One of the most difficult aspects of deciding whether current climatic events reveal evidenceof the impact of human activities is that it is hard to get a measure of what constitutes thenatural variability of the climate. We know that over the past millennia the climate hasundergone major changes without any significant human intervention. We also know that theglobal climate system is immensely complicated and that everything is in some way connected,and so the system is capable of fluctuating in unexpected ways. We need therefore to knowhow much the climate can vary of its own accord in order to interpret with confidence theextent to which recent changes are natural as opposed to being the result of human activities.
Instrumental records do not go back far enough to provide us with reliable measurements ofglobal climatic variability on timescales longer than a century. What we do know is that as weinclude longer time intervals, the record shows increasing evidence of slow swings in climatebetween different regimes. To build up a better picture of fluctuations appreciably further backin time requires us to use proxy records.
Over long periods of time, substances whose physical and chemical properties change with theambient climate at the time can be deposited in a systematic way to provide a continuousrecord of changes in those properties overtime, sometimes for hundreds or thousands ofyears. Generally, the layering occurs on an annual basis, hence the observed changes in therecords can be dated. Information on temperature, rainfall, and other aspects of the climatethat can be inferred from the systematic changes in properties is usually referred to as proxydata. Proxy temperature records have been reconstructed from ice core drilled out of thecentral Greenland ice cap, calcite shells embedded in layered lake sediments in Western Europe,ocean floor sediment cores from the tropical Atlantic Ocean, ice cores from Peruvian glaciers,and ice cores from eastern Antarctica. While these records provide broadly consistentindications that temperature variations can occur on a global scale, there are nonethelesssome intriguing differences, which suggest that the pattern of temperature variations inregional climates can also differ significantly from each other.
What the proxy records make abundantly clear is that there have been significant naturalchanges in the climate over timescales longer than a few thousand years. Equally striking,however, is the relative stability of the climate in the past 10.000 years (the Holocene period).
To the extent that the coverage of the global climate from these records can provide ameasure of its true variability, it should at least indicate how all the natural causes of climatechange have combined. These include the chaotic fluctuations of the atmosphere, the slowerbut equally erratic behavior of the oceans, changes in the land surfaces, and the extent of iceand snow. Also included will be any variations that have arisen from volcanic activity, solaractivity, and, possibly, human activities.
One way to estimate how all the various processes leading to climate variability will combine isby using computer models of the global climate. They can do only so much to represent the fullcomplexity of the global climate and hence may give only limited information about naturalvariability. Studies suggest that to date the variability in computer simulations is considerablysmaller than in data obtained from the proxy records.
In addition to the internal variability of the global climate system itself, there is the addedfactor of external influences, such as volcanoes and solar activity .There is a growing body ofopinion that both these physical variations have a measurable impact on the climate. Thus weneed to be able to include these in our deliberations. Some current analyses conclude thatvolcanoes and solar activity explain quite a considerable amount of the observed variability inthe period from the seventeenth to the early twentieth century’s, but that they cannot beinvoked to explain the rapid warming in recent decades.
Paragraph 1：One of the most difficult aspects of deciding whether current climatic eventsreveal evidence of the impact of human activities is that it is hard to get a measure of whatconstitutes the natural variability of the climate. We know that over the past millennia theclimate has undergone major changes without any significant human intervention. We alsoknow that the global climate system is immensely complicated and that everything is in someway connected, and so the system is capable of fluctuating in unexpected ways. We needtherefore to know how much the climate can vary of its own accord in order to interpret withconfidence the extent to which recent changes are natural as opposed to being the result ofhuman activities.
1. According to paragraph 1, which of the following must we find out in order to determine theimpact of human activities upon climate?
○ The major changes in climate over the past millennia
○ The degree to which the climate varies naturally
○ The best method for measuring climatic change
○ The millennium when humans began to interfere with the climate
Paragraph 2：Instrumental records do not go back far enough to provide us with reliablemeasurements of global climatic variability on timescales longer than a century. What we doknow is that as we include longer time intervals, the record shows increasing evidence of slowswings in climate between different regimes. To build up a better picture of fluctuationsappreciably further back in time requires us to use proxy records.
2. According to paragraph 2, an advantage of proxy records over instrumental records is that
○ they are more-reliable measures of climatic variability in the past century
○ they provide more-accurate measures of local temperatures
○ they provide information on climate fluctuations further back in time
○ they reveal information about the human impact on the climate
Paragraph 3：Over long periods of time, substances whose physical and chemical propertieschange with the ambient climate at the time can be deposited in a systematic way to provide acontinuous record of changes in those properties overtime, sometimes for hundreds orthousands of years. Generally, the layering occurs on an annual basis, hence the observedchanges in the records can be dated. Information on temperature, rainfall, and other aspectsof the climate that can be inferred from the systematic changes in properties is usuallyreferred to as proxy data. Proxy temperature records have been reconstructed from ice coredrilled out of the central Greenland ice cap, calcite shells embedded in layered lake sediments inWestern Europe, ocean floor sediment cores from the tropical Atlantic Ocean, ice cores fromPeruvian glaciers, and ice cores from eastern Antarctica. While these records provide broadlyconsistent indications that temperature variations can occur on a global scale, there arenonetheless some intriguing differences, which suggest that the pattern of temperaturevariations in regional climates can also differ significantly from each other.
