Global nexus relationships and trends

Water, energy, and food are tightly connected, forming the WEF nexus, in which actions in one sector have implications for the other two sectors. Population and socio-economic changes drive demand for each resource, impacting the nexus system trajectory, which in turn feeds-back to affect livelihoods and growth. The demand for each sectors' resource is growing. This has implications for that sector, but also for the provisioning and sustainability of the other sectors due to the tight coupling. For example, energy is required to supply and treat water: as water demand increases, so does energy demand. Recent studies suggest that as a society, we are on course to exceed many of the planet's 'safe operating spaces' - thresholds beyond which the consequences of exceeding them are not well known. To better manage the nexus, improved holistic understanding of the behaviour and potential system trajectories under global change is urgently needed, and studies being undertaken. At the same time, coherent policies across nexus sectors need to be better formulated, especially focusing on leveraging synergies for improved cross-sectoral efficiency regarding meeting multiple targets simultaneously (e.g. the SDGs and climate targets). Ecosystems, so fundamental to enabling societal development, are often neglected from nexus assessments, another area for future development. Finally, there are increasing calls to define metrics for 'growth' not dependent on economic performance, and to 'decouple' economies from nexus resource extraction and consumption. This chapter provides an overview of global nexus trends and relationships and suggests avenues to improve our current understanding.