All language subtitles for Extreme Ice PBS Nova 2009 720p HDTV EN sub

NARRATOR:
In the extreme,
ice-bound regions of the earth,

something unprecedented
is happening.

Everywhere, glaciers
and ice sheets

have begun breaking apart and
accelerating towards the oceans

faster than ever
imagined possible.

Can we put the brakes on it
at any point?

Do we have that much control
over it?

MAN:
There are concerns
that we get to some point

that the changes become
pretty much unstoppable.

NARRATOR:
Over the history of the earth,

ice has freqntly advanced
and receded,

but now it's changing in ways
we don't fully understand.

With the future of the ice
in question,

photographer James Balog
risks everything

to capture what's happening
on film.

BALOG:
This is one of the scariest,
dumbest things

I've done in my life.

Where I'm laying right now was
underwater just six hours ago.

I'm not feeling real
comfortable out here.

NARRATOR:
His incredible imagery
is witness

to one of the earth's most
powerful geological forces--

a force that for the first time
in modern human history

is radically changing
the planet.

"Extreme Ice" revealed,
right now

on this NOVA-
National Geographic Special.

Captioning sponsored
by EXXONMOBIL,

PACIFIC LIFE,

DAVID H. KOCH,

the HOWARD HUGHES
MEDICAL INSTITUTE,

the CORPORATION
FOR PUBLIC BROADCASTING

and VIEWERS LIKE YOU

NARRATOR:
James Balog has a near-fatal
attraction to ice.

BALOG:
Oh, God, that is intense!

NARRATOR:
His fascination is leading him
farther and deeper

into the cryosphere,
the frozen regions of the earth.

BALOG:
I feel like I'm not
on planet Earth right now,

like I'm in truly some
extraterrestrial environment.

The world isn't supposed to look
like this.

NARRATOR:
What began as
a photographic assignment

has become a mind-blowing
odyssey

into an unpredictable world,

where entire landscapes teeter
between solid and liquid states.

On the Greenland ice sheet,
a crack opens,

and a mile-wide lake pours down
a 3,000-foot chasm.

BALOG:
This water is just drilling
down into the ice sheet.

NARRATOR:
One of the world's biggest
glaciers sheers off an iceberg

that is nearly
a thousand feet thick.

BALOG:
You're not supposed to be able
to witness things like this.

Human beings don't generally
get to see

these massive features
of the landscape

changing and vanishing
in front of your eyes.

NARRATOR:
Changes in the ice are normal.

It is volatile
and constantly in flux.

But what Balog is witnessing
suggests

something extraordinary
is going on.

His passion is to document it

and help scientists understand
these monumental changes.

MARK SERREZE:
Many of the changes we're seeing

are unfolding faster

than our ability to really
understand them.

JAMES WHITE:
Our relationship with ice is one

that has very dramatically,
if not violently, shifted

from one of, "Ah, don't worry
about it" to one of,

"Boy, you knowthis is one of
the most important controllers

of the futurenvironment
of the planet."

NARRATOR:
Balog's work frames

one of the most important
scientific questions

humans have ever faced.

How fast will the world's
glaciers and ice sheets melt?

And what will all
that melting mean for us?

As scientists try
to figure it out,

Balog is finding evidence

to help answer some
of these questions.

Got it!

NARRATOR:
His Extreme Ice Survey

is the largest photographic
study of the cryosphere

ever attempted.

He is deploying
26 time-lapse cameras

on glaciers across
the Northern Hemisphere

and programming them
to shoot a frame

every daylight hour
for three years.

It is a massive challenge,

in some of the most hostile
regions on earth.

BALOG:
So everything we are trying is
getting thwarted.

I'm trying not to be frustrated.

NARRATOR:
But the pain is starting
to pay off,

with thousands of frames
revealing unparalleled changes

in the ice.

BALOG:
My hope is that it will be
powerful and immediate enough

that people will say, "Yeah,
I get it, I understand it.

