Deserts Fierce Earth

Welcome to Morocco, North Africa,

and welcome to this - the Sahara Desert.

The biggest hot desert in the world.

Deserts get very little rain and are the most barren places

on the planet, which makes for some of the harshest conditions going.

But, despite that, millions of people live in the desert.

Come with us as we as we take a journey into the dunes,

right to the very heart of the Sahara

as we find out how to survive in the sandy wilderness.

'On today's Fierce Earth, we take to the skies

'to discover how deserts are formed...'

-Give that a blast! Woo-hoo!

-Whoa!

'Leo is put to the test as he finds out how to escape

'the deadly grip of quicksand...'

The more you wriggle, the more you sink in to it.

'We learn how powerful and destructive sand can be

'when it gets whipped up by the wind...'

Today, we're going to try and get right to the heart

of one of these sandstorms.

'..and Leah meets the kids who live a roaming life in the desert

'and finds out how they can survive in this harsh environment.'

What happens when the ground shakes,

the seas rise up and the air tears itself apart?

The Fierce Earth team move in,

taking on the most powerful forces on the planet.

Get ready for Fierce Earth: the Earth and how to survive it.

Deserts make up about one third of the Earth's land surface

and are defined by the lack of rainfall that they receive.

Although they are all really dry, deserts aren't all hot.

The Arctic and Antarctic are covered in snow and ice

and are the two biggest deserts on Earth.

But we're heading to the Sahara, the biggest hot desert

where the lack of water, soaring temperatures

and ferocious winds that howl across it

make this one of the most inhospitable places on the planet.

This is Marrakech.

Just 400 miles to the north is Europe and the coast of Spain,

but the reason why we're here in North Africa is 150 miles south

where the landscape changes to the wilderness that is

the Sahara Desert.

To discover why the Sahara and other hot deserts are so barren,

you have to look a lot further south to the equator.

The equator is the belt around the middle of the Earth.

Because of the angle the sun shines,

it gets the most intense heating.

So what has that intense heating got to do with

the formation of the desert?

Well, to show you, we'll take to the sky.

And what better way to take to the sky

than a flight in a hot-air balloon?

BURNERS ROAR

-We're flying!

-Ooh-hoo-hoo-hoo!

To get our balloon to fly, our pilot here, Maurice,

has to give it a blast of hot air.

BURNERS ROAR

-Argh!

-Whoa!

With every blast he gives it,

the balloon fills up and will rise higher and higher.

-Maurice, give that a blast!

-Yes-ah.

Woo-hoo, ha-ha-ha!

The burner in this balloon is heating the air

just like the sun does around the equator.

The hot air rises, exactly the same as this balloon.

And that's because hot air is lighter than cold air.

Down on the ground, it was quite warm,

but up here, the air is cool.

Now, as air cools it falls back to the ground

and any moisture falls back to the ground as rain

and that's why we have such rich habitats,

like tropical rainforests near the equator

because it's that part of the world that gets the most rain.

Once the air has lost all of the water it contains, it continues

to move away from the equator, only this time without the rain.

And little or no rain means deserts form.

Normally, they receive less than 25cm of rain per year,

sometimes less than five.

And that's why all hot deserts -

some of the biggest being the Sahara, Kalahari,

and the Great Australian -

sit either side of the equator.

Hot deserts also exist

because of the distance they are from large areas of water,

like lakes or the sea.

As we make our way south towards the desert,

there is another reason why the Sahara gets hardly any rain.

These are the Atlas Mountains.

They sit between the Atlantic Ocean and the desert.

These mountains simply block any water getting to the Sahara.

On the other side of the Atlas Mountains,

trees and shrubs start to disappear.

It's here where it starts to get drier and dustier

It's here that the Sahara desert starts.

The Sahara covers an area of 3.5 million square miles -

that's the size of the United States

and it covers one third of the giant continent of Africa.

To the north, you see there's lots of rocks and dirt,

but in the south,

there's hundreds and hundreds of miles of sand.

Sand is formed by the erosion of rocks over thousands,

even millions of years.

That builds up to these massive dunes we see around us -

a giant sand sea.

Sand dunes form when millions,

even trillions of small particles of sand

are blown around by the wind.

When they come across an obstacle like a rock, or even some vegetation,

they start to collect.

And once they collect,

they get bigger and bigger and bigger.

Some sand dunes can even get up to 250m in height -

that's practically a sand mountain.

Now the sand itself, as you can see, is not stable

and with the big desert winds,

that means the sand sea is constantly on the move.

