For the inhabitants of Earth's once tropical waters, 过去地球上热带水域的“居民们”

167. ...as the climate suddenly began to cool...
     气候突然变冷
168. ...a development that was to have dire consequences.
     这将带来可怕的后果
169. Little by little, the sea started to freeze.
     海洋逐渐开始冰冻
170. For the inhabitants of Earth's once tropical waters,
     过去地球上热带水域的“居民们”
171. this was a catastrophe.
     大难临头
172. The shallow seas became a frozen graveyard.
     浅海变成了冰冻的坟墓
173. The world's first mass extinction.
     这是世界上第一次大规模灭绝

来自《我们星球上的生命 第一季 第二集 Life on Our Planet S01E02 第一前线》第 170 行