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Unformatted text preview: that they cannot be invoked to explain the rapid warming in recent decades. Paragraph 1在One of the most difficult aspects of deciding whether current climatic events reveal evidence of the impact of human activities is that it is hard to get a measure of what constitutes the natural variability of the climate. We know that over the past millennia the climate has undergone major changes without any significant human intervention. We also know that the global 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 know how much the climate can vary of its own accord in order to interpret with confidence the extent to which recent changes are natural as opposed to being the result of human activities.
1. According to paragraph 1, which of the following must we find out in order to determine the impact 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 在 Instrumental records do not go back far enough to provide us with reliable measurements of global climatic variability on timescales longer than a century. What we do know is that as we include longer time intervals, the record shows increasing evidence of slow swings in climate between different regimes. To build up a better picture of fluctuations appreciably 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 morereliable measures of climatic variability in the past century
○ they provide moreaccurate 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在Over long periods of time, substances whose physical and chemical properties change with mbient climate at the time can be deposited in a systematic way to provide a continuous record of the a
changes in those properties overtime, sometimes for hundreds or thousands of years. enerally, the layering G
occurs on an annual basis, hence the observed changes in the records can bedated. Information on temperature, rainfall, and other aspects of the climate that can be inferred from the systematic changes in properties is usually referred to as proxy data. Proxy temperature records have been reconstructed from ice core drilled out of the central 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 consistent indications that temperature variations can occur on a global scale, there are nonetheless some intriguing differences, which suggest that the pattern of temperature variations in regional climates can also differ significantly from each other.
3. Which of the sentences...
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This note was uploaded on 09/17/2013 for the course LANGUAGE 13DL208 taught by Professor Wang during the Fall '13 term at East China Normal University.
- Fall '13