南极冰川形成与co2有关-凯发k8官网

南极冰川形成与co2有关
文章来源:未知 文章作者:enread 发布时间:2011-12-02 02:03 字体: [ ] 
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1 carbon dioxide levels 2 by 40 percent before and during the formation of the antarctic ice sheet 34 million years ago, according to a new study. the finding helps solve a long-standing scientific puzzle and confirms the power of co2 to dramatically alter global climate. the study by an international team, published in the journal science, is the first multidisciplinary(有关各种学问的) research of its kind to show that co2 was tracking global cooling at that time. it confirms that significant falls in the greenhouse gas result in global cooling, just as rises result in global warming.

previous studies had suggested that atmospheric co2 over the southern ocean was climbing during the eocene to oligocene climate transition, when ice first formed over antarctica. this presented a 3(难题) , suggesting the climate was warming at the same time as antarctica was freezing.

but when the vastly different ancient southern ocean currents and temperatures of that period were factored in, it quickly became apparent that antarctica's big freeze followed a fall in co2 levels.

the paper, "the role of carbon dioxide during the 4 of antarctic glaciation," reinforces carbon dioxide's place as a primary driver for global temperatures. it was lead authored by mark pagani, of yale university, and co-authored by unsw climate change research centre researcher dr willem sijp.

"our research recognised that the flows of deep ocean currents at the end of the eocene were dramatically different from those of today because of the altered position and shape of 5 masses(大陆块体) ," said dr sijp.

"previous research relied on different temperature estimates and had also not taken these different currents into account. this led to significant upward 6(向上偏误) in calculated co2 which made it appear that carbon dioxide was actually increasing around the southern ocean as the antarctic ice sheet formed. we can now see the reverse was true.

"we found a 40 percent co2 decrease over a three million year period, in agreement with global cooling during that time.

"this decline was a critical condition for global cooling and the 7(出现) of the antarctic ice sheet. in short, the apparent increase of co2 during antarctic glaciation(冰川作用) is refuted."

the nature of ocean currents is vital in calculating atmospheric co2, because the estimates of atmospheric carbon dioxide are 8 from measurements of 9 from 10 deposited on the ocean floor at six ocean sites millions of years ago.

the fundamentally different circulation of the southern ocean during the eocene directly 11 the algae by changing the temperatures of these ocean currents and significantly lowering the 12 load. this had a direct impact on the inferred co2.



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1 6eayr     
adj.大气的,空气的;大气层的;大气所引起的
参考例句:
  • sea surface temperatures and atmospheric circulation are strongly coupled.海洋表面温度与大气环流是密切相关的。
  • clouds return radiant energy to the surface primarily via the atmospheric window.云主要通过大气窗区向地表辐射能量。
2 06a599a54b33c9d941718dccc7739582     
v.颠簸( plunge的过去式和过去分词 );暴跌;骤降;突降
参考例句:
  • the train derailed and plunged into the river. 火车脱轨栽进了河里。
  • she lost her balance and plunged 100 feet to her death. 她没有站稳,从100英尺的高处跌下摔死了。
3 gpxzz     
n.谜语;难题
参考例句:
  • let me give you some history about a conundrum.让我给你们一些关于谜题的历史。
  • scientists had focused on two explanations to solve this conundrum.科学家已锁定两种解释来解开这个难题。
4 bicxf     
n.进攻,袭击,开始,突然开始
参考例句:
  • the drug must be taken from the onset of the infection.这种药必须在感染的最初期就开始服用。
  • our troops withstood the onset of the enemy.我们的部队抵挡住了敌人的进攻。
5 zazyk     
adj.大陆的,大陆性的,欧洲大陆的
参考例句:
  • a continental climate is different from an insular one.大陆性气候不同于岛屿气候。
  • the most ancient parts of the continental crust are 4000 million years old.大陆地壳最古老的部分有40亿年历史。
6 a1eb9034f18cae637caab5279cc70546     
偏见( bias的名词复数 ); 偏爱; 特殊能力; 斜纹
参考例句:
  • stereotypes represent designer or researcher biases and assumptions, rather than factual data. 它代表设计师或者研究者的偏见和假设,而不是实际的数据。 来自about face 3交互设计精髓
  • the net effect of biases on international comparisons is easily summarized. 偏差对国际比较的基本影响容易概括。
7 5p3xr     
n.浮现,显现,出现,(植物)突出体
参考例句:
  • the last decade saw the emergence of a dynamic economy.最近10年见证了经济增长的姿态。
  • language emerges and develops with the emergence and development of society.语言是随着社会的产生而产生,随着社会的发展而发展的。
8 6cddb7353e699051a384686b6b3ff1e2     
vi.起源;由来;衍生;导出v.得到( derive的过去式和过去分词 );(从…中)得到获得;源于;(从…中)提取
参考例句:
  • many english words are derived from latin and greek. 英语很多词源出于拉丁文和希腊文。 来自《简明英汉词典》
  • he derived his enthusiasm for literature from his father. 他对文学的爱好是受他父亲的影响。 来自《简明英汉词典》
9 187c25e49d45ad10b2f266c1fa7a8d49     
分子( molecule的名词复数 )
参考例句:
  • the structure of molecules can be seen under an electron microscope. 分子的结构可在电子显微镜下观察到。
  • inside the reactor the large molecules are cracked into smaller molecules. 在反应堆里,大分子裂变为小分子。
10 tk6yw     
n.水藻,海藻
参考例句:
  • most algae live in water.多数藻类生长在水中。
  • algae grow and spread quickly in the lake.湖中水藻滋蔓。
11 tzuzg0     
adj.不自然的,假装的
参考例句:
  • she showed an affected interest in our subject.她假装对我们的课题感到兴趣。
  • his manners are affected.他的态度不自然。
12 3vpye     
adj.营养的,滋养的;n.营养物,营养品
参考例句:
  • magnesium is the nutrient element in plant growth.镁是植物生长的营养要素。
  • the roots transmit moisture and nutrient to the trunk and branches.根将水分和养料输送到干和枝。
tag标签: ice carbon antarctic
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