2. 外语
  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  105
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.
What is the main idea of this passage?
选项 A、Discussing whether global warming is responsible for extreme weather.
B、Conforming global warming is responsible for the formation of NASH.
C、Describing the severe situations of global warming on the earth.
D、Calling for people to struggle against global warming and extreme weather.
答案A
解析 主旨大意题。通读全文可以发现，文章首先指出科学家对全球变暖的后果提出种种猜测，作者对某些猜测持怀疑态度。他认为我们有必要区分极端天气个案和广义的气候变暖，即某些极端天气并不是由气候变暖造成的。但近期研究又表明至少某些天气变化或极端天气与全球变暖是有关系的；文章列举了美国东南部夏季天气反常的例子进行了说明。最后总结为：虽然科学家还没有正式把所有极端天气同气候变化联系在一起，我们也应该时刻准备着迎接突如其来的情况。因此全文大部分都在讲述极端天气与全球变暖的关系。所以，A)“讨沦是否是由全球变暖引发了一系列异常天气”，符合题意，故为本题答案。B)“证实全球变暖是NASH形成的原因”，与原文不符，故排除；C)“描写全球变暖的严峻形势”，文章并没有花大量篇幅渲染全球变暖的严峻形势，故排除；D)“号召人们与全球变暖和极端天气抗争”，文章没有把重点放在号召人们与全球变暖和极端天气抗争上，故排除。
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