Obtaining fresh water from icebergs

冰山取淡水

     The concept of obtaining fresh water from icebergs that are towed to populated areas and arid regions of the world was once treated as a joke more appropriate to cartoons than real life. But now it is being considered quite seriously by many nations, especially since scientists have warned that the human race will outgrow its fresh water supply faster than it runs out of food.  

   有人曾提出把冰山拖到居民区和干旱地区以取得淡水。这一想法一度传为笑谈，认为它更适合于卡通故事而非真实生活。不过现在却有许多国家极其认真地考虑这个问题，尤其是在科学家警告说人类失去淡水快于耗尽食物以后。

    Glaciers are a possible source of fresh water that has been overlooked until recently. Three-quarters of the Earth's fresh water supply is still tied up in glacial ice, a reservoir of untapped fresh water so immense that it could sustain all the rivers of the world for 1,000 years. Floating on the oceans every year are 7,659 trillion metric tons of ice encased in 10000 icebergs that break away from the polar ice caps, more than ninety percent of them from Antarctica.

   冰川可能是一种淡水源。而这过去一直被世人所忽略。地球上3/4的淡水仍与冰川冰紧密联系在一起。冰川冰是一座未曾使用的淡水库，其蕴量足以维持世界上所有河流1000年。每年有10000座冰山共计7659万亿公吨的冰在大海中流动。这些冰山是从极地冰盖脱离而来，其中百分之九十以上是来自南极。

    Huge glaciers that stretch over the shallow continental shelf give birth to icebergs throughout the year. Icebergs are not like sea ice, which is formed when the sea itself freezes, rather, they are formed entirely on land, breaking off when glaciers spread over the sea. As they drift away from the polar region, icebergs sometimes move mysteriously in a direction opposite to the wind, pulled by subsurface currents. Because they melt more slowly than smaller pieces of ice, icebergs have been known to drift as far north as 35 degrees south of the equator in the Atlantic Ocean. To corral them and steer them to parts of the world where they are needed would not be too difficult.

   巨大的冰川延伸覆盖在浅大陆架上，四季不断，生成许多冰山。冰山与海冰不同。海冰是海水本身冻结而成，更确切地说它们是完全生成在陆地上，在冰川延伸覆盖到海上时断裂。冰山有时在漂离极地时会在次表层流的推动下奇怪地逆风而行。因为冰山融化比小冰块慢，所以它们在大西洋中向北漂流远至赤道以南35度。把这些冰山聚集起来送往世界上需要它们的地方，这大概不会太难。
     The difficulty arises in other technical matters, such as the prevention of rapid melting in warmer climates and the funneling of fresh water to shore in great volume. But even if the icebergs lost half of their volume in towing, the water they could provide would be far cheaper than that produced by desalinization, or removing salt from water.

  难就难在其它技术性的问题上，比如防止冰山在温暖气候下快速融化以及淡水大量地汇集到海滨。但是，即使冰山在拖运过程中损失一半，它们所能产生的水也远比通过淡化或者从水中脱盐得到的淡水便宜。