The desert can get larger and where it moves out onto new land,

that is when you get desertification.

To understand how deserts move, I've come to its very edge,

where the desert is starting to move into the village.

And just with this light wind that we've got here,

you can see it's strong enough to move the small particles of sand.

You can see the sand flying off the sides,

even making very small dunes on the top.

But what if I add water?

Very quickly,

we've stopped any of those small sand particles from blowing.

We can do another thing, though -

we take some vegetation and we have vegetation and water.

The combination of water and vegetation

is a very effective way of stopping the desert from moving.

It's the removal of vegetation by animals grazing

or people chopping down trees for firewood

that destabilises the land, causing desertification.

2 billion people are at risk around the world

as the slow creep of the sand could force people from their homes

and put a strain on natural resources.

But there are measures that people can take

to fight the spread of the sand.

In situations where there isn't much vegetation,

the people can lend a hand.

Here, they've taken palm leaves and created this network of fences

which acts like a sand trap.

You can see the buildings just behind me -

the sand that's trapped here would've migrated all the way over there.

By putting these in -

and they put these in all round the country -

this is how the people can fight against the moving sand seas

and against desertification.

Coming up on Fierce Earth -

Leo ends up in a sticky situation...

I'm stuck!

..and Leah meets the kids

who call the harsh environment of the desert home.

When the winds blow across the desert,

it not only moves the sand - it can unleash massive sandstorms.

Ferocious winds whip up billions of tiny particles

into a massive wall of nastiness.

And it's villages like this

on the very plains on the edge of the desert

that are in most danger - they've got no escape.

Today, we are going to try and get to the heart

of one of these sandstorms.

Sandstorms can be really dangerous,

We are taking no chances today

and are going to follow these basic rules.

Know the warning signs -

sandstorms usually happen when the day is at its hottest.

You can see sandstorms coming from miles away,

so if you're in a car, try and get out of its way.

Be prepared - cover your face with a mask, a scarf,

or even a shirt like this.

And cover your eyes - you can use sunglasses or goggles.

You don't want to get sand in those.

Make sure you have got plenty of water and food -

sandstorms normally blow over pretty quickly,

but you don't know how long you could be out there.

And finally, find shelter -

get beside a wall, inside a house if you can,

or even down by the side of your camel.

We need to put ourselves in the best position

to get to the heart of a sandstorm,

so we head out into the middle of the desert

where there is no shelter

and the wind should be at its strongest.

When the wind does start to blow,

sand and dust is easily lifted into the air.

As it starts to swirl across the flat desert lands,

a sandstorm is born.

Gusts of winds come and go.

Sandstorms are unpredictable

and can blow out within a few seconds

but, sometimes, they can rage for hours

or even days at a time.

The weather is so unpredictable,

you never know when a sandstorm could be on the horizon.

Unfortunately, it's not very windy today -

we have seen a few dust devils,

these little spirals of sand blowing around,

which are kind of like baby sandstorms,

but it's just not windy enough for a proper sandstorm.

Proper sandstorms can cover the desert,

sometimes hundreds of miles across.

Some sandstorms are so big, they can even be seen from space.

Sandstorms do hit this part of the world

and, when they hit, they hit really hard.

The air goes thick with sand.

As sandstorms rage, visibility reaches almost zero

and it becomes hard to breathe.

That power of wind and sand can shut down towns and cities

and then you know you're really in the heart of a true sandstorm.

Now, you've seen what can happen in a sandstorm.

But how can tiny little bits of rock and sand cause such damage?

Well, to find out, I'm going to see a local mechanic.

Because I reckon they'll have the kit I need

to make my very own mini sandstorm.

Every garage has one of these - a compressor.

This sends pressurised air along this pipe

and I've attached it to this, which is a sand blasting gun.

This bag contains dry sand.

I attach it to the gun

and let's just see what this does to an old kettle like this.

As the grains of sand are blasted against the kettle,

they strip away the surface layer by layer -

just like sandpaper, but without the paper.

Wow - just look at that!

We've taken this old rusty kettle down to bare metal.

And that is the same destruction

that, over time, sand can cause to everything in its path.

So how do people live in a hot and harsh environment of a desert,

under constant threat of sandstorms?

Well, they have, for hundreds, even thousands of years,

but in order to do so, they've had to adapt.

Everything about this town

is designed to last in an extreme desert condition.

The first thing you notice...is there are no windows.

That's very good when a sandstorm blows through the town.

