Original subtitles

David Attenborough: In this series,

we have explored

the earth's frozen frontiers.

We have celebrated the astonishing variety

of animals that are found there...

And revealed

the extraordinary ways

by which they manage to survive.

At a time when our icecaps are melting

faster than ever before...

We will meet

the scientists and people who are dedicating their lives

to protecting our frozen planet...

And striving to turn things around

while there is still time to do so.

It won't be easy, but it's doable.

It's crucial that we try to understand

what the impact will be,

not just for the wildlife and the people that live there,

but for you and for me.

We start our journey in the high arctic,

and the vast frozen expanse of Greenland.

This huge island is blanketed by the largest store of ice

in the northern hemisphere.

But now it's shrinking.

Professor alun Hubbard is a glaciologist

and he's spent over 30 years

studying the movement of ice along Greenland's coastline.

Alun: It is quite a beast of a glacier.

It's just growling constantly.

Thundenng". In the background.

Ooh. There we go - bit of activity.

Alun: Calving icebergs is a natural process,

but what we've seen in the last 20 years is

there's been much more melt,

and much more ice calving off,

producing huge icebergs...

So it's quite an intimidating place

to be hanging out.

David: One thing in particular

has caused this increase in melting and calving.

We put this weather station here in 2010.

And the hottest temperature was...

Two days ago...

At 22.37 degrees centigrade.

That is very, very hot for Greenland.

David: As the ice falls into the ocean,

it raises sea levels globally.

These are now rising

by an average of four millimetres a year.

A quarter of that comes from the Greenland ice sheet,

and scientists fear that this figure could increase rapidly.

To investigate, alun has travelled 70 miles inland

to the top of the ice sheet,

where the glaciers start their lives as compacted snow

more than a mile thick.

Here, the effects of a warming climate

are only too clear.

Alun: There are thousands

of these beautiful azure-blue lakes

littered across the surface of the ice sheet.

David: The surface has always melted in the summer,

but not on this scale...

And alun wants to know

what effect the increase in meltwater

is having on the ice sheet as a whole.

Alun: The sheer quantity of water...

Shifting through this system is crazy!

David: Powerful torrents of meltwater are boring shafts -

known as moulins - into the ice sheet.

Alun: This is nuts.

This is a moulin actively being formed,

a moulin in Genesis.

As we speak, that water is finding

the path of least resistance,

sculpting this shaft that's going deep into the ice.

And here it is,

just toppling over a waterfall edge

and dropping into the ice sheet.

David: But where is all this meltwater is going?

And what impact is it having

on the structure of the ice sheet?

To find out,

alun decides to climb inside a dried-up moulin.

Alun: I think I must be 15, 20 metres down here,

but I'm going to go down a bit further.

It's a very narrow shaft here.

David: It's always been assumed that the meltwater

drains straight down and out of the bottom of the ice sheet,

but what alun discovers is very different.

I can hear

a big amount of water moving in this system,

and the water's starting to spread sideways, laterally,

so the drainage system is obviously complex.

It's interlinked.

David: These observations suggest that the meltwater

is branching out in every direction,

causing this once-rigid structure to destabilise.

Whoa.

It's a bit rotten.

Everything's rotting here.

David: The implications of this are frightening.

Alun believes that as the ice sheet begins to thaw,

it's sliding towards the ocean at a much faster rate.

And he's now confirmed that using time-lapse photography.

Alun: The ice at the front can be moving

in excess of 20 metres a day, which is fast.

That is a huge quantity of ice straight into the ocean.

David: Some of Greenland's glaciers are moving

three times faster today than they were 30 years ago.

Alun: As the climate's warming,

the rate at which this ice sheet flows

is absolutely critical.

80 whereas, at the moment,

we're thinking this thing is going to take

thousands of years to melt and disintegrate,

if it does move faster and accelerate,

it means centuries.

That is a really contentious and very important question -

because this ice sheet has enough water in it

to raise global sea level by over seven metres,

and that's a total disaster for humanity.

