To meet growing food demand, in another 40 years the world would need enough water to fill at least three lakes the size of Victoria, Africa's largest body of water, according to a projection in a new policy brief. Lake Victoria's estimated volume is 2,750 km3.
In Saving Water: From Field to Fork – Curbing Losses and Wastage in the Food Chain, a policy brief by the Stockholm International Water Institute (SIWI), the Food and Agriculture Organisation (FAO) and the International Water Management Institute (IWMI), projected food and cereal demand could double by 2050, and the world would need 10,000 to 13,500 km3/year of water supply to keep up with production requirements.
Enormous amounts of water are required to produce food: since the beginning of this century, about 7,000 km3 of water has evaporated or transpired every year in producing crops to meet global food demand, the paper said.
Between the farmer's field and the fork, almost half the food on our tables is lost in food storage, transport, food processing, retailing and in kitchens, the paper noted, arguing that "This loss of food is equivalent to a loss in water."
Depending on the crop, an estimated 15 to 35 percent of food may be lost in the field, the brief said.
"Another 10 to 15 percent is discarded during processing, transport and storage. In richer countries, production is more efficient but waste is greater: people toss the food they buy, and all the resources used to grow, ship and produce the food along with it."
More than enough food is produced to feed a healthy global population, according to Jan Lundqvist of SIWI. "The attention now, because of the global food crisis, has shifted towards improving food production, while no one is paying attention to address the losses and wastage already taking place," he told IRIN.
"Distribution and access to food is a problem, while at the same time many people in many parts of the world over-eat," Lundqvist added.
Growth rates have risen in populous Asian countries such as China and India and some African countries, and "People have access to more money and diets that include meat and milk," Lundqvist pointed out. This meant the production of more grain to feed livestock, which in turn implied a need for more water.
Cereal demand projections are in the range of 2,800 to 3,200 million tonnes by 2050, an increase of 55 to 80 percent compared with today, said the brief, citing several studies.
"Much of the future increase will be fed to animals to satisfy the demand for meat. Today, some 650 million tonnes of grain – nearly 40 percent of global production – is fed to livestock, and this may reach 1100 million tonnes by 2050."
Meat and dairy production is more water-intensive than crop production. "For example, 500 to 4,000 litres of water are evaporated in producing one kilogram of wheat, depending on climate, agricultural practices, variety, length of the growing season and yield," the brief noted.
"However, to produce one kilogramme of meat takes 5,000 to 20,000 litres, mainly to grow animal feed. In terms of the energy content of food, approximately 0.5 m3 of water is needed to produce 1,000 kcal of plant-based food, while for animal-based food some 4 m3 of water is required."
A spanner in the works
Rising global temperatures as a result of climate change are set to impact on water availability. Various scenarios by the Intergovernmental Panel on Climate Change (IPCC) suggest that climate change will affect 75 million to 250 million people in Africa, where potential yields in rain-fed systems in some areas may decline by up to 50 percent by 2020.
"Agriculture in countries in Central, South and South-East Asia, which are largely dependent on river water for irrigation, will be hit by a projected drop in river levels. An estimated 1.4 billion people already live in areas where there is not enough water available to meet all needs from sectors of society, let alone the need of aquatic ecosystems," said the policy brief.
What needs to be done
Governments need to support farmers, especially small farmers, to curb losses of water and food with improved seeds, harvesting technologies, better transport and storage, Lundqvist said.
A large portion of rainfall is unfortunately lost in Africa and Asia, he added. "Countries have to come to up with innovative ways to capture and beneficially use the rain falling on farmers' fields to increase the fraction of the rains that can be productively used, and to lessen stresses on rivers and groundwater."