The houses are built from desert sand,

mixed with clay and straw.

The walls can be up to a metre thick to combat the extreme temperatures.

It keeps you cool during the day and warm at night.

It's the middle of the day here

and the streets of this old town are absolutely deserted.

That's because living in a desert is hot business -

you get up at the crack of dawn

and get all of your work done while the temperature is low.

When the sun hits the midday, it's too hot to do anything -

you get inside some shade, you have a siesta.

There's a little bit of time left at the end of the day

to get any final chores done,

but when the sun goes down, the lights go off -

it's bedtime!

To live in the hot, dry desert, you need water,

and this, like any other old town in the desert,

is built on an oasis.

An oasis is a permanent source of water in the desert,

fed by underground springs and rivers.

There is greenery surrounding the whole of this town.

Where you find an oasis, you find life.

When you leave the security of the towns and villages,

deserts become even more hostile

and potentially deadly environments for humans to live in.

Temperatures soar during the day

and plummet to almost freezing levels at night.

It's this, combined with the lack of food sources -

and, more importantly, water -

that make life in the sandy wilderness tough. Really tough.

And yet, there are people who have adapted for desert living.

Dotted across the Sahara desert,

there are families that make this harsh landscape their home

and today, I have been invited by the Shaoush family

to spend the day with them.

So let's go in.

The Shaoush family are part of the Berber tribe.

There are over 20 million Berbers living in North Africa,

most of whom are nomadic -

families that travel from place to place

and never stay in the same spot for very long.

They set up camp where they can easily get to water,

living in tents and huts.

Sahid is seven and shows me around the family's camp.

This is where Sahid and his family live

and he is going to give me a little tour.

So this is maybe the living room where everyone lives?

-TRANSLATION:

-This is my bedroom -

my mum sleeps there, my sister sleeps there

and I sleep there.

It looks quite cosy -

there are loads of rugs on the floor,

there's pillows to rest your head.

It looks like a really good shelter

because the sand is swirling around right now,

and under there would be the perfect place

to shelter from all the sand.

What's happening here?

My mum is making fabric.

So this is goat's hair, camel hair, and she's using this device here

to knit it all together, effectively,

for the main tent, which we just saw.

Sahid, how long have you been at this camp?

Four months.

And that's quite typical of nomadic tribes -

they move on from place to place.

We travel to find water and food for our animals

A short walk from their camp

is the reason they have chosen this spot

to make their temporary home.

This is brilliant - in the middle of the desert,

the family have their very own water supply.

Their camp is about a minute's walk in that direction.

That's why they based their camp here,

they can come here.

It's not as easy as turning on a tap,

but it's not half bad -

whenever they want to cook or make tea,

they just come here with their bottles,

fill them up, and there's a short walk back.

It's brilliant.

While Sahid helps keep the water supplies topped up,

his sister Rachid takes the family's goats

six hours away from the camp.

Can you tell us why you do this journey?

-TRANSLATION:

-I bring them here to graze.

These goats are like the family's bank account.

They sell them at the local market

so they can buy fruit, vegetables and other essentials.

The responsibility that I had at about her age

was walking to the local newsagent and picking up a paper.

She is in charge of 50 goats in the middle of the Sahara desert

and to have this as your playground, that's pretty cool.

The family's camp is not just tents.

They have built a stone hut as a kitchen

and Sahid's older sister is cooking the evening meal.

It's quite a small space

but you've got everything you need here -

you've got the vegetables, water,

and that what we're boiling over here, a bit of water,

hopefully for some mint tea later on.

But before dinner,

there's a goat-related emergency to deal with.

OK, the goats have got loose, I have no idea how,

so I'm just trying...to get them back in.

I promise I didn't open the gate.

There's another one here.

Come here...no...come on.

There we go.

KID BLEATS

SHE LAUGHS

I don't think he likes that.

I've had a fantastic day with Sahid and his family -

they've made me feel really welcome.

They live a simple life here in the desert,

but it's a tough life and I don't think I could live here.

I'm too used to my home comforts.

But it's amazing to think, in a few weeks' time,

they'll pack all of this up and head off to their new home.

In this incredibly dry environment, water is the most precious thing

and I think I've stumbled across loads of it.

In the desert, all you can see for miles and miles

are rocks and sand.

But over there is a huge lake.

And a lake in the middle of the desert

is a seriously welcome sight.

I need to get to it, so I walk...

..and I walk...

..and I walk.

But when the barren landscape and the soaring heat combine,

they can sometimes hold a nasty trick up their sleeve.

