世界最大冰川比想象中稳定
文章来源:未知 文章作者:enread 发布时间:2013-05-17 07:03 字体: [ ]  进入论坛
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For decades, scientists have used ancient shorelines to predict the stability of today's largest ice sheets in Greenland and Antarctica. Markings of a high shoreline from three million years ago, for example -- when Earth was going through a warm period -- were thought to be evidence of a high sea level due to ice sheet collapse1 at that time. This assumption has led many scientists to think that if the world's largest ice sheets collapsed2 in the past, then they may do just the same in our modern, progressively warming world. However, a new groundbreaking study now challenges this thinking.
 
Using the east coast of the United States as their laboratory, a research team led by David Rowley, CIFAR Senior Fellow and professor at the University of Chicago, has found that Earth's hot mantle3 pushed up segments of ancient shorelines over millions of years, making them appear higher now than they originally were millions of years ago.
 
"Our findings suggest that the previous connections scientists made between ancient shoreline height and ice volumes are erroneous(错误的) and that perhaps our ice sheets were more stable in the past than we originally thought," says Rowley. "Our study is telling scientists that they can no longer ignore the effect of Earth's interior dynamics4 when predicting historic sea levels and ice volumes."
 
The study, published online in Science on May 16, was a collaboration5 that included CIFAR Senior Fellows Alessandro Forte6 (Université du Québec à Montréal) and Jerry Mitrovica (Harvard), and a former CIFAR-supported post-doctoral fellow Rob Moucha (Syracuse).
 
"This study was the culmination7 of years of work and deep collaboration by researchers in CIFAR's program in Earth System Evolution," explains Rowley. "For this study, each of us brought our individual expertise8 to the table: Rob and Alex worked on simulations of Earth's mantle dynamics, Jerry provided calculations on how glaciers9 warp10 Earth's surface, and I shaped our understanding of the geology of the landscape we were looking at. This study would not have been possible without CIFAR."
 
The team studied the coast from Virginia to Florida, which has an ancient scarp tens of metres above present-day sea level. Until now, many research groups have studied this shoreline and concluded that during a warm period three million years ago, the Greenland, West Antarctic and a fraction of East Antarctic ice sheets collapsed, raising the sea level at least 35 metres. But the new findings by Rowley and his team suggest that these ice sheets, particularly the East Antarctic Ice Sheet (the world's largest), were probably more stable.
 
To do their study, the team used computer simulations to follow the movement of mantle and tectonic plates that occurred over time. Their prediction of how the ancient shoreline would have developed over millions of years matched what geologists11 mapping this ancient coast have observed. The next steps for the team are to try to make accurate predictions in other locations around the world.
 
"The paper is important because it shows that no prediction of ancient ice volumes can ever again ignore the Earth's interior dynamics," explains Rowley. "It also provides a novel bridge between two disciplines in Earth science that rarely intersect: mantle dynamics and long-term climate. It is the kind of study that changes how people think about our past climate and what our future holds."


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1 collapse aWvyE     
vi.累倒;昏倒;倒塌;塌陷
参考例句:
  • The country's economy is on the verge of collapse.国家的经济已到了崩溃的边缘。
  • The engineer made a complete diagnosis of the bridge's collapse.工程师对桥的倒塌做了一次彻底的调查分析。
2 collapsed cwWzSG     
adj.倒塌的
参考例句:
  • Jack collapsed in agony on the floor. 杰克十分痛苦地瘫倒在地板上。
  • The roof collapsed under the weight of snow. 房顶在雪的重压下突然坍塌下来。
3 mantle Y7tzs     
n.斗篷,覆罩之物,罩子;v.罩住,覆盖,脸红
参考例句:
  • The earth had donned her mantle of brightest green.大地披上了苍翠欲滴的绿色斗篷。
  • The mountain was covered with a mantle of snow.山上覆盖着一层雪。
4 dynamics NuSzQq     
n.力学,动力学,动力,原动力;动态
参考例句:
  • In order to succeed,you must master complicated knowledge of dynamics.要取得胜利,你必须掌握很复杂的动力学知识。
  • Dynamics is a discipline that cannot be mastered without extensive practice.动力学是一门不做大量习题就不能掌握的学科。
5 collaboration bW7yD     
n.合作,协作;勾结
参考例句:
  • The two companies are working in close collaboration each other.这两家公司密切合作。
  • He was shot for collaboration with the enemy.他因通敌而被枪毙了。
6 forte 8zbyB     
n.长处,擅长;adj.(音乐)强音的
参考例句:
  • Her forte is playing the piano.她擅长弹钢琴。
  • His forte is to show people around in the company.他最拿手的就是向大家介绍公司。
7 culmination 9ycxq     
n.顶点;最高潮
参考例句:
  • The space race reached its culmination in the first moon walk.太空竞争以第一次在月球行走而达到顶峰。
  • It may truly be regarded as the culmination of classical Greek geometry.这确实可以看成是古典希腊几何的登峰造级之作。
8 expertise fmTx0     
n.专门知识(或技能等),专长
参考例句:
  • We were amazed at his expertise on the ski slopes.他斜坡滑雪的技能使我们赞叹不已。
  • You really have the technical expertise in a new breakthrough.让你真正在专业技术上有一个全新的突破。
9 glaciers e815ddf266946d55974cdc5579cbd89b     
冰河,冰川( glacier的名词复数 )
参考例句:
  • Glaciers gouged out valleys from the hills. 冰川把丘陵地带冲出一条条山谷。
  • It has ice and snow glaciers, rainforests and beautiful mountains. 既有冰川,又有雨林和秀丽的山峰。 来自英语晨读30分(高一)
10 warp KgBwx     
vt.弄歪,使翘曲,使不正常,歪曲,使有偏见
参考例句:
  • The damp wood began to warp.这块潮湿的木材有些翘曲了。
  • A steel girder may warp in a fire.钢梁遇火会变弯。
11 geologists 1261592151f6aa40819f7687883760a2     
地质学家,地质学者( geologist的名词复数 )
参考例句:
  • Geologists uncovered the hidden riches. 地质学家发现了地下的宝藏。
  • Geologists study the structure of the rocks. 地质学家研究岩石结构。
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