仔细阅读自然环境类第4关

One fine day about 74 000 years ago, a giant volcano on Sumatra blew its top. The volcano, named Toba, may have ejected (喷射) 1 000 times more rock and other material than Mount St. Helens in Washington state did in 1980. In the process, it cooled the climate by at least 10°C, causing a global famine. Paleoclimate (古气候) evidence suggests that the Toba eruption, which occurred during the last ice age, emitted lots of sulfur dioxide—vastly more than Mount St. Helens did. The eruption also seems to have coincided with the start of a 1 000-year period of even colder temperatures. Some scientists have suggested that Toba caused the deep freeze and that perhaps such an event happening today could bring on a new ice age. But models developed by National Aeronautics and Space Administration and the National Center for Atmospheric Research in Boulder, Colorado, argue otherwise. Researchers led by climatologist Alan Robock of Rutgers University in New Brunswick, New Jersey, ran scenarios that featured eruptions producing up to several times more sulfur dioxide than Toba. The result, published 27 May in the Journal of Geophysical Research—Atmospheres, was a cooler climate that lasted only a few decades. So the 1 000-year cold spell was probably part of the natural cycle that has produced more than a dozen ice ages over the past couple of million years. "The results virtually eliminate mega (非常大的) volcanic eruptions as one of the key drivers of global-scale glaciation," says climatologist Ellen Mosley-Thompson of Ohio State University in Columbus, who was not involved in the study. So, paleoclimatologists should focus on more likely climate coolers, she says, such as changes in ocean circulation or cyclical variations in Earth's orbit around the sun. Still, if Toba erupted today like it did in the past, the results would be catastrophic. Although the volcano isn't expected to blow its top for thousands of years, Robock and colleagues estimate a mega eruption could lower global temperatures by as much as 17°C for several years, followed by a recovery to normal conditions that could take decades. That would hit the human population with the double whammy of dramatically reduced agricultural production and widespread loss of vegetation, leading to widespread food shortages and starvation.

1 What was the disastrous consequence of the Toba eruption?: A.The low temperature made global people freeze to death.
B.The rock and other material caused by the eruption buried numerous people.
C.The great change of climate resulted in the food shortage.
D.The flames caused by the volcano eruption burned down Sumatra.

本题答案： A B C D

参考答案：C
系统解析：
由题干中的consequence of the Toba eruption定位到文章第一段最后一句。推理判断题。由定位句可知，在多巴火山喷发的整个过程中，气温至少降低了10°C，引起了全球性的饥荒。由此可以推知，气候变冷使得食物短缺，导致全球饥荒，因此C)符合文意。

2 What can be learned about the time of the Toba eruption?: A.The eruption coincided with the end of the last ice age.
B.A new ice age triggered off the Toba eruption.
C.The eruption occurred when the Earth was at its coldest time.
D.The eruption happened when a 1 000-year period of colder temperatures began.

本题答案： A B C D

参考答案：D
系统解析：
由题干中的the time of the Toba eruption定位到第二段第二句。细节辨认题。由定位句可知，多巴火山的爆发时间也正是千年寒冷期的开端，因此D)正确。

3 Which view did Alan Robock's research verify?: A.Ancient volcano eruptions caused the Earth to freeze.
B.The 1 000-year cold spell was not caused by the Toba eruption.
C.The ice age is part of the natural cycle of the volcanic eruption.
D.There won't be any new ice age in the future.

本题答案： A B C D

参考答案：B
系统解析：
由题干中的Alan Robock's research定位到第三段第二、三句。推理判断题。由定位句可知，模拟实验的结果显示，火山爆发所导致的气候变冷仅能持续几十年，千年寒冷期很可能是自然循环的一部分，这种循环在过去的几百万年中产生了不下12个冰河时代。因此可以推断，B)符合文意。

4 What does Ellen Mosley-Thompson think of the research of global-scale glaciation?: A.More relevant factors should be taken into account.
B.More emphasis should be put on the volcano eruptions.
C.There are too many irrelevant researches on global glaciation.
D.Paleoclimatologists should cooperate with other climatologists.

本题答案： A B C D

参考答案：A
系统解析：
由题干中的 Ellen Mosley-Thompson 和 global-scale glaciation 定位到第四段最后一句。细节辨认题。由定位句可知，Ellen认为古气候学家们应该集中精力研究更有可能使气候变冷的因素。例如：海洋环流的变化或地球绕太阳轨道的周期性变化。因此A)为正确答案。

5 What would be the results of the Toba eruption if it happened today?: A.It could affect the Earth for thousands of years.
B.Its influence on climate and human would last for many years.
C.It could take no time for the human population to recover.
D.Many kinds of plants would disappear forever.

本题答案： A B C D

参考答案：B
系统解析：
由题干中的 the results of the Toba eruption 和 happened today 定位到原文最后一段。细节辨认题。由定位段可知，一次特大规模的多巴火山爆发会给气候和人类带来很多年的影响，因此B)为正确答案