Original subtitles

It's a mystery continent at the bottom of the world and the largest single mass

of ice on Earth.

For longer than humans have walked the planet, ice

has dominated Antarctica.

But what about the future?

Ice melt from the continent.

Sea level goes up.

As Earth gets warmer, what will happen to Antarctica?

We're going into uncertain lands, uncertain future.

How will the Earth respond?

Today, a pioneering team is searching for answers with a bold new plan and a

revolutionary new machine.

No one has ever drove through an ice shelf.

And they present these challenges.

They must drill down nearly a mile and more than 20 million years deep into

Antarctica's ancient history.

In this unforgiving place, it's never been done before.

It's quite amazing when you think about where we are and what we're doing.

Anything can go wrong at any minute.

The stakes are high because the secret to Earth's future...

lies buried in Antarctica's past.

Right now on NOVA, Secrets Beneath the Ice.

Major funding for NOVA is provided by the following.

In 1968,

As whaling continued worldwide, the first recordings of humpback songs were

released.

Public reaction led to international bans, and whale populations began to

recover.

At Pacific Life, the whale symbolizes what is possible when people stop and

think about the future.

Help protect your future with Pacific Life, the power to help you succeed.

I would love to have been a musician, but I knew that I was going to need a

job. We actually have a lot of scientists that play music. The

innovation, there's definitely a tie there. One thing our scientists are

on is carbon capture and storage, which could prevent CO2 from entering the

atmosphere. We've just built a new plant to demonstrate how we can safely freeze

out the CO2 from natural gas.

It looks like snow.

It's one way that we're helping provide energy with fewer emissions.

And David H. Koch.

And HHMI.

Howard Hughes Medical Institute.

And the Corporation for Public Broadcasting and viewers like you. Thank

Major funding for Secrets Beneath the Ice is provided by the National Science

Foundation, where discoveries begin.

Additional funding is provided by the Earth Science Program at NASA.

It's the coldest, windiest, driest, and most desolate landscape on the

planet, with few permanent residents except penguins and seals.

This frosty continent appears locked in a perpetual ice age.

A colossal cloak of ice covers almost every inch of land, and in some places,

The ice is so thick and so heavy, it depresses the Earth's crust almost half

mile.

Some people call it Earth's freezer, but scientists call Antarctica the ice.

Antarctica plays a fundamental role in the way the Earth functions.

For polar researchers, Antarctica is a giant laboratory more than one and a

times the size of the United States, and home to 90 % of all the ice in the

world. Anything that happens down here, anything that changes, will affect the

rest of the world.

Most people don't think that change in Antarctica matters to them. But when we

look at New York City, and we look that it's in front of the ocean, it matters.

What would happen if all of Antarctica's ice were to melt?

The Antarctica milk sea level goes up 12 stories in New York City. Sea levels

would rise by more than 150 feet.

Flooding coastal cities, displacing hundreds of millions of people.

That would be a change that you could see from space. Earth would look

different. In any case, even a loss of just 10 % of Antarctica's ice would be

catastrophic.

It would raise the sea level over there in Manhattan, about 19 feet, right up

along the edge.

Big sections of Brooklyn would be underwater.

Certainly the Mediterranean, some of my favorite cities like Venice, would look

very different.

Tens of millions of people would have to be relocated. It would be almost a

different planet.

If sea level changes and the climate around the coastal regions change, it's

going to affect the climate where you live, it's going to affect the things

can grow, it's going to affect how you live.

There may be a list of things in store that come as a result of

raising sea levels that we haven't even thought about yet.

Could this be our fate?

Is Antarctica heading for a major meltdown?

If so, it may happen over centuries.

But it could already be starting, because the climate is changing.

And it's changing because burning fossil fuels has increased the level of carbon

dioxide in the atmosphere.

Today, we have something that's completely man -made, and that is the

of carbon dioxide being put into the atmosphere by humanity, by us.

Carbon dioxide is a greenhouse gas.

It prevents the sun's heat from escaping.

I'm in the Brooklyn Botanic Garden in a greenhouse.

Greenhouses, they're basically like heat motels where the sun's rays can come in

and they get trapped inside the greenhouse. They can't get out.

So like glass in a greenhouse, gases like carbon dioxide trap solar energy in

our atmosphere.

