老托福听力93篇集锦:Part C(MP3+字幕) 第56篇:海洋与气温
日期:2015-01-31 09:39

(单词翻译:单击)

One reason oceanographers analyze the sediment on the ocean floor is to see how long-terms changes in Earth's temperature have affected the depth of the ocean.

By analyzing the remains of sea animals in old layers of ocean sediment, oceanographers can determine the depth of the ocean in the past.

They've analyzed hundreds of such layers, including some from the coldest periods of Earth's history the ice ages.

What they've found is that during the ice ages, the amount of water in the oceans decreased. Water levels in the ocean dropped by about four hundred feet.

Water from the ocean evaporated and became frozen in continental glaciers, so it didn't drain back into the ocean.

When temperatures eventually rose again, the glaciers melted, and the oceans returned to their former depths.
Analysis of sedimentary data indicates that periods of glacial freezing and melting occurred in regular cycles of twenty thousand, forty thousand, and one hundred thousand years.

Oceanographers are interested in the history of seawater levels because they hope to use this historical datain order to predict the possible effect that global warming could have on seawater levels.

If industrial pollutants are capable of heating global temperatures to the point that glaciers begin to melt, it is urgent for us to know precisely how high sea levels will rise as a result.




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重点单词
  • globaladj. 全球性的,全世界的,球状的,全局的
  • eventuallyadv. 终于,最后
  • drainn. 下水道,排水沟,消耗 v. 耗尽,排出,排干,喝光
  • capableadj. 有能力的,足以胜任的,有 ... 倾向的
  • continentaladj. 大陆的
  • meltedadj. 融化的;溶解的 v. 融化;溶解(melt的过
  • determinev. 决定,决心,确定,测定
  • glacialadj. 冰的,冰川(期)的,非常冷的,缓慢的
  • meltvi. 融化,熔化,消散 vt. 使融化,使熔化,使消散
  • sedimentn. 沉淀物