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People associate global warming with temperature, but the phrase is misleading-it fails to mention the relevance of water. Nearly every significant indicator of hydrological activity-rainfall, snowmelt, glacial melt-is changing at an accelerating pace (one can arbitrarily pick any point of the hydrological cycle and notice a disruption). One analysis pegged the increase in precipitation at 2 percent over the century. In water terms this sounds auspicious, promising increased supply, but the changing timing and composition of the precipitation more than neutralizes the advantage. For one thing, it is likely that more of the precipitation will fall in intense episodes, with flooding a reasonable prospect. In addition, while rainfall will increase, snowfall will decrease. Such an outcome means that in watersheds that depend on snowmelt, like the Indus, Ganges, Colorado river basins, less water will be stored as snow, and more of it will flow in the winter, when it plays no agricultural role; conversely, less of it will flow in the summer, when it is most needed. One computer model showed that on the Animas River an increase in temperature of 3.6 degrees Fahrenheit would cause runoff to rise by 85 percent from January to March, but drop by 40 percent from July to September. The rise in temperature increases the probability and intensity of spring floods and threatens dam safety, which is predicated on lower runoff projections. Dams in arid areas also may face increased sedimentation, since a 10 percent annual increase in precipitation can double the volume of sediment washed into rivers. The consequences multiply. Soil moisture will intensify at the highest northern latitudes, where precipitation will grow far more than evaporation and plant transpiration but where agriculture is nonexistent. At the same time, precipitation will drop over northern mid-latitude continents in summer months, when ample soil moisture is an agricultural necessity. Meanwhile the sea level will continue to rise as temperatures warm, accelerating saline contamination of freshwater aquifers and river deltas. The temperature will cause increased evaporation, which in turn will lead to a greater incidence of drought. Perhaps most disturbing of all, the hydrologic cycle is becoming increasingly unpredictable. This means that the last century`s hydrological cycle-the set of assumptions about water on which modern irrigation is based-has become unreliable. Build a dam too large, and it may not generate its designed power; build it too small, and it may collapse or flood. Release too little dam runoff in the spring and risk flood, as the snowmelt cascades downstream with unexpected volume; release too much and the water will not be available for farmers when they need it. At a time when water scarcity calls out for intensified planning, planning itself may be stymied.
[填空 ]冲分救命题 -9341
One of the virtues of the essay collection is that it presents_____ views side by side, thereby highlighting the contentious nature of many of the arguments within the discipline.
[阅读&逻辑 ]冲分救命题 -9340
The highlighted sentence serves primarily to
[阅读&逻辑 ]冲分救命题 -9339
The author would most likely agree with which of the following assertions about the environmental impact of hydroelectric power plants?
[阅读&逻辑 ]冲分救命题 -9338
The passage suggests that which of the following contributed to the erosion after the First World War of the progress previously realized by the labor movement in the United States?
[阅读&逻辑 ]冲分救命题 -9337
According to the passage, which of the following statements about the National War Labor Board is true?
[阅读&逻辑 ]冲分救命题 -9336
It can be inferred from the passage that which of the following was one of Local 36’s grievances against the Little Rock laundry owners?
[阅读&逻辑 ]冲分救命题 -9335
The passage is primarily concerned with discussing
[阅读&逻辑 ]冲分救命题 -9334
According to the passage, Appalachian square dancing differs from English country dancing in that Appalachian square dancing
[阅读&逻辑 ]冲分救命题 -9333
The passage suggests that which of the following was true of
[阅读&逻辑 ]冲分救命题 -9332
The statements given are structured to lead to which of the following conclusions?
[阅读&逻辑 ]冲分救命题 -9331
Consider each of the choices separately and select all that apply. It can be inferred that historical demographers generally believe which of the following about communities of fewer than 10,000 people in early-modern Germany?
[阅读&逻辑 ]冲分救命题 -9330
The author suggests that according to historical demographers, the birth rate in early-modem German cities
[阅读&逻辑 ]冲分救命题 -9329
Which of the following most logically completes the argument?
[阅读&逻辑 ]冲分救命题 -9328
The highlighted portion of the passage serves primarily to
[阅读&逻辑 ]冲分救命题 -9327
According to the passage, certain African literatures have
[阅读&逻辑 ]冲分救命题 -9326
It can be inferred from the passage that the Tea Cess Committee reorganized as the Indian Tea Market Expansion Board in order to
[阅读&逻辑 ]冲分救命题 -9325
The passage suggests that "small packets of leaf fragments" were
[阅读&逻辑 ]冲分救命题 -9324
In the argument in the editorial, the part that is highlighted plays which of the following roles?
[阅读&逻辑 ]冲分救命题 -9323
Consider each of the choices separately and select all that apply.Which of the following can be inferred from the passage about the"period of relative warmth"
[阅读&逻辑 ]冲分救命题 -9322
Which of the following best describes the organization of the passage?