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篇章阅读28：气候环境 In the atmosphere, carbon dioxide acts rather like a one-way mirror-the glass in the roof of a greenhouse which allows the suns rays to enter but prevents che heat from escaping. According to a weather experts prediction. the atmosphere will be 3C warmer m the year 2050 than it is today, if man continues to bum 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 re9ulting in an alteration of the earths 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? | 
