Why? The difficulties start with the sheer number of people using the stuff. When, 60 years ago, the world's population was about 2.5 billion, worries about water supply affected relatively few people. Both drought and hunger existed, as they have throughout history, but most people could be fed without irrigated farming. Then the green revolution,in an inspired combination of new crop breeds, fertilizers and water, made possible a huge rise in the population. The number of people on Earth rose to 6 billion in 2000, nearly 7 billion today, and is heading for 9 billion in 2050. The area under irrigation has doubled and the amount of water drawn for farming has tripled. The proportion ofpeople living in countries chronically short of water is set to rise from 8% at the turn of the 21st century to 45% by 2050.
為什么會是這樣呢？首要的困難就是用水的人實在太多。60年前，世界人口約為25億，供水問題只影響到較少的人。那時也有干旱和饑荒，就像它們在整個人類歷史進程中都存在—樣，但是多數(shù)人還可以不靠灌溉農(nóng)業(yè)為生。后來綠色革命興起了，它將新品種的培育、肥料和水的使用有機地結(jié)合起來，使得人口劇增。地球上的人口在2000年猛增到60億，現(xiàn)在已接近70億，到2050年將逼近90億。用水灌溉的土地面積已經(jīng)翻番，農(nóng)業(yè)用水量增加了兩倍。到2050年，居住在長期缺水的國家的人口比例將由21世紀初的8%上升到45%。
Farmers' increasing demand for water is caused not only by the growing number of mouthsto be fed but also by people's desire for better-tasting, more interesting food. Unfortunately, it takes nearly twice as much water to grow a kilo of peanuts as a kilo of soybeans, nearly four times as much water to produce a kilo of beef as a kilo of chicken. With 2 billion people around the world about to enter the middle class, the agricultural demands on water would increase even if the population stood still.
農(nóng)民對水不斷增長的需求不僅僅是因為不斷增加的人口需要養(yǎng)活，還因為人們對味道更好、更刺激他們味蕾的食品的追求。不幸的是，種植一公斤花生比種植一公斤大豆多需要近一倍的水；要生產(chǎn)一公斤牛肉比生產(chǎn)一公斤雞肉要多用近三倍的水。隨著世界上有20億人口就要進入中產(chǎn)階層，即便人口不再增長，農(nóng)業(yè)用水的需求也會增加。
來源:可可英語 http://www.ccdyzl.cn/daxue/201810/566579.shtml
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