Key Transport Conclusions IPCC 5th Assessment Report WG3

The newly published 5th Assessment Report of the IPPCC confirms that the importance and potential of mitigation action by the transport sector to reduce dangerous climate change. The Transport Section Mitigation Pathways of the Summary for Policy Makers highlight the following 5 key conclusions:

  1. The transport sector accounted for 27% of final energy use and 6.7 GtCO2 direct emissions in 2010, with baseline CO2 emissions projected to approximately double by 2050 (medium evidence, medium agreement).
  2. Technical and behavioural mitigation measures for all transport modes, plus new infrastructure and urban redevelopment investments, could reduce final energy demand in 2050 by around 40% below the baseline, with the mitigation potential assessed to be higher than reported in the AR4 (robust evidence, medium agreement). 
  3. Strategies to reduce the carbon intensities of fuel and the rate of reducing carbon intensity are constrained by challenges associated with energy storage and the relatively low energy density of low?carbon transport fuels (medium confidence). 
  4. The cost?effectiveness of different carbon reduction measures in the transport sector varies significantly with vehicle type and transport mode (high confidence). 
  5. Regional differences influence the choice of transport mitigation options (high confidence).
The detailed chapter (8) on transport, to which several SLoCaT members actively contributed  contains a number of additional key messages:

  1. Reducing global transport greenhouse gas (GHG) emissions will be challenging since the continuing growth in passenger and freight activity could outweigh all mitigation measures unless transport emissions can be strongly decoupled from GDP growth (high confidence).
  2. Avoided journeys and modal shifts due to behavioural change, uptake of improved vehicle and engine performance technologies, low?carbon fuels, investments in related infrastructure, and changes in the built environment, together offer high mitigation potential (high confidence).
  3. Both short? and long?term transport mitigation strategies are essential if deep GHG reduction ambitions are to be achieved (high confidence).
  4. Barriers to decarbonizing transport for all modes differ across regions, but can be overcome in part by reducing the marginal mitigation costs (medium evidence, medium agreement).
  5. There are regional differences in transport mitigation pathways with major opportunities to shape transport systems and infrastructure around low?carbon options, particularly in developing and emerging countries where most future urban growth will occur (robust evidence, high agreement).
  6. A range of strong and mutually?supportive policies will be needed for the transport sector to decarbonize and for the co?benefits to be exploited (robust evidence, high agreement).
Compared to the 4th Assessment Report greater emphasis appears to be placed on behaviourial change. 
We invite more detailed reviews and comments on the coverage of transport in the 5th Assessment Report. Please contact if you would like to submit comments or a review.