Rewiring the Domestic US Rice Trade for Reducing Irrigation Impacts-Implications for the Food-Energy-Water Nexus

Food trade connects distant places of food production to places of consumption. Through traded food, associated environmental impacts are also displaced as the consumer benefits from the product without incurring the externalities of production. Taking U.S. rice as an example, we discuss the sustainability implications of rewiring U.S. rice production and trade for reducing the impacts of irrigation (water and energy) and transportation greenhouse gas (GHG) emissions. We model a series of robust optimization scenarios that re-arrange the origin of trade and therefore the production to target virtual water use and GHG emission reductions. For the baseline case, virtual water trade amounts to 35 billion m(3), and embodied irrigation and transportation GHG emissions amount to 6 billion kg CO2-equivalent and 0.7 billion kg CO2-equivalent, respectively. Rewiring consistently achieves better results compared to the baseline even in the presence of uncertainty. However, our findings reveal strikingly sobering national-level savings in optimizing the water use (2%) and GHG emissions (14%) with tradeoffs in other impacts. To achieve these results, all rice-producing states undergo changes, with the state of Mississippi completely stopping production. California's unique ability to produce medium-grain rice at a large scale makes it indispensable for current rice production and hence a major constraint for rewiring rice production. The findings of this work reveal the inflexibility of our food system in balancing the food-energy-water nexus tradeoffs through restructuring trade.