史前星球（2022）
Prehistoric Planet S03E01
Part 3
Dec. 25, 2025, 12:28 p.m.
These changes in the Earth's orbit
也恰好每隔十万年发生一次
also happen every 100,000 years,
与冰河时代的周期完全吻合
matching the timing of Earth's ice ages.
但这并不是全部的答案
But it's not the whole answer.
这些摆动和预知的轨道变化自古就存在
These wobbles, these predictable changes in the Earth's orbit have always happened,
所以我们还需要其他证据
and so we need to look for other evidence
来真正了解冰河时代的起因
to really understand what kicked off the ice ages.
早在冰河时代♥开♥始之前 南美和北美这两大洲尚未连接
Long before the Ice Age, North and South America were not connected
（气候科学家 艾拉吉尔伯特博士）
而一股强大的洋流 穿越了这两者之间的海域
and there was an ocean current that flowed right through the middle.
随着地球板块相互挤压 这引发了连锁的火山爆发
As one plate forced underneath the others, it caused all these volcanoes to erupt.
南北美这两大♥陆♥最终连接了
North and South America joined together
而原本直通的洋流被迫改变方向
and the oceans, which previously flowed straight through, were deflected.
这彻底切断了
This totally disconnected the ocean circulation
太平洋与大西洋之间的海洋环流
between the Pacific Ocean and the Atlantic Ocean.
也加剧了海洋流向北极的速度
And this actually ramped up ocean currents towards the Arctic.
这些洋流变化进一步增强了
These changes in ocean currents amplified
地球轨道摆动带来的影响 使南北两极变得更加寒冷
the effects of the wobbling orbit, making the poles even colder.
然后 随着雪和冰的逐渐积累
Then, once snow and ice started to build up,
便引发了一场失控的降温效应
it started a runaway cooling effect.
这才是最终将地球引入冰河时代的
And this is really what eventually tipped the Earth
决定性因素
into an ice age.
这场灾难性风暴彻底改变了地球
It was a perfect storm that changed Earth forever.
大冰期正式降临
The Big Freeze had arrived.