Virtual water flows between nations in relation to trade in livestock and livestock products

The virtual water content of a commodity is the volume of water used to produce this commodity. International trade in food implies international flows of virtual water. For water-scarce countries it can be attractive to import virtual water (through import of water-intensive products), thus relieving the pressure on the domestic water resources. This study aims to develop a methodology to assess the virtual water content of various types of livestock and livestock products and to quantify the virtual water flows related to the international trade in livestock and its products. The results are then combined with the estimates of virtual water trade flows associated with international crop trade as reported in Hoekstra and Hung (2002, 2003), to get a comprehensive picture of the international virtual water flows. The study covers the period from 1995 to 1999. First, the virtual water content (m3/ton) of live animals is calculated, based on the virtual water content of their feed and the volumes of drinking and service water consumed during their lifetime. Second, the virtual water content is calculated for each livestock product, taking into account the product fraction (ton of product obtained per ton of live animal) and the value fraction (ratio of value of one product from an animal to the sum of the market values of all products from the animal). Finally, virtual water flows between nations are derived from statistics on international product trade and virtual water content per product. The global volume of international virtual water flows is estimated to be 1031 Gm3 per year (695 Gm3/yr from the trade in crops and 336 Gm3/yr from trade in livestock and livestock products). This means that about 20% of the global water use in agriculture is aimed at producing products for export. The countries with the largest net virtual water export are: the United States, Australia, Canada, Argentina and Thailand. The countries with the largest net virtual water import are: Japan, Sri Lanka, Italy, South Korea and the Netherlands. The total water use within a country itself is not the correct measure of a nation’s actual appropriation of global water resources. In the case of net import of virtual water into a country this virtual water volume should be added to the total water use within the country, in order to get a picture of a nation’s real call on the global water resources. Similarly, in the case of net export of virtual water from a country this virtual water volume should be subtracted from the volume of internal water use. The total of internal water use and net virtual water import can be seen as the ‘water footprint’ of a country, the total volume of water needed to produce the goods and services consumed by the inhabitants of the country. This concept is analogous to the ‘ecological footprint’ of a nation, a concept that refers to the amount of land needed to produce the goods and services consumed by the inhabitants of a country. This study calculates the water footprint for each nation of the world. This study does not yet include green water use within the country. Future research on water footprints should include this part of water use as well, to get a more realistic figure