But now those levels are increasing.

The result is our Earth is now warming up.

And the ice is melting, both in Antarctica and the

Arctic.

In the north, there's two clear signals. In the Arctic Ocean, you have lots of

floating ice and not sticking around through the summer.

That's one sign of it getting warmer. The other sign, the edges of the

ice sheet are changing.

And the loss of Greenland's ice is now speeding up.

In August 2010, an iceberg four times the size of Manhattan broke off the edge

of Greenland.

But Antarctica has nearly ten times as much ice as Greenland. And in the past

decade alone, rising temperatures have caused giant pieces of coastal ice to

shrink or crumble.

Polar researchers fear that this could be just the beginning of a chain

reaction.

But have Antarctica's ice sheets ever collapsed before?

That's what an international team of geodetectives wants to find out.

Here we actually have some running water, some melt water coming out of the

To get a more precise picture of Antarctica's future, they plan to dig

answers in the past with a giant drill.

By drilling into areas around Antarctica, we're able to perceive a

has an impact for where we're headed as a planet.

Antarctica was not always locked in a deep freeze.

160 million years ago, it was part of an enormous supercontinent closer to the

equator. At the time, Earth was much warmer than today, and fossil evidence

suggests this giant landmass was a tropical habitat teeming with dinosaurs.

Eventually, the supercontinent broke apart, and Antarctica drifted south.

As Earth was getting colder, falling carbon dioxide levels and powerful ocean

currents cooled the isolated continent even further.

And then, around 34 million years ago, ice slowly began to form.

It would take millions of years for Antarctica to finally lock into a deep

freeze. And during that time, it remained warm enough for plant life to

Evidence of that was recently unearthed in a relatively ice -free valley in the

interior.

Here, geologists Alan Ashworth and Adam Lewis find a remarkable fossil.

Oh, a leaf. It's a leaf.

There's a leaf right there.

That leaf fell into the mud maybe 20 million years ago.

That may be the best leaf yet.

That's a sweet leaf.

And then...

they find something extraordinary.

This is like a peat moss.

And then if we take teeth some of this out, they're like freeze -dried.

Under the microscope, these brittle mosses are in pristine condition.

These moss fossils are not rock, but actual plant tissue, the last vestiges

vegetation from a time when Antarctica was still warm.

They were found under a layer of volcanic ash that dates back millions of

This is the original moss tissue, and even the cells are preserved in these

fossils. These plants were flash frozen when Antarctica plummeted into a deep

freeze that preserved them until today.

It's mind -boggling. The only way is to say the climate remained very, very

cold, it remained very, very dry, and it did not warm up.

for even relatively short periods of time in this location.

Otherwise, these things are gone.

Now, as Earth is heating up, what will happen to Antarctica?

Will it melt, raising sea levels all over the planet?

How sensitive is this frozen land to the temperature changes we currently face?

But before researchers can investigate in Antarctica...

Last -minute testing is taking place here, over 2 ,000 miles away, in the

countryside of New Zealand, with a brand -new drill.

Yeah, it's a shakedown. We've got a few leaking connections and things that

don't quite fit as well as they need to, a little bit of modifications required.

Pretty common with a brand -new piece of equipment.

Weighing in at a whopping 40 tonnes,

This mechanized marvel is as heavy as a humpback whale, and just as large.

Towering some five stories high, the giant rig will soon dwarf everything in

sight, except the ice.

This will be the largest drill rig in Antarctica that's used on land.

And this mammoth rig can drill in more than one place.

That's because it's mounted on a sled.

I think it probably is unusual.

All of the equipment is on sledges, so in Antarctica we pull it all with big

bulldozers. It's been specially designed to drill from the ice in order to

extract hidden secrets from beneath Antarctica itself.

This unique multinational enterprise is called Andril, the Antarctic Drilling

Project.

For team leader David Harwood...

It's a dream come true.

As a scientist, there's a passion. There's a passion that comes in trying

figure this out, trying to identify what has been the past history of the ice

sheet and wondering what the future might hold.

Soon, the giant drill will be dismantled and ready for a long sea voyage.

But now, the Andril team gathers at

Christchurch, New Zealand.

for the six -hour flight to Antarctica in a C -17 cargo plane, jam -packed with

people and gear.

