Iceberg Dangerous Earth

It's a tornado!

Look at that!

Our planet is home to some spectacular natural wonders.

THUNDERCLAP

Yet exactly how and why they form is still a mystery.

But now, new camera technologies are revealing

their inner workings in stunning detail.

My name is Dr Helen Czerski

and I'll be looking at how these extraordinary images

are transforming our understanding of the natural world.

In this programme,

we reveal the latest scientific insights into icebergs.

Ever since one sank the Titanic,

icebergs have been seen as a menace, a hazard on the polar seas.

But each iceberg is also a beautiful ice sculpture,

with a fascinating history and future all of its own.

Now, side scanning sonar is unveiling

what happens at the edge of glaciers, where icebergs are born.

Satellite images are showing that icebergs create hot spots

for life in the polar seas.

And eyewitness pictures are giving us

a unique glimpse of how icebergs transform over time.

And all these new findings also give us vital clues

about our changing planet.

-Wow!

-Oh!

I'm in Greenland to witness one of nature's most violent

and dramatic events - the birth of an iceberg.

Just phenomenal.

Catching on camera 500 million tons of ice

breaking away into the sea, it's an awe-inspiring sight.

Oh, oh!

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.

In recent years, the number of icebergs

calving from the world's glaciers has been increasing steadily.

Which is why it's never been more important

for scientists to study the birth and life cycle of an iceberg.

Research has shown that 95% of all icebergs in the northern hemisphere

come from one place - Greenland.

It's an island covered by a giant ice sheet, up to 3km thick.

Greenland's many glaciers transport these vast masses of ice

towards the sea, where they pump out 20,000 icebergs every year.

Icebergs aren't just broken chunks of sea ice.

They begin their life in a glacier

and are made from frozen fresh water.

But Greenland's glaciers are dwarfed

by those on the other side of our planet.

90% of the world's freshwater ice can be found here, in Antarctica.

And the glaciers here are where the very biggest icebergs are born.

The largest ice stream in the Western Antarctic

is Pine Island Glacier.

In 2011, NASA scientists noticed a strange feature

across the top of it and here it is.

There's a dark line running all the way through the ice.

And when they went to have a look in a research plane,

they flew across the feature,

taking a photograph every two seconds,

and they stitched together this stunning video.

And you can see that that dark line is actually an ice canyon.

It's 50 metres deep, 70 metres across,

and it zigzags across the ice for 30km.

Scientists knew that such a wide crack wouldn't be able

to hold the ice sheet together for very long

and in 2013, 720 square kilometres of ice broke off...

..creating a gigantic iceberg.

You can see it really clearly here on this satellite sequence.

As time goes on into 2014,

it breaks away and the entire iceberg drifts out into the sea.

It's about 500 metres thick, at this point,

about 30km long and 18km wide.

It's gigantic and it became known as iceberg B31.

Three years on, B31 is still floating in the Southern Ocean,

around Antarctica.

And scientists are monitoring it every step of the way.

They're concerned it could travel as far as the South Atlantic,

posing a threat to shipping lanes.

Like any iceberg,

what you see above the water is only a fraction of what lurks beneath.

One of the reasons that icebergs are so dangerous

is that most of an iceberg is actually below the waterline.

You can see, if I put a big cube of ice into the water,

most of it sits below.

You can see that there's only this tiny bit here, the top 10%,

which is above the waterline. Everything else is down below.

And the reason for this

is all to do with the molecular structure of ice.

The secret lies at the heart of an ice crystal.

It's the way the ice crystal forms which is the key

to why it floats the way it does.

Water molecules are held together by loose bonds

which are constantly breaking and reattaching.

When the temperature drops to zero, these bonds begin to hold,

creating a hexagonal lattice.

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

It's this opening out that makes ice less dense than liquid water.

But only just.

The density of the water in this tank

is about 1,000 kilograms per cubic metre.

But the density of the ice is less,

it's only about 920 kilograms per cubic metre.

And that's because when the ice froze, it expanded,

so the ice takes up more space.

If this ice cube was to melt completely,

it would only take up exactly the volume of water

that is below the waterline.

And so, all that bit above, that's how much the ice has expanded by.

But it's the 90% of an iceberg below the ocean surface

that worries mariners most.

Since the sinking of the Titanic in 1912,

icebergs have been a major concern for shipping.

-RECORDED FOOTAGE:

-'Drifting down from the north,

'after breaking away from a glacier,

'the icebergs making their way towards the shipping lanes,

'become a grave danger to navigation.'

The Titanic collided with an iceberg in Iceberg Alley...

..a now notorious stretch of the North Atlantic,

that sees a high number of icebergs.

'There seems to be plenty of ice about.

'Maybe that's had an effect on our weather over here.

'It felt like it anyway.'

To ensure safe passage through the area,

the International Ice Patrol was set up.

It's purpose? To track icebergs and warn ships.

'Never mind how she got there. She WAS there.

'Something had to be done right away.

In its early years, the Ice Patrol didn't just track icebergs...

EXPLOSION

..they tried to destroy them.

