All language subtitles for The Secret Life of Ice BBC 2011 HDTV_Subtitles01.ENG

Ice is one of the most mesmerising
and beguiling substances
in the world.

It's very familiar and yet
never ceases to be other-worldly.

Always a little bit strange.

Ice is full of contradictions.

It's transparent

but it can glow with colour
like nothing on earth.

It's powerful enough
to shatter rock and sink ships.

But can just melt away
in the blink of an eye.

I'm Dr Gabrielle Walker.

I trained as a chemist,
but now I'm a science writer.

And for a long time,
I've been obsessed by ice.

Ever since I first set foot
on Arctic sea ice,

I've been drawn back
year after year.

I've been trying to discover
the secrets hidden deep within ice.

I think the ice crystal has
something extraordinary to reveal

about how the world works.

How it does that

and what it tells us is what I want
to explore in this programme.

This is it. Wow!

Welcome to Nigarsbreen.
It's magnificent!

I'm going to find out how something
so ephemeral is powerful enough
to carve solid rock.

How ice has led to the evolution
of some of the most extraordinary
creatures on our planet.

This is a really small one.

How ice in space might lead us to
discover extra-terrestrial life.

If we've got an ocean underneath
the surface of the moon,

that's a place to search for life.

And how its astonishing ability
to store ancient atmospheres

is helping us understand
our climate.

When they invaded Britain in 1066,
this is the air they were breathing!

Do your worst!

And I reveal how its power
to preserve our past

and inform our future

lies deep within the ice crystal.

First of all,
I've come to southern Norway...

..to visit an enormous glacier
called Jostedalsbreen.

It's the biggest piece of ice
in continental Europe.

It covers nearly 500 square
kilometres of mountain.

Glaciers are one of the most
powerful forces in nature.

They turn fragile ice into enormous
grinding machines

that can erode mountains.

I'm going to explore
one of Jostedalsbreen's many
glacial tongues, Nigardsbreen.

I'm meeting local glaciologist,
Evan Lowe.

Hello, Evan!

Hello. Welcome to Jostedalsbreen.
Thank you.

Gosh, it's gorgeous!

We have a kayak to take us
across the lake.

I want to find out exactly
what makes glaciers so powerful.

How something as malleable as ice

can carve out such a spectacular
landscape.

From the sculpted walls
of the valley

to the colour of the lake.

And full speed onto land.
Full speed.

Even though it's just ten per cent
of the Jostedalsbreen's glacier,

Nigardsbreen covers nearly
50 square kilometres of mountain.

It rises steeply to almost
two kilometres above sea level.

Down here in the valley,
where the temperatures are warmer
than in the high mountains,

the glacier melts abruptly
in a ragged wall.

It's only when you get this much ice
that you can witness
something spectacular.

This is it! Wow!

'Its full range of colours.'

It's magnificent! The blue colour
is absolutely amazing.

It's like looking into the heart
of the glacier.

Yes, it goes from completely white
and all the way to very dark blue,

depending on how the light
hits the surface

and how far into the ice the light
penetrates

before it's reflected to us.

The surface of the glacier
looks white

because its jagged crystals
are deflecting sunlight
in all directions.

Close up, the ice seems transparent.

But it's not.

Pure ice crystals absorb light
at the red end of the spectrum.

So as sunlight travels deeper
into the ice,

a new blue light is reflected back.

When it's in a huge chunk
like a glacier, it looks blue.

But if you grab a chunk of it, it's
just white, ordinary boring ice!

Ice is never boring. Never, ever!

The ice in this front wall
is at the end of its journey
down the mountain.

It's now at the point
of melting away.

Every moment it's changing,

like a moving sculpture.

Melt water is raining down on me

and it's making
the most amazing shapes.

You can see it's eating
into the walls here

and making all these curves
and round parts

and that's why it looks like
the moon outside with all those
incredible curves.

It's beautiful.

Although glacial ice is a solid,

it actually flows like a river.

It's incredible to think
that this much ice

is constantly on the move.

I've been climbing up to see
what drives the glacier.

And it's the phenomenal weight
of this enormous ice pack,

over nine kilometres long,

and up to 500 metres deep.

Millions of tonnes of ice
crammed into this valley.

Built up from layer upon layer
of snow,

this monumental river of ice
is constantly being topped up

by fresh snowfall.

And that keeps it flowing downhill.

It makes very slow progress.
But there is a way to see it move.

