Birth of a 'berg Operation Iceberg

Travel so far north,

the summer sun never sets.

Here is one of the last great wildernesses -

the vast ice sheet of Greenland.

It's the birthplace of the most massive and spectacular objects

on the planet -

icebergs.

Up to 20 billion tonnes in weight and the height of a skyscraper,

these monsters of the ocean have long fascinated us.

Now, in this series,

an international team of scientists and adventurers

wants to explore these wonders of the natural world.

Wow! Look at that!

I knew it was going to be big, but this is massive.

Just phenomenal.

They hope to discover the secret life of icebergs,

from spectacular birth,

to watery death.

This is a dream come true.

A polar bear on OUR iceberg.

They'll be risking their lives in one of the most unpredictable

and violent environments on Earth.

-It's falling here.

-This whole bit's coming off.

Look at the wave! Look at the wave!

Look at the wave!

That's one of the biggest bits of natural destruction

I've ever seen in my life.

In this programme, the team will be exploring an arctic glacier,

to try to answer how icebergs are born,

from blocks of ice of just a thousand tonnes,

to giant mega-bergs.

That, to me, looks like one great big, white mystery.

Every measurement counts because this is like a knowledge void, a data void.

We've been trying to measure these things in St Paul's Cathedrals, but I wouldn't know where to start.

If you think icebergs are nothing more than floating chunks of ice,

prepare to think again.

Greenland's glaciers.

Each year, they pump out 20,000 icebergs,

95% of all icebergs in the northern hemisphere.

The iceberg that sank the Titanic came from here.

And one of the mightiest of all Greenland glaciers is Store.

A group of two dozen scientists, divers and camera crew

has now come to investigate this remote glacier.

Store glacier is on the west coast of Greenland,

a 400-kilometre river of ice.

It meets the sea with an ice cliff eight kilometres wide.

The team's base camp will be on a high peninsula,

overlooking this glacier front.

It's the expedition of a lifetime for naturalist Chris Packham.

All my life I've been fascinated by the natural world,

understanding how it works.

I remember as a kid opening my childhood encyclopaedias

and looking in there and seeing glaciers.

This is Store glacier.

It's magnificent.

If you can suffer landscape culture shock, then I'm in it.

It's a logistical nightmare -

five tonnes of scientific and filming equipment,

and enough supplies for three weeks.

Ocean expert Helen Czerski is also fascinated by Store.

I'm a physicist and I study this stuff all around us.

And so looking at that, that's just

one big jigsaw puzzle to solve from a physicist's point of view.

Andy Torbet used to be an underwater bomb disposal specialist.

Here, he'll be helping the scientists reach places they wouldn't normally get to.

Every morning when I wake up,

that is what I see,

and that is what it's all about.

The medic is Dr Chris Van Tulleken.

This is the kind of injury I absolutely love.

-You're going to have a nice scar...

-Marvellous!

..makes me look a tiny bit heroic,

no-one's actually hurt.

As well as treating the injured,

Chris is keen on finding out how the team copes in this harsh environment.

Right, good news.

I've got another painful experiment, and I need a volunteer.

They've been joined by a group of ice experts from around the world.

We've got three weather stations going in here

so it's nice to see that they've made it.

They're all here to try to understand the birth of icebergs

and, particularly, why glaciers like Store create so many.

All of this ice is moving. It's creeping downwards all the time

and, partly, that's happening because of gravity pulling the ice downwards

towards the sea, down here to where icebergs calve off the front.

But if that was the only thing that's going on,

we wouldn't see as many icebergs as we do.

So there's something else.

This restless glacier releases 15 billion tonnes of ice

into the sea every year, peaking now in summer.

Day one and polar cameraman Doug Allan is filming

the birth of a small iceberg.

It's a process called calving.

But it's nothing to what the team hopes to observe -

a multi-million tonne mega-berg.

The problem with calving, as far as I can see, is its unpredictability.

Is there a point on the glacier

where it's more or less likely to happen?

There's a lot of minor activity in this embayment.

It's kinda carved in that way,

but we'll see the big ones out by these peninsulas.

I so, so want to see it.

I'm quite prepared to put up with being eaten alive by mosquitoes

if, at the end of it,

I can see one of these things happening. It'll be great!

We've just got to keep our fingers crossed that someone's

got a camera running when it happens. If it happens.

