freight makes a major contribution to economic development and social well-being, but it also negatively impacts climate change, air quality, health, social cohesion, and safety. Following a review published 20 years ago in the Annual Review of Environment and Resources (then named the Annual Review of Energy and the Environment) by Lee Schipper, we examine current trends and potential futures, revising several major global transport/energy reports. There are significant opportunities to slow travel growth and improve efficiency. Alternatives to petroleum exist but have different characteristics in terms of availability, cost, distribution, infrastructure, storage, and public acceptability. The transition to low-carbon equitable and sustainable transport will take time but can be fostered by numerous short- and medium-term strategies that would benefit energy security, health, productivity, and sustainability.

Achieving a truly sustainable energy transition requires progress across multiple dimensions beyond climate change mitigation goals. This article reviews and synthesizes results from disparate strands of literature on the coeffects of mitigation to inform climate policy choices at different governance levels. The literature documents many potential cobenefits of mitigation for nonclimate objectives, such as human health and energy security, but little is known about their overall welfare implications. Integrated model studies highlight that climate policies as part of well-designed policy packages reduce the overall cost of achieving multiple sustainability objectives. The incommensurability and uncertainties around the quantification of coeffects become, however, increasingly pervasive the more the perspective shifts from sectoral and local to economy wide and global, the more objectives are analyzed, and the more the results are expressed in economic rather than nonmonetary terms. Different strings of evidence highlight the role and importance of energy demand reductions for realizing synergies across multiple sustainability objectives.

What is necessary to reach net zero emissions in the transport sector on a global level? To keep limiting global warming to 1.5° C within reach, the world has to decarbonise by mid-century, with every sector contributing as much as possible as soon as possible. This paper identifies what has to be done in road transport, aviation, and shipping to achieve net zero emission in the transport sector. For this purpose, it first sets the scene by providing an overview of the origins and impacts of the concept of net zero emissions in international climate policy as well as of the current state and future prospects of global transport emissions using currently available scenarios for low-emission and net zero transport. While for staying below 1.5° C, the basic approach to reducing transport emissions remains unchanged from what has been suggested in the past, the set, intensity and pace of actions as to shift fundamentally. Without first drastically reducing traffic volume and shifting transport demand to low-emission modes, reaching net zero transport will not be feasible: the amount of additional electricity required to fully electrify the sector with renewable energy is otherwise just too huge. After portraying key instruments for achieving net zero emissions in land transport, aviation, and shipping, this paper identifies key barriers for net zero transport. Based on this analysis, the authors recommend the following to be able to move transport to net zero: 1. Adapt Decarbonisation Strategies to Different Transport Sub-sectors 2. Prioritise and Significantly Increase Investment in Zero-/low-carbon Infrastructure 3. Massively Invest in the Development and Roll out of Zero-/low-emission Technologies 4. Focus on a Just Transition to Overcome Social and Political Barriers 5. Increase International Support and Cooperation.