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.

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.

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.

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。

编辑:Liuxuepaper.Com

作文地带知识拓展:

• 英语（English）属于印欧语系日耳曼语族西日耳曼语支，最早被中世纪的英国使用，并因其广阔的殖民地而成为世界使用面积最广的语言。英国人的祖先盎格鲁部落是后来迁移到大不列颠岛地区的日耳曼部落之一，称为英格兰。这两个名字都来自波罗地海半岛的Anglia。该语言与弗里斯兰语和下撒克森语密切相关，其词汇受到其他日耳曼语族语言的影响，尤其是北欧语（北日耳曼语），并在很大程度上由拉丁文和法文撰写。

  英语的英文释义：

  English 名词 uk  /ˈɪŋ.ɡlɪʃ/ us  /ˈɪŋ.ɡlɪʃ/

  the language that is spoken in the UK, the US, and in many other countries

  英语

  American/British English

  美式／英式英语

  Do you speak English?

  你会说英语吗？

  English   形容词 adjective   uk  /ˈɪŋ.ɡlɪʃ/ us  /ˈɪŋ.ɡlɪʃ/

  in or relating to the English language

  英语的

  an English teacher

  英语老师

  relating to or from England

  英格兰的;英国的

  English films/food/people

  英国电影／食品／人

  English law

  英格兰法律