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Water, energy and food (WEF) systems interact with each other and the environment. For instance, food crops require energy for fertilisers, water for irrigation, and rely on environmental processes for cycling of nutrients and pollinating crops. Agricultural practices have also led to declines in pollinators and an excess of nutrients in the environment. The term nexus has been used to describe these interactions since the 1980s. It has become prominent in discussions of international resource policies and is the focus of UK research programmes. Exact definitions of the water, energy and food nexus differ, but all seek to describe interactions across and between relevant systems. Understanding the interactions between WEF systems can help decision makers balance trade-offs made between them, in response to increasing demand. This in turn could increase security in these sectors.

Key points in this POSTnote include:

  • A nexus assessment seeks to describe the interactions of water, food, energy, environmental and social systems to identify the interdependencies and trade-offs between these systems.
  • Failure to take account of interactions and trade-offs creates vulnerabilities to shocks, such as extreme weather events, which can have cascading impacts across systems.
  • There are no set methods for undertaking nexus assessments, but key aspects involve understanding the interactions between systems and people.
  • Awareness of interactions and trade-offs is necessary, but addressing them also requires an understanding of the social, political and environmental context.


POSTnotes are based on literature reviews and interviews with a range of stakeholders and are externally peer reviewed. POST would like to thank interviewees and peer reviewers for kindly giving up their time during the preparation of this briefing, including:

  • Dr Ruth Welters, School of Environmental Sciences, University of East Anglia*
  • Professor Liz Varga, Professor of Complex Infrastructure Systems, Complex Systems Research Centre, School of Management, Cranfield University*
  • Dr Candice Howarth, CECAN, University of Surrey*
  • Dr Adam Cooper, STeAPP, UCL*
  • Dr Geoff Darch, Principal Consultant, Climate Futures, Vice-Chair, Futures Programme, ATKINS*
  • Professor Dan Osborn, Chair of Human Ecology, Department of Earth Sciences, University College London*
  • Dr Rachel Muckle, Defra
  • Dr Gary Kass, Defra/Natural England*
  • Greg Lowe, Executive Director, Capital, Science, and Policy Practice, Willis Towers Watson
  • Professor David Demeritt, Department of Geography, King’s College London*
  • Professor Tim Benton, UK Champion for Global Food Security and Professor of Population Ecology, University of Leeds*
  • Professor James Wilsdon, Professor of Research Policy, Faculty of Social Sciences, University of Sheffield*
  • Dr Hayley Leck, King’s Centre for Integrated Research on Risk and Resilience, Department of Geography, King’s College London*
  • Professor Alice Bows-Larkin, Tyndall Centre for Climate Change Research, School of Mechanical, Aerospace and Civil Engineering, The University of Manchester*
  • Dr Gemma Cranston, Senior Programme Manager, University of Cambridge Institute of Sustainability Leadership*
  • Ben Shaw, Director of Policy Studies Institute and Deputy Director of CECAN, University of Westminster*
  • Professor Declan Conway, Grantham Research Institute, LSE and University of East Anglia*

*Denotes people who acted as external reviewers of the briefing.  


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