Transport is central to the climate change mitigation task. Transport accounts for nearly a quarter of global carbon dioxide (CO2) emissions from fuel combustion. Between 1990 and 2012, CO2 emissions from the transport sector increased by 57 percent globally. They result mainly from road transport: In 2012, the road sector accounted for 75 percent of all transport emissions. The increase in emissions from road transport was less pronounced than in other transport modes, however: Global road traffic emissions grew by 64 percent globally over the 1990 to 2012 period, compared to increases of 80 percent for aviation and 66 percent in maritime transport.