A time-lapse camera shows that
Nigardsbreen's surface ice

travels at around 275 metres
per year,

carving away the rock as it goes.

When you're here, the only clues
you see of the glacier's movement

are crevasses.

Deep gashes that split open
the surface of the ice.

These open up at the top of the ice.

One of the reasons is the top
of the ice is brittle and tough.

Further down, where it's been
squeezed, it's plastic and soft.

But as the glacier moves,
the brittle part breaks open

and creates these great crevasses.

When a crevasse has opened up in the
ice, melt water can gather in it

and start hollowing its way down
towards the bedrock.

Here, it carves out a hidden world
of icy caverns deep within
the glacier.

I'm going to try to abseil right
into the heart of the glacier

to see for myself how it moves.

That was amazing!

We're in the engine room
of the glacier.

You can see just down here right
where the ice melts the ground.

And this is where everything
important happens.

I'm getting wet
with the melting water,

but it's that that helps the glacier
slide on its belly,

one of the things that makes it
so dynamic.

Nigardsbreen's temperate
mountain climate

means the ice at the lower end
of the glacier exists very close
to melting point.

As well as the melt water
flowing beneath the ice,

which helps lubricate the glacier
on its journey down the mountain,

there's melt water within the ice
itself,

seeping out of these walls.

That melting water also makes
this cave, and other caves like it
all around.

I bet this cave wasn't here last
year and it probably won't be here
next.

It's transient, part of the signs
that the glacier is dynamic

and moving and changing
all the time.

When you look at the slick blue ice
in these caves,

it's hard to imagine it began
its life as snowflakes.

But hundreds of years of compression

have gradually turned it into this
glittering mass of ice crystals.

Look at that!

The sides of the ice here are just
like they were in the cave.

They really look like solid
squashed together lumps and cubes.

And here you can really see that.

Like someone's taken a bunch of
cubes and squeezed them together.

And that's what I'm walking on.
Like walking on a giant Slushie!

Every single one of these ice
crystals has an unusual property.

If you throw them into water,
they float.

That's something we take completely
for granted.

But it's incredibly rare in nature.

It's what helps to make ice special.

And what gives it the power
to transform our world.

The secret lies at the heart
of the ice crystal.

I'm going to witness
the very instant it forms,

with chemist and fellow
ice enthusiast, Dr Andrea Sella.

Ice breaks all the rules
that we learn.

Andrea believes this moment is key
to understanding the mysterious
world of the ice crystal

because of the curious way
that water turns from liquid
to solid ice.

Let me show you something
really amazing.

We've got some mineral water here
that we've been cooling for a bit.

I want you to take these bottles
quite gingerly.

Take this and bang it on the table.
Just bang it? Bang it.

There it goes! Look at that!
Instant ice!

It's spreading out these fingers
and shards of ice all the way down.

It's quite amazing. You can see
the crystals growing before
your very eyes!

Ice is a crystal in which the water
molecules are very carefully
arranged.

If you think of guards on parade,

all lined up in neat rows,
that's what a crystal is,
and that's what ice is.

Like any crystal,
ice doesn't form spontaneously,

even in this super-cooled water,

which is well below zero degrees
centigrade.

It needs a seed, a template.

You need someone to kind of blow
the whistle

and provide an initial point,
saying start here.

So I bang it, you get bubbles and
each of those bubbles is a place for
the crystals to form. Absolutely.

You can do it in other ways, too.

Take another bottle,
and this time what we'll do

is try dropping another piece of ice
into it.

Just pop it in.

Ready, steady...

It's really the ice which is acting
as the initial starting point

on which the rest of the ice grows.

It's the way the ice crystal forms
that is the key to why it floats.

Water molecules are loosely
held together by bonds

which are constantly making
and breaking.

When the temperature drops to zero,

these bonds begin to hold. Fast.

Creating a hexagonal lattice,
an ice crystal.

In the lattice, the bonds hold
the molecules far apart.

It's that sudden opening out

that makes ice lighter, less dense,
than liquid water.

In water, the approaches
are quite close.

When we get to ice,
suddenly it expands a bit.

And we end up with a strangely
spacious open structure

which is less dense
and therefore it floats.

It's really quite miraculous.

That's all down to the structure
of the crystal? Absolutely.

Ice is incredibly special.

The irony is that to us
it's completely common.

We take an ice cube and drop it
into a drink and it floats.

