“Resource-carbon” redistribution caused by Japan's cement production and consumption: a life-cycle based multilayer perspective

Abstract

Inter-reginal trade of raw materials, energy, and products within Japan's cement supply chain creates substantial telecoupled material and carbon flows. Temporal dynamics in regional cement consumption and supply chain structure have discrepant effects on production regions and resource suppliers. However, existing literature studies primarily focused on single-year carbon flows and obscured transportation impacts. Therefore, this study developed a process-based life cycle multi-layer supply network integrating transport data, trade statistics, and gravity model to quantify material and carbon flows embedded in Japan's prefectural cement supply network from 2010 to 2022. Results reveal that in 2022, up to 88 % of total material requirement (TMR) and 74 % of carbon footprint (CF) impacts attributed to inter-prefectural trade and energy imports, while transportation processes contributed about 5 % to the total impacts. Domestically, TMR and CF transfers primarily flowed from northern regions (Hokkaido, Iwate) and southern regions (Fukuoka, Yamaguchi, Kochi) toward three major economic centers, while smaller transfer networks emerged around Saitama, Niigata, and Mie prefectures. The production-side TMR and CF of major impact-exporting prefectures have recently declined due to reduced remote consumption, while Hyogo demonstrated slight growth driven by supply increases. Internationally, approximately 38 % of TMR impacts were externalized to coal-exporting countries, with Australia and Indonesia replacing Russia's historical dominance following geopolitical changes, leading to a 22 % increase in long-distance maritime impacts. These findings underscore the need for implementing targeted cross-cutting mitigation strategies (i.e., low-carbon fuels and material-efficient design) to achieve a more sustainable and resilient cement industry in Japan.