"Okay, this is real.

This is forensic evidence of the
reality of what's happening."

NARRATOR:
The fact that the ice
is changing is nothing new.

Over the millennia,

the expansion and contraction
ofce across the continents

has fundamentally altered
the planet,

gouging out lakes and valleys

and pushing man
around the earth.

RICHARD ALLEY:
The waxing and waning
of the ice sheets

have been implicated

in who lives where
and what they do,

and there are even some people
who have suggested

that we're humans now in part
because we were responding

to the changes in our
environment that were linked

to the growth and shrinkage
of the ice.

NARRATOR:
In the past, the cycle of ice
ages and periods of warming

were caused mainly by shifts

in the earth's orbit
around the sun.

But now, humans seem
to be driving these changes.

Since the Industrial Revolution,
our burning of fossil fuels

has ratcheted up the output
of greenhouse gases,

like carbon dioxide, which
trap heat in the atmosphere.

Temperatures are climbing,

and the ice is melting
faster than ever.

WHITE:
I think that if we stay
on the path we're on,

we will change the amount
of land ice

and, therefore,
we will change sea level.

The real questions,
the more complicated ones:

How fast are we
going to get there?

How much is it going to rise?

Can we put the brakes on it
at any point?

NARRATOR:
It is the speed of the melt
that is most astonishing.

And nowhere is it happening
faster than in the glaciers

along the west coast of Alaska.

Glaciers are like
massive ice factories.

High in the mountains,
snowfall builds up

and is compacted
over hundreds of years.

Gravity pulls it down
in colossal rivers of ice.

Some glaciers flow all the way
to the ocean,

shearing off icebergs
in a process called calving.

Over the last 40 years,
temperatures here in Alaska

have risen about
four degrees Fahrenheit,

twice as fast
as the global average.

Now these rivers of ice
are flowing faster

and crashing even more
spectacularly into the sea.

Some people are taking advantage

of the glacial fireworks
while they last.

Surfers towed in by jet skis

are playing a dangerous game
of chicken with the ice.

It is rapidly calving glaciers
like these

that are the main contributors
to rising sea levels.

Alaska's Columbia is one of the
biggest ocean-feeding glaciers

in North America.

In the early 1980s, the Columbia
started flowing faster

and began calving far more ice
into the ocean

than was being replenished
by snowfall upstream.

Balog and the Extreme Ice Survey
glaciologists are trying

to figure out how much ice
the Columbia is losing

and whether or not
it can survive.

In the shallow waters
of Columbia Bay,

melting icebergs jam up

before being carried away
with the tide.

This is the end of the line
for the Columbia,

a crystal maze of deteriorating
ice that draws Balog in.

BALOG:
Basically, we are looking

at a whole landscape
full of crystals.

It's a cool spot.

There is a lot of power here.

It seems to be calm,
it seems to be still,

but there's this constant energy
of the sea coming and going

and carrying
this huge glacier away.

Every time you go in here,
you are taking a risk,

because these bergs
are inherently unstable.

But you get seduced
by the beauty of it.

You know, you just get drawn in.

back through the labyrinth.

Okay, Jeff, right about
on this line here.

BALOG:
The light that really makes
these sculptures come alive

is bouncing off the surface
of the water,

so the bergs are lit
from within.

Oh!

NARRATOR:
At the Extreme Ice Survey camp,

glaciologist Tad Pfeffer tracks
the flow of the Columbia.

As the glacier moves,
it churns up dirt and rocks

that collect on its surface.

The Columbia is so vast, it's
hard to imagine it vanishing.

Pfeffer and his colleague,
Shad O'Neel,

are taking its vital signs,

measuring the speed of
the glacier over several years

to determine whether it's
speeding up or slowing down.

To do this, they fire
a laser survey gun

at reflective targets
that they must deploy

on the surface of the ice.

As the pilot hovers a few inches
above the glacier,

O'Neel positions the target
onto the ice.

