The arctic tundra, covering one tenth of the earth's surface, this ice desert is one of the coldest and driest places on earth.
北极苔原，占据着地球表面积的十分之一，这片冰冻的荒原是全球最寒冷干旱的地方之一。
The piercing subzero temperatures and powerful winds of the tundra challenge even the planet's hardiest creatures.
零度以下刺骨寒冷的气温以及苔原上强有力的寒风，即使对全球最顽强的生物来说也是一种挑战。
This landscape is home to some extraordinary species. But carve out their existence in this land of extreme cold, life here must adapt or perish.
这片土地上生活着诸多非凡的物种，而它们都在为在这片极度寒冷的土地上生存而奋斗着，生命在这里不适应则消逝。
The arctic tundra is a vast treeless landscape that engulfs the earth between the North Pole and the coniferous forests of the Taiga.
北极苔原是一片广阔而没有树木的地带，它覆盖了北极与针叶泰加林带之间的整个地域。
In winter, all the water in the tundra freezes and it's defining as a desert of over twelve and a half million square kilometers reaching right around the planet.
在冬季，苔原上所有的水体都会冻结，它被界定为一片面积超过一千二百五十万平方公里的荒原，完全环绕着整个地球。
Here, the nights can last for months and the vast plains are covered by snow in the winter that lasts three quarters of the year. Beneath this snow, lies a layer of frozen soil nearly one mile thick.
在这里，黑夜能持续好几个月，而这片辽阔的土地每年都有四分之三的时间被积雪覆盖，在这积雪之下，是一层几乎有一英里厚的冻土层。
The animals that make the tundra their home have had to adapt to survive.
在苔原上安家落户的动物们为了生存必须学会适应。
March, on the fringes of Scandinavian tundra, home to one of the hardiest mammals on the planet - the reindeer, also known as caribou.
三月里，斯堪的纳维亚苔原的边缘地带，生活着是最坚强的哺乳动物之一，驯鹿，它也被称为北美驯鹿。
This herd of three thousand reindeer has spent the last six months here, on the northern edge of the Taigaforest, scratching out an existence during the perpetual darkness and temperatures as low as minus thirty degree Celsius.
这群三千多头的驯鹿己经在此生活了六个月，在这泰加林的北部边缘，它们艰难地生活在无尽的黑暗，以及低至零 下三十摄氏度的寒冷中。
But they're about to begin an epic journey north through the bleak and forbidding tundra.
但它们即将开始一场史诗之旅，向北穿越荒凉而寒冷的苔原禁地。
No other animals body is more suited to the journey ahead.
它们的身体构造比任何动物都更适合这趟旅程。
Their thick coat is perfectly evolved to retain their body heat, providing a natural heated blanket.
它们进化得非常完美的厚重皮毛能够保持体温，就像一张天然的电热毯。
By distributing weight evenly over each hoof, reindeer are the most energy efficient animals on earth.
驯鹿能使自己的体重均衡地传导至四蹄，它们是地球上能效最高的动物。
Their hooves have adapted to the season, turning hard and sharp in winter, allowing them to dig down to the last remaining food - lichen, buried under the snow.
它们的四蹄己适应了这季节，在冬季就变得坚硬而锐利，从而使它们能挖出这里最后残留的食物，就是埋在雪层下的地衣。
Over three hundred kilometers north on the North Sea coast lie the reindeer's summer grazing grounds.
往北三百多公里的北海沿岸坐落着驯鹿的夏季牧场。
It will take the herd over two months to get there, so they will start their journey across the tundra nowto arrive in time for the short summer that lasts just a few weeks.
驯鹿群要用两个多月的时间才能抵达那里，所以它们现在就得开始这趟穿越苔原的旅程，以保证能够及时抵达而不错过仅仅持续几周的短暂夏季。
