Changes in the Arctic are already affecting the lives of its highly specialised wildlife.
北极的变化，已经在影响动物们的生活，包括对这种高度专业的野生动物。
Polar bears. These one year old twins still rely on their mother for her milk, protection and crucial survival lessons.
北极熊。这对一岁的双胞胎仍然依靠母亲的乳汁、母亲的保护和重要的生存课。
But they have yet to perfect their swimming technique, and they can't wait to practise.
但是它们还没有完善自己的游泳技术，它们迫不及待地想要练习。
The cubs need to be as at home in the water, as they are on the sea ice.
幼熊需要在水中像在家里一样，如同它们在海冰上一样。
Their mother calls them out.
它们的母亲叫它们出来。
Until they've accumulated a significant layer of body fat, they feel the cold.
直到它们积累了大量的身体脂肪，否则，它们会感到寒冷。
A roll in the snow is a good way to dry off.
在雪地里打滚是擦干身体的好方法。

Then it's back to play while their mother heads off to hunt.
然后当它们的母亲去打猎时，回去继续玩。
Over the coming months, a mother must provide her cubs with not just milk, but meat -- and lots of it.
在接下来的几个月里，母亲必须提供给她的幼崽的，不仅要有乳汁，还要有肉--很多肉。
By midsummer, the sea ice has become so thin that her best chance of catching her preferred prey is by ambushing it from the water.
到了盛夏，海冰变得如此稀薄，所以她猎获喜爱猎物的最佳机会就是从水中伏击。
It's a technique known as aquatic stalking.
这是一种被称为水下潜近的技术。
She approaches downwind and tries to get within a metre of a bearded seal.
她从下风口接近，并试图进入一只髯海豹一米之内。
But today there is less sea ice to provide cover, so she is having to target riskier prey.
但是今天可以提供掩护的海冰越来越少，所以她不得不瞄准风险更大的猎物。