Their flight passes over the Transantarctic Mountains, which divide

continent into two regions, with colossal glaciers called ice sheets

both.

The giant East Antarctic ice sheet is ten times the size of the West.

It's frozen firmly to bedrock high above the sea.

And in some places, the ice towers almost three miles into the sky.

The smaller West Antarctic ice sheet is less stable.

That's because it rests on land well below sea level, and it extends hundreds

miles over the ocean in floating ice shelves.

It's likely East and West Antarctica will respond very differently to a

world.

The Andril team touches down in the west on an icy runway at McMurdo Station,

the largest U .S. research base in Antarctica.

As David Harwood and Richard Levy step out onto the ice, the first thing they

notice is the weather.

It's a bit chilly, but it's beautiful.

It's good to be back.

It's October, springtime, and it's minus 20 degrees.

The earliest I've ever been down to Antarctica, and it's very cold. When the

wind picks up, it's rather an unpleasant place to be working. When the wind

isn't blowing and the sun's shining, it's actually really quite nice, but

cold.

But even a sunny afternoon can turn nasty at a moment's notice.

It's a beautiful day!

McMurdo Station has been a vital hub of research for over half a century.

What began as a tiny outpost has over the years grown into a small town.

McMurdo houses a population of 200 people year round.

But during the research season, it becomes home base for over a thousand.

Every year, McMurdo supports scores of research projects.

providing lab facilities, food and supplies, and survival training for

scientists who will head out to remote field camps.

This season, those numbers include the ANDRIL team of over 50 technicians and

researchers from the U .S., New Zealand, Germany, and Italy.

ANDRIL is funded by their governments and the National Science Foundation.

There's probably a week at least of work in McMurdo where we have to get all of

our gear sorted out, getting everything we need in order to be able to work and

survive out in the field.

As they gather supplies for more than a month on the ice, one item is in high

demand.

Sugar actually heats your body. It gives you quick energy, especially if you're

freezing and we expect to be very cold.

We don't really know how much chocolate is enough. We can take up to 560 candy

bars. But I'm looking at this, and I'm already getting queasy. I'm like, oh, I

don't know if I can eat this or not.

As Andrew researchers prepare for life in the field, they join hundreds of

scientists spanning out across Antarctica.

And many are focused on the same question.

Could Antarctica be headed for a meltdown?

Over here is Mount Boreas.

We're going to have a lot of scientists working together. There is a little bit

of volcanic ash. And challenging each other's theories, challenging what we

know.

Look at that.

As a community, we're going to find the answers.

But the continent won't give up its secrets easily.

The stark beauty of Antarctica masks a treacherous nature.

More than 70 % of all the fresh water in the world is harbored here.

But most of that water is frozen.

And with less precipitation than the Sahara, Antarctica is the driest desert

Earth.

Raging winds of up to 200 miles per hour sometimes blast the frozen terrain,

where temperatures can drop to 100 degrees below zero.

Only during the short Antarctic summer can most researchers gather precious

scientific data from this giant mystery continent.

A four

-hour flight and 400 miles from McMurdo is the center of the West Antarctic Ice

Sheet.

And for one team,

This is the best way to find out about the fact.

This is the side of a snow pit. It's a thin wall between two pits. The other

side is open so the light can shine through.

And you can really see the different layers in the pit.

So this is one year's worth of snow accumulation.

And there's a second year's worth of snow accumulation here below it.

Two years of record right here in the snow pit.

Of course, we want to go back a lot further in time than that.

In order to do that, we can't just use shovels and chainsaws like we did here,

so we have to use a drill.

Ken Taylor's team is drilling through ice.

Their goal is to gather samples from the nearly two -mile -thick West Antarctic

ice sheet.

And the deeper they go, the further back in time they travel.

We're at about 480 meters deep right now. This is right around the time when

Jesus lived. It's right about 0 A .D., right when B .C. years turned into A .D.

years. These ice cores contain tiny bubbles of ancient atmosphere that were

trapped each year as the snow was compressed into ice.

Nice bubble for this one.

There's ancient air in there. When we crush samples like this, it'll get the

out of there, and we can sample the ancient atmosphere.