Well, it is almost unique

in the enormous, the millions
of compounds and materials
that we know about,

in being a solid that floats
on its melt.

If ice didn't float, the world
would be a very different place.

Instead of forming on the surface
of the ocean,

allowing marine life
to survive beneath,

ice would form on the sea bed,

oceans would freeze
from the bottom up

and life as we know it might never
have evolved at all.

We also wouldn't have developed
an elegant British pastime

that began on frozen lakes
and rivers hundreds of years ago.

Every Sunday morning,
members of the Royal Skating Club

meet at Guildford ice rink
to skate in what is called
"the English style".

Once considered England's highest
form of skating art,

"the English style" originates from
the early 19th century.

It combines a Victorian sense
of elegance and understatement

with a high level of skill.

Around a centre marked by an orange,

the skaters perform perfectly-shaped
geometric figures

in absolute unison, holding
their bodies stiff and straight.

Centre change, sub circle.

In keeping with the Victorian horror
of showing off,

the challenge is to make these
complex manoeuvres look graceful

and effortless.

These are lovely.

Elaine Hooper, historian for the
National Ice Skating Association,

has some Victorian pictures
of the English Style.

It was very much a more polite style
of skating. It was very dignified.

The ladies had long dresses and big
hats on and the men had top hats
in Victorian times.

That was the style of skating

that evolved on the frozen lakes
and rivers

as early as the 1600s.

Over the years, different moves were
added when people wanted to make it
more difficult.

The English Style developed
amongst the upper classes

while Britain was experiencing
what became known as
"the little ice age".

From the 13th century to the middle
of the 19th century,

British winters were up to
two degrees cooler.

Many lakes and rivers regularly
froze over.

Pepys himself talks about skating
with Nell Gwyn on the Thames

in one of the great frost fairs
where they would roast hogs
and skate.

It was just a way of life then.
It was much colder.

The Thames doesn't tend to freeze
over now so we can't have that
again.

We can skate because of another
quality of ice.

Its slipperiness.

This may seem completely normal, but
it's actually very rare for a solid.

The reason we can skate is to do
with what happens when ice is
squeezed by a blade.

The way it reacts to pressure.

So Andrea Sella and I are going to
put ice under a lot of pressure

in a classic experiment.

OK, we need to lift it up
and get it onto our platform.

It is pretty heavy.
I'm strong, don't worry!

Good. There we are.

So now we need to unpack things.

Ooh, that's lovely! Gorgeous!

I'll lift it and you pull.

That's great.

What we're going to do is sling
this wire over the top

and hang these two really
rather heavy weights,

we're talking about
seven kilos here.

There we go.

It's now suspended.

What we have to do is wait for
the pressure of the wire

to work its magic on the ice.

As we wait, the wire works its way
through the ice.

Almost cutting it in two.

And behind the wire,
the ice is sealing up again.

Something very strange is going on.

It's amazing. Look at it!

So how's it gone through
the ice like this?

Of course, the wire has the weight
on it. And because the wire's
very thin,

what it does is apply really
quite a large pressure

on a local area of the ice.

We know that ice expands
when it freezes

so if you squeeze it, you can drive
it back towards that molten state.

So when you put pressure on it,
it turns it back to water.

You can re-melt it back to water.

That's one of the key reasons
we can skate.

The pressure of the blades is enough
to melt the top layer of ice
into water

which lubricates the skates.

Friction can also help melt the ice.

In our experiment, as the wire
passed through the block,

the ice sealed up behind.

This shows how ice can engulf
something solid

leaving barely a trace.

I was expecting the wire to cut
through it. And it's completely
sealed.

It looks as though it ought to fall
apart. It's an extraordinary
process.

Effectively, underneath the wire,
the ice melts

and then behind it,
it re-freezes again.

So this whole process is making
the ice

move between those two points
on that knife-edge between
liquid and solid.

The pressure squeezes it,

take the pressure off and it freezes
again. Absolutely.

This formidable ability
to swallow up another solid

is a real insight into just how
peculiar ice is.

It also explains how ice can do
seemingly impossible things

in nature.

In Norway,
at the foot of Nigardsbreen,

glaciologist Evan Lowe
has some local stories to tell

of how glaciers can engulf things
much bigger than a thin metal wire.

From where we're sitting now we can
see a place where a farm used to be,
250 years ago.

Until it was knocked down
by this glacier behind us

and all the buildings and farm
were just swallowed by the glacier.

