Pontus Lurcock and Fabio Florindo
Antarctic climate changes have been reconstructed from ice and sediment cores and numerical models (which also predict future changes). Major ice sheets first appeared 34 million years ago (Ma) and fluctuated throughout the Oligocene, with an overall cooling trend. Ice volume more than doubled at the Oligocene-Miocene boundary. Fluctuating Miocene temperatures peaked at 17–14 Ma, followed by dramatic cooling. Cooling continued through the Pliocene and Pleistocene, with another major glacial expansion at 3–2 Ma. Several interacting drivers control Antarctic climate. On timescales of 10,000–100,000 years, insolation varies with orbital cycles, causing periodic climate variations. Opening of Southern Ocean gateways produced a circumpolar current that thermally isolated Antarctica. Declining atmospheric CO2 triggered Cenozoic glaciation. Antarctic glaciations affect global climate by lowering sea level, intensifying atmospheric circulation, and increasing planetary albedo. Ice sheets interact with ocean water, forming water masses that play a key role in global ocean circulation.
Cape Town's Contested Hierarchy of Demand for Agricultural and Municipal Water in a Rainfed Economy 2017-2018
The article provides an analysis of the stakeholders involved in policy decision making on water utilization, especially during the Water Crisis of 2017–2018. It looks at this through the prism of the meetings and key informants of the South African Parliament Portfolio Committee on Water and Sanitation, the City of Cape Town Council and the farmers of the Western Cape. It also considers the effects of the prioritization of the use of water for drinking water and sanitation over agriculture. The South Africa water policy principles set by its Constitution and the Acts of 1996–1997 provide a comparator.
Michael Gilmont, Lara Nassar, Erica Harper, Nadav Tal, and Steve Rayner
This chapter examines trends in water resources used in Jordan and Israel. Specifically it illustrates how these two economies have circumvented significant limits in their natural freshwater resource endowment to enable continued economic and population growth despite static or declining water availability. Using the concept of resource decoupling, it identifies four specific mechanisms by which economies can decouple their water needs from water availability, including economic diversification, food imports, agricultural water productivity, and nonconventional water resource development. Each of these mechanisms are illustrated for the two countries, including technical and political processes shaping their adoption. The chapter also critiques existing conceptualizations of decoupling relative to the water-specific model, highlighting the importance of understanding the unique characteristics of scarcity, flows, and substitutability of water at a global scale. Finally the chapter nests decoupling within the market modes framing this volume, before evaluating the risks and trade-offs inherent in decoupling strategies.
Eduardo Marone, Ricardo de Camargo, and Julio Salcedo Castro
This article describes the threat costal hazards pose to existing life in light of climate change and natural disaster. It includes an overview of flooding, extreme waves, and other water-related stressors. The article discusses how human-induced risks in the coastal zone, resulting from mismanaged urbanization, persistent pollution, and overexploitation of resources, exacerbate matters and pose extra pressure on the environment, science, and society. Ways of measurement and reaction to these events, as well as best practices for preparedness, are discussed. Businesses, individuals, and ecosystems are under threat of destruction from these circumstances. The article also emphasizes the need to make scientific work in this field accessible and understandable to society and decisión makers.
Anthony J. Reynolds
Conservation agricultural practices have been widely adopted across the world in the past 30 years. Farmers recognized that their soils had been degraded by deep ploughing and by dependence on chemical fertilizers, pesticides, and herbicides. Conservation agriculture, involving the agronomic and technological practices of no-till, cover cropping, and rotation, can be a sustainable alternative to conventional farming both economically and environmentally. While improving soil and crop health, it also has a dramatic and beneficial impact on the soil structure and on organic matter content that in turn can improve drainage and the availability of water. Costs are greatly reduced and crop yields—after an initial decline—return to former levels. Increasing interest and uptake by the global farming community shows that the system can be adapted in a variety of farming situations and significantly aid both the environment and sustainable food production.
Rami Zurayk and Azza Dirar
Since agriculture consumes the largest share of the world’s water, farmers undoubtedly play an instrumental role in the management of this precious resource. As such, various policy approaches have sought to engage farmers in the management of water for irrigation. There is much literature on policy approaches that devolve irrigation management to farmers through organizing them into ‘water user associations’ and mobilizing them into cooperative water resource management. When the implementation experience and success of these approaches are assessed, the results show a great variation in experience with overall limited success. The key challenges stem from various assumptions underlying the policy approaches, namely the way in which farmers are conceptualized as a homogenous group of ‘water users’. Cooperative and participatory approaches to natural resource management cannot be institutionally manufactured without addressing key political ecological realities and the wider contexts in which ‘resource users’ operate.