All right, Doug, would you like a biscuit?

I'll bring you a biscuit.

A chocolate biscuit, thank you very much.

That's what I like about that man.

Like all glaciers,

Store is a constantly moving river of frozen fresh water.

I'm pretty good at that kind of thing!

I mean, Jason's a dab hand, too.

The team's first task is to discover how fast it flows.

British glaciologist Alun Hubbard wants to helicopter in

to plant a GPS tracker to measure its fastest point - the very front.

You think there's a spot we can get down there?

Not to land. I'll just jump out, is the idea.

A quick game is a good game.

OK. So three minutes, GPS on, right at the headland.

It's extremely hazardous.

This part of the glacier will be the next to collapse into the sea.

He's calculated that if we put this device on,

during the time we're here, it will break free

and we'll get all the measurements up to that point,

and that's cutting edge. I mean, you know, that's science at the edge.

There's no room for a full camera crew.

Chris himself will have to film Alun.

Can you get on that?

He needs to secure his GPS to the ice.

But he must be quick.

OK. Two, three minutes, OK?

Oh, my goodness me!

Just look at where he is!

Frankly, that is astonishing.

From where Alun is perched on top of this part of the glacier,

there has to be a 100-metre drop,

and he's got a couple of minutes to get that drill,

and get that material in,

and, frankly, if there's any movement on the ice,

there is no chance of him making it off of there.

It's just a pillar with this enormous crack down one side of it.

-If I was to bet on the next pillar of ice...

-The next thing to go, it'd be that one.

The pinnacle has to topple soon.

Alun's instinct tells him it won't be today.

But he cannot know for sure.

Oh, that is astonishing!

He's putting the pole in.

OK, he's ready to go.

OK, take us in, he's got it fixed. He wants to get out of there.

Four minutes, 30 seconds.

The device is secure.

No wonder so little's known about the birth of icebergs.

It's always quite a thrill to be in such a spectacular place.

And, you know, it's a weird space-time thing, isn't it?

Am I here at the right time or the wrong time?

If all goes to plan, the GPS will beam back to camp

the speed at the very front of the glacier.

I tell you something, though, I hope the machine works.

-If it malfunctions now and we have to go back...

-Exactly!

Oh, no, no, no!

The rate the glacier flows

undoubtedly affects the number of icebergs formed.

But how does the glacier,

a four thousand million-tonne slab of ice, move at all?

There's a theory Helen wants to investigate.

Something is helping it along.

The icebergs form mostly in the summer,

so the glacier is flowing fastest in the summer.

And we think there are some clues to why that happens right up ahead.

15 kilometres up the glacier

is a shimmering expanse of water over a kilometre wide.

It's known as a blue lake.

As we're coming in over the top of it,

it looks like someone's poured blue food dye in there.

Store has half a dozen of these temporary lakes.

They form in spring as the temperature rises

and water begins to pool.

One theory claims water from these lakes drains

to the bottom of the glacier,

and helps it slide across the bedrock.

But is there really enough water in the lake

to move a four billion-tonne glacier?

That's what the team hopes to discover.

Oh, wow! Here's a really nice overlook.

You can really see the colour. That's fantastic.

Canadian glaciologist Michele Koppes believes these blue lakes

help create icebergs.

So what we're really trying to do is figure out where this water goes,

and is it contributing to more calving

at the terminus of the glacier?

So what's happening from here, all the way to the end.

At any moment, the ice below could crack open

and drain the lake, like water pouring down a plughole.

The team want to see how much water collects before it empties.

So if I go in straight for a bit and then turn it sideways?

-Yeah, that's great.

-So about there?

Climatologist Jason Box has been tracking Store's blue lakes.

Satellite images from recent years tells him

that this lake should already have drained.

So this lake's now two days past the average time when it would drain.

It could go at any moment,

so I'm glad that we're here getting this done.

Before it drains, the team will track the rise in water level

using a time-lapse camera and a depth sensor.

We want to get as much information as we can.

Every measurement counts because this is

like a knowledge void, a data void.

A rock acts as an anchor for the depth sensor.

But it needs to be positioned on a stable surface ten metres down.

It's a job for the two most experienced divers - Doug and Andy.

I've never dived anywhere like this.

And I've never dived in a location as remote,

or as wild, or as dynamic as this,

and certainly nowhere where, at any point during the dive,

the water could all just drain under your feet.

