VOA慢速英语2016 南极洲或因融水湖增多而不断瓦解

AS IT IS 2016-10-02 Meltwater Lakes in Antarctica Show Signs of Trouble 南极洲或因融水湖增多而不断瓦解

Antarctica is home to the largest ice mass on Earth.

The continent sits on 14 million square kilometers of rock. About 98 percent of the land surface is covered by ice.

Beautiful lakes have begun to appear on the top of the ice. They look like islands of deep blue in an ocean of white. These lakes are called supraglacial or meltwater lakes.

Although the lakes can be beautiful, the ones scientists studied are a sign of trouble. Amber¹ Leeson is a scientist with Lancaster University in England.

"We really weren't expecting to find lakes as far inland as 20 kilometers, which was the furthest inland lake we found during the study. And it was important that we found the link between the atmospheric² temperature and the depth, number, and size of the lakes..."

Scientists say Antarctica has always had supraglacial lakes appearing on the ice during the summer months. But the more lakes there are, the more unstable³ they make the continent’s ice shelf.

Ice shelves are permanent, but floating pieces of ice that connect to the land. They form where a glacier⁴ or ice sheet reaches a coastline and into the sea.

Leeson says water from the lakes can drip down through the glacier, causing the huge river of ice and snow to weaken.

"If they form on the grounded ice, which is the bit of the ice sheet that sits on the bedrock, then the water they contain can drain away through the ice to the base, where it can lubricate the flow of the ice and make it flow a bit faster. If they form on the floating part of the ice, which is where the ice shelf extends over the ocean and begins to float on the sea, by repeatedly filling and draining they can actually weaken the ice shelf."

Leeson and other scientists believe that lakes are partly responsible for the collapse⁵ of the Antarctica ice sheets.

"...the Larsen B ice shelf collapsed⁶ in 2002 and we think that this is because it was covered in lakes in the years prior to collapse, and that by repeatedly filling and draining, they weaken the ice sheet, leading to its eventual⁷ disintegration⁸..."

And as temperatures rise, the team expects to see more and more lakes appearing in the continent. The scientists fear that all that meltwater could raise the world's sea levels.

南极洲有世界上最大的冰块。

南极洲大陆下面有1400万平方公里的岩石。其地表98%覆盖着冰。

很多美丽的湖泊逐渐在冰层上方显现，看起来就像一片白色海洋中的深蓝岛屿。这些湖泊叫做冰上湖或融水湖。

虽然这些融水湖很美，但有一些科学家发现了麻烦的迹象。其中的安布尔是伦敦兰卡斯特大学的一名科学家。

“我们根本没想到能在内陆20千里的地方发现湖泊，这也是我们本次研究中发现的最远的融水湖。找到气候温度与融水湖深度、数量和大小之间的关系十分重要”。

科学家称，南极洲夏季期间总会在冰面上出现融水湖。但融水湖数量越多，就会使得南极洲大陆的冰架越不稳固。

冰架是永久的，但浮动的冰块也与南极洲大陆相连。它们在冰川或冰原贴近海岸以及到达大海深处的地方形成。

安布尔称，融水湖的水会通过冰川滴落，瓦解融水湖的冰雪。

“如果融水湖在接近底层冰的地方形成，也就是在基岩上的冰原上形成，那么融水湖中的水就会通过冰层到达基部，会对冰块的流动起到润滑作用，加速其流动；如果融水湖在表层浮动的冰上形成，也就是冰架延伸到大海并向海深处浮动的地方，那么通过不断的填水和排水，这些融水湖也会瓦解冰架”。

安布尔和其他科学家认为，融水湖是南极洲冰架坍塌的原因之一。

“……拉森B冰架2002年坍塌过一次，我们认为这就是长年来融水湖覆盖的结果，因为不断的充水和排水会瓦解冰架，导致最终的分解”。

而且，随着气温的升高，该研究组认为会有越来越多的融水湖出现在南极洲大陆上。他们担心，这些融水会升高全球的海平面高度。

Words in This Story

ice mass - n. a large piece of ice

supraglacial lake – n. any pond of liquid water on the top of a glacier

ice sheet – n. a very large and thick area of ice that covers a region

ice shelf – n. a floating sheet of ice permanently⁹ attached to a land mass

glacier – n. an large areas of ice formed from falling snow and building up over the years

1 amber   

n.琥珀；琥珀色；adj.琥珀制的

参考例句：

• Would you like an amber necklace for your birthday?你过生日想要一条琥珀项链吗？
• This is a piece of little amber stones.这是一块小小的琥珀化石。

2 atmospheric   

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。

3 unstable   

adj.不稳定的，易变的

参考例句：

• This bookcase is too unstable to hold so many books.这书橱很不结实，装不了这么多书。
• The patient's condition was unstable.那患者的病情不稳定。

4 glacier   

n.冰川，冰河

参考例句：

• The glacier calved a large iceberg.冰河崩解而形成一个大冰山。
• The upper surface of glacier is riven by crevasses.冰川的上表面已裂成冰隙。

5 collapse   

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。

6 collapsed   

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。

7 eventual   

adj.最后的，结局的，最终的

参考例句：

• Several schools face eventual closure.几所学校面临最终关闭。
• Both parties expressed optimism about an eventual solution.双方对问题的最终解决都表示乐观。

8 disintegration   

n.分散，解体

参考例句：

• This defeat led to the disintegration of the empire.这次战败道致了帝国的瓦解。
• The incident has hastened the disintegration of the club.这一事件加速了该俱乐部的解体。

9 permanently   

adv.永恒地，永久地，固定不变地

参考例句：

• The accident left him permanently scarred.那次事故给他留下了永久的伤疤。
• The ship is now permanently moored on the Thames in London.该船现在永久地停泊在伦敦泰晤士河边。