Mustapha Besbes, Jamel Chahed, and Abdelkader Hamdane
Northwest African countries (NA) consume 70 percent of their renewable water resources, and groundwater overdraft has become a major problem. Blue water irrigation represents 17 percent of overall water resources and is economically significant. Green water represents 83 percent, but is not yet well evaluated, and is not considered in national water strategies, along with virtual water embedded in international food trade. Irrigation enhances local agrifood production but it has not changed the proportion of staple foods. The region remains a major net food importer and, largely due to population increase, water dependency increased from 30 percent to 50 percent between 1970 and 2010. Population forecasts predict that water demand will continue to grow, and could reach more than three times the present level. Given the blue water status, NA must develop approaches to cope with water–food challenges, based on international virtual water flow optimization and better green water valorization.
Peter Johnston and Arthur Chapman
Irrigation is a critical input for raising food production in southern Africa, parts of which are food-insecure, especially as a result of low levels of technology employed, low investments into the sector, small farm sizes, and high levels of exposure to the hazards of climate variability. Most food production (including exports) and irrigation in the region occurs in the arid south—in South Africa by a large margin. Further north, in Angola, Zambia, and the northern parts of Mozambique, water resources are abundant yet irrigation farming is far less developed and inefficient, resulting in water resources being less intensely managed. The region needs to become more tightly integrated economically, with a greater flow of technology, investment, and management capability to the north, allowing the north to produce more food (and other agricultural products) which would flow to the more industrialized south—essentially virtual water flows to that region.
America Lutz Ley, Ryan Lee, Yulia Peralta, and Christopher Scott
The United-States-Mexico food system, and in particular the section located in the Sonoran Desert, is an example of the detrimental effects that result from instensified food production to supply increased demand from regional, transboundary, and global areas. Impacts to freshwater and terrestrial ecosystems in addition to human livelihoods and institutions create serious management and policy challenges. Understanding the region as an integrated water-food system with institutional imbalances reveals the following consequences: (a) an increasing reliance on groundwater resources for the majority of agriculture and livestock production; (b) a net export of nonrenewable water; and (c) a virtual water imbalance that further threatens the region’s water and food security.
Michel Petit and Phillipe Le Grusse
The food and water challenges to be faced in the Mediterranean Basin, particularly those on the southern and eastern shores, are daunting. They form a complex nexus of problems and require policies pursuing several important potentially conflicting goals at the same time: reducing or limiting food import dependency through increased agricultural production in environmentally sustainable ways while protecting the natural resource base and keeping food affordable for poorer populations. The worrisome trends affecting countries on the southern and eastern shores of the common sea can also have seriously negative consequences in the North which explains why the North-South collaboration has a long tradition in the region. But, as the case of water management institutions shows, ineffective advocacy for trade liberalization has led to conflicts and tensions on various issues and has distracted attention from potentially much more fruitful areas of collaboration.
Timothy O. Williams
This chapter examines the links between water, food and society in Africa. Agricultural transformation to promote growth, eliminate poverty and hunger and sustain ecosystems is one of the central pillars of current development agenda in Africa. Achievement of this agenda will crucially depend on sustainable water management. However, agri-food systems and water resources are under greater pressure than ever before due to demographic, economic and climatic changes. The nature and scale of these changes suggest that only a holistic and integrated management of all shades of water resources, green, blue and grey, will allow Africa to eliminate hunger and poverty. Research-based technical solutions as well as institutional and policy measures are proposed that would allow available water resources to be sustainably used to promote climate-resilient farming systems, improve agricultural productivity and food security and spur the development of viable food value chains needed for agricultural and rural transformation.
West Asia is one of the most water-scarce regions of the world and one of its foremost importers of virtual water despite sustained efforts at self-sufficiency, especially in cereal production. Technology-oriented policy solutions eye a reorientation of agriculture towards fruit and vegetables that are less water-intensive than cereals and provide more value added per water unit consumed. Turkey is a role model here; the country has an agricultural trade surplus and ranks among the top ten agricultural economies globally in value terms. Yet technology-oriented policy prescriptions overlook the sociopolitical ‘problemsheds’ that emerge (along with new agro-lobbies) and agriculture as the main water consumer has to compete with other economic sectors and sprawling urbanization. This article looks at the different categories of countries and their specific challenges.
Brendan Bromwich, Tony Allan, Anthony Colman, and Martin Keulertz
Society’s greatest use of water is in food production, a fact that puts farmers centre stage in global environmental management. Management of food value chains, however, is not well set up to enable farmers to undertake their dual role of feeding a growing population and stewarding natural resources. This chapter introduces an analytical framework by which food, water, and society can be investigated. Food value chains comprise three market modes: production; trade and process; retail and consumption. The model demonstrates the interfaces between blue water, green water, virtual water, polluted drainage, and evapotranspiration. By categorizing social, cultural, and political influences on the three market modes the framework enables integrated analysis of food, water, and society . The combined management of food and water through redesign of food value chains emerges as a key challenge for the twenty-first century.