It looks fairly benign at the moment, and I think we can kit up,

get in fairly quickly, do the job, put in the sensors where necessary,

and then we'll get out and everything will be fine.

Famous last words!

No-one has ever dived a blue lake.

If the lake unexpectedly drains,

they could be sucked down into the glacier.

The safety team would then attempt to haul them back on lifelines.

Three, two, one, jump!

It's absolutely beautiful down here.

All these shades of white and blue.

I'm going to...try and place this sensor here.

The sensor will now record any change in depth.

Let's have a bit of an explore,

see if we can find where this plughole is, eh?

Andy is keen to try to track down the opening through which the lake could drain.

The bottom of the crevasse is deepening off here,

as we push further out into the middle of the lake.

But there are worrying signs the lake bed is unstable.

Out into the middle of the lake

and it's very, very calm water conditions,

we've spotted a rising column of bubbles in the deep water.

And that's obviously going to give us cause for concern.

Oh!

HE CHUCKLES

Doug, there's a big cave here going straight down.

I'm just going to have a look.

This could be the lake's plughole.

For Andy, it's a challenge he can't resist.

Getting pretty dark in here.

It's definitely getting narrower.

No way. It's getting too tight.

It's getting way too tight.

I'm still...nowhere near the bottom.

That's 40 minutes on the dive now, 41 now,

so it's getting to be a long dive.

The maximum dive length we agreed on wasn't much longer than this,

and it's cold, and they'll be using air quickly,

so they'll be out very soon, whatever they're doing.

But something more urgent threatens Andy.

HE BREATHES RAPIDLY

I need to surface.

I think this air hose is freezing up.

Ice is blocking Andy's air supply.

In this sort of environment,

you can only do so much about trying to fix your kit underwater.

There comes a point when you need to sack it and go home.

In one piece.

But the time-lapse camera is now in position and the depth sensor will track the water level.

The team will return in a few days to see how much melt water

has accumulated in the lake.

Meanwhile, Chris is joining Alun and his crew on the research yacht Gambo.

At the glacier front,

Store has eight kilometres of ice in contact with the sea.

The team suspects the ocean might also play

a role in the creation of icebergs.

But getting to the front isn't straightforward.

Could you go up front and just tell me left or right, please?

The Gambo is dwarfed by the towering ice front.

I mean, it's difficult to get a sense of scale from here,

but how high, 100 metres?

Yeah, just under.

To understand how the sea affects the glacier,

Alun wants to map its front.

He uses a powerful tool - side-scanning sonar.

It reveals the hidden part of the glacier that's underwater.

That's the actual equipment that sends out the sound wave,

the acoustic wave, which bounces off the glacier and we pick it up.

So we, hopefully, will be able to scan the whole face of the glacier

and its toe.

In charge of gathering data is Nolwenn.

Happy with the speed, skipper?

Yeah, yeah. I just have to restart the software.

It's just crashed at the moment.

Yeah, OK.

To get a detailed scan, Gambo needs to be right up close

to the ice front, just where the icebergs calve.

They're playing Russian roulette with a glacier.

Just a little bit.

Just a little bit!

We're 150 metres now. I would like to keep 200 or 300.

Yeah, OK.

How are we for bergs, Johannes?

You have to go a bit starboard, I think.

It's the first attempt by any research team to map the entire underwater ice front

of a glacier as big as this.

If they succeed,

the scan could explain how the sea helps to trigger calving.

But just then, the giant glacier reminds them of the risks.

Woah, woah, woah!

Over there.

What happened?

We have a calving event and what it triggered off

was a large lump from under the water

that shot up really high out of the water.

That is quite a minor calving event, I hate to say, Chris.

Minor it may be,

but if the berg had calved minutes earlier,

Gambo would've been crushed.

But they've already got results.

What can you see there?

OK, here we've got a 2D slice of the glacier.

So we've got the glacier front here and the sea bed here.

That's the boat here.

And looking at this top section here then,

how deep is it now from the boat to the bottom?

So the bottom of the fjord at the moment is about 400 metres here.

So we're looking at cliffs outside that are about 80 to 100 metres tall

at their highest, but there's 400 metres beneath the water.

Yeah, yeah, at least. It will be even deeper in some places.

-Even deeper?

-Yeah, we went down to 500 metres.

