Assessing Urban Resource Consumption and Carbon Emissions from a Food–Energy–Water Nexus Perspective

This chapter aims to analyze the carbon emissions in the food–energy–water (FEW) nexus from an urban supply-and-demand perspective by quantifying resource consumption flows in FEW supply chains so that carbon dioxide (CO2) emissions from supply and consumption, as well as the contributions of FEW to urban systems, can be calculated quantitatively. By using monetary input–output tables of the Tokyo Metropolitan Government’s Statistics Division, we tracked the flows of water, energy, and CO2; visualized energy and water consumption and carbon emissions in each sector; and assessed resource efficiency in different sectors. We then defined the elements in the food nexus system and established the relationships among the elements of supply and demand, in which the supply-side includes agriculture, animal husbandry, fisheries, and food manufacturing, while the demand-side includes food wholesale and retail, catering, and households. We also calculated water, energy, and carbon flows in the food system. Finally, we allocated reduction targets to specific sectors according to the results of emissions at different scales through embodied flow analysis. The results show that in Tokyo, services have the greatest food-energy-water consumption and carbon emissions. There is considerable potential to conserve resources and reduce emissions in these sectors. This research shows that FEW makes a significant contribution to carbon emissions, and more effort is required to achieve the “Zero Emission Tokyo Strategy” for 2050.