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1、从冰山获取淡水 Obtaining Fresh water from icebergsThe concept of obtaining fresh water from icebergs that are towed to populated areas and arid regions of the world was once treated as a jok e more appropriate to cartoons than real life. But now it is being conside red quite seriously by many nations, espe
2、cially since scientists have warned that the human race willoutgrow its fresh water supply faster than it runs out of food. Glaciers are a possible source of fresh water that has be en overlooked until recently. Three-quarters of the Earths fresh water su pply is still tied up in glacial ice, a rese
3、rvoir 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 e ncased in 10000 icebergs that break away from the polar ice caps, more than ninety percent of them from Antarctica.Hug
4、e glaciers that stretch over the shallow continental shelf givebirth toicebergs throughout the year.Icebergs are not like sea ice, whichis formed when the sea itself freezes, rather, they are formed entirely onland, breaking off when glaciers spread over the sea. As they drift away from the polarreg
5、ion, icebergs sometimes move mysteriously in a direction opposite tothe wind, pulled by subsurface currents. Because they meltmore slowly than smaller pieces ofice, icebergs have been known to drift as far north as 35 degrees southof the equator in the Atlantic Ocean. To corral them and steer them t
6、o p arts 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 producedby desalinization, or removing salt from water。