Texas rice farmers recently had their irrigation water cut off to ensure that there will be enough water for urban and industry needs, as the state suffers from the most serious one-year drought in its history. Mexico’s worst drought in 71 years has lowered food production by 40 percent and left two million Mexicans without adequate food. And in India, climate change is making monsoon rainfall less frequent and more intense, leading to lower yields of many crops.
Extreme weather due to climate change is already affecting agricultural yields and food security around the world. In 2010, wheat prices soared in response to the shrinking of Russia’s wheat harvest after a drought and the country’s subsequent ban on wheat exports.
By December 2010, the Food and Agriculture Organization of the U.N.’s Food Price Index had surpassed its 2008 peak; 2011’s food prices were the highest ever recorded. The rising price of food is one reason why there are one billion hungry people in the world.
The global population, now 7 billion, is expected to reach 9 billion by 2050, and will require 70 percent more food than we are producing today (100 percent in some developing countries). As the world’s population grows and standards of living rise, there is increased demand for grain-fed meat and dairy products. The World Bank has projected a 50 percent rise in cereal consumption by 2030 and an 85 percent increase in meat consumption; this means a greater demand for water, as it takes 10 times as much water to produce a kilogram of beef as it does to produce a kilogram of wheat. In addition, more water will be required for the drinking water and industry needs of the growing populace. By 2030, overall water consumption is expected to rise 30 percent (some scenarios project water for agriculture alone to increase 35 to 60 percent by 2025).
There is enough water on earth to meet the increased demand, but the supply of water is not evenly distributed and often not available where people most need it. As a result, water scarcity affects 40 percent of people today and the U.N. projects that two-thirds of the global population could be living with water stress by 2025.
Agriculture uses 70 percent of the world’s freshwater for irrigation.
Irrigation water is either drawn from surface water (Surface water irrigation’s efficiency ranges from 25 to 60 percent) or underground aquifers. While most aquifers are replenished by rainfall, ancient fossil aquifers, such as the Ogallala in the Great Plains of the U.S., or those in the North China Plain and in Saudi Arabia, do not get recharged. Because farmers have drilled more and more wells to access underground water for irrigation, half the global population now lives in countries where water tables are falling fast, aquifers are being polluted and millions of irrigation wells are drying up. The over-pumping of aquifers is a serious concern, since 40 percent of the world’s food production depends upon irrigation.
Climate change will continue to disrupt agricultural production and food security. In Africa, Asia, and Latin America, where most future population growth will occur, drought is the primary cause of food shortages. Rising temperatures will affect crop yields (grain yields decline 10 percent for each 1˚C rise in temperature above optimum conditions) and water resources, especially in areas such as the Mediterranean Basin, parts of North and South America, Australia and Southern Africa, which are already water stressed.
Extreme weather events damage crops, warming temperatures increase the prevalence of pests and crop diseases, earlier thaw of snow packs lessens runoff in summer months when it’s most needed, melting glaciers will eventually reduce the flow of major rivers that many cities and farmers depend on, and sea-level rise will affect production in low-lying coastal areas and allow saline intrusion into freshwater aquifers. While some regions closer to the poles may experience increased agricultural productivity from the changing climate, those nearer the equator will likely be hard hit by rising temperatures and extreme weather.
Then there is the fact that agriculture is often on the losing side of the battle for water between farmers and the growing urban population. By 2050, 75 percent of the world’s people are expected to be urban. Fast-growing cities around the world that need water are diverting it from farmers, like the Texas rice-growers, because they can offer more for it than farmers can earn by irrigating their crops.
When countries cannot produce enough food to feed their people, they must import grain—for example, South Korea imports 70 percent of its grain and Yemen imports 80 percent. Rich countries, such as Saudi Arabia, South Korea and China, are also buying or leasing land in Indonesia, the Philippines, Brazil, Ethiopia, Democratic Republic of the Congo and Sudan to grow crops. Lester Brown, founder of the Earth Policy Institute, calls land acquisition “a claim on the water resources of the host country.” He says, “Land grabbing is an integral part of a global power struggle for food security,” and is concerned that, along with volatile food prices, it could well lead to political instability.
According to the Institution of Mechanical Engineers’ new report, Population: One Planet, Too Many People?, “Virtually all the world’s prime agricultural land currently available is now used to grow food and fibre for humans and livestock.”