We can also get a record of how things like temperature and sea ice changed in

the past. And by combining these different records, we can understand how

climate system has operated in the past.

But the ice record, valuable as it is, only goes back about 800 ,000 years, a

tiny fraction of geologic time.

To get a more complete picture of Antarctica's climate history, you have

drill farther back in time.

And that's what the Andril team is trying to do.

They want to paint a picture of Antarctica as it changed from warm to

millions of years ago.

In order to do that, Andril will have to drill deep into the earth.

But finding the right location is a major challenge on a continent covered

ice. And even in those few places where the ice has receded, it's still not

easy.

Andril's David Harwood and Richard Levy are searching for places to drill.

But as they fly over a field of rubble, they see that gathering evidence for a

chronological history is not possible here.

Something has stirred things up, and that something is the ice itself.

That's because ice moves.

For tens of millions of years, glaciers have slowly scoured the land, gobbling

up rocks and debris and spreading them all across the landscape in random

This we call glacial paleontology. Some call it garbage pile paleontology

because we're looking and sorting through these moraines to try to get

information that the ice sheet has brought to us.

A moraine is the chaotic accumulation of rocks and debris deposited by glacial

movement. This one here actually has abundant shell fossils.

This shell, brought here by a glacier, comes from a time when the continent was

warmer and water ran through these valleys.

This landscape is a treasure trove of Antarctica's climate history.

But the ice has scrambled all the clues.

We're looking at a jigsaw puzzle.

Yet there's one place where the evidence remains intact.

That's in the seafloor beneath the Antarctic ice shelf, where the glacial

movement has also deposited layer after layer in chronological order.

Drilling gives us an opportunity to get a serial history in time.

Each layer goes back in time, and we know that a rock above was younger than

rock below, so we can put it into history.

The Andril team aims to drill through the Antarctic ice and the sea below.

Then, like a straw thrust through a layer cake, they'll bore deep into the

floor in order to recover millions of years of rock and mud that trace

Antarctica's climate history.

Even after ice began to form in Antarctica around 34 million years ago,

continent remained warm enough for plant life to survive, a lot like areas of

New Zealand today, where ice can be found bordered by trees and plants.

But when did Antarctica plunge into a solid deep freeze, and how did it

Was it gradual or abrupt?

Will the story of how Antarctica changed from greenhouse to ice house reveal new

clues about the continent's climate future and our own?

Charlie, Charlie, I am David Harwood.

The Andril team will spend the next few weeks searching for drilling locations

from the surface of the ice.

But David Harwood remains focused on what lies below.

When I'm driving across there, I'm always thinking about what's beneath us.

over about 15 feet of ice, and over that I'm over about 1 ,500 feet of water,

and then to the sediments below that.

Here at the bottom of the world, the sun never sets in the summer.

And as night blends into day, the work begins in earnest.

The team heads out to McMurdo Sound, a place where the ocean freezes annually,

creating a precarious platform of floating sea ice that will only last a

months.

We're standing right now in the southern part of McMurdo Sound.

Seasonally, this region will break out. The sea ice that we're standing on will

melt out.

It's now strong enough, perhaps 20 feet beneath us is the thickness of ice.

and then 1 ,500 feet of water beneath that as well.

Just to be sure they're in the right place. Fire in the hole.

The team blasts powerful sound waves through the sea ice and into

the sea floor below.

The result is a sonic street map of layer after layer of rock and mud, each

representing a different era of the past.

By looking into the past, we can maybe project into the future how dynamic has

been the behavior of the ice sheets.

Have they been static and slowly changing?

How active a player have they been?

Finally, it's time to tow the giant drill out onto the ice.

to ensure that the weight of the rig isn't supported by the sea ice alone.

Divers attach flotation devices to the drilled pipe, and at the end of that

is a whirling tool with a unique cutting edge, a drill bit made of diamonds that

can bore through almost everything in its path.

The diamond core system that we have, it's almost like melting the core down

through the rocks. It just cuts through whatever's there.

If you hit a big boulder, you'll just end up with a cylinder of that boulder,

and it'll just keep going.

Now the real drilling begins.

There's not a minute to waste, because the Antarctic research season is so

short.

The crews work around the clock.

to recover cores of rock that trace Antarctica's ancient past.

