大学六级-1463及答案解析.doc
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1、大学六级-1463 及答案解析(总分:712.00,做题时间:90 分钟)一、Part Writing(总题数:1,分数:106.00)1.1老一辈常说,能力比相貌重要2如今很多人却认为相貌比能力重要3你的看法(分数:106.00)_二、Part Reading Compr(总题数:1,分数:70.00)Climate ChangeScientists predict increasing droughts, floods and extreme weather and say there is growing evidence that human activities are to bla
2、me.What Is Climate Change?The planets climate is constantly changing. The global average temperature is currently in the region of 15. Geological and other evidence suggests that, in the past, this average may have been as high as 27 and as low as 7.But scientists are concerned that the natural fluc
3、tuation (波动) has been overtaken by a rapid human-induced warming that has serious implications for the stability of the climate on which much life on the planet depends.What Is the “Greenhouse Effect“?The greenhouse effect refers to the role played by gases which effectively trap energy from the Sun
4、 in the Earths atmosphere. Without them, the planet would be too cold to sustain life as we know it.The most important of these gases in the natural greenhouse effect is water vapor, but concentrations of that are changing little and it plays almost no role in modem human-induced greenhouse warming.
5、Other greenhouse gases include carbon dioxide, methane (甲烷) and nitrous (含氮的) oxide, which are released by modern industry, agriculture and the burning of fossil fuels. Their concentration in the atmosphere is increasingthe concentration of carbon dioxide has risen by more than 30% since 1800.The ma
6、jority of climate scientists accept the theory that an increase in these gases will cause a rise in the Earths temperature.What Is the Evidence of Warming?Temperature records go back to the late 19th century and show that the global average temperature increased by about 0.6 in the 20th century.Sea
7、levels have risen 1020 cmthought to be caused mainly by the expansion of warming oceans.Most glaciers in temperate regions of the world and along the Antarctic Peninsula are in retreat, and records show Arctic sea-ice has thinned by 40% in recent decades in summer and autumn.There are anomalies (异常)
8、 howeverparts of. the Antarctic appear to be getting colder, and there are discrepancies between trends in surface temperatures and those in the troposphere(对流层) (the lower portion of the atmosphere).How Much Will Temperatures Rise?If nothing is done to reduce emissions, current climate models predi
9、ct a global temperature increase of 1.45.8 by 2100.Even if we cut greenhouse gas emissions dramatically now, scientists say the effects would continue because parts of the climate system, particularly large bodies of water and ice, can take hundreds of years to respond to changes in temperature. It
10、also takes greenhouse gases in the atmosphere decades to break down.It is possible that we have already irrevocably(不可撤回地) committed the Greenland ice sheet to melting, which would cause an estimated 7m rise in sea level. There are also indications that the west Antarctic ice sheet may have begun to
11、 melt. though scientists caution further research is necessary.How Will the Weather Change?Globally, we can expect more extreme weather events, with heat waves becoming hotter and more frequent. Scientists predict more rainfall overall, but say the risk of thought in inland areas during hot summers
12、will increase. More flooding is expected from storms and rising sea levels.There are, however, likely to be very strong regional variations in these patterns, and these ere difficult to predict.What Will the Effects Be?The potential impact is huge, with predicted freshwater shortages, sweeping chang
13、es in food production conditions, and increases in deaths from floods, storms, heat waves and droughts. Poorer countries, which are least equipped to deal with rapid change, will suffer most.Plant and animal extinctions are predicted as habitats change faster than species can adapt and the World Hea
14、lth Organization has warned that the health of millions could be threatened by increases in malaria, water-home disease and malnutrition.What Dont We Know?We dont know exactly what proportion of the observed warming is caused by human activities or what the knock-on effects of the warming will be.Th
15、e precise relationship between concentrations of carbon dioxide (and other greenhouse gases) and temperature rise is not known, which is one mason why there is such uncertainty in projections of temperature increase.Global warming will cause some changes which will speed up further warming, such as
16、the release of large quantities of the greenhouse gas methane as permafrost(永久冻结带) melts.Other factors may mitigate(减轻) warming. It is possible that plants may hake more carbon dioxide from the atmosphere as their growth speeds up in warmer conditions, though this remains in doubt.Scientists are not
17、 sure how the complex balance between these positive and negative feedback effects will play out.What about the Skeptics?Global warming “skeptics“ fall into three broad camps:those who maintain temperatures are not rising;those who accept the climate is changing but suspect it is largely down to nat
18、ural variation;those who accept the theory of human-induced warming but say it is not worth tackling as other global problems are more pressing.Nevertheless, there is a growing scientific consensus (舆论) that. even on top of the natural variability of the climate, something out of the ordinary is hap
19、pening and humans are to blame.A scientific report commissioned by the U.S. government has concluded there is “clear evidence“ of climate change caused by human activities. The report, from the federal Climate Change Science Program, said trends seen over the last 50 years “cannot be explained by na
20、tural processes alone“.It found that temperatures have increased in the lower atmosphere as well as at the Earths surface. However. scientists involved in the report say better data is badly needed.Observations down the years have suggested that the troposphere, the lower atmosphere, is not warming
21、up, despite evidence that temperatures at the Earths surface are rising. This goes against generally accepted tenets (原则) of atmospheric physics, and has been used by “climate skeptics“ as proof that there is no real warming.The new report, Temperature Trends in the Lower Atmosphere, re-analyses the
22、 atmospheric data and concludes that tropospheric temperatures Ire rising. This means, it says, that the impact of human activities upon the global climate is clear. “The observed patterns of change over the past 50 years cannot be explained lay natural processes alone: nor by the effect of short-li
23、ved atmospheric constituents (such as aerosols and tropospheric ozone) alone.“ it says.Holes in the DataBut there are some big uncertainties which still need resolving. Globally, the report concludes, tropospheric temperatures have risen by 0.10 and 0.20 per decade since 1979, when satellite dam bec
24、ame generally available. The wide gap between the two figures means, says the report, that “.it is not clear whether the troposphere has warmed more or less than the surface.“Peter Thorne, of the U.K. Meteorological Office, who contributed to the report, ascribes this uncertainty to poor data. “Basi
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- 大学 1463 答案 解析 DOC
