i[♩Intro♩]Whooooo!

It is so cold outside! Oooh, thanks for the hot chocolate.

My fingers feel frozen! You know, it’s snowing today, and it snowed a few days ago. And when it stays this cold outside, all that snow can turn into layers of ice – kind of like a glacier![Squeaks is impressed.]I know, right?

Glaciers are so neat! They’re enormous, they store a frozen supply of about three quarters of the earth’s freshwater… they can be thousands of years old… they grow, and shrink… and they move around! Usually glaciers move very slowly – like a very slow, icy river.

But sometimes glaciers can move really fast, too! Glaciers are made up of many layers of snow. When one place gets a lot of snowfall, and stays cold for a long time, the weight of all that snow compresses the snow at the bottom – or weighs it down, until it turns into a huge, thick, heavy mass of ice!

The process of layers of snow becoming a glacier can take a long time – sometimes more than a hundred years. Some glaciers have grown to be really huge! The world’s biggest glacier is the Lambert-Fisher Glacier in Antarctica.

It’s 400 kilometers long and 100 kilometers wide! And some of the glacier ice in Antarctica is 5 kilometers thick![Squeaks is alarmed.]Don’t worry, Squeaks. In most places, the spring and summer are warm enough to make all the winter snow melt.

So the Fort won’t turn into a glacier. But there are glaciers all over the world… they cover about one tenth of the earth! Most glacier ice is very far north of us, in Greenland, or very far south of us, in Antarctica.

But lots of other areas of the world – like places with tall, snowy mountains – have glaciers too. There are glaciers on every single continent in the world! The earth has been around for a long time.

Around 4 and half billion years! And it goes through phases – cycles of hot and cold. It’s kind of like a washing machine, except with much longer cycles than a washing machine.

And thousands of years ago, the earth was having a really cold cycle. It’s what scientists call an ice age. It was so cold back then, that gigantic glaciers formed on huge chunks of the planet – about a third of all the land area on earth was covered with ice!

Including a lot of places you and I have visited, Squeaks – like New England, the Upper Midwest,and large parts of Canada and Alaska! And some of the glaciers that formed back then are still around! Only they’re much smaller now.[Squeaks gives a little jump.

Wow!]Glaciers grow slowly, a little bit of snow at a time – usually during the winter, andusually high up, at the tallest part of the glacier. When it snows a lot and stays cold enough for the snow to stick around, glaciers will grow, piling up more snow in the winter than they lose in the summer. And over long periods of time, glaciers will move.

When a glacier gets really big, that means it’s also really heavy! The ice at the bottom can’t hold up the weight of all the ice above it, and like a really big stack of blocks, it’ll give way -- so the ice at the middle and the bottom will flow out, and move forward, or advance. Or sometimes glaciers will retreat, or move back.

That usually means that there’s more of the glacier melting away in the summer than building up in the winter. When glaciers move, that tells us that something in the earth is changing. So glaciers can give scientists important tools to look into the history of the earth.

By studying a piece of glacier ice, we can learn a lot about what the earth was like hundreds or even thousands of years ago! Glaciers grow, move, and retreat all the time. But they’re very sensitive to changes in the environment.

When the earth gets even a tiny bit warmer, that can change the cycle for a glacier. Lately, glaciers all over the world have done a lot more retreating than growing. Within the last hundred years, as the earth has gotten warmer, some glaciers have disappeared altogether.

Glaciers melting can sometimes be helpful! It’s normal for glaciers to melt and flow a little bit at a time. Lots of the world’s rivers flow out of glaciers, and lots of people, plants and animals need the water from those rivers.

And some scientists and engineers have worked together to use the energy from melting glaciers to generate electricity! But we don’t want them to melt too much.. As more glacier water melts and flows into the ocean, the sea levels get higher, which can create a lot of problems![Squeaks is concerned]You’re right, Squeaks.

Glaciers are really interesting, and really helpful! I hope the ones we have on earth stick around for a long, long time. Thanks for joining us!

If you want to keep learning and having fun with Squeaks and me, hit the subscribe button,and we’ll see you next time here at the Fort![♩Outro♩]