Water- Energy- Food- Ecosystem Services (WEFE) nexus assessment in the context of climate change: a literature review and conceptual model development for the Adige River basin (Italy).
Authors: Sambo Beatrice , Cocuccioni Silvia , Carnelli Fabio , Terzi Stefano , Sperotto Anna , Torresan Silvia , Pittore Massimiliano , Zebisch Marc , Critto Andrea 
Published: February 2023

Water, Energy, Food and Ecosystems are inextricably linked within a complex system (&#8220;the WEFE Nexus&#8221;) dominated by interactions, feedback, and scale effects. The analysis of the WEFE nexus is increasingly relevant in both academic and policy discussion; since its systematic approach could contribute addressing some fundamental EU challenges and policies, supporting the achievement of multiple Sustainable Development Goals.Existing studies are still focused on dual interactions between sectors (e.g. water-energy, water-food) and don&#8217;t fully consider the ecosystem services components, despite their importance is widely recognized. There are still some challenges on how to use heterogeneous and sector-specific data and large climate projection datasets within the nexus concept.The aim of this analysis is to explore how the WEFE nexus components and their interactions have been examined in recent scientific literature, and how they can be conceptualized in the Adige River basin (Italy), in order to identify synergies and trade-offs among different resources and uses.Firstly, an in-depth state-of-the-art review on the main methodologies which allow the full integration of ecosystem services and climate change effects was undertaken for publications in the time frame 2010-2022. The review focused on i) how complex interlinkages among the sub-sectors of the WEF nexus and Ecosystem Services are modeled and how researchers operationalized these interlinkages in current conceptual frameworks; ii) how the spatial (from source to sea) and temporal dynamics of nexus are changing under future scenarios of climate and socio-economic changes; iii) which are the recent applied tools, methods and models which allow to operationalize the WEFE nexus behaviors and to support decision-making policies. The review shows that the interrelations among the WEFE sectors within conceptual frameworks are mainly modeled by qualitative methods (e.g. causal loops, multi-criteria decision analysis); while the spatio-temporal dynamics are mainly assessed by quantitative approaches (e.g. System Dynamics, Bayesian Networks). Furthermore, ecosystem services and climate change are mainly considered as external drivers influencing the WEF nexus sectors rather than a nexus component.Based on the collection and review of peer-reviewed, grey literature and newspaper articles dealing with the water management topic, a first conceptualization of the sectors involved in the WEFE Nexus for the Adige River basin was performed. The framework, finalized with expert-based discussions in the context of two local stakeholders&#8217; workshops, allowed the identification and qualitatively characterization of the relations among the WEFE sectors as well as the pressures by external components on the system (i.e. climate and socio-economic drivers). Five levels of conceptualization have been conceived to represent the main dynamics for each nexus&#8217; sectors (i.e. water, energy, food, and ecosystem services) and their overall interactions.The results of the analysis are part of the Horizon2020 project NEXOGENESIS, and pave the way for the application of a complex science methodology able to disentangle the role of ecosystem services and climate change in the frame of the nexus approach