大概是一次冰河时代导致了这场大灭绝。南半球表面形成的一个巨大的冰盖引起了全球气候剧变，海平面剧变下降，导致海水中化学成份变得混乱。

An ice age has been blamed for the extinctions - a huge ice sheet in the southern hemisphere caused climate change and a fall in sea level, and messed with the chemistry of the oceans.

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去年曾被媒体称为生死攸关的一年。然而去年在哥本哈根召开的首脑会议，局面混乱，并没有达成一个具有法律约束力的协议来遏制全球气候变化。

Last year's summit in Copenhagen, billed as a make-or-break year, ended in disarray without a legally binding deal to curb global climate change.

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