Global climate change, often seen as a process stretching over thousands of years, could in fact occur abruptly and unexpectedly

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问题     Global climate change, often seen as a process stretching over thousands of years, could in fact occur abruptly and unexpectedly-—quickly pushing up temperatures by as much as 18 degrees Fahrenheit and wreaking havoc (大破坏,浩劫) on human society, scientists warned on Wednesday.
    "Climate change is not always smooth. Sometimes it is abrupt," said Richard Alley, a climate expert at Pennsylvania State University and lead author of a new National Academy of Sciences report on the threat of rapid climatic shifts.
    "If you have a very large, abrupt change, a lot of people and a lot of ecosystems are going to notice," he said. "The bigger and faster it is, the harder it will be to deal with. "
    The new National Academy of Sciences report, released this week, warns that gradual global warming coupled with other human impacts on the environment could "trip the switch" for sudden climate change.
    At the American Geophysical Union meeting on Wednesday, Alley and other environmental scientists said the geological evidence indicated that such rapid climate shifts had occurred frequently in the past—moving temperatures drastically in the space of just a few decades.
    "This can happen in less than a human generation, and then it will persist for thousands of years," said David Battisti, an atmospheric scientist at the University of Washington.
    The most immediate dangers posed by abrupt climate change range are devastating droughts and floods which could seriously affect both water supply and agriculture across vast stretches of the planet.
    Longer term impacts could include changes in the basic systems which determine regional global temperatures. Scientists believe that the Gulf Stream, a current (水流) of warm Atlantic water which now keeps much of Northern Europe temperate, could theoretically reverse direction if enough cool fresh water runs into the north Atlantic from melting ice, a change that would quickly impact European weather.
According to the passage, in the long run, abrupt climate change______.

选项 A、could make the Gulf Stream warmer
B、could melt much ice on Earth
C、could submerge the whole European continent
D、could evaporate all fresh water on Earth

答案B

解析 细节题。根据最后一段,突然气候变化的长远影响有;改变决定地区性全球气温的基本系统;从理论上讲,the Gulf Stream,一股现在维持着北欧大部分气温的大西洋暖流,会由于大量的冰融化的冷水流人大西洋而倒流,这一变化会很快影响欧洲气候。由此可知,B导致地球上冰雪融化是正确答案。
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