EXPLOSIONS

But the experiments proved unsuccessful

and the Ice Patrol eventually abandoned the project.

Today, the Ice Patrol still monitors the North Atlantic

and warns mariners of dangerous icebergs.

Icebergs may be a threat for some

but, for others, they're veritable treasure troves.

In fact, rather than being inert lumps of ice...

..new research shows that icebergs can transform the oceans.

Jemma Wadham collects samples from the bottom of glaciers

just before they turn into icebergs

and brings them back to this low-temperature facility

here, at the University of Bristol.

So, what we've got here is a large chunk of ice

that we've chain sawed out from the bottom of an ice sheet.

And you can see, very clearly,

there's a very thick band of sediment through the middle

and that sediment will then eventually end up in icebergs

which melt into the ocean.

The sediment is the really interesting bit.

Jemma wants to know which elements are present in the sediment layer.

To analyse it, she first needs to prepare the sample.

When she gets the results, they reveal something extraordinary.

We can see, here, a really nice well-defined bump.

And that bump indicates the presence of iron in our ice samples,

which is really quite astonishing

because you might look at an iceberg sometimes

and think, "There's nothing in it",

but, actually, there's quite a lot of iron.

Iron is a key nutrient for life in the oceans.

But it can't be used by marine life in all of its forms.

The cool thing about icebergs is because they freeze this sediment

into their underbellies, that freezing process preserves the iron.

And as the icebergs move out into the ocean, they melt

and, as they do, that sediment drops out of the iceberg into the ocean

and releases that really nice, tasty iron.

Jemma's research shows that ice can preserve the iron

for thousands of years.

And when an iceberg melts,

it releases the iron into the surrounding oceans.

There, it's used by phytoplankton - tiny floating plants.

Each phytoplankton is scarcely bigger than a speck of dust.

But, ultimately, they feed almost all the life in the sea...

..from tiny fish to the giants of the ocean.

This is a picture created by scientists

at the University of Sheffield.

It's based on satellite images of the ocean around Antarctica

before and after several giant icebergs have passed by.

So, in the wake of this iceberg,

you can see this yellow colour and this red colour,

just is a band in the wake of the iceberg and the surface ocean,

and what that is is satellites, seeing from space,

chlorophyll concentrations in the surface ocean.

Now, chlorophyll is a pigment required for photosynthesis.

The more chlorophyll, the more productive the phytoplankton are

in the surface ocean, so we've got a really nice high productivity band

of phytoplankton here, in the wake of the iceberg.

And it's really fascinating

that they can see the product of the ocean from space.

The oceans flourish in the wake of melting icebergs.

But on their journey through the seas,

icebergs don't simply melt.

They're also battered by collisions with other bergs

and eroded by waves.

And so, over time,

icebergs can take on the most bizarre shapes and forms.

And as they do so, they weaken.

Just occasionally,

there's an iceberg that looks completely different.

This photo was taken by Alex Cornell on a trip to Antarctica in 2014.

What we see here is the iceberg's underside.

Through years of melting and eroding,

its centre of gravity has shifted

and it became so unstable that it rolled over.

This is a spectacular image of a blue iceberg

and its true colour. The ice really is this colour.

It's not often that you see this,

but what's happening is that light comes in from the atmosphere

and, as it travels through the ice, very gradually,

the red light and the green light get absorbed

and by the time the light finds its way back out,

the only colour left is blue. So, this is the true colour of ice.

But that leaves a question, because normally,

when we see icebergs, they look white like this one.

And the reason is all to with a very small structure of the ice.

So, if we look in, zoom in to a small piece of iceberg,

you can see it's full of bubbles here,

because, perhaps thousands of years ago,

layers and layers of snow fell on top of a glacier

until the ice and snow underneath was crushed together.

So, the ice formed a solid block

and the air was squeezed into separate little bubbles.

So, when light hits an iceberg, white light comes in,

it bounces off all these internal surfaces, all the bubbles,

and white light comes back out.

And that's why icebergs look white,

even though the true colour of ice is blue.

Deep in the ice, these air bubbles are gradually squeezed out,

which is why the flipped iceberg looks blue.

But as long as the bubbles are present, icebergs look white,

as do glaciers and ice sheets.

And because they're so bright,

anything that isn't white, really stands out.

That's how Peter Fretwell from the British Antarctic Survey

made a surprising discovery.

He was using satellite images to map the Antarctic coastline,

when he spotted something unusual.

We were mapping Antarctica and the coastline for our pilots,

who need specific information on their maps.

This is a satellite image of Antarctica

and we can see here the coastline, this is the sea.

In between the coastline and the sea, these white areas are sea ice.

And there are some strange brown stains on it

and we weren't sure what these brown stains were.

The sea ice, which is frozen seawater, should be pristine.

It should be pure white.

When we zoomed in with the satellite imagery,

it started to resolve itself as to what these were.

We had brown areas and strange black areas as well there.

And I put two and two together

and realised that what we were looking here, with the satellites,

wasn't just brown stains on the ice. It was actually penguins.

The brown area is the guano,

the stain that they leave on the ice from their droppings and their poo

over the eight months or so that they inhabit this area.

