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When Europeans arrived in the America, they caused so much death and disease that it changed the global climate. European settlers killed 56 million people over about 100 years in South, Central and North America, causing large amounts of farmland to be abandoned and reforested. The increase in trees and vegetation across an area the size of France resulted in a great decrease in carbon dioxide ( CO₂) in the atmosphere.
Carbon levels changed enough to cool the Earth by 1610, researchers found. Columbus arrived in 1492, “CO₂ and climate had been stable until this point,” said Professor Mark Maslin, one of the study’s co-authors. “So, this is the first major change we see in the Earth’s greenhouse gases.”
Before this study, some scientists had argued the temperature change in the 1600s, called the Little Ice Age, was caused only by natural forces. But by combining archaeological evidence, historical data and analysis of carbon found in Antarctic ice, the researchers showed how the reforestation—directly caused by the Europeans’ arrival—was a key factor of the global chill, they said.
Researchers analyzed Antarctic ice, which traps atmospheric gas and can show how much carbon dioxide was in the atmosphere centuries ago. “The ice showed that there was a larger dip in CO₂ (than usual) in 1610, which was caused by the land and not the oceans,” said Alexander Koch, lead author of the study.
The study goes beyond climate science and also contribute to research in geography and history, Maslin said, noting that deaths of Americans directly contributed to the success of the European economy. Natural resources and food shipped from the New World helped Europe’s population to expand. It also allowed people to stop farming and begin working in other industries for spare money. “Strangely, the depopulation of the Americas may have allowed the Europeans to dominate the world,” Maslin said. “It also allowed for the Industrial Revolution.”

1.What’s the main idea of the first paragraph?

A Why the Europeans arrived in the America caused so much death.

B How the global climate was changed by the European settlers.

C How many native Americans were killed by the European settlers.

D What led to the carbon dioxide in the atmosphere increase sharply.

解析：选B。段落大意题。根据第一段第一句When Europeans arrived in the America, they caused so much death and disease that it changed the global climate.可知欧洲殖民者到达美洲后带来了许多疾病，并大量屠杀土著居民，这使得全球的气候发生了改变，指明了欧洲殖民者改变全球气候的方式，后面的内容都是对首句的具体阐释。故选B。

2.What does the underlined words “this point” in the second paragraph refer to?

A During 100 years.

B By 1610.

C In 1492.

D In the 1600s.

解析：选C。词意指代题。根据第二段第一句Carbon levels changed enough to cool the Earth by 1610, researchers found.可知到1610年，碳含量的变化足以使地球降温，说明碳含量在1610年之前已经发生改变了。结合画线句子的语境可知1492哥伦布达到美洲，在这之前二氧化碳和气候都是稳定的，因此可知this point指代的就是1492年这个时间节点。故选C。

3.Which of the following is NOT the fact from the passage?

A The Little Ice Age began in the 1600s.

B The reforestation caused by the Europeans’ arrival directly made the world cold.

C The amount of the carbon dioxide centuries ago could be analyzed through Antarctic ice.

D The atmospheric carbon dioxide levels in 1610 were much lower than before.

解析：选B。细节理解题。根据第三段最后一句的the researchers showed how the reforestation—directly caused by the Europeans’ arrival—was a key factor of the global chill可知重新造林是导致全球变冷的关键因素，而非直接原因。故选B。

4.How did the depopulation of the Americas lead to the success of the European economy?

A It provided the European settlers with rich natural resources and food.

B It contributed to the population growth of European countries.

C It prompted huge changes in the industrial structure of European countries.

D All the above.

解析：选D。细节理解题。根据最后一段第二、三句Natural resources and food shipped from the New World helped Europe’s population to expand. It also allowed people to stop farming and begin working in other industries for spare money.可知美洲土著居民的大量减少为欧洲殖民者提供了丰富自然资源和食物，促进了欧洲国家的人口增长，也使其产业结构发生了改变，为工业革命提供了条件，从而促使欧洲经济取得了成功。故选D。