David: Calculations predict

that nearly half a billion people

living in coastal communities around the world

will be displaced by flooding by the end of the century.

But if the Greenland ice sheet

slips into the ocean more rapidly,

this could all happen far sooner.

Greenland isn't the only large body of ice in the arctic.

In winter, the ocean here freezes over,

creating a cover of ice

larger than the entire United States.

This sea ice has always got smaller in summer,

but today it's rapidly disappearing.

Hotter temperatures are melting it at an unprecedented rate...

With worrying consequences

for the wildlife that depends on it.

For harp seals, the sea ice is an excellent place

for giving birth out of the water.

It provides the defenceless newborn pups

with a safe space for their first six weeks,

until they're big enough to swim proficiently.

But with the sea ice

disappearing increasingly fast...

Will they be able to adapt?

Radio: Coastguard 432.

Coastguard radio. Coastguard 432. Check out.

David: In Canada's Gulf of Saint Lawrence,

a group of seal biologists are trying to find out.

It's a pretty dangerous, pretty inhospitable place,

but it's the perfect environment for these seals

to spend the first few weeks of their lives.

There's a group just down here to the right now.

David: But the fragile sea ice is a challenging place

in which to work.

Here... let's go a little further out.

David: To support a two-tonne helicopter, the ice must be

at least 30 centimetres thick,

and the only way to find out if that's so is with a drill.

It's just not safe here.

There's a couple just down here below us now.

We've got a pretty short window here.

David: The team are trying to discover

where the seals go when they become independent.

So, this is a juvenile harp seal.

This is exactly what we've been out on the ice trying to find.

Hey, little guy.

They're absolutely beautiful.

We'll be putting a satellite transmitter

on the top of this animal's head,

so that every time the animal comes to the surface,

we can get a location estimate for where he is at sea.

It won't harm them in any way, and, in return,

the amount of information we get from them is invaluable.

It'll be really interesting to see where these animals go

as the ice starts to break up over the coming months.

David: The results from the study so far

do not look encouraging.

Despite migrating huge distances,

when the time comes to have pups of their own,

harp seals almost always return to the area

where they themselves were born.

But as the sea ice shrinks,

so does its suitability as a nursery.

The problem really comes about if the only ice available

in the traditional areas is very thin.

They'll still use that ice and then you get

an increased mortality.

David: In short, the pups risk drowning

if the ice isn't thick enough.

And the bigger question is,

will the ice continue to exist at all?

In my lifetime, we've lost about two-thirds

of the summer sea ice in the arctic.

And it's likely that in the next 30 years

we're going to end up with an ice-free arctic in the summer.

I think one of the issues with climate change

is that it's really difficult to see.

But in the case of harp seals, it's really quite simple.

If we lose the sea ice in the arctic,

we lose the harp seals.

For harp seals, their future, it has to be said,

appears uncertain.

But what about the most famous face of climate change -

the polar bear?

Can this keenly intelligent animal

adapt to a rapidly changing world?

As the summer sea ice melts away,

many polar bears are forced to head for dry land.

Some swim up to 400 miles to get there.

This is wrangel,

a remote island in arctic Russia.

David: Without the sea ice, the hungry bears cannot hunt seals

and feed on their calorie-rich flesh,

but find other sources of food, including human food supplies.

Each summer, gennadiy is joined by polar bear expert

dr Eric regehr.

- We need to cross that Ridge. - Ok.

David: Eric wants to find out

just how many bears are ending up here.

Eric: In 20 years of studying polar bears,

I've never been anywhere like wrangel island.

The density of bears is unlike anything I've ever seen before.

This past two years, we've seen about 500 bears.

My sense is that's just a fraction of how many are here.

David: But with so many hungry animals in one place...

Is there enough food to go round?

Gennadiy, if you can keep an eye out for us, please,

like up on the hill

or just wherever you've got a good view.

All right, thank you.

This is a hair trap.

So, bears like anything that smells strong,

and so this has a little bit of spoiled cheese,

milk and fish in it.

