The water, energy and food nexus (WEF nexus) is currently quite popular in environmental management. The concept found a fertile ground in science and policymaking, but there is no consistent view on the meaning of integration within the nexus. Here, a wealth of publications is reviewed in an endeavour to: (1) reveal the lines of justification for the need of the WEF nexus debate and (2) identify the range of tools for analysing the interdependent resource issues of the nexus using an integrated framework of science and policy. There are three drivers behind the emergence of the nexus thinking. These are a) increasing resource interlinks due to growing scarcities, b) recent resource supply crises, and c) failures of sector-driven management strategies. Evaluation of the WEF nexus integrative debate can be carried out using four key criteria, namely ability to change current policy debates, issue and thinking novelty, practicability and measurability, and clearness and implementation roadmap. It is clear that, although the nexus has been quite successful in changing policy debates, issue prioritization is missing and seems to be left to specific case studies and policymakers' choices. There is a high need for ‘incorporation’ and ‘cross-linking’ of issues between the three resources. In this regard, nexus governance is the missing link in the nexus debate.

The COVID-19 pandemic offers an opportunity to examine the impacts of system-wide crises on key supply sectors such as water, energy and food. These sectors are becoming increasingly interlinked in environmental policy-making and with regard to achieving supply security. There is a pressing need for a systematization of impacts and responses beyond individual disruptions. This paper provides a holistic assessment of the implications of COVID-19 on the water–energy–food (WEF) nexus. First, it integrates the academic literature related to single cases and disruptions to provide a broader view of COVID-19 demand- and supply-side disruptions and immediate effects. Then, the major, long-term impact categories of medicalization/hygienization, (re)localization of production, and demand fluctuations are highlighted. These impacts result in priority cross-links such as irrigation, energy requirements for local food production, energy use for water and wastewater treatment, or water for energy use. Finally, sector-level insights on impacts and responses are provided, drawing from illustrative cases. The analysis of impacts of COVID-19 on the WEF nexus reflects heterogeneous experiences of short-term adaptations, and highlights the revaluation of the water–food–trade nexus. Revived debates on food sufficiency can benefit from green applications to minimize expected trade-offs. The current crisis also reveals some gaps in the WEF nexus debates with regard to the lack of risk-based perspectives and the need for a better consideration of spatial aspects in resource integration. Regarding resource-security issues in the WEF nexus, the COVID-19 stress test boosts debates concerning the adequacy of the production value chains (e.g., contingency and storage, diversification, and self-sufficiency) and the value of cross-border integration (e.g., trade, globalization, and aid).