Environmental effects of transport

The transport sector is a major emitter of anthropogenic CO2. The annual growth rate of transport-related greenhouse gas emissions is larger than that of other mature industrial sectors. In the light of the United Nations Framework Convention on Climate Change (UNFCCC), the Kyoto Protocol and possible follow-up Protocols, this rate of increase creates a severe problem when trying to achieve emission reduction targets. Additionally, the impact of the transport sector on climate is complex and is mediated through more than just the list of gases in the Kyoto Protocol.

The emission of gases and particles from transport has impacts both on the chemical composition of the atmosphere and on climate. In addition to the direct or indirect impact on climate, transport emissions change the oxidising capacity of the atmosphere, have an impact on local air quality (e.g., via formation of ground-level ozone or via an emission of particles) and modify the UV radiation at the surface (e.g., by changing total ozone). Measures to reduce the negative climate effects of transport have to taken into account the rather long time scales involved: some transport means have long development and operation times, some emissions have long residence times, and the thermal inertia of the climate system protracts possible effects.