Pfeffer locks onto the target

and shoots a laser
that reflects back

to the stationary gun,
recording the position.

(high-pitched beep)

I got it. You're good.

Come on back.

Okay, first one down,
1.1 kilometers away.

NARRATOR:
The target moves with the ice.

By tracking its movement with
the laser over several days,

they will be able to calculate
the speed of the Columbia.

Just down the fjord,

Balog and Extreme Ice Survey
engineer Adam LeWinter

climb down to one of
the time-lapse cameras

they installed a year ago.

Oh, yes!
Here it is!

Still all there.

Yeah, the camera's here, but
what happened to the glacier?

When I was here a year ago,

the calving face
was just right there.

All right,
we have pictures!

NARRATOR:
The time-lapse brings to life

the dynamic nature
of the glacier,

the ebb and flow of the ice
as it calves.

BALOG:
It's a revelation every time
we open up these boxes

and download these images and
bring them up on the computer

and play them back.

Your eyes are popping
out of your head.

NARRATOR:
Although calving is normal,

the Columbia is hemorrhaging ice
so quickly

that in the last 30 years,

the glacier has receded
ten miles up the fjord.

Balog's time-lapse images
capture a rate of retreat

that shows no sign of stopping.

In the last year alone,

the Columbia lost
another half-mile of ice.

BALOG:
I really never expected

that we were going to see
changes

of anything like this kind
of magnitude

in the period of time
we had to work on this.

NARRATOR:
This rapid calving
of the Columbia

is a symptom of its decline,
but it's poorly understood.

If Pfeffer and O'Neel
can figure out

what's causing it
to calve more ice,

it may help them predict
the glacier's future.

They are taking a curious tack
by using earthquake technology

to crack open the mystery
of the ice.

They are installing seismometers
that pick up the vibrations

of "ice quakes,"
tremors that reverberate

through the ice as it calves.

From the seismic data,
a pattern emerges

that points to one
clear culprit, water.

They knew water
was melting the ice,

but it appears that it's
prying the ice apart

like a powerful lever.

O'NEEL:
You can hear meltwater
running right now

and it's all getting stuck
in the glacier,

and if you have a fracture with
high-pressure water in it,

it can ratchet the crack open.

NARRATOR:
The seismic record confirms

that the calving events have
the unique signatures

of fractures caused by water.

As rising temperatures create
more surface melt,

the water pours
into the cracks in the glacier

and wedges it apart.

The result is increased calving

and a quicker demise
of the glacier.

BALOG:
Oh, there's a big one coming up
from underneath.

There it is!

NARRATOR:
Balog is seeing this powerful
fracturing effect firsthand

as the fjord below comes alive.

BALOG:
That basal ice has come up

from the very bottom
of the glacier,

that dark blue out there.

As the ice and the snow
are squeezed together,

the air gets driven out of it,

and so the color becomes
more and more pure.

The air bubbles are
what make it white.

And so when the base
of the glacier breaks up,

you get these fantastic
sapphires and turquoises

boiling up out of nowhere,
you know,

and that's what these bergs are.

NARRATOR:
Meanwhile, after several days
of laser tracking,

Tad Pfeffer knows how fast
the Columbia is moving--

50 feet per day, eight times
faster than it was 30 years ago.

PFEFFER:
Go back to 1980.

Here on this bedrock,
we had ice above us 1,500 feet.

Look at the trim line
over there.

That's where the ice surface was
in 1980.

And all of that volume is lost
because this calving is so fast,

and snowfall upstream
isn't resupplying it.

So in that sense,
yeah, it's going too fast,

and the glacier
is kind of collapsing.

NARRATOR:
Pfeffer suspects
that the Columbia

is long past its tipping point

and it's only a matter of time
before it withers away entirely.

BALOG:
This kind of ice
is called "dead ice"--

it's no longer part
of the living, active glacier.

It's stranded up on the side
of the ice stream,

and it's melting away
and collapsing.

