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  3. Global warming, after all, isn’t just about hotter summers. As the earth’s temperatures rise, scientists speculate, there will b

Global warming, after all, isn’t just about hotter summers. As the earth’s temperatures rise, scientists speculate, there will b

admin2012-07-11  112
问题     Global warming, after all, isn’t just about hotter summers. As the earth’s temperatures rise, scientists speculate, there will be a lot more than warming going on. The change in ocean temperatures and sea levels will affect everything from rain patterns to wind direction. But how much of that is already happening, and how much is speculation?
    Though we’ve seen increasingly unusual weather patterns in recent years,it’s important to separate individual instances of extreme weather from the broader category of climate change. Those heavy snows from last winter, according to researchers at Columbia University, were the result of two large colliding weather fronts—probably just a natural aberration (越轨), rather than necessarily a symptom of climate change. And tornado in Brooklyn was definitely bizarre—it occurred not only in a part of the country not known for touchdowns,but also during an unusual time of day and season and in the midst of a regional drought. However,it can’t be precisely pinned on global warming.
    Still,recent research has begun to show that at least in some cases, those altered and extreme weather patterns can be definitively linked to global warming. A just-released analysis by researchers at Duke University shows that’s the case for summertime weather in the southeastern United States. Eleven of the past 30 summers were either abnormally wet or abnormally dry in the Southeastern states. And there were twice as many instances of " extreme" rainfall as there had been compared to the rainfall during the 30 preceding summers. Summer weather in that part of the country—along with that of the entire eastern U. S. .Western Europe,and North Africa,is influenced by the North Atlantic subtropical high (NASH) ,a high-pressure system that has intensified an average of 0.9 geo-potential meters (位势 米) every decade over the past 60 years.
    In layman’s terms,that means that the system extended higher and higher above sea level,making NASH more powerful. And its reach extended in other ways too; the area of the system grew, meaning that it came westward, closer to the eastern coast of the United States, and also increased its north-south movement. But slight shifts in NASH’s path can have a big impact;If NASH goes slightly more northward than usual，it can make for a dry summer; southward, and the summer is an extremely wet one. Researchers at Duke say they thoroughly investigated naturally occurring phenomena for the growth of NASH,but found no seemingly reasonable explanations. They concluded that the change is a result of alterations to the climate that were caused by humans.
    More dramatic are the claims that global warming could bring about or aggravate civil wars in Africa because of agricultural resources scarcity. That may or may not come about, but the broader lesson seems to be that even if science hasn’t yet formally connected all the dots on climate change,we should expect the unexpected.
How does NASH make the weather abnormal?
选项 A、It intensifies its core by about 0.9 geo-potential meters per decade.
B、It grows and comes westward to the eastern coast of U. S. at high speed.
C、Its slightly aberration from usual path makes the weather abnormal.
D、Its irregular shape and density make the weather abnormal.
答案C
解析 推理判断题。定位句指出，即使是NASH路径的微小变化也会造成极大的影响：如果NASH较往年略偏北，则夏旱；相反则夏涝。闲此NASH是通过改变路径来影响夏季天气的。所以，C)“它从正常轨道的略微偏移导致天气异常”，符合题意，故为本题答案。A)“它以平均每卜年0．9位势米的速度加强”，这指的是NASH的上升趋势，原文中并未明确指出NASH的上升是如何影响天气的，故排除；B)“它扩张并迅速两进到美国东海岸”，未提及NASH的南北运动，故排除；D)“它的不规则形状和密度引发了天气异常”，原文未提及。故排除。
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