The powerful drill bores down over three quarters of a mile, bringing up 12 feet

of core at a time, each foot averaging a thousand years of climate history.

It's an astonishing feat.

It's quite amazing when you think about where we are and what we're doing.

We've got a drill rig, a 60 ton to 90 ton with all the equipment on a drill

sitting behind us here on eight meters of sea ice, about 380 meters of water.

And then we're drilling down into the seafloor below that with a three to four

inch diameter pipe that's turning round and round like a piece of spaghetti

hanging down through the water and into the ground and it's wobbling around a

bit and we're turning around and bringing core up from deep within the

Anything can go wrong at any minute with this process.

And all too soon, it does.

Sometimes even a drill bit made of diamond can run into trouble.

We haven't been getting particularly good quality core, and we're suspecting

that the drill bit has been damaged in places that are a little bit narrower

than it should be for the size of the diamond bit.

And that means we have to pull all of our pipe out.

about 1 ,700 meters, and replace the bit, and then put the pipe back down the

hole, and that's going to take us about 24 hours to 36 hours.

Removing and replacing nearly a mile of pipe is no easy task, especially when

it's your job to change it all out, piece by piece.

But for other members of the Andro team, it's a welcome break.

In an extreme environment like Antarctica, nobody's on a diet.

Your body is working so hard to stay warm. Packing away 6 ,000 calories or

a day is not an indulgence.

It's a necessity.

And because Antarctica is drier than the hottest desert,

dehydration is a constant concern.

And keeping the drill up and running.

is another.

Finally, after a day and a half of hard work, the new bid is in place.

And drilling is back on track.

They recover a 12 -foot length of cord wrapped in a protective cover.

Workers carefully carry it back to the lab to be examined.

When they crack it open, It's in perfect condition.

This mud and rock is more valuable than gold because each core is a time

machine. We're currently down at a depth of about 440 meters.

That's about a quarter mile down, corresponding to a time at least 15

years ago when Antarctica was still warm.

As the cores are recovered,

Each section is sliced lengthwise, x -rayed, and scanned in labs at the drill

site and back at McMurdo.

These cores came out of the ground three days ago. They were split yesterday.

They were imaged yesterday.

Sedimentologists worked the night shift, 12 hours, describing these cores

millimeter by millimeter, looking at the color, size ratios, any kind of

structure they see in a core, trying to understand how these sediments were

deposited.

Each core tells a story, depending on its texture, color, and contents.

And some of those stories are spectacular.

We're seeing some macro fossils, some large shells.

These shells are evidence of warmer times, even as Antarctica is icing up.

This is one of the most spectacular fossils found within Andrea this season.

This is a scallop. Now, this kind of scallop simply do not live in extreme

waters.

And there are other clues, some of them nearly invisible.

Hidden inside these cores are shells of microscopic algae called diatoms.

For androclimate detectives, these tiny diatoms create a highly revealing

picture of the past.

Because not all diatoms are alike.

Some species are adapted to colder conditions, while others flourish in

waters.

We use them as biological markers, index of different environmental conditions,

cold or warm, frozen waters or open ocean waters.

Again, the Andral team examines cores from around 15 million years ago.

They find smooth green sands containing diatoms that thrived in relatively warm

water, confirming this was the time before Antarctica finally froze over.

This is a very well -defined warm period.

iceberg -free waters, open waters where diatoms are growing and thriving.

You can see this persisted for quite some time.

A picture is beginning to form of a long period of transition, starting 34

million years ago, when a cooling climate led to the formation of ice.

But even so, conditions remained relatively mild.

But when did Antarctica finally slip into a deep freeze?

The answer lies in cores from around 14 million years ago.

Instead of smooth and green, these cores are rocky and gray, and some contain

diatoms that thrived in cold glacial waters.

This amazing discovery reveals a rapid change from cool to frozen.

It fills in what has always been a blank page in Antarctica's climate history.

Next season, they'll attack another crucial question.

After Antarctica froze 14 million years ago, did the ice ever melt?

Or has it remained a frozen wilderness right up until today?

That answer will have to wait.

Cracks in the sea ice tell the team it's time to return to base.

We've seen the ice break in quite a bit in the last month, but it's not broken

in anywhere further south than it is right now.

