Aided by the recent ability to analyze samples of air trapped glaciers, scientists now have a clearer idea of the relationship between atmospheric composition and global temperature change over the past 160,000 years. In particular, determination of atmospheric composition during periods of glacial expansion and retreat (cooling and warming) is possible using data from the 2,000-meter Vostok ice core drilled in Antarctica. The technique involved is similar to that used in analyzing cores of marine sediments, where the ratio of the two common isotopes of oxygen, 180 and 160, accurately reflects past temperature changes. Isotopic analysis of oxygen in the Vostok core suggests main global temperature fluctuations of up to 10 degrees centigrade over the past 160,000 years. Data from the Vostok core also indicate that the amount of Carbon dioxide has fluctuated with temperature over the same period: the higher the temperature, the higher the concentration of carbon dioxide and the lower the temperature, the lower the concentration. Although change in carbon dioxide content closely follows change in temperature during periods of deglaciation, it apparently lags behind temperature during periods of cooling. The correlation of carbon dioxide with temperature, of course, does not establish whether changes in atmospheric composition caused the warming and cooling trends or were caused by them. The correlation between carbon dioxide and temperature throughout the Vostok record is consistent and predictable. The absolute temperature changes, however, are from 5 to 14 times greater than would be expected on the basis of carbon dioxide’s own ability to absorb infrared radiation, or radiant heat. This reaction suggests that, quite aside from changes in heat-trapping gases, commonly known as greenhouse gases, certain positive feedbacks are also amplifying the temperature change. Such feedbacks might involve ice on land and sea, clouds, or water vapor, which also absorb radiant heat. Other data from the Vostok core show that methane gas also correlates closely with temperature and carbon dioxide. The methane concentration nearly doubled, for example, between the peak of the penultimate glacial period and the follwing interglacial period. Within the present interglacial period it has more than doubled in just the past 300 years and is rising rapidly. Although the concentration of atmospheric methane is more than two orders of magnitude lower than that of carbon dioxide, it cannot be ignored: the radiative properties of methane make it 20 times more effective, molecule for molecule, than carbon dioxide in absorbing radiant heat. On the basis of a simulation model that climatological researchers have developed, methane appears to have been about 25 percent as important as carbon dioxide in the warming that took place during the most recent glacial retreat 8,000 to 10,000 years ago.
50. The passage provides information to support which of the following statements about methane?
51. According to the passage, which of the following statements best describes the relationship between carbon dioxide and global temperature?
52. It can be inferred from the passage that a long-term decrease in the concentration of carbon dioxide in the Earth’s atmosphere would ______.
53. The passage suggests that when the methane concentration in the Earth’s atmosphere decreases, which of the following also happens?
问题1选项
A.Methane is more effective than carbon dioxide in absorbing radiant heat.
B.The less the methane concentration, the more the clouds formed in the Earth’s atmosphere.
C.The higher the concentration of carbon dioxide in the Earth’s atmosphere; the lower the concentration of methane.
D.Most of the global warming that has occurred during the past 10 years has been associated with increased methane concentration.
问题2选项
A.Carbon dioxide levels change immediately in response to changes in temperature.
B.Carbon dioxide levels correlate with global temperature during cooling periods only.
C.Once carbon dioxide levels increase, they remain high regardless of changes in global temperature.
D.During cooling periods, carbon dioxide levels initially remain high and then decline.
问题3选项
A.increase methane concentration in the Earth’s atmosphere
B.accompany a period of glaciation
C.encourage the formation of more oxygen isotopes in the Earth’s atmosphere
D.promote the formation of more water in the Earth’s global environment
问题4选项
A.Glaciers melt faster.
B.The concentration of carbon dioxide increases.
C.The global temperature decreases.
D.Carbon dioxide absorbs more radiant heat.
