A framework for unravelling the complexities of unsustainable environmental change in food production

Food production is responsible for over 70% of freshwater use by humans and is the primary cause of land conversion globally. The global system of food production and trade is complex, with interdependencies between natural and socioeconomic conditions in importing and exporting regions, as well as the physical and socioeconomic infrastructure linking the two. Given this complexity, policy or environmental changes can have non-linear and cascading impacts for water and land resources along the supply chain. As the world becomes more globalised and more urbanised our dependence on this complex system increases. Thus, in order to achieve sustainable food security, we require an understanding of the complexity of the food production and trade system.In this paper we set out a framework for modelling the complex feedbacks between food production policy and water and land resource use and the how these are linked globally via trade. Our framework couples a multi-agent policy network with a model of the physical environment based on the global hydrological model PCR-GLOBWB and the dynamic vegetation model LPJ-GUESS. Cities are nodes in our network and are linked via physical trade infrastructure. Our framework provides a template for new type of Earth System model that captures the complex feedbacks between policy and environmental change and how these are linked globally via trade.