And the ice was still touching the bottom?

Still touching the bottom, yeah.

-Wow!

-Yeah, clearly, it's touching the bottom.

There is four times as much ice cliff below the water than above.

And a scan reveals another surprise -

the bottom of the glacier is undercut.

Now, what's the distance between the front of the cliff

and the back, how deep is that undercut?

-At the moment it's about 150 metres. At least.

-150 metres?

-At least.

It might be deeper but we can't see it

because of the kind of angle we are.

The huge undercut means the glacier above is unstable.

It could explain why the ice front is so prone to collapsing.

It's the end of a long day and the team will need to return to find out

how this undercut has been formed.

The expedition has been under way for a week.

The team came prepared for the dangers of the glacier,

but no-one bargained for a far more maddening threat.

BUZZING

Mosquitoes.

During the short Arctic summer,

the mosquitoes survive on nectar from plants.

But they much prefer the blood of mammals, any they can find.

Let's look at this. There are quite proper bites, actually, aren't they?

Dr Chris is an expert in tropical medicine.

He didn't expect to be using those skills here.

He wants to find out if some people are especially attractive to mosquitoes.

Good news, everyone! I've developed another experiment.

It's going to be painful and I need a volunteer.

Andy Torbet, thank you.

LAUGHTER

-I hate you!

-Let's go.

With friends like these...

-So what's the plan?

-We're going to sit here with our shirts off,

no insect repellent on, and see who gets more bites.

-I like straightforward experimental protocols.

-You're a genius(!)

So, obviously, there is a competitive element to this.

Whoever gets bitten more loses blatantly.

Hmm. So what they'll be doing is smelling us,

and they're first of all attracted to our carbon dioxide.

They'll be following the carbon dioxide trail in,

and when they get close,

they start to smell sweat and body odour.

Some people have chemicals in their sweat that mosquitoes really like.

-Argh!

-There.

They're all females, and this one is swollen with blood.

The person bitten most will be producing

more of the chemicals that attract mosquitoes.

There's absolutely nothing on you. So how are we doing?

-I've got one there.

-Two, three.

-Four.

-Four.

-Five.

-Five.

-My go.

-8, 9, 10, 11, 12, 13, 14, 15, 16, 17.

So why have you got 32 on your right side

and only two on your left side?

I think it's the down-wind side.

They're attracted to the CO2 from there,

and they're not getting blown away.

So they're more attracted to you. You're getting bitten more.

My sweat is more appealing to mosquitoes than yours.

So if I had these chemicals like Octanol in my sweat,

mosquitoes really like that.

Hence, I've won!

-All I've won is more mosquito bites.

-Correct.

It's been several days since the team were at the blue lake

to set up the time-lapse camera and the depth sensor.

So, what's happened?

The lake is quite definitely still there.

It hasn't drained and the lake's got bigger,

so it looks as though it's been rising. It's filled up.

It was full of ice islands before and it's not any more.

The lake has risen so much,

the camera is centimetres away from being drowned.

The equipment was supposed to be retrieved from the shore.

Andy will have to improvise.

I just want him out of the water as quickly as possible.

I'm finding it like...

I'm finding it a bit stressful watching him.

I know he's good and I know he's a good swimmer and he knows what

he's doing in the water, but...

this water is not a human habitat. Erm...

Yeah.

Give it to me. Oh, good man! Success!

It's getting a bit cold now, though.

Right. Cup of tea, I think!

But for Helen and Jason, it was worth it.

The time-lapse footage

and the data from the sensor reveal what's been happening.

-It's so smooth and still on top...

-It's so glassy!

..but you can see it's just creeping, creeping up the sides of the ice.

It's just filling up.

I love the way you can see the bits blown by the wind.

Because they're speeded up, they just zoom across the field of view.

Yeah, we call those speed-bergs.

-Did you see that one? Nyerrrrm!

-SHE LAUGHS

But more precise is Jason's depth sensor.

It shows exactly how much the lake's risen.

-It filled up fairly smoothly.

-Yeah.

It just kept going, kept going, kept topping up,

-and then slowed down a bit at the end.

-Yeah.

It looks like it filled on... You can see on this axis,

let's call that, like, 18 to 25.

-Seven metres.

-Yeah, that's impressive.

-That's a lot of water.

-Right!

