Researchers, policymakers and the international development community need to understand the dynamic interactions occurring within the nexus so that they can identify the key vulnerabilities and risks facing developing countries in terms of water, food and energy security. This will enable them to formulate strategies and policies to mitigate these nexus risks and to promote economic efficiency, social equity and environmental sustainability in food, energy and water provision to their citizens.
Nexus linkages, drivers and risksEnergy, food and water systems need to be understood in terms of their entire value chains, including production, processing, storage, distribution, consumption and waste disposal stages and their supporting infrastructures. Nexus analysis highlights the interconnections and interdependencies at all of these life cycle stages. For example, energy inputs – primarily petroleum fuels and electricity – are required at all stages of the food system value chain, including pumping water for irrigation; powering tractors for tillage and harvesters; production of synthetic fertilisers and pesticides to produce crops and antibiotics to treat livestock; refrigeration; food processing; transporting and distributing food products; cooking; and fuel for transporting food waste to disposal sites. Energy inputs are also needed at various stages of the water system value chain including extraction from lakes, rivers and aquifers; desalination; water treatment; construction of dams, reservoirs and pipelines; pumping for distribution to consumers; and waste-water treatment. Water, in turn, is essential for agricultural production and food processing, and for the extraction and processing of fossil fuels, hydropower generation and cooling in thermal power plants. A number of agricultural crops are converted into bioenergy, which also depends on large amounts of water. Furthermore, certain energy industries – especially fossil fuels – and high-input agricultural production can have adverse impacts on water and soil quality.
Several major global and local drivers are placing increasing pressure on nexus linkages and posing growing challenges for food, energy and water security. On the demand side, these drivers include expanding populations, economic growth, rising affluence, shifting consumption patterns (generally towards greater resource intensity), urbanisation and globalisation. Supply-side drivers include the depletion of conventional fossil fuel reserves (resulting in increasing reliance on more polluting and water-intensive unconventional oil and gas resources), and the degradation of soils, fresh water supplies and ecosystems. Climate change is exerting increasing pressure on water resources and can have destabilising impacts on agricultural production and certain forms of energy generation, especially hydropower. Shocks to the nexus arise principally from extreme weather events such as droughts and floods, and oil and food price spikes – which are sometimes triggered by geopolitical conflict and financial speculation. The main nexus-related risks to energy, food and water security vary according to countries’ levels of development. Low-income, largely agrarian economies typically have high levels of dependence on traditional biomass energy, which renders them vulnerable to deforestation, energy poverty (especially a lack of access to electricity), low-productivity rain-fed agriculture with poor nutritional outcomes and limited access to improved water sources. Droughts can have especially severe impacts in such countries. More advanced developing economies with established industrial capacity generally perform reasonably well in terms of basic energy, food and water security access and consumption levels, with the notable exception of several southern African nations that have high levels of income inequality and poverty. However, many of these middle income countries rely heavily on fossil fuels to power high-input, mechanised agriculture and industries, and complex water supply infrastructures – and are thus exposed to international oil price shocks. Many also face energy-related pollution threats to their water and soil resources.