ShmoopTube

00:04

[Coop and Dino singing]

00:13

If you live in a part of the country that has a real winter... [Woman standing in the rain]

00:16

And no, three days of drizzle doesn't count, California...

00:19

Then you've probably gotten out of bed in February, stared at a blanket of dirty snow

00:23

and thought... “will this ever end??” [Man shivering in snow]

00:25

The answer is no.

00:27

This is your life now.

00:28

Winter forever.

00:29

…Just kidding.

00:29

Of course winter ends!

00:30

If it didn't that friendly little groundhog would be out of a job! [Groundhog laying on the snow]

00:33

And then five months later in July, you'll be sweating buckets and counting down the

00:37

days until winter. [Boy sweats and falls into buckets]

00:38

But throughout our planet's history, there have been a few times when the animals living

00:42

here really did have to wonder if winter would ever end...

00:45

Yup.

00:46

There were times when summer didn't come the next season. [Squirrels at Nutty's gravestone]

00:48

Or the next year.

00:49

Or for an entire lifetime…

00:51

…We guess Puxatawney Phil was cashing in his vacation hours.

00:54

Anyway, these seemingly endless winters have a name…yup, we're talking about ice ages!

00:59

They've happened four or five times in the lifespan of Planet Earth. [Coop discussing ice ages]

01:02

Luckily, we're not in one of those right now.

01:04

In fact, we're currently in the “warming phase” after the latest ice age that occurred.

01:09

So how do we know that these ice ages even really occurred?

01:12

The same way we know about so much of the Earth's past: Instagram! [Person checks instagram post on phone]

01:16

…just joshin'.

01:17

It's actually through fossil evidence!

01:18

No, we haven't found fossilized ice…and unfortunately there weren't thermometers back

01:22

then for us to dig up and take a look at. [A thermometer on top of a fossil]

01:25

Instead, we look at the fossils from Ice Age animals to understand how they lived, and

01:29

specifically, how they migrated.

01:31

Because just like birds that fly south for the winter today, animals back then were forced [Bird flying south]

01:35

to migrate to find food and a better habitat – and by finding evidence of that, we can

01:39

determine when ice ages occurred.

01:41

We're also able to discover how animals migrated across ice or bridges of land that no longer [Polar bear family in the snow and snow melts]

01:46

exist – another good sign that things were a lot more frozen than they are today.

01:50

Scientists can also look to glaciers to learn about ice ages. [Dino discussing glaciers]

01:53

Glaciers are large bodies of ice, sometimes miles and miles long, that formed when water

01:58

froze due to extremely cold temperatures.

02:00

These glaciers move very, very slowly – so slow that you can't even tell they're moving [Girl looking at glacier with binoculars]

02:05

by looking at them.

02:06

We're talking slower than grandma going up the stairs.

02:09

But while their movement is slow, it certainly isn't weak: in fact, glaciers often have the

02:14

power to carve out mountains and valleys, sometimes leaving giant boulders behind them.

02:19

All of this evidence tells us tons about the ice ages that have occurred throughout the [Coop teaching the ice age evidence]

02:22

history of our planet, forcing animals to move, killing many others off, and creating

02:26

gigantic glaciers that sculpt the landscape of the Earth.

02:29

It all sounds pretty inconvenient to us…but it can't have been all bad. [Wolly Mammoth migrating]

02:34

Think of all the great skiing and snowboarding those ice age animals got to do! [Squirrels skiing]

Full Transcript