If something goes into the ice,
what happens to it?

A bit further south, there's a plane
with a pilot who crashed in the '70s

on top of the glacier.

Before the rescuers could get there,
the whole thing was covered by snow.

And it never appeared again.

Some guy calculated that it should
come out of the glacier

some 25 years later,
but they're still waiting for it.

No-one's seen any trace of it.
So there's a plane, body
and everything.

Somewhere!

That's a spooky ghost story to tell
just before bed!

When it comes to a glacier shaping
the landscape,

this ability of ice to absorb things

is a real secret to its strength.

Ice on its own is far too fragile
to leave any mark on solid rock.

It can only carve out a valley
by picking up tools.

The ice engulfs rocks and boulders
as it moves down the mountainside.

They pass through the ice and get
dragged along in its underbelly.

Together they scrape and chip away
at the rock beneath.

It's easy to imagine that this was
once just one big mountain.

And now all this space
that we are in now

is the result of the glacier

taking its bites like this
during thousands of years.

I like the way you say, "taking
bites". The rocks are the teeth
of the glacier

and that's what it's using
to grind away.

It's still doing it up there,
making the valley bigger and wider.

If it were some other solid
like steel or rock,

it would just sit there.
It couldn't do this.

That's one of the secrets of the ice

that it's strong enough to carry
big rocks to work on the surface

but it's also soft enough to move.

Over the thousands of years that
Nigardsbreen has been advancing
and retreating,

it's been grinding down the rock

like an enormous sheet
of sand paper.

Gradually, it's turned boulders
and bedrock into dust so fine

that when it's washed into the lake,

it remains suspended there.

And it's the minerals in this dust

that give the lake its colour.

So that piece of ice there
has done everything.

It's shaped and smoothed these rocks

and it's made these scrape marks
and teeth marks

and down there, the bigger boulders
and the pebbles and the silt

all the way through to the colour
of the lake,

even the shape of the valley,

everything about everything I see
has been dictated and defined
by the ice.

But ice itself is ruled
by temperature.

That's what determines everything
from how long it lasts

to how and where it forms.

And nowhere is this more true
than in the sky,

where ice is at its most
unpredictable.

Clouds are usually made
of water vapour.

But if it's cold enough, you can get
clouds entirely made of
ice crystals.

When you get ice in the sky, that
can cause havoc with the weather.

One of the most treacherous forms
of icy weather

is an ice storm.

11 Canadians have been killed and
two million are without electricity

after devastating ice storms
swept the country.

In 1998, eastern Canada was hit
by a massive ice storm,

its worst on record.

Over five days, freezing rain turned
into a slick glaze of ice

and built up to 7.5 centimetres
thick in some places.

It became heavy enough to bring down
trees and power lines.

The ice storm forced the government
to declare a state of emergency.

Ice storms can begin
high in the atmosphere.

Here, ice crystals grow into
delicate snowflakes

with stunningly symmetrical
branches.

If snowflakes fall into
a warmer band of air,

they'll melt away into rain.

But in the unusual circumstances
that lead to an ice storm,

there's much colder air
beneath this warm layer

and it's very close to the ground.

As the rain falls through
this cold air,

it becomes super-cooled,

ready to freeze again in an instant.

It crystallises as soon as
it touches something,

creating layer upon hazardous layer
of ice.

MAN: Millions of people here
in Montreal are affected.

WOMAN: It's like a war scene,
almost.

We're going round house to house
suggesting to people that it'll be
a while before the power's back

and it might be wise to relocate
to a shelter.

The damage cost the country
$3 billion.

In some areas, the ice didn't melt
for three months.

Temperature is truly the master
of ice.

And there's a mysterious phenomenon
called hot ice,

which freezes at room temperature.

Hot ice is created by putting water
under enormous pressure,

far greater than any glacier
on our planet.

This is ice that we wouldn't
normally find anywhere on Earth.

Professor Paul Macmillan
is going to show me how to make
this high-pressure ice.

What we've got is a little drop
of liquid water

and it's placed between
two diamonds.

Inside here we've got two tiny
diamonds that are pressing together.

You're going to turn this knob here
very gently.

Because otherwise you'll force
the two diamonds together too fast
and they'll break.

I'll be very careful.

I'm about to put a tiny drop
of water under more pressure

than occurs naturally anywhere
on the Earth's surface.

When this gets to around 12,

I want you to start to watch
the screen. OK.