The goal here is to get a polar bear to come in

and put its hand or its head inside this box,

and when that happens,

these little wire brushes will pull out a few pieces of hair

that we can use for scientific analysis.

You can learn a lot about polar bears

just from a piece of their hair.

We can figure out which individual it is,

or you can get information on what they're eating.

There we go - hair collected.

David: Eric's molecular studies of the polar bear's hair

show that the bears on wrangel

appear to be finding enough food.

But with more and more bears coming here,

will there still be enough food to go round?

One of the main things we expect to happen

with sea ice loss is changes in the movements

and the distribution of polar bears, so polar bears

are going to appear in places they never were before

and they're going to disappear from places that they were.

David: Some coastal towns in Siberia

have been overrun with up to 50 bears at a time.

They are desperate to eat whatever they can.

And in the city of norilsk,

one female was found

an incredible 250 miles away from the coast.

Lost and starving, she was eventually rescued.

But many are not so lucky.

They are intelligent animals, but there's simply

no food on land that can compare to the seals

that the bears eat on the sea ice.

A future without polar bears would be very sad,

but the sea ice is not just essential for animals.

It's a lifeline for many of the four million people

who call the arctic their home.

David: Aleqatsiaq peary lives in qaanaaq

on Greenland's west coast,

the most northerly inuit town in the world.

For centuries, life here has depended on the sea ice.

Not only are dog sleds

a way to reach neighbouring communities,

which can be over 100 miles away,

but, in a land where no crops can grow,

travelling over the sea ice is a vital route to food,

fur and livelihood.

But the dwindling of the sea ice is making this way of life

not only difficult, but increasingly dangerous.

Today, they must turn back.

For qaanaaq's 650 residents,

the loss of sea ice is the loss of an entire way of life,

and it is creating an uncertain future.

And there's a reason

for this accelerating rate of change.

In the last 30 years,

over 14 trillion tonnes of ice

have been lost from the arctic,

creating a vicious cycle

of ever-increasing temperatures.

Normally,

large areas of snow and ice would act as a mirror,

reflecting up to 85% of the sun's rays back into space.

But as the ice melts,

the great white mirror is being replaced

by the darkness of the ice-free ocean.

The dark ocean absorbs the sun's rays,

so causing even more ice to melt,

creating a feedback loop that contributes to further warming.

Because of this,

the arctic is now warming more than twice as fast

as the earth as a whole.

That has far-reaching consequences,

not just for the arctic ocean,

but for the vast frozen lands that surround it -

the tundra.

In summer, the open tundra provides refuge

for great concentrations of life.

But today, its thick surface soil

that has been deeply frozen for thousands of years

is thawing...

And the pooling water is creating millions of new lakes.

Katy: Here in Alaska,

we've seen a 40% increase in the lake area since the '80s.

David: Professor Katy Walter Anthony

has worked across Alaska and Siberia

studying their lakes.

She is interested not so much in the lakes themselves

but in what is seeping out of them.

We are seeing a bright spot in the satellite image

that we suspect is gas bubbling.

To identify the gas in these bubbles,

Katy must collect some of it.

I'm surrounded by tiny bubbles that are rising.

Methane appears to be the dominant gas.

David: Methane is produced by the decaying remains

of prehistoric plants and animals.

As the frozen soil beneath the lake starts to thaw,

it releases stores of this potent greenhouse gas,

which is up to 30 times more effective than carbon dioxide

when it comes to trapping heat in the atmosphere

and accelerating global warming.

Katy: 45 parts per million are these tiny bubbles.

It's rising higher and higher.

Now it's going above 70.

This is a huge amount of methane.

It could be a mega seep.

Katy: We are discovering more and more

of these methane mega seeps, so streaming out

and entering into the atmosphere.

David: Methane can be seen escaping from lakes...

But it also rises from the land

wherever the frozen soil, known as the permafrost,

begins to thaw.

And the arctic tundra is thawing

and collapsing

at an unprecedented rate.

