2017年6月10日托福阅读真题+题目+答案：The Eocene Warming

2017年6月10日托福阅读真题+题目+答案：The Eocene Warming

█Approximately 55 million years ago, during the Eocene epoch, Earth’s climate experienced a dramatic warming trend. █ Heating of this kind can be achieved in several ways. █There are, however, two main contenders: altering the circulation patterns of the oceans to more efficiently redistribute heat from the tropics to the higher latitudes, or increasing the concentration of greenhouse gases (gases that trap heat) in the atmosphere. █

Originally, the oceans were favored as the key to the perplexing Eocene climate. Often regarded as the heat engine of Earth, the oceans have an enormous capacity for storing and redistributing tropical warmth in surface currents that migrate poleward, driven by prevailing wind patterns and changes in salinity that happen en route as water evaporates. The Gulf Stream, which flows from Florida across the Atlantic and into northern Europe, is a well-known example of this heat transport. It ensures that Europe is several degrees warmer than it would otherwise be. One idea, then, for explaining the Eocene warmth was to somehow increase the transport of heat from the equator up to the high latitudes. But there turned out to be some problems with this explanation, because later calculations showed that to get the polar regions warm enough required increasing the poleward transport of heat by 30 percent, an incredibly large amount. And in spite of diverting the attention of the world’s climate scientists for several decades, no one has yet found a satisfactory means of achieving such as massive shift in either the sprightly circulation of surface ocean or the more stately paced circulation of the deep oceans.

1. The word “dramatic” in the passage is closet in meaning to

A) striking

B) temporary

C) gradual

D) favorable

2. The word “perplexing” in the passage is closest in meaning to

A) variable

B) puzzling

C) early

D) complex

3. The word “prevailing” in the passage is closest in meaning to

A) predictable

B) unstable

C) dominant

D) powerful

4. According to paragraph 2, all of the following are true of the Gulf Stream EXCEPT

A) Its migration is caused by wind patterns and changes in salinity.

B) Its capacity for storing heat has declined since scientists started studying it several decades ago.

C) It moves poleward as it passes through the Atlantic.

D) It has a considerable effect on Europe’s temperature.

5. Paragraph 2 indicates which of the following about explaining Eocene warmth as an effect of increased heat transport from the equator to the high latitudes?

A) Research has found that while ocean surface currents can increase heat in certain areas by up to 30 percent, most currents migrating from the equator poleward cannot.

B) The information that has been gathered so far is limited because calculations of heat transport by ocean currents have focused on the circulation of the surface ocean rather than that of the deep oceans.

C) Scientists cannot explain what could have caused a shift in ocean current circulation that could account for a 30 percent increase in heat transport during the Eocene.

D) After decades of unsuccessful research on ocean circulation, scientists are now paying more attention to changes in wind patterns as a more likely explanation of the Eocene warmth.

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