We can only be on this site for so long before the sea ice starts to melt,

before the conditions change, and for safety reasons we have to get off the

ice.

The precarious sea ice of West Antarctica may come and go with the

But what about the giant East Antarctic ice sheet?

A mountain of ice so high, it covers mountains.

This is like an MRI of the ice sheet. Some places it's really thick, two miles

thick, and pretty flat and boring.

But then there are other places where what we discovered were hidden mountain

ranges the size of the Appalachians, but totally hidden by the huge East

Antarctic ice sheet.

There's ten times as much ice in the east as in the west.

But a small portion of the east has almost no ice at all

It's an unearthly location

that defies the very image of Antarctica

These

are the dry valleys cold barren and except for

a few scientists

almost completely devoid of life.

The landscape is so alien, NASA has used it as a test site for space programs.

It's a fantastic place.

You can't find this anywhere else on Earth.

Its closest analog is the surface of Mars.

Mullins Valley is the ultimate remote field camp.

It serves as home base for a pioneering band of glaciologists led by Dave

Marchant.

Marchant and his team are conducting research the rugged, old -fashioned way.

They'll live in tents and won't be picked up for two months.

They need to be self -sufficient, and for the most part, They like it that

Good day.

The good

thing about working out here is it's

actually a double -edged sword.

You come out here, you have no contact with the outside world, no email, no

telephone contact, so you can totally immerse yourself in the science.

And that allows you to think 24 hours a day about what you're doing. The other

side of that is you have no idea what's going on outside.

Hi. At the beginning of the season, I didn't like it when you would breathe

the frost would form on the outside of the sleeping bag. But it's warmed up

and it's a little more comfortable in the morning.

Small set -ups like we have, which are helicopter -supported, are isolated.

They're among the most isolated in the region.

And as a result, we have to check in daily with McMurdo.

I'm trying to heat the batteries up so that we can get a signal out right now.

There appears to be no satellite coverage, and the batteries are a little

cold, so I'm trying to warm it up.

Sometimes you have to contort your body in various ways to get the signal.

No, we don't have enough signal yet.

Well, here we go. We've got something that might work.

MacOps, this is Gulf 054 Mullins Valley.

We have seven on board.

And all is well. Over.

Ah, we lost transmission.

This valley holds an incredible record. This area is so dry and so cold that the

landscape is pristine. The rocks we see here are millions of years old.

Marchant believes that little has changed here for millions of years.

What? to me is exciting, is that we're walking on an ancient landscape.

Imagine living 10 million years ago in Antarctica. This is what you'd see,

exactly as it is today, hardly modified at all.

But when Marchand's team drilled beneath this rubble, they found something

totally unexpected.

A hidden glacier.

that extends hundreds of feet below the surface.

This is, in my opinion, the oldest dated buried glacier on Earth. Is it all out?

Yep, it's all out.

Are you getting it? Yeah.

The evidence comes from volcanic ash.

The dry valleys are surrounded by extinct volcanoes that erupted millions

years ago.

We're finding ash deposits on top of ice.

Ash dates are coming back as old as 8 million years.

And according to Marchand,

This volcanic ash shows this hidden glacier, once frozen, has never melted.

This volcanic ash that erupted from a volcano and has been sitting there for

millions of years.

It shows no chemical alteration which you'd expect if there were any amount of

liquid melt water over that duration.

The fact that it's dry and pristine tells me it's always been here, which is

incredible.

Equally astonishing.

and just 300 miles away, there appears to be a completely different picture.

Exploring East Antarctica, closer to the South Pole,

Andrews David Harwood found leaf fossils and pieces of wood.

Surprisingly, according to Harwood, these date to a relatively recent time,

Antarctica was not only warmer than today, there were plants and trees.

This is a piece of southern beach.

This wood is not fossilized in the sense that it is petrified. It could still

burn. To find the wood and leaves together is pretty phenomenal.

It's really phenomenal for Antarctica, particularly for Antarctica in this time

period, about 4 million years ago.

This season, the drill is set up to find evidence of what happened in Antarctica

during this period, 3 to 5 million years ago.

It's a time known as the Pliocene. Now what's important about that is that the

Pliocene was globally warmer than today.

The same temperatures as our Earth may be headed for at the end of the century,

if climate change predictions are correct.