And as it does that,
all the erosional debris

that's on the top continues
to concentrate,

until you have this ice
covered in blackness.

I'm really interested
in the mortality

of the glacier right here.

There's something very rich
and very intense

about the changing landscape.

You know, I feel the end,
I feel the death right here.

(shutter clicks)

NARRATOR:
The problem is,

it's not just the Columbia
that's on its way out.

Glaciers everywhere,

across the Rockies, Andes,
Alps and Himalayas,

are in their death throes.

The people that live
near the mountains

and watch the glaciers know
that the world is changing.

We are heading towards
Glacier National Park

without any glaciers.

We're seeing huge changes

in Glacier Bay in Alaska
and other places.

If you go, if you look,
you see it.

NARRATOR:
The consensus is that
in the next 50 to 100 years,

mountain glaciers
almost everywhere

will simply disappear.

From the loss of mountain
glaciers alone,

sea levels will rise
by almost a foot,

displacing millions of people
around the world.

But the biggest cost
will be the loss

of these huge natural reservoirs
of fresh water,

water that one-sixth of the
world's population depends on.

The hardest hit will be in Asia,

where nearly a billion people
get their drinking water

from Himalayan glaciers.

The abrupt collapse of the
world's mountain glaciers

raises even more
disturbing questions

about the earth's
biggest tracts of ice,

the polar ice sheets
of Antarctica and Greenland.

SERREZE:
The real wild cards are

what the big ice sheets
are going to do.

We're already seeing
the Greenland ice sheet

start to behave in rather
disturbing ways.

WHITE:
We're playing with fire,
if you will,

when it comes to the ice sheets.

We don't know

whether if we get

these big, massive, freight
train-like beasts going,

whether we can stop them.

NARRATOR:
The potential for
the polar ice sheets

to flood the planet
is staggering.

If all of Greenland
and Antarctica were to melt,

the oceans would rise 200 feet.

But over geologic time,
these ancient bulwarks of ice

have withstood many bouts
with climate warming.

Until a few years ago,

scientists thought the ice
sheets were simply too big

and too dense
to be an immediate risk,

but the latest evidence
is making them rethink.

The first wake-up call came from
the West Antarctic Peninsula.

In the summer of 2002,
a NASA satellite photographed

a Rhode Island-sized slab
of ice called Larsen B

as it sheered off the ice shelf.

Other collapses followed,
turning the assumption

that it would take thousands
of years

for the big ice sheets to melt
on its head.

ALLEY:
The ice sheets surprised us.

We sort of thought that
the little glaciers would melt

when it got warmer, and that the
big ice sheets wouldn't do much.

And all of a sudden, the big ice
sheets started rumbling faster

and the Larsen B
was falling apart,

and we said, whoa, that wasn't
supposed to happen.

NARRATOR:
On the other side of the globe,

Greenland's cache of ice
is also showing signs

that it's starting to feel
the heat.

In the last decade,
temperatures here have shot up

by about five degrees
Fahrenheit.

NASA satellites are already
detecting a meltdown

around the edges
of the ice sheet.

Global warming is hitting
hardest in the Arctic,

and all eyes are now fixed
on Greenland's ice.

Its next move could be the game
changer for rising sea levels.

In the heart of Greenland,
Balog and scientists encounter

an entirely different realm,

a single slab of ice about 1,500
miles long and 500 miles wide.

It's mid-July, and the summer
melt on the Greenland ice sheet

is in full swing.

BALOG:
It's sort of like a ice version
of Kansas out here.

It feels like you're out
in the Great Plains,

and it just happens to be white,

and there's this vast dome
in the sky overhead.

It's... it's unbelievable.

There's no sound at all,
no sound,

except the wind and the water.

It looks quite featureless
when you just look horizontally,

but as you walk over it
and you look down on it,

there's a tremendous amount
of texture and detail in here.

This entire surface is like
one gigantic Swiss cheese.