Nine and a half now. Yes.

So what's happening is
the pressure is going on

and the diamonds are squeezing
that drop of water. Yes.

It's close to 12. I would slow it
down just a wee bit.

At the moment this is liquid water,
but it's really squeezed now.

The pressure's going up...

Look at that!

It's crystals!

Yeah. Oh, that is cool. You've just
made ice crystals in there.

They're growing as well,
not just sitting there.

It's a whole faceful
of tiny crystals.

The ice has formed even though
it's way above zero degrees.

See the room temperature
is 25 degrees.

So we've made water freeze
at 25 degrees C? Yes.

These are icebergs floating
in dense water.

'The hot ice is at a pressure
of 15,000 atmospheres.

'That's 15 times more pressure

'than you find at the bottom
of the deepest ocean on Earth.'

What would it be like, then? I know
we can't take it out and look at it

or do things with it
because it's under that pressure.

But how is it different from real,
normal ice?

The first thing is that it doesn't
melt at normal temperatures.

This one here, you'd have to take
this up to well over 100 degrees
centigrade

for it even to start to melt.

So you can go above boiling
point and it doesn't melt?

Exactly. This is a high-density form
of ice.

The structure is very like
a little cube.

You would never get
the hexagon snowflake shapes

that you get with normal ice.

'This kind of ice might occur
naturally out in space.'

We think that it probably does exist
in the solar system,

deep inside some of the icy moons
out there

like Titan, which is the large moon
of Saturn.

And we know that the pressure inside

gets to these pressure values.

So it's like having a telescope
to look into the heart
of Saturn's moon. Exactly.

We know already that the surfaces
of some of the moons of Jupiter
and Saturn

are covered in more normal ice, the
type we're familiar with on Earth.

Recently, we've been able to get
close enough to see it

in more detail.

And that's revealed something
startling.

It might be protecting oceans
of liquid water out in space.

Professor Michele Dougherty
is a space physicist
who explores these outer planets.

It was Jupiter's moon, Europa,

that first attracted her attention

thanks to a surprising photograph
taken by the Galileo spacecraft.

This image shows us what looks like
an ice shelf

which is floating on a liquid.

We could almost say it was
the Antarctic or Greenland.

What you can clearly see are these
icebergs which look as if they're
moving around on the surface.

The only way for that to happen is
for there to be liquid underneath

that's helping shift them around
on the icy surface.

By studying data from Galileo,

scientists reckon that Europa's ice
is covering an ocean

of liquid water.

If true, this will be
an amazing discovery.

But frustratingly, there's no way
yet of penetrating the surface

to confirm it.

However, in 1997,

an unmanned probe called Cassini

was sent into space.

Its mission, to explore Saturn,
700 million miles from Earth.

When it flew by a tiny ice-covered
moon called Enceladus,

it gave a reading that Michele and
her team simply couldn't explain.

So she asked the mission planners if
Cassini could make a closer fly-by.

And this revealed a spectacle

that had never been seen before

anywhere in the solar system.

This is the image we took when we
went really close to Enceladus.

You can clearly see this large plume
of water vapour

coming off from the south pole.
A gorgeous image!

As Cassini has shown us that water
definitely exists under
Enceladus's ice,

that makes it a fantastic place
to search for evidence of
extra-terrestrial life.

The reason that this discovery
is so amazing

is that it's telling us there's
water under the surface of Enceladus

and in the plume itself
there is water vapour,

there are ice crystals

and there are organic compounds -
nitrogen, carbon, hydrogen -

all the things that you need for
the basic building blocks of life.

Michele and her colleagues
are currently working on building
much smaller probes

that will be able to analyse the
plumes jetting out from Enceladus.

They'll look for more evidence
of life.

Ice in space may bring us one step
closer to finding out

if other life forms have evolved
in our solar system.

Although icy environments
even on our own planet

seem too hostile to support life,

in fact they can be
a very favourable place
for life to flourish.

Under the sea ice around the edges
of the Antarctic continent,

at temperatures that would kill
most living things,

live some of the most intriguing
creatures on Earth.

In total, I've been to the Antarctic
13 times.

'At the laboratories of
the British Antarctic Survey,

'Professor Lloyd Peck studies
these creatures to find out

'just how they survive

'and what makes the icy ocean
so advantageous for some forms
of life.'

If we move down here,

we can see some of our
really special animals.

These little fish are called
the plunder fish.

