The yellow outline shows the median sea ice extent observed by satellite sensors in September and March from 1979-2000. "extent" is the total area with an ice concentration of at least 15 percent.

黄色勾勒出由卫星传感器自1979——2000年所观测到得海冰面积的在九月和三月中间范围。

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Gradually as the concentration of greenhouse gases goes down, Earth starts to cool again, and eventually you slip back into an Ice Age.

随着温室气体浓度的下降，地球开始再次变冷，最终又将回到冰河时代。

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The formation of sea ice causes the concentration of salt in surface waters to increase; less sea ice would mean a smaller increase in the concentration of salt.

海冰的形成导致表水中盐的浓度增加；海冰的减少意味着盐浓度的增加幅度较小。

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The area is prone to changes in winds and local currents, and ships can quickly become trapped, sometimes for weeks, when the concentration of pack ice increases.

BBC: HMS Protector approaches MS Fram

The corporate dominance is also apparent in the magazine's concentration on the sports that sell on the newsstands: American football, ice hockey, baseball and basketball.

ECONOMIST: Americans at play