大学共同利用機関法人　人間文化研究機構　総合地球環境学研究所

Japan is one of the representative food trade countries, thus it is required to understand the holistic impacts of food policy, trade, and land use on water-energy-food security at the same time. However, water,energy, and food are interrelated, and changes in each resource can affect other resources. For example, food trade drives water conservation or water loss in terms of virtual water, which refers to water embedded in food products. It is possible to evaluate water saving (or loss) to importing countries by evaluating virtual water trade. In addition, water saving derives the energy savings for water supply to crop area, and CO2 emission could be reduced through energy savings.

Currently, the ‘Nexus’ is highlighted as a new perspective for assessing the relationship among water, energy, and food. The Nexus among water, energy and food was identified during the 2008 World Economic Forum annual meeting and the Water-Energy-Food (WEF) nexus was identified as a Global Risk in 2011. WEF Nexus assessment tools could be used for supporting decision makers providing evaluation information regarding different the implications of current decisions on projected pathways into the future, providing an understanding of expected trade-offs among resource systems, and environmental and other externalities associated with different decisions. For that purpose, national datasets supporting the characterization of the water-energy-food system components need be used within a “nexus analytics” system that will support stakeholder decision evaluation.

Stakeholders include policy makers, private sector, and civil society, all of whom need to be involved, at different stages and scales, in this dialogue.

In this study, a WEF Nexus modelling tool is developed for evaluating the impacts of food trade, target food self-sufficiency, and change of land use on water-energy-food security with focusing on wheat and rice products in Japan. In the WEF Nexus tool, the virtual water is suggested to consider both food and water security. This Nexus tool is based on that framework which offers a common platform for scientists and policy-makers to evaluate scenarios and identify sustainable national resource allocation strategies.