Sustainable lifestyle: Urban household carbon footprint accounting and policy implications for lifestyle-based decarbonization

Cities, as the primary hubs of economic activities and the end-points of goods and services consumption, bear significant responsibility for the majority of global greenhouse gas emissions. Consequently, there is a pressing need for more granular data at the subnational level to formulate effective and feasible measures in line with current decarbonization targets. In this study, we present the carbon footprint embodied in household consumption behavior of 11 major metropolitan areas in Japan. Furthermore, our study innovatively introduces a temporal perspective, employing time organization as an insightful indicator to delineate the disparities in carbon footprints that arise from varying carbon intensities of distinct activities. The results are given from the following three aspects: 1) structural comparison of urban household carbon footprints; 2) time-based activity differences and drivers; and 3) inequality analysis among different activity-based carbon footprints. Here, we found that eating contributes most substantially to the carbon footprint. Conversely, transportation activities manifest the greatest regional inequality in carbon footprints. These findings provide indispensable evidence for the development of city-specific net-zero-emission goals within Japan. Furthermore, they exemplify the value of incorporating a temporal dimension into household carbon footprint analyses, thereby providing a broader perspective for future investigations in this field.