The transport sector, comprising road traffic, shipping and aviation, is a significant contributor to global warming and has detrimental effects on air quality. The combustion of fossil fuels emits gases and particles that alter the chemical composition of the atmosphere. In addition to CO₂, non-CO₂ effects (NOx, contrails, aerosols, and aerosol-cloud interactions) are also important, some of which have warming and others cooling effects on the climate.
Driven by growing demand, the contribution of aviation to climate change is expected to increase, and emissions from road traffic and shipping may also rise depending on evolving mobility patterns and technological development. It is therefore crucial to develop and implement measures that reduce the climate footprint of transport. Mitigation options include alternative fuels such as electricity and hydrogen, technological improvements such as exhaust after-treatment systems, and operational measures such as optimized routing. A change in the share of demand between transport modes (modal shift) can complement these technical and operational measures.
Assessing the effects of such measures with numerical atmospheric models relies heavily on state-of-the-art emission inventories. Providing information on the uncertainties in emission data is essential for a reliable assessment of air quality and climate effects; these uncertainties further interact with those associated with the representation of physical, chemical, and dynamical processes in atmospheric models.
The objective of this session is to bring together the community that develops transport emission inventories with the community that uses them. The session has two aims: first, to establish a shared understanding of the requirements for, and uncertainties in, transport emission inventories; second, to review the latest research on the non-CO₂ and air-quality effects of transport emissions. The overarching goal is to reduce the uncertainties in the assessment of the climate and air-quality impacts of the transport sector. Contributions are welcome on topics ranging from measurement campaigns and modelling studies to strategies for reducing the environmental impact of transport.