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Whooooo! It is so cold outside!
噢，外面真冷！
Oooh, thanks for the hot chocolate. My fingers feel frozen!
喔，谢谢你的热巧克力。我的手指感觉冻僵了！
You know, it's snowing today, and it snowed a few days ago.
今天下雪了，而且几天前也下了。
And when it stays this cold outside, all that snow can turn into layers of ice, kind of like a glacier!
如果外面一直这么冷，雪会变成一层层的冰，那就有点儿像冰川了！
I know, right? Glaciers are so neat!
我知道，对吧？冰川很干净！
They're enormous, they store a frozen supply of about three quarters of the earth's fresh water
它们非常巨大，冻结储存了地球上大约四分之三的淡水，
they can be thousands of years old, they grow and shrink and they move around!
它们可能有几千年的历史了，它们增大消融并四处移动。
Usually glaciers move very slowly, like a very slow, icy river.
冰川通常移动得非常缓慢，就像一条非常缓慢、冰冷的河流。
But sometimes glaciers can move really fast, too!
但有时，它也可以移动得很快！
Glaciers are made up of many layers of snow.
冰川是由许多层雪构成的。
When one place gets a lot of snowfall, and stays cold for a long time,
当一个地方有很多降雪，并且长时间寒冷时，
the weight of all that snow compresses the snow at the bottom or weighs it down,
所有雪的重量都压在底部的雪上，
until it turns into a huge, thick, heavy mass of ice!
直到它变成巨大笨重的厚冰块。
The process of layers of snow becoming a glacier can take a long time,
积雪层的形成过程可能需要很长时间，
sometimes more than a hundred years.
有时甚至要花一百多年。
Some glaciers have grown to be really huge!
有些冰川已经变得非常巨大了！
The world's biggest glacier is the Lambert-Fisher Glacier in Antarctica.
世界上最大的冰川是南极洲的Lambert-Fisher冰川。
It's 400 kilometers long and 100 kilometers wide!
它有400公里长，100公里宽。
And some of the glacier ice in Antarctica is 5 kilometers thick!
而南极洲的某些冰川厚度达5公里！
Don't worry, Squeaks.
吱吱，不用担心。
In most places, the spring and summer are warm enough to make all the winter snow melt.
在大多数地方，春天和夏天都很温暖，足以让冬天的雪融化。
So the Fort won't turn into a glacier at time soon.
所以沃斯堡短时间内不会变成冰川。
But there are glaciers all over the world, they cover about one tenth of the earth!
冰川分布于全球，覆盖了地球的十分之一。
Most glacier ice is very far north of us, in Greenland, or very far south of us, in Antarctica.
大多数冰川在离我们很远的北部——格陵兰，或更远的南部——南极洲。
But lots of other areas of the world, like places with tall, snowy mountains, have glaciers too.
但是世界上很多其他地方，比如高高的雪山也有冰川。
There are glaciers on every single continent in the world!
世界上的每个大陆都有冰川。
The earth has been around for a long time.
地球已经存在很长时间了。
Around 4 and half billion years!
大约有45亿年。
And it goes through phases cycles of hot and cold.
它经历了冷热循环阶段。
It's kind of like a washing machine, except with much longer cycles.
除了长时间循环，它有点儿像洗衣机。
And thousands of years ago, the earth was having a really cold cycle.
几千年前，地球经历了一个非常寒冷的周期。
It's what scientists call an ice age.
它就是科学家们所说的冰河时代。
It was so cold back then, that gigantic glaciers formed on huge chunks of the planet,
当时的天气太冷了，巨大的冰川在地球的大块区域形成，
around a third of all the land area on earth was covered with ice!
大约三分之一的土地覆盖着冰。
Including a lot of places you and I have visited, Squeaks,
吱吱，我们参观的很多地方
like New England, the Upper Midwest, and large parts of Canada and Alaska!
比如新英格兰、美国中西部、加拿大和阿拉斯加的大部分地区都被覆盖了！
And some of the glaciers that formed back then are still around!
当时形成的一些冰川仍然存在。
Only they're much smaller now.
只不过现在小多了。
You're right, they do grow really slowly, a little bit of snow at a time,
你说得对，它们增长得很慢，一次一点儿雪，
usually during the winter, and usually high up at the tallest part of the glacier.
而且通常是在冬季和冰川的顶部。
When it snows a lot and stays cold enough for the snow to stick around,
当雪下得很多、并且天气足够冷让它化不了时，
glaciers will grow, piling up more snow in the winter than they lose in the summer.
冰川就会变大，因为冬天堆积的雪比夏天损失的多。
And over long periods of time, glaciers will move.
经过很长一段时间，冰川将会移动。
When a glacier gets really big, that means it's also really heavy!
当冰川变得非常大时，意味着它也很重。
The ice at the bottom can't hold up the weight of all the ice above it,
底部的冰承受不住上面所有冰的重量，
and like a really big stack of blocks, it'll give way.
就像一个巨大的积木堆，它会倒塌。
so the ice at the middle and the bottom will flow out, and move forward or advance.
于是中间和底部的冰会漂走并向前移动。
Or sometimes glaciers will retreat, or move back.
或者冰川会后退。
That usually means that there's more of the glacier melting away in the summer than building up in the winter.
这通常意味着夏季冰川融化的比冬天积累的要多。
When glaciers move, that tells us that something in the earth is changing.
冰川移动是在告诉我们地球上的某些东西正在改变。
So glaciers can give scientists important tools to look into the history of the earth.
因此，冰川可以给科学家提供研究地球历史的重要工具。
By studying a piece of glacier ice,
通过研究一块冰川的冰，
we can learn a lot about what the earth was like hundreds or even thousands of years ago!
我们可以了解到地球几百年甚至几千年以前是什么样子。
Glaciers grow, move, and retreat all the time.
冰川在不断地增大、移动和后退。
But they're very sensitive to changes in the environment.
但是它们对环境变化非常敏感。
When the earth gets even a tiny bit warmer, that can change the cycle for a glacier.
地球变暖会改变冰川的循环。
Lately, glaciers all over the world have done a lot more retreating than growing.
最近，世界各地冰川消退的速度远远超过它们的生长速度。
Within the last hundred years, as the earth has gotten warmer,
在过去的一百年里，地球变暖了，
some glaciers have disappeared altogether.
一些冰川已经完全消失了。
Glaciers melting can sometimes be helpful!
冰川融化有时是有益的。
It's normal for glaciers to melt and flow a little bit at a time.
它们融化和流动很正常。
Lots of the world's rivers flow out of glaciers,
世界上许多河流都是从冰川流出的，
and lots of people, plants and animals need the water from those rivers.
很多人、植物和动物需要这些河流的水。
And some scientists and engineers have worked together
一些科学家和工程师一起
to use the energy from melting glaciers to generate electricity!
利用冰川融化的能量来发电。
But we don't want them to melt too much.
但我们不希望它们融化太多。
As more glacier water melts and flows into the ocean,
因为更多的冰川水融化流入海洋时，
the sea levels get higher, which can create a lot of problems!
海平面会上升，造成很多问题。
You're right, Squeaks.
吱吱，你说对了。
Glaciers are really interesting, and really helpful!
冰川非常有趣，而且非常有用。
I hope the ones we have on earth stick around for a long, long time.
我希望地球上的冰川能存留很久很久。
Thanks for joining us!
感谢您的收看！
If you want to keep learning and having fun with Squeaks and me, hit the subscribe button,
如果你想继续学习，与我和吱吱共度美好时光，就点击订阅吧，
and we'll see you next time here at the Fort!
我们下期见，沃斯堡等你哦！