I haven't seen this.

That's a beauty! Is it all right?
Yeah, they're fine.

If a predator comes along,
they open their mouth, push
their gill cases out

and push their spines out
to stop being eaten.

They breed in our tank.
They're one of the classic types
of Antarctic fish.

How cold is it?
The water is below zero degrees.

But it's sea water
so it doesn't freeze.

What you see here is,
those animals living there

are permanently living
below zero degrees.

Why don't they freeze?
Well, the fish would freeze

except for the fact they've got
antifreeze in their blood,
their tissues and their bodies.

They need antifreeze to live
in these temperatures.

They have antifreeze in their blood?
They make their own antifreeze.
They have antifreeze proteins.

There's antifreeze everywhere
because without it,

ice crystals would grow inside
their cells and inside their blood

and it would rip their tissues
apart.

OK. I've got another animal here
to show you.

This is a sea spider.

Oh, look at him!

In Antarctica, the sea spiders
get really big.

The biggest ones are 40 centimetres
from leg tip to leg tip.

So that's twice the size
of this one? About twice the size.

And the biggest sea spiders
in the Antarctic

are a thousand, maybe two thousand,
three thousand times heavier

than the biggest sea spiders
in Europe. Why do they get so big?

Well, the reason they get big
is because it's cold!

Two things happen when sea water
gets cold.

One is that the amount of oxygen
you get in the water goes up.

There's nearly twice as much oxygen
in the sea in Antarctica
as in the tropics.

Because it's cold, their metabolic
rates run much slower than animals
elsewhere.

So it's like live cheaper,
grow bigger?

Live cheaper, grow bigger.
And it's not just the sea spiders.

This is a 40-arm starfish.

Its Latin name is Labidiaster.
Oh, my God!

Have a hold of that.

OK? This is a really small one.

The big ones get up to 70, 80
centimetres across. They're huge.

They're one of the big predators
in the Antarctic on the sea bed.

There's his stomach. They crawl
over the top of animals, put their
stomachs out and eat them.

What is it about the ice that makes
all these weird adaptations
and strange animals?

The ice helps keep the temperature
constant in the seas.

What it's done is kept that
temperature low and constant

for maybe 25 million years.

So it's not just cold,
it's also steady.

It is. The Antarctic Ocean
is possibly the most constant
temperature place on Earth.

And it's been there for such a long
time that animals have been able
to adapt to it

in a very fine-scaled way,
in a way that hasn't happened
anywhere else on Earth.

These creatures are the product of
a unique eco-system

that revolves around ice.

By studying how they managed not
just to adapt, but to thrive,

we can learn about the impact
of cold

and how well icy environments
can support life.

Antarctica is the coldest,
windiest continent on the planet.

It's covered by the largest single
mass of ice on Earth.

Back in the 1950s,

a team of scientists set out
with a seemingly impossible dream,

to discover how thick
the Antarctic ice sheet was

and what might be lying beneath.

Part of that team was glaciologist,
Dr Charles Swithinbank.

He's a legend in the world
of Antarctic science.

He's spent a lifetime exploring
the heart of the white continent.

That's it. That's you?

That's me. I was mad keen
and always have been.

Here was a chance of real adventure
and real exploring

in a really unknown part
of the Antarctic.

It was Charles' job to try
to measure the depth of the ice.

Taking a sled loaded with dynamite
out onto the ice,

he and his colleagues set off
an explosion at the surface.

They measured how long it took
for its echo to bounce back.

From this, they could work out
how far it had travelled

and how thick the ice sheet was.

We found thicknesses
up to 2,500 metres.

That's nothing nowadays.
People have found a lot deeper.

But it staggered us

because here we were,
walking over solid ice

without any idea how thick it was.

But as it took a day to make
one single measurement,

mapping the whole continent
was going to take decades.

Until another ice secret was
unlocked by American army engineer,
Amory Waite.

In the 1950s, experienced pilots
were crashing into the Antarctic
ice sheet and no-one knew why.

Waite knew the planes' altimeters
used radar to measure how high
they were above the ground.

He started hitting ice with
different frequencies of radio waves

and realised some of them were
going straight through the ice.

This could have given the pilots
a false reading of their height.

Waite realised that despite being
a solid,

ice was transparent to radar.

Once this was known,
planes stopped crashing,

saving countless lives.

But it also revolutionised
Charles Swithinbank's job

of surveying the Antarctic ice sheet
and the land beneath.

