原文视听

As the weather warms,
随着天气变暖
the ice beneath the bears' feet starts to break up and then melt.
北极熊脚下的冰层开始分裂融化
And as the ice dwindles,
冰层消逝
so do the bears' chances of a successful hunt.
北极熊狩猎的成功率也随之骤降
Most of the ice is lost over these shallow coastal waters,
近海浅水表面的大部分冰层都已融化
where most of the seals live.
大多数海豹生活在这里
It's now summer and these bears have a choice-
现在处于夏季 北极熊们有两种选择
take their chances on the shrinking ice floes,
前往正在消融的浮冰上冒险觅食
or make for the safety of the land.
或留在陆地上确保安全
It's a case of sink or swim.
不想被淹没 就得游走
Bears have always gone hungry in the summer,
在夏季 北极熊容易饥饿
but the length of time when there's enough ice
但北极大部分地区的冰层
for them to go hunting
正在迅速消融
is getting shorter and shorter, across much of the Arctic.
所以它们的狩猎时间也越来越短
This is hitting cubs particularly hard,
这对熊宝宝的打击尤其大
because they can't survive for as long
因为如果像母亲那样长时间不进食
without feeding as their mother.
它们就无法生存
Cubs that were born underweight are at the greatest risk.
出生时体重过轻的熊宝宝 危险最大

重点解释

the ice beneath the bears' feet starts to break up and then melt.北极熊脚下的冰层开始分裂融化

break up:破碎, 解散

The Government has broken up the large private estates.

政府把大片的私人地产分割开。

The ice began to break up on the river.

河上的冰开始碎开。

because they can't survive for as long without feeding as their mother.因为如果像母亲那样长时间不进食它们就无法生存

as long as:和 ... 一样长

This line is four times as long as that one.

这条线是那条线的四倍长。

It's now summer and these bears have a choice-take their chances on the shrinking ice floes,
现在处于夏季北极熊们有两种选择，前往正在消融的浮冰上冒险觅食

take chance:冒险

You should never take chances when driving a car.

开车时决不应冒险。

We mustn't take chances,we'd better play safe.

我们不能冒险，我们最好来稳当的。