Floriane Clement and Alan Nicol
Whereas international debates have increasingly acknowledged the role of gender in food and water security, they have often focussed somewhat exclusively on the role of women in agricultural production. This chapter aims at broadening our understanding of gendered inequities in food and water systems by examining how power structures produce gender-differentiated capabilities along the real-virtual water spectrum. The analysis reveals how gender, intersecting with class, ethnicity, and other social categories, shapes the capabilities to engage in, benefit from, and influence food and water systems. The findings show the relevance of using a commodity chain analysis to highlight the linkages between, for example, food standards in the Global North and gendered exploitative work conditions in the food export industry in the Global South. To conclude, this chapter calls for deliberative approaches to develop just food and water systems by considering the values, preferences, and trade-offs of diverse social groups engaged in these systems.
Given that food production requires a lot of water, more than any other economic sector, one would expect that the world’s food production concentrates in places where water is relatively abundant. This chapter, however, highlights the paradox that various water-poor countries produce food for export to water-rich countries. Food commodity prices do not reflect the cost of water inputs or of damaged water ecosystems, so that the global food market lacks economic incentives to source from places with less harmful impacts on local water systems. The costs of ‘traded’ embedded water thus remain invisible. The chapter proposes an international water label for water-intensive products and argues that international trade rules should include regulations on sustainable water use.
Amir Kassam and David Coates
Conventional tillage agriculture has a built-in propensity for soil erosion and land degradation leading to loss of ecosystem services that are required to sustain agricultural production as well as minimize off-farm impacts. It is associated with suboptimal crop and land productivity. The global uptake of Conservation Agriculture (CA), which is a recognized flagship alternative crop production approach, is built upon three practical interlinked principles of: no or minimum mechanical soil disturbance (‘no-till’), soil cover management, and diversified cropping. The current spread of CA globally is 180 M ha of annual cropland (12.5 per cent), increasing annually at 10 M ha. Knowledge of how CA positively affects ecosystem services at the field and landscape level, with emphasis on water-related services and food security, shows that CA has the potential to meet, or exceed, most of the current shortfall in projected global agricultural water demand by 2050.
Green water is defined as the water in soil that is potentially available to plants for uptake and subsequent transpiration. Despite the fact that crop biomass is directly related to transpiration and the global transpiration flow alone matches that of all the rivers in the world, green water has until recently been largely neglected in research on food security. That long neglect is redressed by a review of recent research on the role of green water in the production of agricultural commodities to meet current and future world food demand, including how the differences in water requirement between plant-based and animal-based commodities play out in respect to the food-water nexus. Informed by current literature, a case is made for optimizing green water management to achieve a global increase in food production from 20 to 40 percent without an expansion of either agricultural land use or the volume of water withdrawn for irrigation.
David Leslie Dent
All fresh water is delivered by the soil. There are two critical junctures: when rain hits the ground—where it may infiltrate or run off carrying the soil with it; and in the soil itself—where it may evaporate from a bare surface, be taken up by roots, or drain to streams and groundwater. Both partitions are managed by farmers so every land-use decision is a water-use decision. Green water is held in the soil and used by plants—the more green water, the more primary production; and the best soils supply orders of magnitude more than the poorest. Practices that maximize the green water resource, such as conservation agriculture, arrest soil erosion, maximize soil water storage and groundwater recharge, and moderate floods. But water consumed in the fields where it falls is not available for use elsewhere.
Incentive Programs to Address the Challenges of Hunger, Undernutrition, and Obesity in the United States
Gus Schumacher and Emily Nink
Across the world, many people remain food insecure, and unhealthy dietary patterns are driving up health costs. Solutions to these problems will impact food production and water scarcity. This chapter reviews the history of government interventions to improve food security and nutrition in the United States, which have enjoyed a “broad coalition” of support over seven decades. More recently, nutrition incentive programs have emerged, aiming to increase purchases and consumption of fresh fruits and vegetables by low-income consumers who benefit from the federal nutrition programs. This chapter explores the development and programmatic success of nutrition incentives, impacts on consumers’ food security and nutrition, impacts on farmers and farmers’ markets, and potential contributions to shifting dietary patterns. As they mature, evolve, and scale, nutrition interventions may deliver shorter supply chains, increase fruit and vegetable consumption, and contribute to a shift toward more sustainable and nutritious foods.
Roger Moussa and Bruno Cheviron
Floods are the highest-impact natural disasters. In agricultural basins, anthropogenic features are significant factors in controlling flood and erosion. A hydrological-hydraulic-erosion diagnosis is necessary in order to choose the most relevant action zones and to make recommendations for alternative land uses and cultivation practices in order to control and reduce floods and erosion. This chapter first aims to provide an overview of the flow processes represented in the various possible choices of model structure and refinement. It then focuses on the impact of the spatial distribution and temporal variation of hydrological soil properties in farmed basins, representing their effects on the modelled water and sediment flows. Research challenges and leads are then tackled, trying to identify the conditions in which sufficient adequacy exists between site data and modelling strategies.