Obtaining Fresh water from icebergs
[size=3][color=#29384e][font=Times New Roman]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[/font][font=宋体]，[/font][font=Times New Roman] especially since scientists have warned that the human race will outgrow its fresh water supply faster than it runs out of food.[/font][/color][/size][size=3][color=#29384e][font=Times New Roman] [/font][/color][/size]
[size=3][color=#29384e][font=宋体] [/font][font=Times New Roman]Glaciers are a possible source of fresh water that has been overlooked until recently. Three-quarters of the Earth[/font][font=宋体]‘[/font][font=Times New Roman]s fresh water supply is still tied up in glacial ice[/font][font=宋体]，[/font][font=Times New Roman] a reservoir of untapped fresh water so immense that it could sustain all the rivers of the world for 1[/font][font=宋体]，[/font][font=Times New Roman]000 years. Floating on the oceans every year are 7[/font][font=宋体]，[/font][font=Times New Roman]659 trillion metric tons of ice encased in 10000 icebergs that break away from the polar ice caps[/font][font=宋体]，[/font][font=Times New Roman] more than ninety percent of them from Antarctica.[/font][/color][/size]
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[size=3][color=#29384e][font=宋体] [/font][font=Times New Roman]Huge glaciers that stretch over the shallow continental shelf give birth to icebergs throughout the year. Icebergs are not like sea ice[/font][font=宋体]，[/font][font=Times New Roman] which is formed when the sea itself freezes[/font][font=宋体]，[/font][font=Times New Roman] rather[/font][font=宋体]，[/font][font=Times New Roman] they are formed entirely on land[/font][font=宋体]，[/font][font=Times New Roman] breaking off when glaciers spread over the sea. As they drift away from the polar region[/font][font=宋体]，[/font][font=Times New Roman] icebergs sometimes move mysteriously in a direction opposite to the wind[/font][font=宋体]，[/font][font=Times New Roman] pulled by subsurface currents. Because they melt more slowly than smaller pieces of ice[/font][font=宋体]，[/font][font=Times New Roman] 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.[/font][/color][/size]
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[color=#29384e][font=宋体][size=10.5pt] [/size][/font][size=10.5pt]The difficulty arises in other technical matters[/size][font=宋体][size=10.5pt]，[/size][/font][size=10.5pt] 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[/size][font=宋体][size=10.5pt]，[/size][/font][size=10.5pt] the water they could provide would be far cheaper than that produced by desalinization[/size][font=宋体][size=10.5pt]，[/size][/font][size=10.5pt] or removing salt from water[/size][/color]
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