3. Which of the sentences below best expresses the essential information in the highlightedsentence in the passage? Incorrect choices change the meaning in important ways or leave outessential information
○ Because physical and chemical properties of substances are unchanging, they are usefulrecords of climate fluctuations over time
○ For hundreds or thousands of years, people have been observing changes in the chemicaland physical properties of substances in order to infer climate change
○ Because it takes long periods of time for the climate to change, systematic changes in theproperties of substances are difficult to observe.
○ Changes in systematically deposited substances that are affected by climate can indicateclimate variations over time.
4. According to paragraph 3, scientists are able to reconstruct proxy temperature records by
○ studying regional differences in temperature variations
○ studying and dating changes in the properties of substances
○ observing changes in present day climate conditions
○ inferring past climate shifts from observations of current climatic changes
Paragraph 4：What the proxy records make abundantly clear is that there have been significantnatural changes in the climate over timescales longer than a few thousand years. Equallystriking, however, is the relative stability of the climate in the past 10.000 years (the Holoceneperiod).
5. The word striking in the passage is closest in meaning to
○ noticeable
○ confusing
○ true
○ unlikely
Paragraph 3：Over long periods of time, substances whose physical and chemical propertieschange with the ambient climate at the time can be deposited in a systematic way to provide acontinuous record of changes in those properties overtime, sometimes for hundreds orthousands of years. Generally, the layering occurs on an annual basis, hence the observedchanges in the records can be dated. Information on temperature, rainfall, and other aspectsof the climate that can be inferred from the systematic changes in properties is usuallyreferred to as proxy data. Proxy temperature records have been reconstructed from ice coredrilled out of the central Greenland ice cap, calcite shells embedded in layered lake sediments inWestern Europe, ocean floor sediment cores from the tropical Atlantic Ocean, ice cores fromPeruvian glaciers, and ice cores from eastern Antarctica. While these records provide broadlyconsistent indications that temperature variations can occur on a global scale, there arenonetheless some intriguing differences, which suggest that the pattern of temperaturevariations in regional climates can also differ significantly from each other.
Paragraph 4：What the proxy records make abundantly clear is that there have been significantnatural changes in the climate over timescales longer than a few thousand years. Equallystriking, however, is the relative stability of the climate in the past 10.000 years (the Holoceneperiod).
6. According to paragraphs 3 and 4, proxy data have suggested all of the following about theclimate EXCEPT:
○ Regional climates may change overtime.
○ The climate has changed very little in the past 10.000 years.
○ Global temperatures vary more than regional temperatures.
○ Important natural changes in climate have occurred over large timescales.
Paragraph 5：To the extent that the coverage of the global climate from these records canprovide a measure of its true variability, it should at least indicate how all the natural causesof climate change have combined. These include the chaotic fluctuations of the atmosphere, theslower but equally erratic behavior of the oceans, changes in the land surfaces, and the extentof ice and snow. Also included will be any variations that have arisen from volcanic activity,solar activity, and, possibly, human activities.
7. The word erratic in the passage is closest in meaning to
○ dramatic
○ important
○ unpredictable
○ common
8. All of the following are mentioned in paragraph 5 as natural causes of climate change EXCEPT
○ atmospheric changes
○ the slow movement of landmasses
○ fluctuations in the amount of ice and snow
○ changes in ocean activity
Paragraph 6：One way to estimate how all the various processes leading to climate variabilitywill combine is by using computer models of the global climate. They can do only so much torepresent the full complexity of the global climate and hence may give only limited informationabout natural variability. Studies suggest that to date the variability in computer simulationsis considerably smaller than in data obtained from the proxy records.
9. According to paragraph 6, which of the following is true of computer models of the globalclimate?
○ The information they produce is still limited.
○ They are currently most useful in understanding past climatic behaviors.
○ They allow researchers to interpret the data obtained from proxy records.
○ They do not provide information about regional climates
Paragraph 7：In addition to the internal variability of the global climate system itself, thereis the added factor of external influences, such as volcanoes and solar activity .There is agrowing body of opinion that both these physical variations have a measurable impact on theclimate. Thus we need to be able to include these in our deliberations. Some current analysesconclude that volcanoes and solar activity explain quite a considerable amount of theobserved variability in the period from the seventeenth to the early twentieth century’s, butthat they cannot be invoked to explain the rapid warming in recent decades.