Katy: It's concerning because permafrost,

or frozen ground, occupies about a quarter

of the northern hemisphere land surface.

As permafrost thaws, if even a small fraction

of that trapped methane escapes”.

It will accelerate climate warming...

And you cannot reverse it.

David: It's clear that in the arctic,

changes to permafrost on the land

and floating ice on the sea

will have far-reaching consequences

to the planet as a whole.

And there is nowhere better to see the extent

of these global changes...

Than from space.

Woman: All of my life, I've thought about

how this would feel -

to gaze back on the planet with my own eyes.

David: NASA scientist Jessica meir

has spent six months in orbit.

Jessica: From the space station, you have the planet

spinning beneath you,

and you're passing over it at 17, 500mph.

And we are going around the entire planet every 90 minutes.

So you can begin to see larger-scale phenomenon

in ways that you just can't experience on the ground.

And we can see the change in these systems over time.

We cannot deny that we are having

an incredible effect on the fate of our planet,

and the effect that we have as humans on our planet.

Right there, actually, I'm looking down at several fires.

I'm not sure where those are.

Let's take a quick peek.

So, right now we're flying over Europe

and I can see some fires over in that direction.

And that is, of course,

something that we have to contend more and more with,

as our climate changes.

David: As the arctic warms,

wildfires are not only getting more intense,

but they're breaking out

in parts of the northern hemisphere

where they have never occurred before.

Some scientists believe that unusually warm air

rising in the arctic

is disturbing high-altitude wind currents,

like the polar jet stream.

Once disturbed,

the jet stream produces hotter and drier conditions

much further south.

All of these factors that contribute to wildfires -

the temperature, the soil moisture,

the presence of trees and shrubs and other fuel -

have either strong direct or indirect ties

to climate change.

David: A warming arctic

may not only be responsible for the outbreak of wildfires...

But it may also be leading to extreme weather conditions

across the whole of the northern hemisphere.

I've always cared so much about the environment

and known that we all need to do our part in protecting it,

but after seeing this view with my own eyes,

after seeing all of those ecosystems from up here,

it really makes it resonate even more loudly.

David: Outside the arctic,

there's another frozen realm

that stretches across the world's continents -

our high mountains...

Home to an extraordinary array of species.

But here, too, there's a problem.

Across the world, mountain glaciers which have existed

for tens of thousands of years

are shrinking and vanishing.

By the end of this century,

some ranges may have no ice remaining at all,

and this will affect not just animals, but people too.

Hamish: Ice loss from the mountain glaciers

from the great ranges of the world

have a huge consequence for the populations downstream,

and that consequence is their water supply.

Davi d: Glaciers in the himalayas

are the source of ten of the largest rivers in Asia,

which together provide reliable fresh water

for around a billion people downstream.

If the glaciers disappear,

so too will the water they supply.

Hamish: We know that these glaciers are losing

about half a metre of ice a year.

What we don't know is how much ice is left.

So if we know how many metres of ice are left,

we can work out how long they'll last,

how long this water supply will keep going.

David: Dr Hamish pritchard is part of a team of scientists

who have devised a new instrument

to measure one of the largest himalayan glaciers.

What we're putting together here is a long frame structure,

and it's designed to hang underneath a helicopter.

We're going to put a radar on it,

and the radar will send out the radio waves

and then they'll bounce back

off the bottom of the glacier

and we'll be able to measure how thick the ice is.

David: Once his team know how thick the ice is,

they can start to work out how long it will last.

Yeah, it's a nervous moment. We're just waiting

for it to get lifted up for the first time.

We're hoping it's going to be nice, steady, stable,

a nice easy liftoff.

But we're about to find out.

Radio: Line is clear.

Line is lifting.

Hi, it's Hamish here. How is it flying?

Radio: Yeah, when the wind picks up, it's a little...

A little more squirrel/y, but no problems otherwise.

Yeah, you might want to gain a little bit of height there.

Yeah, no problem.

