Evaluating carbon inequality by household type and income level across prefectures in Japan

•Prefectural carbon footprint varies substantially according to household type.•Income groups with highest/lowest carbon footprints are in low-GRP prefectures.•Carbon footprint of single-person households in high-GRP prefectures is lower.•Carbon inequality gradually decreases as household income increases.•Even in the same sector, carbon inequality differs by household type. Affected by income level, household type, and other socioeconomic factors, carbon inequality among households substantially differs across prefectures in Japan, thereby profoundly affecting the country's sustainable development. Therefore, it is necessary to explore the carbon footprint of different households on the basis of systematically grouped income levels and evaluate carbon inequality in all prefectures. Using the 2005 multi-regional input–output table of Japan, we identified detailed structures of household carbon footprint (HCF) across single- and multi-person households of different income levels in Japan's 47 prefectures. We elucidated carbon inequality across prefectures through the carbon footprint Gini coefficients of the aforementioned households. The results showed that substantial differences in HCF exist among prefectures, thus contributing to variances in carbon inequality levels. Multi-person households are currently the main contributors to Japan's HCF, but the contribution of single-person households has considerable potential to grow. Income level has the most direct influence on HCF, which considerably determines the amount and structure of household consumption. Changes in carbon inequality among prefectures indicate that the aggravation of income inequality widens the HCF gap among income groups—a situation inconducive to the reduction of per-household CF during climate mitigation.