Motoshita, Masaharu; Pfister, Stephan; Sasaki, Takao; Nansai, Keisuke; Hashimoto, Seiji; Yokoi, Ryosuke; Finkbeiner, Matthias

Freshwater is an inevitable natural resource for life on the earth, while it is unevenly distributed worldwide. We often need to depend on freshwater resources in a different place through domestic or international trade. The dependency on remote water resources is invisible and hard to be realized by consumers who induce water consumption. Besides, the pressure on the sustainability of water resources differs from watersheds. We analyze the Japanese national water footprint, as a major economy and consumer of traded goods, by adopting a Global Link Input-Output (GLIO) model and regional carrying capacity indicators of water consumption. We show that 10 % of total water consumption induced by the Japanese final demand exceeds the regional safe operating space of water resources in worldwide watersheds, while the global average proportion of overconsumption is 24% of the total water consumption. Japan induces a large amount of overconsumption in the US, while the national overconsumption rate of the US is relatively lower (around 20%) than the global average (24%). On the other hand, Japanese induced overconsumption amount in Chile is roughly 1/8 of that in the US, while the national overconsumption rate of Chile is relatively larger (around 50%) than the global average. Besides, Japanese induced overconsumption amount and the national overconsumption rate in Thailand are not relatively high. However, the proportion of overconsumption induced by Japan to the national total overconsumption is the highest among all partner countries. These results imply the importance of three aspects in terms of regional sustainability of water resources: the absolute amount, regional pressure on the carrying capacities, and the magnitude of responsibility for the local overconsumption.