LONG-TERM TRENDS IN AUTOMOBILE CO₂ EMISSIONS BY CITY: 28 YEAR TRACKING OF NATIONWIDE PERSON-TRIP SURVEYS

Abstract

 Relations between urban structure and automobile CO₂ emissions have attracted attention as important aspects of environmental policy, with respective introduction of urban facility location planning systems and carbon taxes. Particularly, Newman–Kenworthy type scatter plots provide fundamentally important information. Nationwide person-trip surveys have been used in Japan to accumulate these data. However, differences in annual fuel consumption and survey items during the calculation process strongly affect results over long examination periods. This study investigates city-specific automobile CO₂ emissions over 28 years, using data from the sixth survey administered in 2015 along with retroactively changed index values. Results show that automobile CO₂ emissions per city 28 years ago were actually lower than those reported from earlier research. Results also show that inter-city disparity in automobile CO₂ emissions per person has been expanding recently.