Water and Food: How, When, and Why Water Imperils Global Food Security

Every October, World Food Day calls attention to global food security and the actions needed to combat hunger and malnutrition. This year, the Food and Agriculture Organization of the United Nations (FAO) is highlighting sustainable water management as key to the future of food. The United Nations anticipates agricultural production will have to grow 50 percent to meet rising demands in 2050, prospectively requiring global water withdrawals 30 percent higher than today. Yet an estimated 2.4 billion people now live in countries confronting water stress and almost 40 percent of global croplands already experience water scarcity, fueling concerns that mounting needs risk colliding with increasingly strained supplies.

Q1:What is the connection between water resources and food production?

A1: Every person needs 50 to 100 liters of water per day to meet basic drinking, cooking, and hygiene requirements. By comparison, it takes 2,000 to 5,000 liters of water per person per day to grow the food to support diets of 2,800 kilocalories daily, the benchmark for food security used by the FAO. To harvest a kilogram of wheat, for example, necessitates over 1,800 liters of water. Raising a kilogram of beef takes over 15,000 liters (mostly to grow the feed consumed by the cattle). All told, agriculture accounts for 72 percent of global freshwater withdrawals—amounting to nearly 3,000 cubic kilometers of water—taken from the world’s rivers, lakes, and groundwater aquifers each year. In many developing countries from India to Ethiopia, agriculture’s share of water withdrawals tops 90 percent. Healthy freshwater systems and cycles also sustain other important food resources such as livestock pasturage, freshwater fisheries, and aquaculture.

Humanity’s agricultural water use has grown so significant that it shapes global climate mechanisms and even shifts the planet on its axis. South Asian irrigation systems redirect so much water from rivers and aquifers to farmers’ fields that agriculture on the subcontinent substantially influences the Indian Ocean monsoon, impacting precipitation patterns from East Africa to East Asia. Worldwide, relentless pumping from underground reservoirs has removed enough water to measurably tilt the Earth’s axis of rotation.

Q2: What is the relationship between water scarcity and food security?

A2: Water and food security are inextricably interlinked. Food security is defined in terms of food availability, access, utilization, and stability, such that all people at all times have physical and economic access to sufficient quantities of safe and nutritious food that meets their dietary needs and food preferences. Water scarcity, in turn, affects not just the quantities, but also the quality, variety, and seasonal availability of foods that can be produced and consumed. Thus, at the global level, water resource stresses, such as droughts in cereal-producing nations, can contribute to grain supply shortfalls jeopardizing food security for hundreds of millions of people. From 2007–2008, for example, a confluence of low global grain reserves, rising energy prices, reduced harvests, international trade restrictions, and other factors precipitated a global food price crisis that plunged an additional 75 million people into chronic hunger. As world wheat prices surged by 72 percent, one study calculated that the recurrent droughts that then parched Australia—a major exporter—were responsible for over a fifth of the global price shock at the time. At local and farm levels, water constraints can push producers to employ polluted water sources that may then compromise or contaminate food supplies.

Similarly, household water insecurity can undermine household food security via multiple pathways. Scarce or polluted water supplies can hamper people’s ability to grow a garden, raise livestock, or safely prepare available foods. Water shortages can force families to spend more financial resources and effort to obtain water, obliging choices among other necessities and detracting from time devoted to work or school. And limited water supplies can push families to alter the foods they cook and consume, shifting their diets to less water-intensive but also less nutritious foods.

Q3: How does increasing water stress put global food systems at risk?

A3: In the coming decades, the world’s population will grow by close to 2 billion people, climbing from 8 billion people in 2022 to 9.7 billion in 2050. Nearly all of this growth will occur in Africa and Asia. Global GDP is anticipated to more than double by mid-century, expanding from $101 trillion in 2020 to $205 trillion (2015 USD) in 2050. Likewise, global GDP per capita is projected to rise from $16,784 in 2020 to $42,304 per person in 2060 (2005 USD). With higher incomes, dietary preferences and possibilities shift, boosting demand for more water-intensive foods such as dairy, eggs, and meat. Larger, richer populations typically demand and can afford greater water use overall. The Organization for Economic Cooperation and Development projects that global water use will jump 55 percent from 2000 levels by 2050, including a 400 percent spike in demand from manufacturing, a 140 percent rise in withdrawals for electricity production, and a 130 percent increase in domestic needs. Growing claims from other sectors could come to squeeze agricultural requirements. As water demands expand and evolve, the World Bank considers some 25 to 40 percent of global water withdrawals will need to be reallocated to higher-value uses, shifting from relatively lower-value applications such as agriculture.

Parts of the world are already bumping up against the limits of their renewable water resources. For several major river systems supplying key agricultural regions —including the Colorado, Ganges, Indus, Nile, Tigris-Euphrates, and Yellow River—yearly water withdrawals nearly equal or even exceed long-term flow balances and ecosystem needs. Hydrologists consider these rivers “closed,” meaning that, under prevailing practices, almost all of their annually available renewable waters are already committed to various human or environmental requirements, with little if any buffer remaining to accommodate new demands. Underground aquifers currently supply one third of all water use, providing half of global irrigation needs. But withdrawals in many major aquifers surpass natural rates of replenishment, progressively lowering water tables and exhausting groundwater reserves. Considering both surface and groundwater sources together, one recent global assessment found that two to three billion people live in areas where total net water withdrawals outstrip locally available renewable supplies for four to six months of the year. For half a billion people, net demand outpaces supply all year round. Without substantial changes to present policies and practices, over 80 percent of global croplands could face water scarcity by mid-century.