Peter had discovered an emperor penguin colony from space.

At well over one metre, emperors are the tallest penguins on Earth.

They live in large colonies and thrive in freezing conditions.

And they breed in the middle of the harsh Antarctic winter,

using frozen seawater as their breeding platform.

But Peter's most recent satellite images show something unexpected.

We found this colony, one where the penguins weren't on the sea ice.

In this case, they were actually on an iceberg.

Here, we can see a satellite image with a number of icebergs

and one of them is almost totally covered

in brown stain, guano, the penguin poo.

It seems that there wasn't enough sea ice for the emperor penguins

at the beginning of their breeding season.

Early in the season here, the sea ice hasn't formed

when the emperors have turned up at their breeding location.

So, the emperors have been left with nowhere to go,

but in this case, they've moved up onto the iceberg

to give them somewhere to do their courtship

and their mating and their breeding.

Peter has since observed emperors on icebergs in other locations

and it's something that's likely to become even more common

as the climate changes.

We've lost huge amounts of sea ice in the Arctic

as the climate's warmed.

And all of the predictions and the models suggest

that Antarctica will go the same way

and that we could lose lots of sea ice in Antarctica,

which will be terrible for the emperor penguins.

But having this adaptation, to be able to move onto icebergs

or, in some cases, up onto the ice shelf,

will be critically important to be able to save

some of those emperor penguin colonies from extinction.

Climate change isn't just having an effect on sea ice.

It's also affecting the world's glaciers

that are pumping out more icebergs than ever before.

To find out why this is happening,

we need to go dangerously close to the glacier front.

It's all in a day's work for Alun Hubbard

from Aberystwyth University.

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

On board the research yacht Gambo,

he's trying to map the front of Greenland's Store Glacier.

Alun uses a powerful tool - side scanning sonar.

It reveals the hidden part of a glacier that's under water.

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.

To get a detailed picture,

Gambo needs to go right up to the ice front,

just where the icebergs calve.

-We are 150 metres now. I would like to keep 200 or 300.

-Yeah, OK.

How are we for bergs there?

Have to go a bit starboard, I think.

It's the first attempt by any research team

to image the entire underwater ice front of a glacier as big as this.

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

CREW MEMBERS SHOUT

Back in the UK, Alun has had a chance

to analyse the sonar images from Store Glacier.

This is the result from the side scanning sonar.

We've got the seabed here and this is the glacier front here.

And it shows us that the glacier front is far from a plane

or flat block surface. And this is 5km, so it's a big place.

But what I love here is, all the way along here,

we're getting very obvious undercuts at the base,

where the ice is sitting on the sea floor.

To find out why the glacier front is so undercut,

Alun had to compare scans from several different days

and when he analysed the data,

he discovered that the glacier front is melting at an extraordinary rate.

Here we get submarine melt rates

in excess of four or five metres a day,

which is pretty phenomenal when you think about it.

So, that's actually four metres of ice flowing into that front

every day and it's just being taken away, melted away.

Where that is really focussing is at the base of the glacier

and that's what's leading to these big undercuts

that we're seeing in the front of the glaciers.

It's this submarine melting

that's causing the huge undercut at the bottom of Store Glacier.

We've come to realise that submarine melting

has a really important role to play, in terms of undercutting the glacier

and preconditions the glacier to fail in particular places.

The undercut makes the glacier above unstable,

which is why so many icebergs are calving off it.

And when the underside of an iceberg rises above the ocean's surface,

you can see evidence of submarine melting.

The grooves on this mega berg are caused by it.

The fresh melt water from the base of the iceberg

rushes to the surface because it's less dense than seawater.

And it brings with it the warmer ocean water from the seabed,

creating grooves in the ice as it rises up.

Since the year 2000, the sea temperatures around Greenland

have gone up by one degree, exacerbating submarine melting

and the effect it has on iceberg production.

But the melting doesn't just weaken the glacier.

It leads to an overall loss of ice from the ice sheet.

Climate change, without doubt,

is happening in Greenland and affecting Greenland.

The ice sheet used to be in balance with its climate

just two decades ago.

It's certainly not in balance with its climate at the moment.

The Greenland ice sheet is losing

around 300,000 million tons of ice per year

that's not being replaced by snowfall in the middle,

so it's losing that mass

and that's going into a global sea level rise

which is about a millimetre per year.

So, Greenland's the largest contributor

to global sea level rise -

much greater than all of Antarctica put together.

The Arctic and the Antarctic are covered in and shaped by ice.

We see ice as harsh and unyielding,

but these frozen places are particularly sensitive

to warming temperatures.

Although the polar regions are remote,

they're an important part of the Earth's system,

linked into all our lives,

so what happens at the poles affects all of us, no matter where we live.

In recent years, new camera technologies have allowed us

to get closer to icebergs than ever before.

We now have a much greater understanding

of the complex processes that lead to the birth of an iceberg...

..determine its life cycle...

..and how it can transform the surrounding polar seas.

And the study of icebergs is also giving us an important insight

into how climate change is affecting our planet.