The team calculates just this one lake now contains

over five million cubic metres of water.

That's 2,000 Olympic swimming pools.

A staggering quantity.

Together with the other blue lakes and melt water on Store,

that's easily enough water to help the glacier

slide towards the sea and create more icebergs.

Glaciologists believe the water drains down shafts

into the heart of the glacier.

At the bottom, it spreads across the bedrock,

and it's this lubricating water that allows the ice to slide quickly.

So just how fast does the glacier travel?

The GPS Alun set up at the ice front should give them the answer.

But at four o'clock in the morning,

when only the unmanned cameras are watching, this happens.

CRACKING

Not just the ice pillar that Alun stood on,

but a whole section of the glacier front collapses,

taking the GPS with it.

It's the biggest calving the team has seen so far.

But before the GPS took the plunge,

it sent back data about the glacier's speed.

It's quite revealing. Its mean velocity is about 25 metres a day.

That's just under 10km a year right at the ice front,

and you can see it's varied from something down at ten metres a day

and just before it toppled in,

you can see it's moving at over 50 metres a day.

It's a lovely idea cos we've been looking at this thing

and in my head I'd imagined it was almost steady movement and it isn't.

You're saying it speeds up and slows down, and it speeds up and slows down, as the days go on.

That average of 25 metres a day is the length of two buses.

It makes Store one of the fastest glaciers in the world.

So the fact that the front of Store glacier

is moving at such a high speed

means there's lots and lots of ice coming through,

and that's generating lots and lots of icebergs.

Of course. It is an iceberg-producing machine.

This speed is only possible thanks to the lubrication by melt water.

But the team still wants to find out how the ocean

drives the creation of icebergs.

The Gambo has returned to the glacier front.

They're back to investigate why there's such a severe undercut at the base.

Yeah, try to get it somewhere like here.

Nolwenn suspects the temperature of the water could be responsible,

and lowers a probe to the sea bed.

Much of the Gambo's kit has been ingeniously lashed together.

Where did this come from?

The top pulley is actually a pram wheel.

-What on earth is going on here, Nolwenn?!

-That's a brake.

Look at that! Depth is spelt incorrectly!

It says D-E-P-H-T! There's no P in "Speed".

LAUGHTER

Keep winching!

Marvellous(!) It's a contraption without...

It's a grade ten contraption, without a shred of a doubt.

But it works.

And the temperature readings are a revelation.

So here we've got the temperature against the depth,

so here we've got the depth, surfaces here, 800 metres here.

-Yeah.

-That's zero degrees and that's six degrees here,

so what we can see is that on the surface

we get relatively warm water that's cooling down pretty quickly,

and after that, it's warming as we go further down,

with a maximum at 2.7 degrees.

This water, from 300 metres to the bottom at 800, is at 2.4 degrees.

The water of the sea bed is unexpectedly warm,

well above freezing.

The impact of such water is dramatic.

It's melting the undercut at the glacier's base,

weakening the ice front,

creating icebergs.

-Hmm, top data!

-Yeah, really great! Yep.

-Terrible winch.

-Yeah, terrible winch.

Can't win 'em all.

The team believe the warm water that's undercutting the glacier

might get even warmer due to climate change.

Across the Greenland ice sheet itself,

warmer spring temperatures are leading to a dramatic increase

in the amount of ice and melt water draining into the sea.

It's something that particularly concerns Jason Box.

There's a net loss of ice from Greenland in the last decade

of about 300 billion tonnes per year.

That's producing approaching 1mm per year of sea level rise,

so in ten years, that adds up to a centimetre.

But then it's not a linear increase.

By the end of the century,

this should produce a global sea level rise

between one and two metres.

Sea level rise is something, which I think

is...frightening lots of people.

It could have a massive effect on the way that we live on this planet.

Yeah, that's a colossal problem

for hundreds of large cities around the world.

Climate change is likely to accelerate the mechanisms

the team has witnessed at Store.

So far, they've seen how melt water lubricates

the base of the glacier, speeding it towards the sea.

And they've also revealed how the sea weakens

the bottom of the glacier front.

ALL: Cheers! Kasuutta!

-ALUN:

-Iechyd da!

Together, it solves the mystery of how Store,

and glaciers like it, create icebergs.

But if the team think they've now cracked all the forces at play,

they're in for a shock.

Can we get this stuff out of the water?