If we go back three to five million years into the geological past, we know

that was a time when Earth's climate was warmer than it is today, perhaps by

three to four degrees.

So it's the best example we have of where the climate's heading in the next

hundred years.

The drill's new location is on the giant Ross Ice Shelf, which extends out and

over the ocean.

It's the largest ice shelf in the world.

And it helps hold back the massive Antarctic ice sheet from flowing into

sea. These ice shelves are very important. What they do is hold back the

ice. It's actually trying to flow out into the ocean.

We call that buttressing.

If warming oceans caused the Ross Ice Shelf to break up and melt into the sea,

the West Antarctic Ice Sheet would eventually follow right behind.

The Andral team is looking for the answer to a critical question.

When Earth was warming during the Pliocene, what happened to the ice?

Did the Roth's ice shelf melt, taking the giant ice sheets with it?

Drilling on an ice shelf brings with it a unique set of technological

challenges,

including constant

problems with mud and water.

Unlike drilling through sea ice, which is just 26 feet thick, the ice shelf

is 400 feet.

We're looking at at least doubling or trying to double our capability below

sea floor and penetrate to 1 ,000 meters or better into the sea floor.

But that's only the beginning.

No one has ever drilled through an ice shelf. And they present these

The ice shelves, they float up and down with the tide. So you've got to deal

with this vertical elevation change.

They move sideways. They flow.

So eventually your drill pipe's going to get bent.

Can the drill bore through a thick layer of ice that's constantly moving without

breaking or getting yanked out of the sea floor?

To confront this unique challenge head on, the Andril team invents a new tool,

hot water drill.

This marvel of engineering is a moving ring of heat that blasts jets of

water to melt a wide hole so the drill can operate freely through 400 feet of

shifting ice.

And once again, time is so precious, the team must work around the clock, not

only retrieving cores, but also analyzing them.

It's 2 a .m., but you wouldn't know it.

Geologists are busy logging cores like it's early afternoon.

We're laying out the cores in a proper sequence, from top, the highest point of

the core, all the way to the very slowest point of the core here.

An 80 -foot core that dates back about 3 million years is closely examined.

It contains microfossils of single -celled animals known as sphorums.

They're from the crucial warm period called the Pliocene.

And these tiny shells are precise indicators of ocean temperature.

These guys are about the size of a grain of sand.

Because the same species lived through time, we can use the chemistry of modern

examples to allow us to calibrate, if you like, the chemistry of the ancient

examples.

What Gab's doing here...

is he's measuring the amount of two metals, magnesium and calcium, that are

the ocean and get incorporated into the shell of the foram when it's growing in

that ocean. And that process is dependent on the temperature of the

we know the magnesium, we know the calcium, we can determine the

the ocean at the time that foram lives.

And because of that, Andrew researchers can now calculate Antarctic water

temperatures during the Pliocene.

What this is telling us is temperatures with three to four, perhaps five degrees

above present.

Even just one degree rise in ocean temperatures in the waters surrounding

Antarctica will attack and begin to melt the ice cells from below very quickly.

The air temperatures will stay cold enough to keep things frozen at the

but what we're worried about is the ice being attacked from beneath, not from

above.

And the cores reveal that this is what happened during the Pliocene, when

climate was warming.

But they display even more change than expected, revealing not only a patchwork

of glacial rubble, but also smooth mud from open seas, indicating that ice both

froze and then melted many times.

There's a really important change right here. This interval shows us quite a

dramatic change in the environment.

There was ice.

And then there was no ice.

The ice sheet has gone backwards and forwards. It's advanced and it's

As they examine core after core from the Pliocene, they continue to see

surprising signs of change.

The results of the drilling are simply spectacular.

They give us a picture of a dynamic ice sheet coming and going regularly more

than 60 times.

What we're seeing in this record is telling us that Antarctica is not just a

benign spectator.

It's a player.

What this means is while it was generally warm during the Pliocene,

also brief periods of cooling, and the ice was exquisitely sensitive to even

small changes in climate.

Just a few degrees could tip the scale from ice to no ice.

So what's in store for our future?

As Earth continues to warm, how much Antarctic ice will melt, and how high

sea levels rise?

Andro scientists turn to computer models by Rob Ducato and Dave Pollard.