第1题:
【选项释义】
The passage provides information to support which of the following statements about methane? 这篇文章提供了信息来支持下面关于甲烷的哪个陈述？
A. Methane is more effective than carbon dioxide in absorbing radiant heat. A. 甲烷在吸收辐射热方面比二氧化碳更有效。
B. The less the methane concentration, the more the clouds formed in the Earth’s atmosphere. B. 甲烷浓度越少，地球大气中形成的云就越多。
C. The higher the concentration of carbon dioxide in the Earth’s atmosphere; the lower the concentration of methane. C. 地球大气中二氧化碳的浓度越高，甲烷的浓度越低。
D. Most of the global warming that has occurred during the past 10 years has been associated with increased methane concentration. D. 过去10年发生的大部分全球变暖都与甲烷浓度上升有关。
【考查点】事实细节题。
【解题思路】根据倒数第二句Although the concentration of atmospheric methane is more than two orders of magnitude lower than that of carbon dioxide, it cannot be ignored: the radiative properties of methane make it 20 times more effective, molecule for molecule, than carbon dioxide in absorbing radiant heat（尽管大气中甲烷浓度的数量级，比二氧化碳低两个量级还多，但不能忽略：单个分子比较来看，甲烷的辐射特性，导致它吸收辐射热的效率是二氧化碳的20倍）可知A项“甲烷在吸收辐射热方面比二氧化碳更有效”正确。
【干扰项排除】
B、C、D项均未在文中体现，属于无中生有。
第2题:
【选项释义】
According to the passage, which of the following statements best describes the relationship between carbon dioxide and global temperature? 根据文章，下面哪个陈述最好地描述了二氧化碳和全球温度之间的关系？
A. Carbon dioxide levels change immediately in response to changes in temperature. A. 二氧化碳水平会随着温度的变化而立即变化。
B. Carbon dioxide levels correlate with global temperature during cooling periods only. B. 只有在冷却期间，二氧化碳水平才与全球温度相关。
C. Once carbon dioxide levels increase, they remain high regardless of changes in global temperature. C. 一旦二氧化碳水平增加，无论全球温度如何变化，它们都保持高水平。
D. During cooling periods, carbon dioxide levels initially remain high and then decline. D. 在冷却期间，二氧化碳水平最初保持在高位，然后下降。
【考查点】事实细节题。
【解题思路】根据文章第五句Data from the Vostok core also indicate that the amount of Carbon dioxide has fluctuated with temperature over the same period: the higher the temperature, the higher the concentration of carbon dioxide and the lower the temperature, the lower the concentration. Although change in carbon dioxide content closely follows change in temperature during periods of deglaciation, it apparently lags behind temperature during periods of cooling（Vostok岩心的数据还表明，同一时期二氧化碳的含量随温度波动：温度越高，二氧化碳浓度越高，温度越低，二氧化碳浓度越低。尽管二氧化碳含量的变化紧跟在冰川消退时期的温度变化之后，但在冷却时期，二氧化碳含量的变化明显滞后于温度）可知D项“在冷却期间，二氧化碳水平最初保持在高位，然后下降”正确。
【干扰项排除】
A、B、C项均与文章表述不符，属于曲解原文。
第3题:
【选项释义】
It can be inferred from the passage that a long-term decrease in the concentration of carbon dioxide in the Earth’s atmosphere would ______. 从这篇文章中可以推断出，地球大气中二氧化碳浓度的长期下降将会______。
A. increase methane concentration in the Earth’s atmosphere A. 增加地球大气中的甲烷浓度
B. accompany a period of glaciation B. 伴随冰川时期
C. encourage the formation of more oxygen isotopes in the Earth’s atmosphere C. 鼓励地球大气中更多氧同位素的形成
D. promote the formation of more water in the Earth’s global environment D. 促进地球环境中更多水的形成
【考查点】推理判断题。
【解题思路】根据文章第六句Although change in carbon dioxide content closely follows change in temperature during periods of de-glaciation, it apparently lags behind temperature during periods of cooling（尽管二氧化碳含量的变化紧跟在冰川消退时期的温度变化之后，但在冷却时期，二氧化碳含量的变化明显滞后于温度）来推断，在冰消时期，二氧化碳的含量变化是紧跟冰消时期的温度变化而变化，冰消时期温度是升高的，所以二氧化碳含量会增高；而在冷却时期，即冰川时期，温度下降二氧化碳含量也会下降，只是滞后于温度的变化；由此可以推断，如果二氧化碳的含量长期下降，温度肯定是比二氧化碳的含量下降的更明显，所以将会伴随着冰川时期，故B项“伴随冰川时期”正确。
【干扰项排除】
A、C、D项均未在文中体现，属于无中生有。
第4题:
【选项释义】
The passage suggests that when the methane concentration in the Earth’s atmosphere decreases, which of the following also happens? 文章指出，当地球大气中的甲烷浓度降低时，下列哪一种情况也会发生？
A. Glaciers melt faster. A. 冰川融化得更快。
B. The concentration of carbon dioxide increases. B. 二氧化碳浓度增加。
C. The global temperature decreases. C. 全球气温下降。
D. Carbon dioxide absorbs more radiant heat. D. 二氧化碳吸收更多的辐射热。
【考查点】推理判断题。
【解题思路】根据文中的Other data from the Vostok core show that methane gas also correlates closely with temperature and carbon dioxide（Vostok核的其他数据显示，甲烷气体也与温度和二氧化碳密切相关），以及最后一句methane appears to have been about 25 percent as important as carbon dioxide in the warming that took place during the most recent glacial retreat 8,000 to 10,000 years ago（在8000到10000年前的最近一次冰川消退中，甲烷大约贡献了二氧化碳的25%）可推断，当大气中甲烷浓度降低时，二氧化碳浓度可能会同样下降，那么可能会伴随冰川消退，所以温度会下降，C项“全球气温下降”正确。
【干扰项排除】
A项“冰川融化得更快”并不是甲烷浓度降低会带来的后果，属于答非所问；
B项“二氧化碳浓度增加”与文章表述不符，二氧化碳浓度会下降，属于曲解原文；
D项“二氧化碳吸收更多的辐射热”，二氧化碳吸收辐射热的多少和甲烷浓度没有直接关系，属于曲解原文。
