现代大学英语精读4第二版Unit 5A For Want of a Drink课文原文知识讲解

现代大学英语精读4第二版Unit 5A For Want of a Drink课文

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For Want of a Drink

1. When the word water appears in print nowadays, crisis is rarely far

behind. Water, it is said, is the new oil: a resource long squandered, now growing expensive and soon to be overwhelmed by insatiable demand. Aquifers are falling, glaciers vanishing, reservoirs drying up and rivers no longer flowing to the sea. Climate change threatens to make the problem worse. Everyone must use less water if famine, pestilence and mass migration are not to sweep the globe.

2. 2.The language is often overblown, and the remedies sometimes ill-

conceived, but the basic message is not wrong. Water is indeed scarce in many places, and will grow scarcer. Bringing supply and demand into equilibrium will be painful, and political disputes may increase in number and intensify in their capacity to cause trouble. To carry on with present practice would indeed be to invite disaster.

3.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 of people living in

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countries chronically short of water is set to rise from 8% at the turn of the 21st century to 45% by 2050.

4.Farmers' increasing demand for water is caused not only by the growing number of mouths to 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.

5.Industry, too, needs water. It takes about 22% of the world's withdrawals. Domestic activities take the other 8%. Together, the demands of these two categories quadrupled in the second half of the 20th century, growing twice as fast as those of farming.

6.Meeting that demand is a difficult task. One reason is that the supply of water is finite. The world will have no more of it in 2025 or 2050 than it has today, or when it lapped at the sides of Noah's Ark. This is because the law of conservation of mass says, broadly, that however you use it, you cannot destroy the stuff. Neither can you readily make it. If some of it seems to come from the skies, that is because it has evaporated from the Earth's surface, condensed and returned.

7.Most of this surface is sea, and the water below it—over 97% of the total on

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Earth—is salty. In principle, the salt can be removed to increase the supply of fresh water, but at present desalination is expensive and uses lots of energy.

8.Of the 2.5% of water that is not salty, about 70% is frozen, either at the poles, in glaciers or in permafrost. So all living things, except those in the sea, have about 0.75% of the total to survive on. Most of this available water is underground, in aquifers or similar formations. The rest is falling as rain, sitting in lakes and reservoirs or flowing in rivers where it is, with luck, replaced by rainfall and melting snow and ice. There is also, take note, water vapor in the atmosphere.

9.The value of water as a commodity of course varies according to locality, purpose and circumstance. Take locality first. Water is not evenly distributed—just nine countries account for 60% of all available fresh supplies—and among them only Brazil, Canada, Colombia, Congo, Indonesia and Russia have an abundance. America is relatively well off, but China and India, with over a third of the world's population between them, have less than 10% of its water.

10.Even within countries the variations may be huge. The average annual rainfall in India's northeast is 110 times that in its western desert. And many places have plenty of water, or even far too much. Flooding is routine, and may become more frequent and damaging with climate change.

11.Scarce or plentiful, water is above all local. It is heavy—one cubic water weighs a tonne—, so expensive to move. Surface water—mostly rivers, lakes and reservoirs—will not flow from one basin into another without artificial diversion,

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and usually only with pumping. Within a basin, the water upstream may be useful for irrigation, industrial or domestic use. As it nears the sea, though, the opportunities diminish to the point where it has no uses except to sustain deltas, wetlands and to carry silt out to sea.

12.These should not be overlooked. If rivers do not flow, nothing can live in them. Over a fifth of the world's freshwater fish species of a century ago are now endangered or extinct. Half the world's wetlands have also disappeared over the past 200 years. The point is, though, that even within a basin water is more valuable in some places than in others.

13.Almost anywhere arid, the water underground, once largely ignored, has come to be seen as especially valuable as the demands of farmers have outgrown their supplies of rain and surface water. Groundwater has come to the rescue, and for a while it seemed a miraculous solution: drill a borehole, pump the stuff up from below and in due course it will be replaced. In many places, however, from the United States to India and China, the quantities being withdrawn exceed the annual recharge. This is serious for millions of people not just in the country but also in many of the world's biggest cities, which often depend on aquifers for their drinking water.

14.The 20 million inhabitants of Mexico City and its surrounding area, for example, draw over 70% of their water from an aquifer that will run dry within 200 years, maybe sooner. Already the city is sinking as a result. In the Hai river basin in China, deep-groundwater tables have dropped by up to 90 meters.

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15.Part of the beauty of the borehole is that it requires no elaborate apparatus. A single farmer may be able to sink his own tube well and start pumping. That is why India and China are now perforated with millions of irrigation wells, each drawing on the common resource. Sometimes this resource may be huge. But even big aquifers are not immune to the laws of physics. Many places are seriously overdrawn. In those places, farmers probably have to pay something for the right to draw groundwater. But almost nowhere will the price reflect scarcity, and often there is no charge at all and no one measures how much water is being taken.

16.Priced or not, water is certainly valued, and that value depends on the use to which it is harnessed. Water is used not just to grow food but to make every kind of product, from microchips to steel girders. The largest industrial purpose to which it is put is cooling in thermal power generation, but it is also used in drilling for and extracting oil, the making of petroleum products and ethanol, and the production of hydroelectricity. Some of the processes involved, such as hydro power generation, consume little water(after driving the turbines, most is returned to the river), but some, such as the techniques used to extract oil from sands, are big consumers.

17.Industrial use takes about 60% of water in rich countries and 10% in the rest. The difference in domestic use is much smaller, 11% and 8% respectively. Some of the variation is explained by capacious baths, power showers and flush lavatories in the rich world. All humans, however, need a basic minimum of two litres of water in food or drink each day, and for this there is no substitute. No

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one survived in the ruins of Port-au-Prince for more than a few days after January's earthquake unless they had access to some water-based food or drink. That is why many people in poor and arid countries—usually women or children—set off early each morning to trudge to the nearest well and return five or six hours later burdened with precious supplies. That is why many people believe water to be a human right, a necessity more basic than bread or a roof over the head.

18.From this much follows. One consequence is a widespread belief that no one should have to pay for water. The Byzantine emperor Justinian declared in the 6th century that \"by natural law\" air, running water, the sea and seashore were \"common to all.\" Many Indians agree, seeing groundwater in particular as a \"democratic resource.\" In Africa it is said that \"even the jackal deserves to drink.\"

19.A second consequence is that water often has a sacred or mystical quality that is invested in deities like Gong Gong and Osiris and rivers like the Jordan and the Ganges. Throughout history, man's dependence on water has made him live near it or organize access to it. Water is in his body and in his soul. It has provided not just life and food but a means of transport, a way of keeping clean, a mechanism for removing sewage, a home for fish and other animals, a medium with which to skate and sail, a thing of beauty to provide inspiration, to gaze upon and to enjoy. No wonder a commodity with so many qualities, uses and associations has proved so difficult to organize.

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