10. The word deliberations in the passage is closest in meaning to
○ records
○ discussions
○ results
○ variations
11. The word invoked in the passage is closest in meaning to
○ demonstrated
○ called upon
○ supported
○ expected
12. What is the author's purpose in presenting the information in paragraph 7?
○ To compare the influence of volcanoes and solar activity on climate variability with theinfluence of factors external to the global climate system
○ To indicate that there are other types of influences on climate variability in addition tothose previously discussed
○ To explain how external influences on climate variability differ from internal influences
○ To argue that the rapid warming of Earth in recent decades cannot be explained
Paragraph 7：In addition to the internal variability of the global climate system itself, thereis the added factor of external influences, such as volcanoes and solar activity .There is agrowing body of opinion that both these physical variations have a measurable impact on theclimate. Thus we need to be able to include these in our deliberations. Some current analysesconclude that volcanoes and solar activity explain quite a considerable amount of theobserved variability in the period from the seventeenth to the early twentieth century’s, butthat they cannot be invoked to explain the rapid warming in recent decades.
13. Look at the four squares [] that indicate where the following sentence could be added tothe passage.
Indeed, the contribution of volcanoes and solar activity would more likely have been to actuallyreduce the rate of warming slightly.
Where would the sentence best fit?
14.Directions: An introductory sentence for a brief summary of the passage is providedbelow. Complete the summary by selecting the THREE answer that express the most importantideas in the passage. Some sentences do not belong in the summary because they expressideas that not presented in the passage or are minor ideas in the passage. This question isworth 2 points.
A number of different and complex factors influence changes in the global climate over longperiods of time.
Answer choices
○ In the absence of instrumental records, proxy data allow scientists to infer informationabout past climates.
○ Scientists see a consistent pattern in the global temperature variations that have occurredin the past.
○ Computer models are used to estimate how the different causes of climate variabilitycombine to account for the climate variability that occurs.
○ Scientists have successfully separated natural climate variation from changes related tohuman activities.
○ Scientists believe that activities outside the global climate system, such as volcanoes andsolar activity may have significant effects on the system.
○ Scientists have concluded that human activity accounts for the rapid global warming in recentdecades.
参考答案：
1. ○2
2. ○3
3. ○4
4. ○2
5. ○1
6. ○3
7. ○3
8.○2
9. ○1
10. ○2
11. ○2
12. ○2
13. ○4
14. ○1 3 5
#p#副标题#e#
气候变化
确定现在的气候事件是否证明人类活动影响的最大困难之一在于很难找到一种方法来确定是什么构成了气候的自然可变性。我们知道在过去的几千年里，气候在没有重大人类干预下也经历了主要变化。我们还知道全球气候系统是非常复杂的，所有因素都在某些方面互相联系，因此这个系统以意想不到的方法变化着。因此，我们需要知道气候在多大程度上是自然变化的，以便于确切解释出最近的变化在多大程度上是自然的，或相反是人类活动的结果。
仪器记录不能追溯回那么久远以提供给我们长于一个世纪的时间标准下的全球气候可变性的可信测量方法。我们所确知的就是当我们想包括更长久的时间跨度，记录揭示了在不同制度中缓慢的摇摆的更多的证据。为了建立一个略久远变化的更好的变化描述，需要我们使用替代记录。
经过很长一段时间，物理和化学特征随着当时周围的气候变化的物质将会以系统的方法沉淀，这可以提供那些特征在超长时间里变化的连续记录, 这个超长时间有时可达几百年或几千年。通常，分层堆积是每年发生的，因此在记录中可观察的变化可以用来确定日期。 关于温度，降雨和气候的其他方面的信息通常都是指替代数据，这些信息可以从这种特征的系统变化中推断出来。替代温度记录已被重建通过：钻取自格陵兰冰帽中部的冰核，西欧深嵌在分层湖底沉积物中的方解石壳，取自热带大西洋的海底沉积物核，取自秘鲁冰河的冰核,和取自东南极洲的冰核。尽管这新记录提供了广范一致的迹象指出温度变化可在全球范围内发生，但仍存在引人发问的差异，这些差异表示区域性气候的温度变化方式可以如此不同。
代理记录所充分解释的是在长于几千年的时间跨度里存在着显著的自然气候变化。但同样令人惊讶的是在过去的一万年(全新世)中气候的相对稳定。【*全新世：在地质年表上第四纪后两世从更新世结束一直到现在岩石时期的泥沙时期——译者】
这些记录中对全球气候的覆盖度已经达到了可以提供气候可变性的方法的程度，它应该至少揭示所有引起气候变化的自然原因是怎样结合的。这些原因包括混乱的大气波动，相对较慢但相当混乱的海洋活动，地表变化和冰雪的覆盖度。还包括任何火山活动、太阳活动将会引起的变化。或许也包括人类活动引起的变化。
一种可估计所有这些导致气候变化的不同过程是如何结合的方法就是使用计算机全球气候模型。它们可以做的只有这么多来描绘全球气候的全部复杂性，因此只能提供自然变化的有限信息。研究表明迄今为止计算机模拟的可变性比取自代理记录的数据少得多。
除全球气候系统本身的内部变化之外，还存在其他外部影响的因素，如火山或太阳活动。有越来越多的观点认为这两种物理变化对气候有着可测量的影响。因此我们需要能够考虑到这些。一些现在的分析断定火山和太阳活动解释了自17世纪到20世纪早期的相当多的可观察到的变化但他们不能用以揭示最近几十年的迅速变暖。