I'm sorry, I want to get out of here.

Wow! Look at that!

A wall of ice is splitting from the glacier.

Compared to anything the team has seen so far, this is vast.

It's made a new embayment in one go.

That is a major calving event.

What are we doing, Nolwenn, are we out of here?

Yeah, yeah, we're escaping.

Look at the wave! Look at the wave!

Look at the wave!

It's a ten-metre wave.

Is that going to be a monster?

It looks big. It was massive on the front.

It hasn't reached us yet, but it looks really big.

Up at base camp, the rest of the team look on anxiously.

The Gambo - where is the Gambo?

They're right down there, next to it.

She was on this side of the fjord.

I think they're down here.

Which way are these big ones?

It's the calving...of a mega-berg.

That is absolutely enormous.

140 million tonnes of ice,

travelling so fast it could outrun the Gambo.

It's a huge surge of water,

a massive wave that rose up the side of the front of the glacier,

and, quite clearly, is going to slowly spread out towards us here.

Major event, Alun?

If we'd been there, Nolwenn, we'd have been wiped out.

-I don't want to think about it!

-We'd have been wiped out, man.

Yeah, we would have been wiped out.

It's calving on a scale far bigger than the team has yet witnessed.

The forces they've seen so far don't explain these mega-bergs.

To understand them, they'll need a new theory.

Those are the lumps of ice, which break off the front intact

and drift out to sea as huge icebergs.

There's another mechanism helping those icebergs calve,

and I want to find out what it is.

The team's focus returns to the upper glacier.

They know melt water from here lubricates the base of the glacier.

But could some water also be helping create the mega-bergs?

I'm a little bit sceptical that all the water can get

all the way from the surface all the way down to the bottom.

Michele wants to explore the many holes that riddle the glacier.

Melt water from a blue lake once ran down this one.

It's called a moulin.

Moulin is a grinder in French,

so think of the water grinding its way through the ice down to the bed.

So these are like big drainpipes going down

-and the question is how far down they go?

-Exactly.

Andy is going to climb down into the heart of the glacier.

Andy's very excited about this.

I think that a lot of people would say he's brave.

I think he might be being a bit foolish.

It's very dangerous, I think.

How far do you think you'll be able to get into this?

I have no idea where it stops.

What would be great to find out from you, Andy,

is as you go down, what do you see?

The moulin's big and - at the moment - dry,

giving Andy the best chance of exploring.

But the glacier is constantly moving.

There was a big rumble just then.

All the walls are pretty unstable,

with all these big icicles and big, like, snowflakes,

so the quicker we get down and out the better.

As team medic, Dr Chris is nervous.

I feel fairly redundant,

because of all the things that can happen to him,

there are very few I'm going to be able to fix.

We know very little about what happens to water below the surface.

I mean, we know more about what's going on

on the surface of the moon than what happens inside the ice.

You can see the floor beneath me.

There's these huge blocks of ice.

Things as big as cars are lying down there,

and they weigh tonnes, and they've all peeled off from up above me.

So if that was to happen while I was hanging here, that'd be it.

Woah!

There's a massive, absolutely enormous side passage.

You could drive a double-decker bus,

with another double-decker bus on top of it,

and it would still fit through there quite easily.

It's a remarkable discovery, on a massive scale.

When this tunnel was active,

it would've channelled vast amounts of water.

Not downwards, but sideways.

And there's been no-one down here before us and the chances are

there'll never be anyone down here again.

This is proper exploration.

This is all completely virgin territory.

And this...

This is the crowning glory,

this immense cathedral-like tunnel.

The team lowers a camera crew down to explore.

But just as they're preparing to enter the tunnel...

CRACKING

-I think we should get out.

-Yeah.

OK. We've got to get out of here. That stuff up top is not good.

CRACKING

The tunnel roof has started to crack.

If it collapsed, it could bury the team.

Glad to be out of there.

It was huge, absolutely massive.

And we got out, which is even better!

Which is always nice.

Having said that, the footage is still at the bottom of the hole. Will I get it out?

Yeah, the camera is yet to be lifted up.

So let's not celebrate too soon!

While some melt water flows to the bottom of the glacier,

other water appears to take an alternative route.

The glacier has a hidden plumbing system,

a vast network of tunnels

carrying melt water through the ice, horizontally.