Q4: How will climate change impact world water and food resources?

A4: Global climate change threatens to exacerbate pressures on water resources and food production. As temperatures rise, crop water productivity will largely fall, all else being equal, necessitating larger water inputs to realize the same yields. Consequently, the FAO estimates that meeting growing agricultural demand under climate change will require an additional 40 to 100 percent more water than would have been needed absent its impacts. Climate change is projected to upset elemental patterns and processes such as the El Niño-Southern Oscillation and the onset of the monsoon. Such impacts could scramble the seasonal availability or shuffle the geographical distribution of crucial water supplies for agriculture worldwide. Shifts in the volume, timing, location, and form of precipitation could particularly disrupt the majority of global agricultural production that is rain-fed and unsupported by managed irrigation.

Climate change will also affect the occurrence of water-related disasters. Climate models project that heavy precipitation, floods, and droughts will strike more frequently and severely. Warming of 2 degrees Celsius above preindustrial averages could double the global population annually exposed to significant river flooding and increase the population exposed to drought threefold or more. Agri-food systems often bear the brunt of such catastrophes, absorbing 63 percent of loss and damages compared to other sectors. Extreme storms, floods, and droughts can wipe out crops and livestock and damage or destroy agricultural equipment and infrastructure. For 8 of the 15 years from 2000 to 2014, global grain consumption exceeded production, primarily due to harvest-diminishing droughts in key breadbasket regions. Absent robust adaptations to global warming, climate impacts could reduce major crop yields by 11 percent in the coming decades.

Q5: What kinds of policy solutions can help address these challenges?

A5: Several changes in policy, technology, and consumer behavior can help improve water and food security.

Reduce food wastage. Perhaps a third of global food production is lost or wasted from field to fork along the food supply chain. Lost and wasted food means wasted water. While supply chain inefficiencies exist worldwide, in more developed countries, significant amounts of food are also discarded for cosmetic reasons, such as bruises, scars, or blemishes on products. In developing countries, more food is lost in processing and transport phases due to inadequate infrastructure to store foods and move them to market without spoilage. Cutting food waste by 25 percent would curb the associated water demands and provide food to feed 900 million people.

Reform subsidies. Governments worldwide devote $817 billion a year to subsidizing agriculture and $320 billion to water (and sanitation) subsidies. Subsidies can be important tools promoting water and food security when they are effectively designed and targeted. Too often, however, subsidies are distortionary, encouraging overexploitation of resources and generating environmental damage while failing to benefit the poorest and most vulnerable. Worldwide, the most water-intensive commodities, like beef and dairy, receive the most subsidy support—while also producing comparatively more climate-warming greenhouse gas emissions than other agricultural sectors. Meanwhile, more than half of global water subsidies go to the wealthiest 20 percent of the population, while just 6 percent of subsidies reach the poorest 20 percent.

Reuse and recycle. Planned recovery and reuse of wastewater for agricultural purposes is common in countries around the Middle East and Mediterranean, as well as parts of Australia, China, Mexico, and the United States. Wastewater streams are typically rich in dissolved nutrients, making them attractive irrigation sources, especially in peri-urban areas and where conventional surface and groundwater supplies are increasingly stressed. Between 2 to 7 percent of the world’s total irrigated land is irrigated with raw or diluted wastewater, though much of this use may be unsafe if the reclaimed waters are inadequately treated for agricultural application. With appropriate treatment, however, the 330 cubic kilometers of municipal wastewater generated annually could potentially cover the needs of 15 percent of all irrigated croplands.

Promote information innovation. Effective water management depends on accurate, timely, and consistent information. Advances in remote sensing technologies increasingly allow systematic data collection on important indicators such as crop water use, land use changes, groundwater depletion, and water quality. Drone-based sensors can supply data on individual fields and streams. Innovation in “big data” analytics can enable water managers to integrate multiple data streams, from rainfall patterns to demand trends, to formulate predictive models to guide decisionmaking—and inform early warning systems for risks to water and food security.

Promote infrastructure innovation. Too many agricultural communities labor without adequate infrastructure for effectively storing, treating, moving, and utilizing water. Common irrigation methods, for example, can be highly wasteful, applying considerably more water than necessary. Precision irrigation techniques, in contrast, integrating system-scale irrigation infrastructure with “on-farm” water delivery equipment and data-driven management tools, can allocate irrigation water down to the individual field plot and plant-level, achieving far greater crop per drop. Not all innovative practices, though, rely on the latest technologies. Managed aquifer recharge, sometimes called “groundwater banking,” capitalizes on existing natural infrastructure, collecting excess surface waters when available—by capturing stormwater runoff, floodwater flows, reservoir releases, etc.—to strategically replenish underground aquifers for later use.

David Michel is the senior fellow for water security with the Global Food and Water Security Program at the Center for Strategic and International Studies in Washington, D.C.