In the past, gains in crop yield were made through the development of higher-yielding crops, intensive use of fertilizer and increased irrigation, and were based on getting the most from each unit of land. Now, as we face aquifer depletion, soil erosion, water pollution from fertilizer and pesticide runoff, melting glaciers, heat waves, drought, and ecosystem and biodiversity losses, the focus needs to shift to maximizing crop yield per unit of water used.
The ways to conserve water, make irrigation more efficient and increase agricultural yield are well known. According to the engineers’ report, many of the food and water issues that confront us can be met using technologies that are already available or nearing availability. “…Sustainable engineering solutions largely exist for many of the anticipated challenges. What is needed is political and social will, innovative financing mechanisms, and the transfer of best practice through localisation to achieve a successful outcome.” In other words, it is not what needs to be done, but how, that presents the biggest challenge.
Some of the Earth Institute’s centers are figuring out just how to get things done.
Punjab, considered the “breadbasket of India,” produces 20 percent of the country’s wheat and 12 percent of its rice. The intense annual wheat and rice cropping uses large amounts of fertilizer to keep yields up, and copious amounts of groundwater for irrigation. As a result, water tables are falling in 90 percent of the state. The Columbia Water Center is working with Punjab Agricultural University to identify water-saving strategies for rice cultivation, promote more water-efficient cropping strategies, and scale up the use of tensiometers.
Tensiometers are affordable tools that measure soil moisture and let farmers know when it’s necessary to water and when it’s not. In a pilot project, 525 farmers were given tensiometers; they ended up using 22 percent less water and 24 percent less energy (for irrigation pumping).
In Nusa Tenggara Timur, one of Indonesia’s poorest provinces, agriculture depends mainly on rainfall, which can vary greatly each year. Harvests often fall short, resulting in acute malnutrition among children. The International Research Institute for Climate and Society and its partners are using monsoon forecasts and other climate information to inform decision making about the timing of planting so that crop failures might be averted.
The Earth Institute is working with African scientists to develop detailed digital maps of soils in 42 countries of sub-Saharan Africa. The Africa Soil Information Service project is using digital soil mapping and other techniques to evaluate, map and monitor the soils; testing new soil management techniques that improve crop yields and soil fertility; and identifying soil areas at risk of degradation and appropriate rehabilitative measures. The Center for International Earth Science Information Network is helping to build the information systems for collecting, analyzing, and disseminating the data to potential users. The project is part of a larger plan to map the world’s soils.
Here are additional solutions to the food/water challenges put forth by U.N. Water, the Food and Agriculture Organization of the U.N., F.A.O.Water, the Institution of Mechanical Engineers, and the Earth Policy Institute.
- Stop the practice of delivering water of drinking water quality regardless of its intended use
- Recycle treated wastewater, drainage water, and desalinated water for agricultural use
- Provide separate sewage and stormwater systems so that stormwater can be stored and used for drier times, and for domestic and commercial washing functions, toilet flushing, etc.
- Improve water harvesting and retention with dams, pits, and green infrastructure
- Replenish aquifers through natural infiltration, wells, or the use of treated wastewater, recycled stormwater or rainfall
- Change from less-efficient flood or furrow style irrigation to overhead sprinklers (which reduce water use by 30 percent) or drip irrigation (which reduces water use by 50 percent), and improve the efficiency of irrigation through the use of sensors on sprinkler arms that deliver water, or that detect areas with water stress
- Minimize food waste because food waste is water waste. About 30 percent of the food produced worldwide is lost or wasted each year.
- Practice conservation agriculture, which involves reduced soil disturbance, organic soil cover and diversification of crops
- Give farmers access to quality seeds, fertilizers, tools, and technical assistance and training to help increase crop yield
- Plant crops that are more water-efficient
- Employ biotechnology to develop crop varieties that are more drought, heat and cold tolerant
- Practice multiple-cropping so that land can produce more than one crop a year
- Protect forests to prevent soil erosion and desertification, and reduce the effects of floods and droughts
- Defend against sea level rise; a 3-foot rise could flood some of the world’s important low-lying rice growing areas
- Promote the technologies and training needed to enable farmers to take charge of their own community’s water development and management
- Raise the price of water to reflect its true value and provide incentives for farmers to use more efficient irrigation techniques
- Establish micro-financing, loans and new models of personal and community ownership to reduce the capital investment and encourage the adoption of local sustainable technologies
- Prioritize research into desalination to increase its energy efficiency and bring its cost down