His team could now criss-cross
the continent in a plane,

using radar to see through the ice

by bouncing radio waves
off the bedrock below.

And he could now take hundreds
of readings every second.

It was staggeringly exciting

because we were getting
a cross-section of the ice sheet
as we flew over it.

We went to a number of places
where I'd worked on the ground

and dreamed and wondered
how thick the ice was.

And in the matter of a minute -

pow! - we'd measured
how thick it was.

It was very, very exciting.

Beneath the white and pristine
Antarctic surface,

an entire new world was uncovered.

A world made of valleys,
mountains and plateaus

hidden in parts by ice
more than four kilometres thick.

And all laid bare thanks to
discovering another secret
of the ice crystal.

While the Antarctic lies
on mountainous bedrock,

on the other side of the world,
the Arctic is a treacherous ocean

of floating sea ice,

where exploration has often been
driven by commerce.

For hundreds of years, sailors
searched for a short and lucrative
trade route through these waters

between Europe and the Pacific.

One that would be cheaper than
the long route via India and China.

The elusive North-West Passage.

For the expedition that found it,
there was a prize of thousands
of pounds.

I'm interested in the story
of one particular expedition.

It was led by a celebrated
naval officer, Sir John Franklin.

But it turned out to be
the worst disaster in the history
of British polar exploration.

What draws me to this story

is that it plays out
like a detective mystery

with ice as the key witness.

And some of the clues are here, at
the Scott Polar Research Institute.

This is the leader of the
expedition, Sir John Franklin.

In 1845, he was already
59 years old.

He'd fought with Nelson
at the Battle of Trafalgar.

He'd been to the Arctic three times
and mapped thousands of miles
of coastline.

The British public had been
captivated by stories of how he
and his men

staved off hunger by eating
their own leather boots.

Franklin was clearly the man
for the job.

Before he set off, he arranged to
have portraits taken of himself
and his senior officers

with the very latest technology.

Curator Heather Lane has these
precious early daguerreotypes

for me to see.

If you'd like to pick it up
and open it. I'd love to.

Very happy.

And there he is.

Quite extraordinary to think you're
seeing him on the day they set off.

'Franklin had assembled a team
of experienced officers to sail
with him to the Arctic,

'many of whom had been there
before.'

They all look quite sure
of themselves. Franklin had been
sensible.

He's pulled together a team he knows
will actually obey orders

in what are likely to be
quite difficult circumstances.

In total, 133 men set sail
with Franklin from Kent

in two sturdy ships,
the Erebus and the Terror,

both of which had seen service
in the Polar regions before.

They were expecting to sail
from the Atlantic Ocean

through the ice-bound islands
of Northern Canada

to the Pacific Ocean,
and return within three years.

They'd refitted these ships
with state-of-the-art equipment.
They were steam-powered,

they had water purification,
they had central heating on board.

They really put a huge amount
of effort into ensuring

that this was the expedition that
was going to make it all the way
through the North-West Passage.

Then suddenly, they disappear.

The ice has swallowed
this expedition whole.

And it's the beginning of a great
Victorian mystery - what has
happened to Franklin and his men?

Over the next few years,

more than 30 rescue missions
searched the icy Arctic
for survivors

but failed to find any.

It wasn't until 1858 that the likely
fate of Franklin's men was confirmed

by a message discovered in a can
on a small uninhabited island.

Written by two senior officers,

it announced that Sir John Franklin
had died in 1847,

two years after he'd set sail.

Both ships had been abandoned
in the ice

and second-in-command
Captain Crozier was attempting
to lead 105 survivors to safety.

But why had an expedition
with experienced Polar navigators

in state-of-the-art ships,

ended up like this?

Well, although the records end here,

the detective story doesn't.

What I find fascinating
about the Franklin story

is it doesn't seem to die.
Clues keep on showing up in the ice.

And eventually, it would be the ice
that would provide the answer.

In 1986, a team of
forensic archaeologists

travelled to Beachy Island
in northern Canada.

This was where, in 1850,

a search party had found
empty food cans,

evidence that the expedition
had wintered here.

And not far from them, three graves.

Over two intense weeks,
Dr Owen Beatty and his team

exhumed the bodies of able seaman
John Hartnell

and Private William Brain

to try to find out how they'd died.

The forensic team had no idea
what to expect. What condition
the bodies would be in.