Now that we've seen this moulin,

we've seen that it's not a simple picture.

It's not straight down the plughole to the bottom.

It's much more complex.

Water goes down a little way and then maybe it goes sideways,

and then maybe it falls down a bit more.

Eventually, all going towards the sea,

but getting there by a huge variety of different routes.

The team wonders if these side channels

could be linked to the creation of mega-bergs.

While the science team devise their next experiment,

Chris is making friends with a local.

This little arctic fox has been coming in to our camp

almost every day, on the scrounge for food, of course.

But then things aren't easy up here, there's not a lot of food about.

They feed on young birds they find them in their nest.

Ptarmigan, hare - that'd be a pretty special day,

but I'm just tempting him in with some of this pasta.

I have to say, a lot of people haven't taken a shine to the fox.

They come up with these stories about them

breaking into the tents, chewing all the cables.

I can't see it myself.

In the winter, he'd be bright white,

and they have an amazing winter coat,

cos they are a bit different than our foxes.

Much smaller of course, blunter nose, smaller ears, shorter legs.

That's all about conserving heat when it's cold here.

(Oi!)

You're going to get me into trouble.

I'm going to get told off for encouraging you into the camp.

I don't care, though.

I'd rather have the fox than the food.

Back on the upper glacier,

the team has cooked up an ambitious experiment.

They want to try to trace the route of melt water

through the horizontal tunnels and out the glacier front.

We've found a moulin that's about 8km up from the ice front,

and it looks like the water that's flowing down into this moulin

is making a direct connection down to the north side of the ice front.

They're going to throw 30 plastic balls,

called cryospheres, into a moulin.

They may look home-made,

but they're packed with sophisticated electronics.

It looks reasonably likely that the water flowing past us here

will, at some point, flow out of the glacier front

that we've been watching for the past week or so.

Exactly. It's the "at some point" that is the big question.

-So if we can find these at the other end...

-Big if!

-..lots of useful information is going to come out of them.

-Yeah.

That's it. Looking good!

If the team's lucky,

some cryospheres may travel from this moulin

all the way to the glacier front,

without getting stuck inside the ice.

Michele, number 19 is going at 5.56.

The cryospheres will measure the speed and pressure of the water...

-Off it goes.

-..and, crucially, reveal where the tunnels come out.

Woo-hoo!

You know, glaciology is an experimental science.

We've gotta try new stuff.

That's why I've got one left and I'm going to wish it...

..happy returns.

Mwah!

Electronics expert Mark Neal designed the cryospheres.

He'll stake out the fjord from a mountain top.

Meanwhile, Chris, back on the Gambo, also has his eyes peeled.

The terms wild, goose and chase, and needle, haystack come to mind.

What's we're looking for is about, you know, 30 ping pong-size balls

in amongst all of this ice bobbing on the surface.

I mean, I've spent some crazy evenings in my life

but this adds up to another one of them, you know.

Chris is relying on his bird-spotter's training.

But Mark takes a hi-tech approach.

We should have the image from the telescope on the screen here,

and then I can activate my filtering software

which will tell us if we can see any orange dots.

-Hello.

-Just have a look up the mast for you.

Well, good luck. My eyes are bleeding down here,

and I'm prepared to offer you a South American country,

a front-engine racing Ferrari,

and a night with a supermodel of your choice,

if you spot one of these balls.

That's generous of you.

It's a generous offer but I'm confident that I won't be exposed.

Mark is also finding it tricky.

No sign of any orange things.

If they've come out or if they are going to come out,

they probably have come out by now.

I'm not going to tell you how many hours we've been out here now,

looking for these tiny orange ping pong balls,

which are packed full of this...scientific paraphernalia,

but we haven't found them.

The experiment has been less than successful.

But, during the search, Chris spotted something which

might give a clue about the route of melt water to the ice front.

This body of water here is very different than everywhere else.

There's brash ice everywhere and yet this is open, it's turbid,

and parts of it are boiling.

Well, not boiling, but there's a lot of Jacuzzi action.

Jacuzzi action! That's a pretty cool word for it.

The upwelling plumes - these Jacuzzis - I suspect,

are absolutely fundamental to the processes going on at the ice front.

The team wonders whether the Jacuzzis could have

anything to do with the hidden tunnels within the glacier.

To find out, they've flown in a secret weapon -

imaging expert Richard Bates.

