Managing complex systems to enhance sustainability

With increasing populations, global resources and processes must be managed sustainably to ensure the continuation of livelihoods. However, this must be achieved in a fair and just manner, safeguarding people’s most basic needs and satisfying human rights. Both planetary resource boundaries and the inter-related social foundations can involve complex, non-linear relationships and may well include a wide range of tipping points (where a small change in a driving force results in a strongly non-linear response). Using models can help to develop an understanding of complex systems, to demonstrate trade-offs and potential tipping points, and to provide a testing ground for new practices and policies. Nevertheless, they do not remove the risk associated with decision making. Frameworks (such as the Driver-Pressure-State-Impact-Response framework and the United States Environmental Protection Agency ecological risk assessment) can perform three vital roles to help manage complex systems: (i) to guide research direction; (ii) to simplify outputs to the level desired by many policy-makers; and (iii) to evaluate the risks associated with specified actions. The application of the techniques outlined in this chapter help decision makers to act promptly, despite both high complexity and uncertainty, to reduce pressures on environmental systems and avoid catastrophic changes of state.