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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

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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. "
What does the expression "smoking gun" (Line 5, Para. 4) most probably mean?
选项 A、A problem-solving approach.
B、A temperature watchdog.
C、A definite evidence.
D、A theoretic breakthrough.
答案C
解析 语义理解题。最后一段提到海洋温度升高与飓风频率之间的关联性存在不确定性，而且相关的物理学框架还没有构建。这就说明，最后一句的代词this指代的是这些研究结果。后面又提到要依此来预测，所以Elsner是让这些结果作为预测依据的，因此选项[C]正确。文中的研究结果显然不是什么理论上的重大突破，排除[D]“理论突破”。选项[A]“解决问题的途径”，[B]“温度监视器”均与原文意思不符。
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