Editorial: Tuyeni H Mwampamba, Rob Bailis, Adrian Ghilardi Urbanization, food, and water consumption trends in many tropical countries show that demand for charcoal (as a source of cooking energy), meat, grain and water will rise to proportions that surpass the ability of existing ecosystems to supply these services simultaneously and at desired qualities. Consequently, drastic changes to policy and practice are needed to improve ecosystem potential and/or alter demand trends. Traditional charcoal production in sub-Saharan Africa, South East Asia and Latin America often competes or co-exists with livestock keeping and agriculture and has a tendency to occur in water-limited woodlands. The co-occurrence of charcoal and food production results in complex landscapes characterized by strong interactions between subsystems, managed by multiple sets of actors, with potentially competing objectives. These social-ecological systems provide goods and services that are essential to millions of people throughout the global south. Nevertheless, there have been very few detailed studies of such systems, particularly on the individual and combined effects of charcoal, crop, and livestock production on the hydrological system that maintains them and vice versa. As a result, these multi-use landscapes are typically managed by short-sighted, highly generalized, mono-sectorial policies that ignore important tradeoffs and undercapitalize on synergies. A system-level approach could provide important insights that improve and expand current understanding of this energy-food-water nexus. Tackling urgent and complex problems composed of multiple and interrelated factors lies at the heart of nexus thinking - an approach that “examines the inter-relatedness and interdependencies of environmental resources and their transitions and fluxes across spatial scales and between compartments” (UNU-FLORES 2015) and relies on interdisciplinary research and multi-sector policy teams. It has attracted significant interest from international organizations, the private sector and governments as a way to develop integrated equitable solutions that involve inputs from multiple stakeholders. However, this approach is notably absent in the research arena. Identifying appropriate interventions for achieving sustainable charcoal and food production and maintaining the underlying hydrological system on which they depend requires that the systems are considered simultaneously and that their biophysical, social, and political inter-relations are well understood. Taking charcoal as the nexus entry-point, this Research Topic aims to generate new understanding of charcoal production systems by incorporating agriculture and hydrology into the matrix. We were interested in empirical articles, reviews, meta-analytical articles and perspective papers that address at least two of the three nexus components and which offer provocative and insightful perspectives into the nexus as a whole. We hope that this Research Topic will 1) facilitate identification of research gaps, policy opportunities and priorities for the nexus, 2) kick-start the development of a community of researchers and practitioners working on the nexus, and 3) permit the development of a research agenda that explores the nexus globally across multiple study sites.

The book’s primary intention is to serve as a roadmap for professionals working in developing countries interested in the Nexus Water-Energy-Food-Ecosystems (WEFE) approach. The book shows a multi-disciplinary approach, showcasing the importance of the proper use of Nexus WEFE when implementing certain development programs in regions around the globe. It can be presented as a manual for an individual that either wishes to implement intervention projects following the NEXUS approach or students interested in cooperation and development. The book begins with a general explanation of the theoretical concepts and implementation processes of Nexus WEFE and continues getting into case studies, explaining the importance of proper implementation and potential drawbacks and solutions to them. This book has a particular focus on the European Union cooperation policies when implementing such an approach in developing countries.

The water–food–energy nexus is emerging as a critical issue in Asia and the Pacific. It is clear that solutions must be found to assure water security, thereby eliminating the immediate---and increasing---risk to food security, energy security, and economic growth and stability: water must be recognized as an economic as well as a social good. Governments need to be encouraged to think differently about water, take the longer-term view, and be mindful of the strategic and economic value of this limited resource. This publication is the result of a scoping study initiated by the Asian Development Bank to better understand the issues associated with the water–food–energy nexus in Asia and the Pacific. It provides high-level guidance on the choices available to address the region's water security issues.

This will be the first textbook on the integration of food, energy and water systems (FEWS). In recent years, the world has seen a dramatic rise in interdisciplinary energy and environmental courses and degrees at the undergraduate and graduate levels. In the US for instance, the number and variety of such programs has increased significantly over the past decade, Simultaneously, national and international initiatives that integrate food, energy and water systems have been launched. This textbook provides a substantive introduction to the food-energy-water nexus suitable for use in higher level undergraduate and graduate level courses and for scholars moving into the field of nexus studies without a strong background in all three areas and the many aspects of nexus studies.

Organic waste composting is another excellent example to demonstrate the power and the benefits of nexus thinking. Even though organic waste composting itself is not a new topic, those who want to start a new project or align an ongoing project with nexus thinking, find it difficult to gather the necessary information. With nine case studies from four continents, this book aims to fill above gap in literature. While current literature on composting is often found to be limited to either soil/agriculture sector or waste management sector, this book presents a combined point of view. This open access book starts with an introductory chapter that describes the need to bring the waste management aspects and soil nutrient management aspects of compost production into one integrated theme. The relevance of nexus thinking and the Sustainable Development Goals (SDGs) are also presented in this introduction. The first three chapters after the introduction covers composting from the solid waste management and its policy aspects, taking examples from three developing countries. The next three examples are mostly about the benefits composting can provide to the soil and agriculture. These examples are also from three developing countries, but with a mixture of urban as well as rural settings. Last three chapters present more insight into the latest developments taking examples from Europe, as well as new methods adapted from the traditional styles from Africa.

Environmental engineers support the well-being of people and the planet in areas where the two intersect. Over the decades the field has improved countless lives through innovative systems for delivering water, treating waste, and preventing and remediating pollution in air, water, and soil. These achievements are a testament to the multidisciplinary, pragmatic, systems-oriented approach that characterizes environmental engineering. Environmental Engineering for the 21st Century: Addressing Grand Challenges outlines the crucial role for environmental engineers in this period of dramatic growth and change. The report identifies five pressing challenges of the 21st century that environmental engineers are uniquely poised to help advance: sustainably supply food, water, and energy; curb climate change and adapt to its impacts; design a future without pollution and waste; create efficient, healthy, resilient cities; and foster informed decisions and actions.

Forests are intrinsically linked to water – forested watersheds provide 75 percent of our accessible freshwater resources (Millennium Ecosystem Assessment, 2005) – and both forest and water resources are relevant to the achievement of all 17 Sustainable Development Goals. Despite the important interlinkages, the forest-water nexus is often unaccounted for in policy and planning. For example, three quarters of forests are not managed for soil and water conservation, which poses a fundamental challenge to achieving sustainable and resilient communities and ecosystems. It is paramount to employ an integrated approach to forest and water resources in management and policy that takes into account the complexity and contextual nature of forest-water relationships. To achieve this, we must improve our understanding of forest-water relationships within local contexts and at different scales, as well as our ability to design, implement, and learn from landscape approaches that both rely on these forest-water relationships, and impact them. In this context, FAO’s Forest and Water Programme has developed a module-based capacity development facilitation guide for project and community stakeholders involved in forest, water and natural resource management to ensure we apply our knowledge to better manage forests and trees for their multiple benefits, including water quantity, quality and the associated socio-economic benefits that people within and outside forests so heavily depend on.