Question

    Antarctica(南极洲)’s melting ice, which has caused global sea levels to rise by at least 13.8 millimeters over the past 40 years, was thought to primarily come from the unstable West Antarctic Ice Sheet(WAIS). Now, scientists have found that the East Antarctic Ice Sheet (EAIS)—considered largely unaffected by climate change—may also be melting at an unexpectedly rapid speed.

The WAIS, whose base is below sea level, has long been considered the most likely to break down. Besides gravity, a deep current of warm water slips beneath the sheet, melting it from below until it becomes a floating shelf at risk of breaking away. In contrast, extreme cold and a base mostly above sea level are thought to keep the EAIS relatively safe from warm waters.

But as greenhouse gases warm much of the planet, driving stronger polar winds, some scientists think warm water carried by a circular current will start to invade East Antarctica’s once unassailable ice. A cooperation of more than 60 scientists last year, published in Nature, estimated that the EAIS actually added about 5 billion tons of ice each year from 1992 to 2017.

Eric Rignot of the University of California, Irvine, and colleagues combined 40 years of satellite imagery and climate modeling and found that overall Antarctica now sends six times more ice into the sea each year than it did in 1979, with the majority coming from West Antarctica. But East Antarctica was responsible for more than 30% of Antarctica’s contribution to the 13.8-millimeter sea level rise over the past 40 years. “The more we look at this system the more we realize this is fragile,” Rignot says. “Once these glaciers become unstable there is no red button to press to stop it.”

Rignot hopes the study brings greater attention to a part of Antarctica that has traditionally been understudied. Helen Fricker, a glaciologist (冰川学家) in California, agrees. “We need to monitor the entire Antarctica and we just can’t do that without international cooperation.”

1.What is the new finding of scientists?

A.The east Antarctica is losing ice at an increasing rate.

B.The west Antarctica is melting six times faster than in 1979.

C.5 billion tons of ice is added to Antarctica each year.

D.The sea level has risen by 13.8 mm over the past 40 years.

2.Which factor leads to the EAIS’s melting fast?

A.A base mostly over sea level. B.The force of gravity.

C.The invasion of a warm current. D.Extremely low temperature.

3.Which of the following best explains “unassailable” underlined in Para. 3 ?

A.Fragile. B.Unattackable.

C.Mild. D.Unstable.

4.Which way does Helen Fricker specially advocate?

A.Satellite imagery. B.Global monitoring.

C.Worldwide climate modeling. D.Worldwide combined efforts.

Answer

1.A

2.C

3.B

4.D

【解析】

本文是一篇说明文，介绍了科学家发现南极东部的冰层正在以出人意料的速度融化，其中一个因素就是海洋暖流的入侵，科学家主张通过国际合作来监测南极洲。

1.细节理解题。根据第一段中的“Now, scientists have found that the East Antarctic Ice Sheet (EAIS)—considered largely unaffected by climate change—may also be melting at an unexpectedly rapid speed.”可知，科学家发现南极东部的冰层正在以出人意料的速度融化，故选A。

2.细节理解题。根据第二段中的“some scientists think warm water carried by a circular current will start to invade East Antarctica’s once unassailable ice.”可知，科学家认为海洋环流携带的温暖的海水入侵南极东部的冰层导致其加速融化，故选C。

3.词义猜测题。根据画线词后的“A cooperation of more than 60 scientists last year, published in Nature, estimated that the EAIS actually added about 5 billion tons of ice each year from 1992 to 2017.”可知，1992年到2017年，南极东部的冰层每年增加50亿吨冰，按照常理推断体积如此庞大的冰层是坚不可摧的，由此可知画线词词义为“坚不可摧的”，故选B。

4.细节理解题。根据最后一段中的“We need to monitor the entire Antarctica and we just can’t do that without international cooperation.”可知，Helen Fricker认为我们需要监测南极洲，没有国际合作我们无法做到这一点，由此可知，Helen Fricker主张通过全世界共同的努力来监测南极洲，故选D。