Yeah, we'll fly out and then head towards Everest.

David: After hours of scanning,

the projection for this particular glacier

is finally revealed.

Yep, that's pretty nice and clear.

I can see exactly how thick that ice is.

That's about 150 metres.

So, at the current rate of melting,

this section would last maybe 200 to 300 years.

But we know that the melt rates are increasing.

And this is one of the biggest glaciers,

so there are many, many glaciers which are much smaller

than this, much thinner ice...

And they're going to be

disappearing much, much earlier than that.

David: Water is already scarce in parts of Asia

and as glacial water supplies dry up,

there will be even less to go round.

Hamish: So what happens if these glaciers disappear...

Is that in dry summers the rivers dry up...

Tensions rise...

Especially between nations

that share water across borders...

So one of the big risks of losing this ice

is that it raises the risk of conflict.

And that's a frightening prospect.

I have a one-year—old son.

Children born at the same time as him will see this happen.

We need to act now to turn those trajectories round.

There's no doubt that large tracts

of our frozen wilderness are undergoing dramatic changes.

But what about the largest body of ice of all - Antarctica?

We have already seen how, even here,

animals living around the fringes

are starting to be affected by climate change -

including chinstrap penguins.

But for another penguin, the adelie,

the consequences are even more extreme.

Man: I arrived here for the first time in 1974.

This part of the world was just incomprehensibly wild.

It was filled with life.

Antarctica absolutely captured me.

David: Professor bill Fraser

has dedicated his entire 45-year career

to studying the adélie penguin.

Bill: What really fascinated me was the incredible hardiness

of these penguins -

feisty, determined,

beautiful little animal.

But this environment is changing.

In the last 45 years,

the tremendous warming that has occurred

has had an incredible impact.

The changes have been very rapid,

more rapid than anyone anticipated.

David: Bill has witnessed first-hand how these changes

have affected one of the largest colonies of adelies

on the western side of the antarctic peninsula.

Bill: Four decades ago, this area contained 20,000 adults.

Currently, we only have

somewhere in the order of 400 breeding pairs.

One of the issues

that adélies are clearly experiencing right now

is just the increase in rainfall.

Adélies are a creature of the high antarctic.

They evolved in a dry, cold polar system.

They simply cannot tolerate being continuously wet.

The chicks are soaking.

The rain is penetrating their down,

breaking down their ability to insulate themselves.

That's why you see they're shivering -

because they're just trying to maintain

their body temperature, and they can't.

It's sad.

This tiny chick at this point

has zero chances of surviving.

They can't even react to the presence of a predator.

We are standing,

looking at climate change

actually killing off these adélie penguins

one at a time.

David: Before he leaves Antarctica for the last time,

bill is visiting an island that was once an adélie paradise.

When we used to walk onto this island,

you could immediately hear the adélies.

They were everywhere.

In 1974, the populations here

were somewhere in the order of 1,000 breeding pairs.

All that remains are these little pebbles

scattered throughout the area,

stones that were used in former nest sites.

The pebbles are still visible, they're very abundant,

but, uh, the birds are gone.

This is where we recorded

the first island-wide extinction of adélie penguins.

And now the silence that exists here is pretty overbearing.

Hold it.

There's no...

There's no words that can...

Really describe what I'm feeling at the moment.

Bill: We're working with canaries in the coalmine.

Adélie penguins are, without a doubt,

indicator species that are telling us

that the globe is changing,

the globe is getting warmer.

It's happening.

And we need to do something about it.

David: The disappearance of adélie penguins

along the antarctic peninsula

is just one example of how record warming temperatures

are affecting life here.

But warming temperatures are also affecting

the very coastline itself...

With serious implications for global sea levels.

Man: Across the glaciological community,

we've identified that sea-level rise from Antarctica

is the most pressing question

for the next 50 to 100 years.

And we as a collaborative group

have come together to try and understand it,

and governments

have come together to try and understand it,

because it's important.

David: Professor sridhar anandakrishnan

has been working in the polar regions

for over three decades.

