冰河时期海平面每百年上涨5.5米
时间：2020-09-23 09:34:19 来源：达达文档网 本文已影响 人 
Land-ice decay at the end of the last five ice-ages caused global sea-levels to rise at rates of up to 5.5 metres per century, according to a new study. An international team of researchers developed a 500,000-year record of sea-level variability, to provide the first account of how quickly sea-level changed during the last five ice-age cycles.The results, published in the latest issue of Nature Communications, also found that more than 100 smaller events of sea-level rise took place in between the five major events.Dr Katharine Grant, from the Australian National University (ANU), Canberra, who led the study, says: "The really fast rates of sea-level rise typically seem to have happened at the end of periods with exceptionally large ice sheets, when there was two or more times more ice on the Earth than today."Time periods with less than twice the modern global ice volume show almost no indications of sea-level rise faster than about 2 metres per century. Those with close to the modern amount of ice on Earth, show rates of up to 1 to 1.5 metres per century."Co-author Professor EelcoRohling, of both the University of Southampton and ANU, explains that the study also sheds light on the timescales of change.. He says: "For the first time, we have data from a sufficiently1 large set of events to systematically2 study the timescale over which ice-sheet responses developed from initial change to maximum retreat.""This happened within 400 years for 68 per cent of all 120 cases considered, and within 1100 years for 95 per cent. In other words, once triggered, ice-sheet reduction (and therefore sea-level rise) kept accelerating relentlessly3 over periods of many centuries."Professor Rohling speculates that there may be an important lesson for our future: "Man-made warming spans 150 years already and studies have documented clear increases in mass-loss from the Antarctic and Greenland ice sheets.. Once under way, this response may be irreversible for many centuries to come."The team reconstructed sea-levels using data from sediment4 cores from the Red Sea, an area that is very sensitive to sea-level changes because it's only natural connection with the open (Indian) ocean is through the very shallow (137 metre) Bab-el-Mandab Strait. These sediment samples record wind-blown dust variations, which the team linked to a well-dated climate record from Chinese stalagmites. Due to a common process, both dust and stalagmite records show a pronounced change at the end of each ice age, which allowed the team to date the sea-level record in detail.The researchers emphasise5 that their values for sea-level change are 500-year averages, so brief pulses of faster change cannot be excluded.The study was funded primarily by Natural Environment Research Council (NERC) and the Australian Research Council (ARC).词汇解析：1 sufficiently adv.足够地，充分地参考例句：It turned out he had not insured the house sufficiently.原来他没有给房屋投足保险。The new policy was sufficiently elastic to accommodate both views.新政策充分灵活地适用两种观点。2 systematically adv.有系统地参考例句：This government has systematically run down public services since it took office.这一屆政府自上台以来系统地削减了公共服务。The rainforest is being systematically destroyed.雨林正被系统地毀灭。3 relentlessly adv.不屈不挠地；残酷地；不间断参考例句：The African sun beat relentlessly down on his aching head. 非洲的太阳无情地照射在他那发痛的头上。He pursued her relentlessly, refusing to take 'no' for an answer. 他锲而不舍地追求她，拒不接受“不”的回答。4 sediment n.沉淀，沉渣，沉积(物)参考例句：The sediment settled and the water was clear.杂质沉淀后，水变清了。Sediment begins to choke the channel's opening.沉积物开始淤塞河道口。5 emphasisevt.加强...的语气，强调，着重参考例句：What special feature do you think I should emphasise? 你认为我该强调什么呢？The exercises heavily emphasise the required readings.练习非常强调必须的阅读。更多英语学习方法：企业英语培训/