He's turning the entire underwater scan into a 3D world.

Richard, what have we got, then?

This is the side-scanning sonar results,

but you've transformed them with some software in to something?

Yeah, that's right. If I put that into 3D, you can start to see now.

Ooh! So that's just the sea floor, no ice?

-That's just the sea floor we're looking at here.

-Right, OK.

We can put the ice back into that and there you can see the ice

stretching from the north side to the south side of the glacier.

Look at that!

But then round the corner, into that embayment - huge cave.

And this on the south side, here -

that's where the plume's coming from.

Exactly. These places match where all that water's coming out.

Seen for the first time, they're the mouths of the horizontal tunnels,

spewing out millions of litres of fresh melt water into the sea.

These are the source of the Jacuzzis.

Most tunnels are at the base of the ice,

but not all.

Is that a cave in the face of the glacier, then?

Yes, it is a hole or a cave,

or at least a heavily fractured zone in there.

That's coming out within the face and that's something very new.

What an astonishing view!

It's lovely, isn't it?

You can really visualise the fact that

this glacier front is not just a big flat wall.

-This is the best data we've got.

-Is this the money shot?

This, for me, is it.

Our time on the Gambo has been very well spent.

Look at that!

But it's the effect of the plumes that most intrigues Alun.

He believes they melt the glacier front at particular locations,

forming a series of deep bays,

with powerful consequences.

What we're seeing is the embayments are generally cutting back.

That's leaving these very exposed promontories,

these massive headlands, with towering ice above the water line.

They're 100, 120 metres high in places,

and that's where we're getting the really big mega-bergs forming.

For the team, it means all the pieces have finally come together.

We've seen that huge amounts of melt water are produced at the surface,

and they percolate down into the ice through moulins and crevasses,

and one theory was that all of that water

flowed down to the bedrock and underneath the ice,

lubricating the movement of the glacier as it surges forward.

But we've also seen that there's a new theory that water could be

taking a different route, through a small number of huge tunnels,

and that helps melt away the ice where the tunnels are formed,

and so we get these bays,

and in between the bays there are headlands,

and those seem to be the bits that break off intact,

and that form the huge lumps of ice

that carry on out to the open ocean as icebergs.

The team's packing up.

I believe I've got a cake!

They're leaving the glacier that's been part of their lives for three weeks.

It has started to feel like home,

although I'm definitely ready for a shower!

But Store has one last surprise for Operation Iceberg -

the culmination of everything they've discovered.

Wow!

HE LAUGHS

-Oh, wow, look!

-Wow!

That is massive.

Just as Alun predicted, an entire headland is collapsing.

It's the biggest and most violent calving they've seen.

Just phenomenal!

The mega-berg to end all mega-bergs.

That iceberg is a kilometre across.

We talk about glaciers as like a metaphor for slowness and tedium,

but this thing's completely alive.

There's a wave of kind of fractures going along the top end of it,

so all the stuff that was the cliff is now just crumbling.

And that's the first time the water in that

has seen the light of day for thousands of years.

It's great!

You know how we're all kids at heart and love a really good car crash?

Well, that was a really, really good car crash.

That's one of the biggest bits of natural destruction

I've ever seen in my life. It was fantastic!

But from this destruction, a new iceberg is born.

And what's more,

the team has come to understand the forces that led to this moment.

And now that I've seen all of what's going on to produce just one iceberg,

all of the things that happen behind the scenes, if you like,

watching an iceberg calve is a much richer event.

We've been trying to measure these things in St Paul's cathedrals,

but I wouldn't know where to start.

I wonder where that iceberg will end up.

Where's it going to drift to? Where's it going to finally melt?

Where's it going to be when the last little piece,

the size of a golf ball, melts and becomes part of the ocean?

Makes you wonder, doesn't it?

Next on Operation Iceberg,

the team is on the hunt for one of the largest icebergs in the whole Arctic.

-Happy?

-Yep. Let's go!

They've seen how an iceberg is born.

Now they hope to follow its life - and death - out at sea.

But to succeed, they'll need to confront the Arctic's most dangerous predator.

It's all my Christmases come at once!

I really, really hoped to see one but I never thought that we would.

And it's a world where the ice beneath them

can collapse at any time.

This is a new crack forming. This whole bit's coming off.

Subtitles by Red Bee Media Ltd