We present a network model of interstate food trade and report comprehensive estimates of embodied irrigation energy and greenhouse gas (GHG) emissions in virtual water trade for the United States (U.S.). We consider trade of 29 food commodities including 14 grains and livestock products between 51 states. A total of 643 million tons of food with a corresponding 322 billion m³ of virtual water, 584 billion MJ of embodied irrigation energy, and 42 billion kg CO₂-equivalent GHG emissions were traded across the U.S. in 2012. The estimated embodied GHG emissions in irrigation water are similar to CO₂ emissions from the U.S. cement industry, highlighting the importance of reducing environmental impacts of irrigation. While animal-based commodities represented 12% of food trade, they accounted for 38% of the embodied energy and GHG emissions from virtual irrigation water transfers due to the high irrigation embodied energy and emissions intensity of animal-based products. From a network perspective, the food trade network is a robust, well-connected network with the majority of states participating in food trade. When the magnitude of embodied energy and GHG emissions associated with virtual water are considered, a few key states emerge controlling high throughput in the network.

The inadequacy of water resources to meet the needs of food production is a very important issue that will increase in importance in the future. If local renewable water sources (in soil) and water (in rivers, lakes, reservoirs, aquifers) are sufficient to produce a reference food supply (including 3000 kcal of daily requirement, of which animal products include 20 percent) for all residents. If not, we consider a food production unit to have a lack of green-blue water. If it is not enough for all residents, we consider a food production unit to have a lack of green-blue water. The number of people living in food production units affected by green-blue water scarcity has increased from 360 million people in 1905 (21% of the world's population at that time) to 2.2 billion (34%) in 2005. During this period, the lack of green-blue water has spread to large areas and has increased in previous areas. Water security is a concept that is examined in different dimensions and aspects. Four dimensions of these cases were identified, each of which consists of two complementary aspects: direct-indirect, macro-micro, technical-political and peace-conflict. In this study, the indirect role of water on food security on a global scale was investigated using a quantitative spatial approach. Since food security is intertwined with water security in many ways, the role of water scarcity on the disruption of food production and the impact of trade on this interaction was analyzed, and while examining the relationship of social resilience with these issues, the areas that It was identified that they were facing certain challenges in this field. With this work, the concept of water security became systematic and finally related to the issues of vulnerability, resilience and sustainability.

Alan Nicol, Simon J. Langan, Michael Victor, Julian Gonsalves, 'Building resilience: Climate change, water, and food security', International Water Management Institute (IWMI); CGIAR Research Program on Water, Land and Ecosystems (WLE); Global Water Initiative East Africa (GWI EA), 2015

Ensuring resilient food systems and sustainable healthy diets for all requires much higher water use, however, water resources are finite, geographically dispersed, volatile under climate change, and required for other vital functions including ecosystems and the services they provide. Good governance for resilient water resources is a necessary precursor to deciding on solutions, sourcing finance, and delivering infrastructure. Six attributes that together provide a foundation for good governance to reduce future water risks to food systems are proposed. These attributes dovetail in their dual focus on incorporating adaptive learning and new knowledge, and adopting the types of governance systems required for water resilient food systems. The attributes are also founded in the need to greater recognise the role natural, healthy ecosystems play in food systems. The attributes are listed below and are grounded in scientific evidence and the diverse collective experience and expertise of stakeholders working across the science-policy interface: Adopting interconnected systems thinking that embraces the complexity of how we produce, distribute, and add value to food including harnessing the experience and expertise of stakeholders s; adopting multi-level inclusive governance and supporting inclusive participation; enabling continual innovation, new knowledge and learning, and information dissemination; incorporating diversity and redundancy for resilience to shocks; ensuring system preparedness to shocks; and planning for the long term. This will require food and water systems to pro-actively work together toward a socially and environmentally just space that considers the water and food needs of people, the ecosystems that underpin our food systems, and broader energy and equity concerns.

