公共英语四级辅导：PETS4阅读精讲（38）

　　The General House Effect
　　The green house effect is not a new phenomenon. Scientists have known for centuries that a layer of gases naturally surrounds the earth like an insulating blanket, trapping the reflected energy of the sun and preventing it from escaping into space that is what makes the earth warm enough for people, plants and animals. However, recent human activity has boosted concentrations of greenhouse gases and enhanced their heat-trapping ability. The man culprit is carbon dioxide which scientists estimate accounts for nearly half of global warming.Co2 is released from burning fossil fuels and from clearing and burning forests.
　　There are other important greenhouse gases too and they cannot be ignored. CFCs, for example, may account for 25 per cent of global warming in the text century if their production is not scaled back. But carbon dioxide is the pivotal one. The UN International panel on Climatic Change now says that Co2 levels could double within in 40 years if present rates of fossil-fuel burning and deforestation continue. That means an average temperature increase between two and four degrees centigrade and a sea-level rise of perhaps a foot by 2050.
　　No one knows for certain how local weather will change as a result of this warming. But one thing is clear-it will be no picnic. Indications are that the earth will be take place not over thousands of years, but over decades. And it is the speed of the change, which makes the precise impact so difficult to predict.
　　The most sophisticated computerized climate models in the US and UK , agree that weather around the world will become more irregular and more extreme. In general, temperatures will become more towards the poles than at the equator. overall rainfall will also increase as higher temperatures boost evaporation from the seas. But the distribution of precipitation will shift. Some areas will become wetter, others will be drier. In middle latitudes, Climate zones will march poles-wards. In tropical and subtropical parts of the third would, warming will be less but the impact on a relatively stable climate will be greater.
　　Global warming will also cause ocean levels to rise---though not, as popular wisdom has it, due to the Antarctic ice cap melting. If this catastrophe occurs it will not be for at least another century. Instead, sea levels will rise simply because water expands as it warms. people living in low-lying coastal regions will be in danger. The world’s great river deltas, home to millions in Asia and Latin America and containing some of the Third World’s richest food-growing land, could become brackish graveyards.
　　6. Which gas is the most responsible for global warming?
　　A. Carbon Dioxide.
　　B. CFCs.
　　C. Green houses.
　　D. other gases in the atmosphere.
　　7. What will happen if man continues to burn fossil fuels and forests at present rates?
　　A. All fossil fuels, like coal, oil and gas, will run out.
　　B. Deforestation will give rise to the loss of co2.
　　C. The temperature will increase two to four degrees Fahrenheit.
　　D. The rise of sea-level will reach about a foot by 2050.
　　8. Why is the precise impact the global warming will exert on local weather hard to predict?
　　A. Because the great changes in temperature will take place in just decades.
　　B. Because the course of changes will last thousands of years.
　　C. Because people are not sure whether the earth will be warmer than before.
　　D. Because there are many other factors involved in this change.
　　9. Which of the following is true according to the passage?
　　A. The earth, as a whole, will become much wetter.
　　B. The temperature around equator will rise more than around the poles.
　　C. The amount of rainfall will be the same from place to place.
　　D. The weather around the world will be more unusual in the next few decades.
　　10. It can be concluded that 来自www.Examw.com
　　A. The rise of ocean levels is due to the Antarctic ice cap melting.
　　B. The temperature increase will take a gradual course.
　　C. Human beings will have to suffer more from environmental damage.
　　D. Without greenhouse gases the earth would be extremely hot.