联合国：“虚拟水”贸易解决全球缺水
英国《金融时报》安德鲁•邦兹(Andrew Bounds)、菲奥娜•哈维(Fiona Harvey)伦敦报道2006年11月10日 星期五
这已成为一个灾难预言者的标准预言：未来内战或地区战争争夺的目标将是水，而不是石油。
然而，正如今年联合国(UN)人类发展报告昨日所指出的，这并不反映全球层面的水资源短缺。地球水系向陆地传输的水量，相当于地球上每个人得到6900立方米的水，是支撑农业、工业以及环境所需总水量的4倍以上。
不幸的是，水资源的分配并不均衡。而且，虽然启动了市场机制来应对失衡状况，但政府补贴有时会造成市场的扭曲。
随着干旱国家开始进口小麦和其它需水量很大的基础作物等大宗商品，“虚拟水”交易开始成形。正如水资源管理学术专家阿尔亚恩•胡克斯特拉(Arjen Hoekstra)所指出的，这是比较优势理论的经典应用。各经济体各展所长。在较为湿润、气候相对温和的地区，土壤中含有更多水分，农业可以依靠廉价的降雨而非成本高昂的灌溉体系。这些地区可以通过农作物，将水“出口”到较为炎热干旱的国家。
世界银行(World Bank)估计，2000年的“虚拟水”交易量达13400亿立方米，是全球作物生长用水的四分之一。这可能意味着推翻数千年的生产模式，连传统主食也进入进口之列。
最近几十年来，埃及从法老王时代以前就开始食用的扁平面包，已越来越多地使用进口粮食制作，而非尼罗河水养育的小麦。如果埃及所有的谷物都由自己种植，所需水量将占阿斯旺(Aswan)大坝水库蓄水量的六分之一。
但是，与任何贸易一样，虚拟水作物的国际贸易也存在扭曲和失效问题。最常见的原因是政府对农民的补贴，这种做法有时会被冠以国家安全的理由。以埃及为例，该国大约一半的小麦仍由自己种植。
事实上，灌溉用水的供应和定价，有时更多地是受到富裕农民的影响，而非出于比较优势。
提出虚拟水概念的伦敦亚非学院(School of Oriental and African Studies)学者托尼•阿兰(Tony Allan)指出，富裕的约旦农民将水资源密集型蔬菜出口到湿润的欧洲。
译者/ 陈家易
SUBSIDIES INTERRUPT FLOW OF ‘VIRTUAL WATER'
By Alan Beattie and Fiona Harvey in London
Friday, November 10, 2006
It has become a standard doomsayers' prediction that the civil and regional wars of the future will be over water rather than oil.
However, as this year's United Nations human development report yesterday pointed out, this does not reflect a global shortage. The planet's hydrological system transfers about 6,900 cubic metres of water to the land for every human on earth, more than four times the amount needed to support farming, industry and the environment.
Unfortunately, that water is unevenly distributed. And, while market mechanisms have sprung up to cope with imbalances, these markets are sometimes distorted by government subsidy.
A trade in so-called “virtual water” arose as dry countries began importing commodities such as wheat and other basic grains that require a lot of water. As Arjen Hoekstra, an academic expert in water management, points out, this is a classic application of the theory of comparative advantage. Economies do what they are relatively good at. Wetter and more temperate regions, where the soil holds much more water and agriculture can rely on cheaper rainfall rather than expensive irrigation, export water to hotter, drier countries.
The World Bank estimates that 1340bn cu m in “virtual water”, a quarter of all the water used on the planet to grow food, was traded in 2000. This can mean overturning millennia-old patterns of production, even importing traditional staple foods.
In recent decades the flatbread eaten in Egypt since before the time of the pharaohs has increasingly been made from imported grain rather than wheat grown by the Nile. If Egypt grew all its own cereals, it would require one-sixth of the water in the Aswan dam reservoir.
But like any trade, the international commerce in virtual-water crops has distortions and inefficiencies. The most familiar reason – government subsidies to farmers – is sometimes given a national food security rationale. Egypt, for instance, still grows about half its own wheat.
In truth the provision and pricing of water for irrigation sometimes owes more to the clout of rich farmers than it does to comparative advantage.
Tony Allan, an academic at the School of Oriental and African Studies in London who developed the concept of virtual water, points at the rich Jordanian farmers who export water-intensive vegetables into damp Europe.
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