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  3. In the atmosphere, carbon dioxide acts rather like a one-way mirror—the glas

In the atmosphere, carbon dioxide acts rather like a one-way mirror—the glas

游客2024-04-13  50
问题     In the atmosphere, carbon dioxide acts rather like a one-way mirror—the glass in the roof of a greenhouse which allows the sun’s rays to enter but prevents the heat from escaping.
    According to a weather expert’s prediction, the atmosphere will be 31 warmer in the year 2050 than it is today, if man continues to burn fuels at the present rate. If this warming up took place, the ice caps in the poles would begin to melt, thus raising sea level several meters and severely flooding coastal cities. Also, the increase in atmospheric temperature would lead to great changes in the climate of the northern hemisphere, possibly resulting in an alteration of the earth’s chief food-growing zones.     In the past, concern about a man-made warming of the earth has concentrated on the Arctic because the Antarctic is much colder and has a much thicker ice sheet. But the weather experts are now paying more attention to West Antarctic, which may be affected by only a few degrees of warming: in other words, by a warming on the scale that will possibly take place in the next fifty years from the burning of fuels.
    Satellite pictures show that large areas of Antarctic ice are already disappearing. The evidence available suggests that a warming has taken place. This fits the theory that carbon dioxide warms the earth.
    However, most of the fuel is burnt in the northern hemisphere, where temperatures seem to be falling. Scientists conclude, therefore, that up to now natural influences on the weather have exceeded those caused by man. The question is: Which natural cause has most effect on the weather?
    One possibility is the variable behavior of the sun. Astronomers at one research station have studied the hot spots and "cold" spots(that is, the relatively less hot spots)on the sun. As the sun rotates, every 27.5 days, it presents hotter or "colder" faces to the earth, and different aspects to different parts of the earth. This seems to have a considerable effect on the distribution of the earth’s atmospheric pressure, and consequently on wind circulation. The sun is also variable over a long term: its heat output goes up and down in cycles, the latest trend being downward.
    Scientists are now finding mutual relations between models of solar-weather interactions and the actual climate over many thousands of years, including the last Ice Age. The problem is that the models are predicting that the world should be entering a new Ice Age and it is not. One way of solving this theoretical difficulty is to assume a delay of thousands of years while the solar effects overcome the inertia(惯性)of the earth’s climate. If this is right, the warming effect of carbon dioxide might thus be serving as a useful counter-balance to the sun’s diminishing heat. [br] On the basis of their models, scientists are of the opinion that _____.
选项 A、the climate of the world should be becoming cooler
B、it will take thousands of years for the inertia of the earth’s climate to take effect
C、the man-made warming effect helps to increase the solar effects
D、the new Ice Age will be delayed by the greenhouse effect
答案 A
解析 最后一段的第2句提到“科学家们研究的结果应该是地球进人新的冰川时期，然而却没有出现这种情况”，这与A项的内容吻合。D项为本题的强干扰项，根据文章，该项的含义正确。但就本题而言，题干针对的是models(模型)，因而判断范围只能针对solar-weather interactions，即太阳的作用。
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