Assessing the transition to low-carbon urban transport: A global comparison

• The urban transport CO 2 emissions in 180 global cities are comparatively analyzed. • A 4-phase framework is proposed to assess the transition to low-carbon urban transport. • There is regional disparity in urban transport CO 2 emissions across continents. • The peaks of CO 2 emissions per GDP, CO 2 emissions per capita, and total CO 2 emissions occur sequentially. • The transition to low-carbon urban transport in developed countries began earlier. The transition toward low-carbon urban transport is essential for achieving the global goal of “carbon neutrality”. However, a global comparison of urban transport CO 2 emissions is still insufficient due to the lack of comprehensive, comparable, and consistent data on transport at the city level. To assess the transition to low-carbon urban transport globally, this study measures the total CO 2 emissions, CO 2 emissions per capita, and CO 2 emissions per GDP of urban transport in 180 global cities using a unified method based on extensive data collected in 44 countries across 6 continents from 1960 to 2012. Then, the regional disparity and historical trend of the three indicators are analyzed to characterize the transition to low-carbon urban transport. Finally, the transition progress of low-carbon urban transport in the 180 cities is assessed with a multiphase framework that consists of pre-development phase, take-off phase, acceleration phase, and stabilization phase. The results show that the changing patterns of urban transport CO 2 emissions vary across continents. There is a common trend that the peak times of CO 2 emissions per GDP, CO 2 emissions per capita, and total CO 2 emissions usually occur in sequence. Historically, cities in North America began the low-carbon transition earliest, followed by cities in Oceania, Europe, and Asia. Currently, the transition progresses in most developing cities are relatively slow and are still at the take-off phase of transition. Overall, this study can help cities better manage the transition to low-carbon urban transport for the goal of “carbon neutrality”.