We developed these climate models based on our best understanding of the physics

of the climate system, and in this case, ice sheets.

And now, information from Andril is added to the climate model.

This is a computer model simulation of the Antarctic ice sheet over the last

several million years and covers a good chunk of the interval that was recovered

by the Andril sediment core. So we're looking for the same kind of behavior in

our model that we're seeing in the geological record.

As the model simulates the warming periods of the Pliocene, all of the ice

shelves disappear.

followed by the entire West Antarctic ice sheet and edges of the east.

And as temperatures change, the ice refreezes and melts again and again.

And that's important because the changes in the ice sheet that we're seeing here

reflect pretty significant changes in sea level.

According to DeCanto's model, sea levels rose about 23 feet during the Pliocene.

Temperatures back then were 3 to 5 degrees higher than now, just what's

projected to take place by the end of the century.

But there's a lag time in the way ice responds that may delay the impact for

hundreds, if not thousands of years.

Regardless, coastal cities all over the world would be at risk, potentially

displacing millions.

We would be remapping.

Places like Boston and New York, the Bay Area.

Not to mention, of course, places like Louisiana, Miami, New Orleans, of

But even that might not be the worst case scenario.

Things were very similar to today in terms of our climate.

Tim Naish brings Rob DeCanto to New Zealand to look at a possibility that's

more frightening.

This is the first time I've seen the actual direct evidence for what the

are doing.

You're seeing a deepening sea level rise up through here.

We're going to look at some rocks that are the same age as rocks that were

drilled in Antarctica that give us the record of global sea level changes.

Here along the Rangitiki River, tectonic forces have razed the land and the

river has cut into the earth to expose layer after layer of sediment that once

was the sea floor.

What they find are shells dated to the warming era of the Pliocene.

These shells provide a way to chart sea level in the past because some of these

species still exist today.

Many of these shells you see in here actually live today.

So they live around the coastline, and we know the water depth they live in

today.

So by breaking them out of these rocks and identifying them, we can say the

depth they were living in over 3 million years ago.

Because these shellfish live on the seafloor and can only survive in water

specific depths, they suggest that sea levels in the Pliocene were much higher

than even the computer models predict.

This is really it, Rob.

This is where we would say we have the evidence for sea level being up to as

much as 20 meters above present.

That's over 60 feet.

In order for sea level to have risen that high, an enormous amount of ice

have melted.

And this raises a startling possibility that a large part of the vast East

Antarctic ice sheet melted along with the West.

And if it melted once...

Could it melt again?

That could be a very bad thing because that would actually produce a

contribution to future sea level change that we really haven't been thinking

about.

This presents an even more dangerous and unpredictable picture of Antarctica.

What's been surprising is... Even geologists thought that glaciers and ice

sheets were these large static features, which we would never really see change

in our lifetime. But glacial processes are no longer quite as glacial. Things

are moving faster than we had thought.

What's driving these changes are rising levels of greenhouse gas.

In the next five years, greenhouse gas levels will be like they were in the

Pliocene. But we're not just going back to the Pliocene. Some of the projections

put CO2 levels at twice the concentrations of the Pliocene by the

next century.

We're essentially going back to the time of the dinosaurs when there was very

little ice on the planet and there were forests covering Antarctica.

And signs of change are already here.

Scientists were completely caught by surprise when in 2002, the Larson Ice

shattered apart without warning in just a few weeks.

And today, the Wilkins Ice Shelf, a block of ice approximately the size of

Connecticut, barely hangs on.

I would say it's inevitable that West Antarctica will disappear.

How long it will take East Antarctica to engage is something that's not yet

known. In the coming years, the Andro team will continue to explore

climate history in order to gain valuable insight into Earth's future.

new core, we gain new knowledge about a continent that's always been shrouded in

mystery. But its fate remains very much tied to our own.

A date which will live in infamy.

The United States of America was suddenly and deliberately attacked.

Do we know the whole story?

After almost 70 years, can scientific detectives solve the mystery of a

secret weapon?

It's almost like a CSI situation where we have a crime scene. There was a hunt

for these submarines.

Killer Thubs in Pearl Harbor, next time on NOVA.

Major funding for NOVA is provided by the following.

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Algae are amazing little critters.

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