Tim Barnett and David Pierce of the Scripps Institution of Oceanography estimate that to adjust to a sustainable level of supply, consumers of Colorado River water will have to get along with 20 percent less water than they use today. That is still a lot of water to lose, but the loss may not be catastrophic. Urban users are already conserving about as much as they can per capita. Farmers, on the other hand, who consume about 80 percent of the western water supply, including in California, are wasting much through inefficient management and low-value crops. Half of the water goes to raise alfalfa to feed cattle, and much of the rest evaporates or soaks into the sand. If some of agricultures share could be diverted to cities, there might be enough to sustain the current population. Rural communities would decline, some lucky farmers would retire with a potful of money, and the public would have to figure out where to get its lettuce, tomatoes, oranges and meat. The cost of water would go up dramatically, and those without money would go thirsty and leave. New hierarchies would take the place of old ones.
Thirty million people now depend on the Colorado River. Perhaps they can manage to adjust to a diminished flow and to declines in domestic food supplies and hydroelectric power. But more people are on the way: Demographers calculate that the population of the Southwest may increase by 10 or 20 million between now and 2050. Some of those people will come from other parts of the country, some from Mexico and Central America, and some from other nations that are coping poorly with their current problems or are overwhelmed by climate change. Whatever their origin, the new arrivals will go to the familiar oases, hoping to find the good life with a swimming pool and a green lawn.
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