Estimation of passenger car CO2 emissions with urban population density scenarios for low carbon transportation in Japan

•We determined passenger car CO2 emission parameters by mesh cell size in Japanese municipalities.•The parameters were applied to compact and dispersed population distribution scenarios for the year 2030.•A compact distribution had the potential to reduce passenger car CO2 emissions in many of municipalities.

The aim of this study is to quantify the potential reduction of CO2 emissions by passenger vehicles over the long term through the introduction of compact cities. We determined the correlation between population distribution and passenger car CO2 emissions from 1980 to 2005 and simulated passenger car CO2 emissions in 2030 under both compact and dispersed scenarios. We conducted correlation analysis and scenario analysis with the data sets of municipal CO2 emissions of passenger cars, national population census figures, and future population distribution scenarios. Then, we estimated the annual CO2 emissions of passenger cars per capita by mesh cell density category. The results show that the difference in emissions per capita between the compact and dispersed scenarios is roughly 5% in Japanese municipalities as a whole.