题目内容
If pollution continues to increase at the present rate, formation of aerosols in the atmosphere will cause the onset of an ice age in about fifty years’ time. This conclusion, reached by Dr. S. I. Rasool and Dr. S. H. Schneider, of the United States Goddard Space Flight Center, answers the apparently conflicting question of whether an increase in the carbon di- oxide content of the atmosphere will cause the earth to warm up or increasing the aerosol content will cause it to cool down. The Americans have shown conclusively that the aerosol question is dominant. Two specters haunting conservationists have been the prospect that meddling with the environment might lead to the planet’s becoming unbearably hot or cold. One of these ghosts has now been laid, because it seems that even an increase in the amount of carbon dioxide in the atmosphere to eight times its present value will produce an increase in temperature of only 2(上标)C, which would take place over several thousand years. But the other problem, now looms larger than ever. Aerosols are collections of small liquid or solid particles dispersed in air or some other medium. The particles are all so tiny that each is composed of only a few hundred atoms. Because of this they can float in the air for a very long time. Perhaps the most commonly experienced aerosol is industrial smog of the kind that plagued London in the 1950s and is an even greater problem in Los Angeles today. These collections of aerosols reflect the sun’s heat and thereby caused the earth to cool. Dr. Rasool and Dr. Schneider have calculated the exact effect of a dust aerosol layer just above the earth’s surface on the temperature of the planet. As the layer builds up, the present delicate balance between the amount of heat absorbed from the sun and the amount radiated from the earth is disturbed. The aerosol layer not only reflects much of the sun’s light but also transmits the infrared radiation from below almost unimpeded. So, while the heat input to the surface drops, the loss of heat remains high until the planet cools to a new balanced state. Within fifty years, if no steps are taken to curb the spread of aerosols in the atmosphere, a cooling of the earth by as much as 3.5。C seems inevitable. If that lasts for only a few years, it would start another ice age, and because the growing ice caps at each pole would themselves reflect much of the sun’s radiation, it would probably continue to develop even if the aerosol layer were destroyed. The only bright spot in this gloomy forecast lies in the hope expressed by Dr. Rasool and Dr. Schneider that nuclear power may replace fossil fuels in time to prevent the aerosol content of the atmosphere from becoming critical. What might avert the danger of the building up of a high concentration of aerosols
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Scotland Yard’s top fingerprint expert, Detective Chief superintendent Gerald Lamhourne had a request from the British Museum’s Prehistoric department to force his magnifying glass on a mystery somewhat outside my usual beat. This was not a question of Whodunit, but Who Was lt. The blunt instruments, he pored over were the antlers of red deer, dated by radio-carbon examination as being up to 5,000 years old. They were used as mining picks by Neolithic man to hack flints and chalk, and the fingerprints he was looking for were of our remote ancestors who had last wielded them. The antlers were unearthed in July during the British Museum’s five-year-long excavation at Grime’s Graves. near Therford, Norfolk, a 93 acre site containing more than 600 vertical shafts in the chalk some 40 feet deep. From artifacts found in many parts of Britain it is evident that flint was extensively used by Neolithic man as he slowly learned how to farm land in the period from 3, 000 to 1, 500 B. C. Flint was especially used for ax-heads to clear forests for agriculture, and the quality of the flint on the Norfolk site suggests that the miners there were kept busy with many orders. What excited Mr. CT. Sieveking, the museum’s deputy director of the excavations, was the dried mud still sticking to some of them. "Our deduction is that the miners coated the base of the antlers with mud so that they could get a better grip," he says. "The exciting possibility was that fingerprints left in this mud might at last identify as individuals as people who have left few relics, who could not read or write, but who may have had much more intelligence than had been supposed in the past." Chief Superintendent Lambourne, who had "assisted" the British Museum by taking the fingerprints of a 4, 000-year-old Egyptian mummy, spent two hours last week examining about 50 antlers. On some he found minute marks indicating a human hand--that part of the hand just below the fingers where most pressure would be brought to bear the wielding of a pick. After 25 years’ specialization in the Yard’s fingerprints department, Chief Superintendent Lambourne knows all about ridge structures--technically known as the "tri-radiate section". It was his identification of that part of the hand that helped to incriminate some of the Great Train Robbers. In 1995 he discovered similar handprints on a bloodstained tee-maker on a golf-course where a woman had been brutally murdered. They eventually led to the killer, after 4, 065 handprints had been taken. Chief Superintendent Lamboure had agreed to visit the Norfolk site during further excavations next summer, when it is hoped that further hand-marked antlers will come to light, But he is cautious about the historic significance of his findings. "Fingerprints and handprints are unique to each individual but they can tell nothing about the age, physical characteristics, even sex of the person who left them," he says. "Even the finger prints of gorilla could be mistaken for those of a man. But if a number of imprinted antlers are recovered from given shafts on this site I could at least determine which antlers were handled by the same man, and from there might be deduced the number of miners employed in a team." "As an indication of intelligence I might determine which way up the miners held the antlers and how they wielded them." To Mr. Sieveking and his museum colleagues, any such findings will be added to their dossier of what might appear to the layman as trivial and unrelated facts but from which might emerge one day an impressive new image of our remote ancestors. (620) The idea that mud was applied to the antlers deliberately was ______.
If pollution continues to increase at the present rate, formation of aerosols in the atmosphere will cause the onset of an ice age in about fifty years’ time. This conclusion, reached by Dr. S. I. Rasool and Dr. S. H. Schneider, of the United States Goddard Space Flight Center, answers the apparently conflicting question of whether an increase in the carbon di- oxide content of the atmosphere will cause the earth to warm up or increasing the aerosol content will cause it to cool down. The Americans have shown conclusively that the aerosol question is dominant. Two specters haunting conservationists have been the prospect that meddling with the environment might lead to the planet’s becoming unbearably hot or cold. One of these ghosts has now been laid, because it seems that even an increase in the amount of carbon dioxide in the atmosphere to eight times its present value will produce an increase in temperature of only 2(上标)C, which would take place over several thousand years. But the other problem, now looms larger than ever. Aerosols are collections of small liquid or solid particles dispersed in air or some other medium. The particles are all so tiny that each is composed of only a few hundred atoms. Because of this they can float in the air for a very long time. Perhaps the most commonly experienced aerosol is industrial smog of the kind that plagued London in the 1950s and is an even greater problem in Los Angeles today. These collections of aerosols reflect the sun’s heat and thereby caused the earth to cool. Dr. Rasool and Dr. Schneider have calculated the exact effect of a dust aerosol layer just above the earth’s surface on the temperature of the planet. As the layer builds up, the present delicate balance between the amount of heat absorbed from the sun and the amount radiated from the earth is disturbed. The aerosol layer not only reflects much of the sun’s light but also transmits the infrared radiation from below almost unimpeded. So, while the heat input to the surface drops, the loss of heat remains high until the planet cools to a new balanced state. Within fifty years, if no steps are taken to curb the spread of aerosols in the atmosphere, a cooling of the earth by as much as 3.5。C seems inevitable. If that lasts for only a few years, it would start another ice age, and because the growing ice caps at each pole would themselves reflect much of the sun’s radiation, it would probably continue to develop even if the aerosol layer were destroyed. The only bright spot in this gloomy forecast lies in the hope expressed by Dr. Rasool and Dr. Schneider that nuclear power may replace fossil fuels in time to prevent the aerosol content of the atmosphere from becoming critical. How would the increasing area of ice itself lower the temperature of the planet
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