He's part of a team of scientists undertaking

the largest antarctic expedition

for more than 70 years.

Their destination is a remote part of western Antarctica

called the thwaites ice shelf.

Sridhar: Without getting out on the ice, you can't measure

things underneath the ice.

Radio: And take-off.

Sridhar: Those kinds of things can't be done from space.

They can't be done by drones

or aircraft flying over it.

You actually have to go and put your instruments on the ice.

David: The interior of Antarctica is covered

in a giant sheet of ice...

Which for millennia

has been slowly flowing to the coast.

But because it's so cold here,

rather than calve into the sea,

the ice continues to flow out into the ocean,

forming a floating platform known as an ice shelf.

As an ice shelf grows, it begins to act as a dam,

preventing more of the ice sheet behind it

from slipping into the sea.

And the thwaites ice shelf

holds back a body of ice

the size of Florida.

But scientists are concerned

that the ice shelf itself is now at risk of melting.

We're going down through 600 metres of ice.

Once we drill the hole,

I'm going to put the explosive charge down.

David: Small seismic surveys...

Ok. Firing the hole.

Help establish exactly where to sink

their robotic underwater probe,

which the team hope will record the temperature

of the seawater directly beneath the ice shelf.

Ok, Andy, ready to descend.

Radio: Try to go a little slower.

Coming up on 75 metres.

75 metres now.

425 metres.

We've arrived at the ice-ocean interface.

David: Early results are not encouraging.

Have we noticed a huge change in the temperature?

Er, yeah. It is warm water.

Can you see it melt? Like, what is going on there?

David: Because of climate change,

warmer seas directly beneath the ice shelf

are melting it from below...

So it's no longer a question

of if this giant dam will disappear,

but when.

When the vast ice sheet behind it

spills into the ocean,

it could have catastrophic consequences

for global sea levels over the coming centuries.

Sridhar: The amount of water that Antarctica contains

that could go into the ocean is so huge.

This is a global problem.

The oceans are all connected together,

so as soon as a glacier puts water into the ocean,

it rises all over the world.

Da vid: If sea levels rise as predicted,

by the year 2050,

150 million people could be displaced from coastal areas.

And by 2070,

cities, including Miami, New York, Shanghai and Mumbai,

will be at risk of serious flooding.

Sridhar: How much water will Antarctica contribute

to sea-level rise?

The biggest wildcard in all of that

is how we as humans affect climate.

Recently, at cop26, 120 nations came together

in an effort to limit global warming to 1.5 degrees.

While a 1.5-degree rise

will still bring significant changes with it,

to stand any chance

of saving what remains of our frozen planet,

and saving ourselves

from the devastating consequences of its loss,

we must stick to this commitment, and honour it,

no matter how challenging it might be.

James: We know that climate change is happening.

We know that the main driver of climate change

is human activities, it's human emissions.

Jessica: As a whole human species,

we are not recognising the impact that we're having

and the fact that we do need to do something.

Alun: But the important thing is that

I believe all of these processes are reversible.

Jessica: If everybody can make the effort

of doing just one thing -

reducing their carbon footprint.

Alun: Consume less,

think about what we need, what we really want.

Think more sensibly about the journeys we take,

about the food we eat, how that's produced.

Figure out a lifestyle that is sustainable.

Sridhar: And we're right at the point

where we can generate all the power that we need

from renewable sources, like solar and wind.

To do that,

you need to really transform society as a whole.

James: We can speak to our representatives to try

and reconsider energy policies.

If enough of us are educated

about the effects of carbon in the atmosphere,

even the most poorly educated politician will respond

to what their citizenry wants.

Hamish: The awareness and the concern is greater now

than it ever has been, so that gives us some hope.

It won't be easy, but it's doable.

Aleqatsiaq: If you can do something about it,

then do it...

Instead of just thinking about it.

If you can do something about it, then do it.

David: We can do it.

It's within our power to do it.

We can do it.

We must do it.

Then there will be a future for the planet.