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  3. For more than a decade, scientists have been trying to determine whether climate change is linked to intense storms, such as 200

For more than a decade, scientists have been trying to determine whether climate change is linked to intense storms, such as 200

admin2012-06-02  74
问题     For more than a decade, scientists have been trying to determine whether climate change is linked to intense storms, such as 2005’s Hurricane Katrina. Meteorologist Michael Mann of Pennsylvania State University, and colleagues attacked the question by turning to the past. They looked through drill cores from coastal waters for signs that sediments had been disturbed by major storms. Eight sites along the U. S. East Coast and Puerto Rico provided a reliable record of the number of significant hurricanes going back about 1500 years. Other climate data and models added clues to water temperatures and hurricane intensity.
    As the researchers report tomorrow in Nature, they found strong evidence that Atlantic hurricane activity peaked about 1000 years ago, producing up to 15 hurricanes a year on average — a level matched in recent times only over the past decade and a half. At the time, according to estimates constructed from other geologic data, Atlantic water temperatures were relatively warm, "though not as warm as today," Mann says. And Pacific temperatures were relatively cool, thanks to La Nina events. Warmer Atlantic waters whip up more storms, but warmer Pacific temperatures tend to create stronger jet streams that break up those storms. So the twin conditions a millennium ago produced kind of a "Perfect Storm" for hurricanes, he explains.
    Of particular interest, the sediments reveal a close link between warmer water and the number of hurricanes during the past 150 years or so. Dropping temperatures produced seven or eight hurricanes a year, while a rising thermometer, such as in the earlier part of this decade, pushed the total to 15. "All other things being equal, " Mann says, "this suggests that we are indeed likely to see not only stronger hurricanes in the Atlantic but perhaps more of them" in the near future.
    Meteorologist James Eisner of Florida State University in Tallahassee agrees with the findings, but adds a caveat. The historical data do show that a link between warmer ocean temperatures and higher hurricane frequencies has existed for at least 1500 years, he says. However, there’s a high degree of uncertainty in the data. That and the fact that the physics explaining the link haven’t yet been established, Eisner explains, "indicate this is not the ’ smoking gun’ we’ve been looking for that would allow us to confidently project what will happen as the oceans continue to warm. "
Why does Mann foresee stronger and more hurricanes in future Atlantic Ocean?
选项 A、All other factors resulting in hurricanes were equal during the past 150 years or so.
B、A rising thermometer has pushed the number of hurricanes a year up to 15 in recent years.
C、Atlantic temperatures today have dropped to the lowest because La Nina events these years.
D、Atlantic temperatures today are even higher than temperatures in the Perfect Storm.
答案D
解析 推理判断题。文章第三段中提到检测的沉积物反映了在过去大约150年内海水变暖与飓风数量之间的密切关系。而在第二段中已经提到了“现在的大西洋海水温度更高”这个信息。由此可以推测，Mann预测会有更多更强飓风是因为这个温度的原因。其他选项都不正确。
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