PR | IFPRI4; CRP2 | EPTD; PIM | CGIAR Research Program on Policies, Institutions, and Markets (PIM)

The emerging popularity of the nexus discussion reflects the ongoing transition from a sectoral or silo approach to an integrative approach to address the global challenges pertinent to the three essential resources: food, energy, and water (FEW). Cities are critically important for advancing regional sustainable development and are thus placed at the center of the FEW nexus. This paper provides a comprehensive literature review to debate the current concepts and methods of the FEW nexus at different scales, with the aim of developing a conceptual knowledgebase framework for scientific analysis and policy making associated with the urban FEW nexus. Although the concept of nexus thinking has been widely accepted, a consistent and explicit cognition of the FEW nexus is still lacking, and a sophisticated methodological modeling framework is urgently required at various scales. As such, we proposed a three-dimensional conceptual framework of the urban FEW nexus from the perspective of resource interdependency, resource provision and system integration. This framework is useful in steering the systematic modeling and integrative management of the complex nexus issues of urban systems with different perspectives. Finally, the future directions of urban nexus research are identified from four aspects, including systematic characterization, cross-region tele-connection mechanisms, co-decision model development, and governance transition.

Notwithstanding the dispersed nature of the water, energy and food (WEF) nexus scholarship in the African continent, its strategic importance to the African agenda has gained widespread attention in research and planning circles. In this regard, the bibliometric science mapping and content analysis of the WEF nexus scientific publication trends, the conceptual, intellectual and social structures, as well as the inherent paradigmatic shifts in the WEF nexus body of knowledge in the African continent have been undertaken, using the nexus body of literature accessed from the Web of Science and Scopus core collection databases. The review results confirmed that, whilst the WEF nexus scholarship has expanded since 2013, there is also evidence of growth in the conceptual, intellectual and social structures of the WEF nexus in the African continent. These shifts have resulted in the emergence of hot topics (subfields) including modelling and optimization, climate variability and change, environmental ecosystem services sustainability, and sustainable development and livelihoods. The review further determined that these structures have evolved along two main perspectives of WEF nexus research development, i.e., the interdisciplinary and transdisciplinary domains. In support of the interpretation of the visual analytics of the intellectual structure and changing patterns of the WEF nexus research, the shifts in positivist, interpretivist and pragmatic paradigmatic perspectives (these are underpinned by the ontology, epistemology, and methodology and methods) are considered when explaining WEF nexus research shifts: (a) From the unconnected silo paradigms that focus on water, energy and food (security concerns) to interconnected (and sometimes interdependent or nested) linkages or systems incorporating environmental, social-economic and political drivers (also viewed as subfields) in a bid to holistically support the Sustainable Development Goals (SDGs) across the African continent; and (b) in the evaluation of the WEF nexus scholarship based on novel analytical approaches. We contend that whilst the theories of science change underpin this apparent expansion, the macro-economic theory will find use in explaining how the WEF nexus research agenda is negotiated and the Integrative Environmental Governance (IEG) is the duly suited governance theory to bridge the inherent disconnect between WEF nexus output and governance processes uncovered in the literature. Overall, operational challenges and opportunities of the WEF nexus abound, transitioning the WEF nexus research to practice in Africa, motivating the need to take advantage of the scholar–practitioner research underpinnings, as contemplated in the transdisciplinary research approach, which is characterised by the dual quest for new knowledge and considerations of use. Yet, there is need for more coordinated and collaborative research to achieve impact and transition from WEF nexus thinking to WEF nexus practice. | The Water Research Commission of South Africa. The APC was funded by the University of KwaZulu-Natal’s Centre for Transformative Agricultural and Food Systems. | https://www.mdpi.com/journal/sustainability | dm2022 | Geography, Geoinformatics and Meteorology | School of Health Systems and Public Health (SHSPH)

Global freshwater assessments have not addressed the linkages among water vapor flows, agricultural food production, and terrestrial ecosystem services. We perform the first bottom-up estimate of continental water vapor flows, subdivided into the major terrestrial biomes, and arrive at a total continental water vapor flow of 70,000 km3/yr (ranging from 56,000 to 84,000 km3/yr). Of this flow, 90% is attributed to forests, including woodlands (40,000 km3/yr), wetlands (1400 km3/yr), grasslands (15,100 km3/yr), and croplands (6800 km3/yr). These terrestrial biomes sustain society with essential welfare-supporting ecosystem services, including food production. By analyzing the freshwater requirements of an increasing demand for food in the year 2025, we discover a critical trade-off between flows of water vapor for food production and for other welfare-supporting ecosystem services. To reduce the risk of unintentional welfare losses, this trade-off must become embedded in intentional ecohydrological landscape management.