Deep reductions in transport emissions are possible

[Press release - 10.11.2017]

Paris, November 10, 2017 - On the occasion of the Transport Days at COP23, the Institute for Sustainable Development and International Relations (IDDRI) publishes a report on how to decarbonize the passenger transport sector. A deep reduction of the transport sector’s emissions while satisfying people’s mobility needs is possible. But this requires, beyond the deployment of low-carbon technologies, the full transformation of the transport system.

In 2014, the transport sector was responsible for 23% of total energy-related CO2 emissions (i.e. 7.5 GtCO2). Reaching the climate objective of the Paris Agreement requires decreasing significantly the transport sector’s emissions. But it has been often said that the transport sector is difficult to decarbonize. This is confirmed by the ambition pledged for the transport sector under the Nationally Determined Contributions (NDCs), which remains very limited.

IDDRI’s report analyzes national strategies for the passenger transport, reaching deep emission reductions compatible with the Paris Agreement objectives, in four countries: France, Japan, Mexico and the United Kingdom. They all achieve deep reductions of emissions per capita, between 50% and 80 % across all countries and all scenarios, reaching a range of 0.1-0.5 tCO2 per capita in 2050, down from 0.9-1.7 in 2010.

This analysis can serve to inform the 2018 Facilitative Dialogue and the preparation of future, more ambitious NDCs by 2020. Michel Colombier, IDDRI scientific director, explains: “Opening the box of sectoral transformations is key for the progressive revision of NDCs and their implementation: it helps to identify concrete policies and measures and gives credibility to the emission targets”.

IDDRI’s report highlights five cross-cutting messages:

  • Deep decarbonization of the passenger transport sector requires strong actions on four pillars: mobility demand management, energy efficiency, decarbonization of electricity and fuels and a shift to vehicles and transport modes using these low-carbon energies. Only consistent articulation of these synergistic pillars allows effective emission reductions. 

"Decarbonizing the transport sector requires a comprehensive strategy. For example, with higher energy efficiency and reduced mobility demand, deep decarbonization can be reached with a smoother deployment of electric vehicles", explains Yann Briand, DDPP-Transport coordinator.

  • Deep decarbonization can help alleviate the time and monetary burden of constrained mobility for households, but this requires addressing certain challenges.

Reducing distance traveled through spatial reorganization, teleworking or modal shifts towards less expensive public transport and non-motorized transport support both decarbonization and the alleviation of the travel burden for households.

"The positive effect of decarbonization strategies on budgets in 2050 should not hide the transition challenges in the next decade, especially for the most vulnerable. Addressing these challenges requires forward-looking policies on infrastructure and clear economic signals", analyses Henri Waisman, Deep Decarbonization Pathways Project (DDPP) director.

  • Deep decarbonization can be compatible with satisfying mobility needs

In developing countries, it is possible to decarbonize the transport sector while ensuring a significant increase of mobility for the categories of population currently with lowest mobility rates. In industrialized countries, the challenge lies in the capacity to control the trend of continuous mobility increase, triggered by factors like urban sprawl and the organization of transport in cities. More compact cities and the development of remote conferencing and working are key to trigger a reduction of the average distance per capita.

  • Deep decarbonization should combine context-specific actions, adapted to the different countries, mobility needs and travel distances.

The determinants of mobility are fundamentally different in metropolitan areas and non-metropolitan areas. In metropolitan areas, given higher density of populations, modal shift towards public transport and non-motorized modes for short distances plays a key role in decarbonization On the other hand, non-metropolitan transport will continue to rely on private modes, making the deployment of low-carbon options essential.

  • Deep decarbonization should consider an early ramp-up of low-carbon technologies in the next decade, consistent with the high shares required by 2050.

Staying within 2°C requires a dominant share of low-carbon vehicles by 2030. This requires a massive rollout starting now to scale research, development and innovation funding, increase incentives for quicker deployment of alternative vehicles, and plan the necessary infrastructure."


The DDPP-T, coordinated by IDDRI, is a sectoral companion project of the Deep Decarbonization Pathways Project (DDPP,, which investigated low-emission trajectories for the energy sector. It gathers in-country research teams, working independently of their governments, which are responsible for the development of their country study. Research partners are: UCL Energy Institute (UK); CIRED, EDF R&D and IDDRI (France); Tempus Analitica (Mexico); NIES, Mizuho and IGES (Japan). The project will continue in 2018 to include the freight transport sector and cover more countries.