They had to pick-axe their way
through the frozen ground

which is what the grave-diggers must
have had to do when they buried
the bodies in the Arctic winter.

They found that the ice
had preserved the bodies
almost perfectly.

When they released them,
using warm water,

there was so little decay, it was
relatively easy to investigate
how they'd died.

John Hartnell had had tuberculosis,
but he was also incredibly thin.

He had no food in his stomach
or intestines.

Scattered around the camp, Beatty
had found empty cans that had been
soldered with lead.

He put two and two together.

He tested the men's bodies

and found dangerously high levels
of lead

in their hair, bones
and soft tissue.

To date, about 17 more
of Franklin's men

have been found to have had toxic
levels of lead in their bones.

New research suggest the lead might
not have come from the cans at all

but is more likely to have leeched
out of the new lead piping
in the ship's water system

and contaminated their water.

Lead poisoning is a horrible way
to die.

It paralyses your muscles and eats
away at your brain and central
nervous system.

So then what you get is
disorientation and anorexia.

The worst things that can happen
if you're trying to survive
an Arctic winter.

We know so much about the tragic
fate of Franklin and his men

because of the miraculous ability
of ice to preserve.

But it doesn't just preserve history
by slowing down decomposition.

It also has the ability to preserve
something much more delicate
than bodies.

And one that might prove
even more valuable.

In the Antarctic, teams
of scientists have been
reaching back into history.

They've been drilling thousands
of metres into the ice sheet

to remove columns of ice
that can bear witness to our past.

These ice cores preserve air from
hundreds of thousands of years ago.

They're helping us understand one of
the most complex aspects of nature,

our climate.

I'm with Dr Robert Mulvaney

at the British Antarctic Survey's
ice core freezer in Cambridge

where he studies this ancient ice.

So if I take a piece of this out.

Let's put that down on here.

You can probably make out
the tiny air balls in there.

It's the magic of the ice that it's
able to take these air molecules

into its matrix without altering
them, and release them back to us
later. A storage box. Yes.

What we'll do is cut a piece off and
see if we can see the air bubbles.

The deeper you go,
the older the ice gets.

Scientists are able to date
each layer of ice

from chemical markers
within the ice crystal itself.

It's starting to clear. I think you
can see the air bubbles in that.

Fantastic, isn't it?

This air is about 1,000 years old!

So when they were invading Britain
in 1066,

this is the air
they would have been breathing!

The Saxons and Normans.
Saxons and Normans.

That is wild! It is, isn't it?

This is quite a long way down
in the ice sheet.

This is about 80,000 years old. You
can probably see the air in that.

So this is before... This fell
as snow and trapped air

before human civilisation?

That's right. Fascinating, isn't it?

As well as preserving
past atmospheres,

the ice crystals preserve
another important secret.

Tiny variations in their chemistry

reveal the temperature of the
climate when they originally formed.

This has allowed us to see
in more detail than ever before

how our climate has changed
throughout history.

It's also enabled us
to explore a link

between temperature and levels
of atmospheric carbon dioxide.

Our oldest ice core goes back
800,000 years.

In that period, we've been in
and out of an ice age eight times.

And all through that period,
the atmosphere and the temperature
have been very closely linked.

So as we go into an ice age,
the levels of carbon dioxide,
greenhouse gases, decrease,

and as come out of an ice age
they start to increase.

The ice core record shows that there
was a strong relationship between
temperature and carbon dioxide.

They've moved in tandem throughout
history for 800,000 years.

To many scientists, this historical
record supports current theories
of global warming,

suggesting that if carbon dioxide
levels rise, as they're doing today,

temperatures will also rise.

It's a warning from the past
that many find hard to ignore.

And all because of
the unique ability of ice

to capture air and preserve it.

Ice is one of the most enigmatic
substances in nature.

A solid can pass through it,
without leaving a trace.

It can shatter rock
and sculpt our planet.

In space, its protective shell
may conceal life forms

just waiting to be discovered.

It can last for millions of years

or just melt in an instant.

I'm drawn to ice because of
its contradictions.

Although is seems so fragile, it's
capable of carving out landscapes
and preserving histories,

even giving us warnings
about the future of our world.

But what's really struck me
about making this programme

is discovering where all that power
comes from.

Because actually, the very thing
that makes ice seem fragile
and vulnerable,

the fact that it's always
on the point of disappearing

turns out to be the source
of all its strength.

Subtitles by Red Bee Media Ltd