The carbon dioxide emission reduction potential in China's road transport sector in 2020

China is the world's second largest greenhouse gas emitter. Emissions from the road transport sector represent one of the fastest growing carbon dioxide (CO2) sources in China. Based on previous research of projections about China's future vehicle ownership and the CO2 emission in the road transport sector, this paper reviews all recent environmental policies in the automobile industry and employs scenario analysis to estimate different emission inventories in different development strategies. The new policy scenario considered all possible mitigation options available in the road transport sector from a bottom-up perspective and examined the fuel efficiency improvement effects and costs of these mitigation options - vehicle technology improvement, a Bus Rapid Transit system, and a fuel switch, through which the carbon dioxide emission reduction potential was estimated. Not only does this paper indicate that a large emission reduction potential exists in China's road transportation sector, but it infers that vehicle technology improvement, especially engine technology, is likely to be the most effective means to meet emission reduction targets. This paper concludes by identifying key barriers to implement those options in China and induces China's demand, mainly in technical, financial and institutional aspects, for national capacity building and international aids, to achieve emission reduction goals.