Carbon dioxide (CO2) is not a pollutant but a greenhouse gas which contributes mainly to global warming effects and which is associated with climate change. Transport is one of the sectors targeted where effective public interventions are being called for to reduce CO2 emissions and where adaptation measures are needed to reduce the vulnerability to climatic changes. Currently, the CO2 emissions in the transport sector are about 30% in the case of developed countries and about 23% in the case of the total man-made CO2 emissions worldwide. There is widespread agreement to reduce CO2 emissions from transport by a minimum of 50% at the latest by 2050.

At a number of international conferences, transport ministers have addressed the need for CO2 abatement and improved fuel efficiency in the transport sector, mainly through:

  1. Innovative vehicle technologies, advanced engine management systems and efficient vehicle power trains;
  2. The use of sustainable biofuels, not only of the first generation (vegetable oil, biodiesel, bio-alcohols and biogas from sugar plants, crops or animal fats etc.), but also of the second (biofuels from biomass, non-food crops including wood) and third generations (biodegradable fuels from algae);
  3. An improved transport infrastructure together with Intelligent Transport Systems (ITS) to avoid traffic congestion and to foster the use of intermodal transport (road, rail and waterways);
  4. Consumer information (campaigns for eco-driving, use of public transport and modal transport etc.);
  5. Legal instruments (such as tax incentives for low carbon products and processes, taxation of CO2 intensive products and processes, etc.).

Sustainable transport refers to the broad subject of transport that is or approaches being sustainable. It includes vehicles, energy, infrastructure, roads, railways, airways, waterways, canals, pipelines, and terminals. Transport operations and logistics as well as transit-oriented development are involved. Transportation sustainability is largely being measured by transportation system effectiveness and efficiency as well as the environmental impacts of the system.