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Section29 Global Warming Some people say the earth is getting warmer.有人说地球正在变暖。 They blame something called greenhouse gases.人们把它归结为温室效应。 The greenhouse gasses destroy the higher atmosphere that keeps our planet from getting too hot.温室效应破坏了高空大气层，而高空大气层可以保护地球以免过热。 CFCs are the gases that cause one of the biggest problems in global warming.氟氯化碳是导致全球变暖的主要气体。 CFCs destroy some of the ozone that is in the higher atmosphere.氟氯化碳破坏了高空的部分臭氧层。 The ozone layer helps us by filtering out some of the harmful ultraviolet rays from the sun.臭氧层过滤了阳光中的部分有害的紫外线。 These rays can cause skin cancer in humans.这些射线会使人致癌。 These rays can also help to heat up our planet.这些射线也会使我们的星球升温。 Over the polar ice caps, we now have holes in the ozone layer.在两极的冰川地带，人们发现了臭氧层的破洞。 These, people believe, contribute to worldrsquo;s global warming.人们认为这些是因为地球变暖导致的。 One of the effects it could have is to speed up the melting of the polar ice caps.其影响之一，就是加速极地冰川的融化。 | 
