Peak Car in the Big City: Reducing London's transport greenhouse gas emissions

•Car use in London is declining as population density increases.•Declining car use mitigates transport greenhouse gas emissions.•Key policies are investment in rail but not roads, and constraints on car use.•The experience of London may be relevant to big cities elsewhere.

Road transport is substantially dependent on oil. Car ownership is expected to continue to grow, particularly in the developing economies. The transport sector is therefore seen as more problematic than other sectors as regards reducing greenhouse gas emissions. However, there is emerging evidence that per capita car use in many developed economies has ceased to increase. Moreover, a marked decline in the proportion of journeys by car is evident in a city such as London, with a growing population where road capacity is not being enlarged to meet demand. The expected global growth of urban populations suggests that car ownership and use, and the resulting greenhouse gas emissions, may be significantly lower than usually supposed.