Ugh - that was annoying.

As far as my eyes could see, there was a lake in front of me,

but the closer I thought I got to it,

the further away it seemed.

But there is no lake, there is no water.

This is a mirage.

Mirages happen when the air near the very hot ground

becomes much hotter than the air above it.

The light from the sky is bent back up

as it passes through cooler and then hotter air.

So what we see is a reflection of the sky on the ground

and it looks like water.

If you find yourself stuck, stranded in this vast desert,

you will look for that and you'll think it's a lake,

but it's an optical illusion, a mirage -

it doesn't actually exist.

It's really annoying.

Finding water in the desert is nearly impossible

because it just doesn't rain for weeks, months

or even years at a time.

But when it does rain, it really rains!

The rain provides much-needed water for the people of the desert

as rivers and lakes appear almost instantly across the dry sand.

But the water doesn't stay around for long

and when it disappears from the surface

and the rivers and lakes start to dry up,

it causes another potentially deadly problem.

Check this out - looks just like any other bit of this vast desert.

But watch what happens when I poke it with a stick.

You see that?

It wobbles like jelly.

That's because this isn't any ordinary sand -

this is quicksand.

Quicksand forms when sand mixes with water.

It becomes sticky, gloopy, and more importantly, deadly!

From the surface, you really can't spot it,

and that's what makes it really dangerous!

When you stray into quicksand, you sink,

and getting out is the stuff of nightmares.

I'm about to take the plunge -

I'm going to jump into this quicksand.

The challenge is to see if I can get out.

OK, Leo, off you go - good luck. I'm here all the way for you.

Finding quicksand in the desert

is like finding a needle in a haystack.

So what do you when you're in the middle of the desert

and you want Leo waist-deep in quicksand?

If we can't find quicksand, we'll have to make our own.

So the boys are doing really good,

but we still don't know if we're able to recreate quicksand

in the middle of the Sahara.

Quicksand forms where rivers or lakes run dry

or where water oozes up from desert springs.

The ground is usually so dry

that a lake or river could go from water to dry sand

in just a few hours.

To recreate these conditions,

we need to fill the hole with water and mix it with sand.

Quicksand is dangerous.

We've got a team of people in case Leo gets into serious trouble.

Do NOT try this at home or on the beach.

The test will be how quick he'll be able get out.

If this is above my waist,

I don't know if I'll be able to get out.

This heat will just drain any energy that you've got

and that will be the big problem.

Leo can now take the plunge.

Here we go...

Ugh!

I'm sinking!

I'm stuck.

Leah? Help!

It doesn't take long before I sink up to my chest.

The sand has a firm grip as I get pulled deeper...and deeper.

When sand and water are mixed,

they make this horrible...sticky, gloopy mess.

The more you wriggle, the more you sink into it.

You may think that sinking in over your head

is what kills you in the quicksand, but it's not -

it's the sun that gets you out here in the baking hot desert.

If you were trapped for a long time, you'd die of dehydration.

There's a camel over there.

Wonder if they can get me out?

The camels can't help me in here, so I have to try and relax

and get myself out of this sticky situation.

If you ever get stuck in quicksand,

the trick is don't panic, try not to fight it.

If you fight it, it's quite scary

and you feel like you're sinking...ooh.

But if you just relax,

it feels a little bit like you're swimming in a giant jelly

or a blancmange.

So what you need to do is kind of like swimming -

spread your weight out.

The more surface area you've got, the less likely you are to sink,

so I can almost...lie on top of it.

Oh...OK...

And then you can almost push off...the quicksand itself,

Here we go...

Ah...yes...!

HE PANTS

I made it.

That is how you escape from quicksand.

Hey, Leo, well done!

I would give you a hug, but...

Please don't.

It sets around you like concrete.

Quicksand, best avoided.

On our Saharan adventure,

we've discovered what creates dry, hot deserts

as the hot air from the equator rises and falls back to earth

with little moisture.

We got dressed up

to tackle one of the biggest and most deadly threats of the desert -

the sandstorm.

I discovered how a trick in the bright sunlight

can fool you into seeing things that don't really exist.

As far as my eyes could see, there was a lake in front of me.

That lake was really a mirage.

And I spent the day with a Berber family -

part of a tribe who have lived in the Sahara

for thousands of years.

Next time on Fierce Earth -

the temperature plummets and the snow just keeps on coming...

The winds are starting to really pick up here.

And Leo is chilled to his bones when we create the perfect blizzard.

It's cold!