Jenny Kehl Straits Times 18 Mar 13;
ONE often does not hear of water "moving" across oceans, locked in sacks and cartons of food. Yet food exports hide the significant global trade in water, which could be made transparent and reorganised to reduce water stress and increase global food security.
Several of the world's most water-scarce regions are producing the most water-intensive crops - for example, water-intensive rice grown in arid parts of Australia, Mexico and the American West for export to Asia or Europe.
Many of these water-intensive crops are traded globally along with their water content and the water consumed in the production process. The trade, now referred to as virtual water exports, constitutes a net loss of water from water-scarce regions.
Why virtual water matters
VIRTUAL water is the embedded water used to produce agricultural and industrial goods. Estimates by Unesco-IHE, the international institute for water education, found some 1,040 billion sq m of virtual water are traded each year globally. This trade could be reorganised for water-scarce regions to become virtual importers, a reversal of their current net loss, and water-rich regions to become virtual exporters.
The reality is that it takes more water overall to produce water- intensive crops in water-scarce regions. This constitutes an inefficient use of water. For example, it requires twice as much water to produce grain in water-scarce regions as in water-rich regions.
A 2005 study suggests that producing 1kg of grain in favourable climactic conditions requires up to 2,000kg of water; the same amount in an arid country requires up to 5,000kg. The difference is due largely to high temperature, high evaporation, soil conditions and other climate factors.
It also means that global coordination is needed as water scarcity increases. Water scarcity and food security are inextricably linked.
Agriculture is the largest water user, requiring about 70 per cent of all water used for human production and consumption. For example, it takes around 500 litres of water to produce one cup of rice and 4,500 litres to produce a 300g serving of beef.
Virtual water is deemed a consumptive use, meaning it's not returned to its local hydrological system, often resulting in a net water loss from the region when the products are exported. Virtual water exports exacerbate scarcity, food insecurity, and income loss. The imbalances could subsequently decrease political stability and stunt economic prosperity.
Approximately one-fourth of all water used in production is traded through water-intensive commodities in the international market. In short, this means that one-fourth of water use is exported as virtual water. The amount is even higher in countries that are large food and grain exporters. For example, the United States exports approximately one-third of its total water withdrawal in the country. The scale of the virtual water trade is expected to increase as global demand for food increases with population growth and economic development.
Water-scarce regions can mitigate food shortages and improve water-use efficiency by importing agricultural products with high virtual water content and exporting products with low virtual water content. Yet the opposite is the current reality.
Water-scarce regions are overwhelmingly producing and exporting water-intensive products. Arid parts of Egypt, Turkey and Eastern Europe produce large quantities of water-intensive cotton for export to Asia and Europe.
What S'pore, Malaysia did
YET international water-use inefficiencies are not a fait accompli. International water trade and food output can be improved if the idea of comparative advantage is applied to decisions about importing versus exporting water- intensive crops. Water-scarce countries should import water- intensive grains and export products with less virtual water content.
Based on scarce land and water resources, Singapore and Malaysia have used the international food market to import water- intensive grains and meats; they export mostly non-agricultural value-added manufactured goods. This lets them maintain food security while harnessing scarce water resources for competing uses.
Internationally, adjusting to the new information and emerging realities can improve water- use efficiency and food security. Virtual water flows in the international economy are measured as net water gain/water loss in global water-use efficiency.
A net water loss, for example, occurs if a water-intensive grain is produced in a water-scarce country. Such loss will be seen in two ways: First, the water-scarce country is exporting virtual water, which constitutes a domestic net water loss. Secondly, it decreases global water-use efficiency because it requires more water overall to produce certain crops in water-scarce regions.
Global cooperation needed
CORRECTING inefficiency in global water-use requires substantial international coordination. A high level of cooperation is possible in this area, as the food crop trade is globalised and food security highly interdependent. It is the dearth of information about the hidden water trade and the current lack of coordination that perpetuates global water-use inefficiencies.
Finally, the Food and Agriculture Organisation of the United Nations and the Organisation for Economic Cooperation and Development have the experience, and are best suited, to provide information about global water-use efficiency and coordinate the world's large food producers and consumers. We must look for the water hiding in plain sight.
YALE GLOBAL
The writer is the endowed chair of the School of Freshwater Sciences and director of the Centre for Water Policy, University of Wisconsin-Milwaukee.