NARRATOR:
During the melt season,

the sun's heat transforms
the surface of the ice,

creating a landscape
that constantly shifts

between solid, liquid and vapor.

The meltwater courses
through the ice sheet,

searching for a path down.

Figuring out how this complex
plumbing works is essential

for predicting the future
of the ice sheet.

Oh, man!

Look at that.

Whoa!

That is intense!

Oh, my God.

I can see, I think, maybe
250 feet down into the dark,

no sign of the bottom.

this great mystery of where
does all this water go,

and what does it do
to the flowing and the melting

of the ice sheet
in sending it out to sea?

Nobody really knows.

NARRATOR:
Balog wants to get a shot

that delves deep
into the underbelly of the ice.

The only way to secure his ropes

is to thread them
through the ice sheet.

BALOG:
You know, this ice sheet is
cooking down

and melting a lot, so this whole
top foot and a half,

where you would normally put
an ice screw,

is rotten and loose,

whereas here we are actually
using the ice sheet itself

and the strength of the ice
to anchor the ropes.

So, here we go.

Yay, how about that?

NARRATOR:
These giant holes,
called moulins, are thought

to bore thousands of feet
through the ice to the bedrock,

but nobody has ever been
down there to find out.

BALOG:
Oh, God, that's the first time

I've really seen the hole
down there.

This whole balcony could go
any second.

There it goes!

It's a strange, evil, gorgeous,
horrible, fantastic place.

Wow-- I mean, there's hundreds
of years of ice here layered in,

and we're looking
into the cross section

of this life history
of the glacier.

And it's so beautiful,
this insane aquamarine,

and all this scalloping
and fluting from the water.

What a spot!

NARRATOR:
Balog is just scratching below
the surface of the ice sheet.

Below him is another half-mile
of solid ice.

In these compressed layers
of the ice sheet,

there are clues to how fast
Greenland could melt.

At the National Ice Core Lab
in Lakewood, Colorado,

a giant freezer stores
over 45,000 feet of ice

drilled from 34 sites
around the cryosphere.

Dating back hundreds
of thousands of years,

these ice cores are time
capsules that allow scientists

like Jim White to peer
deep into the history of ice.

WHITE:
This piece of ice
is interesting,

because it has a couple of
things you can see right away.

One is there are bubbles
throughout here.

These bubbles are
little packets of air.

It's these bubbles we can take
out and measure CO2

and methane and nitrous oxide.

It's the only medium that really
collects the atmosphere itself.

The other thing you can see
in here quite clearly

is you can see the layers,

and the thickness
is going to tell you

how much snow fell that year.

So you get a couple of pieces
of climate information

and a dating scale,
just out of visually looking

at this ice core.

NARRATOR:
Most importantly,
scientists have identified

a direct historical link between
increases in greenhouse gases,

like carbon dioxide, and steep
rises in global temperatures.

At every peak, big rises
in sea level followed,

as Greenland's ice sheet shrank.

The ice core records also reveal
a particularly telling moment

in Greenland's history.

Roughly 125,000 years ago,

temperatures rose by about
seven degrees Fahrenheit.

The entire southern portion
of the ice sheet melted,

and global sea levels rose
by over ten feet.

It was caused by a change in the
earth's orbit around the sun,

which increased temperatures

and released carbon dioxide
from the oceans.

The more recent ice core record
shows the potential

for a similar meltdown.

Right now, greenhouse gas levels
in the atmosphere

are even higher than they were
125,000 years ago,

higher than they've ever been

in the last half-million years.

Temperatures are already
following suit.

The only explanation is
the burning of fossil fuels.

WHITE:
What we see in this ice core

is very solid evidce

that what's happening today
in the atmosphere is different.

It's not a normal part
of the climate cycle;

it's something caused
by human beings.

NARRATOR:
Rising temperatures are once
again pushing Greenland

towards a major meltdown,

but what the ice cores
can't tell us

is how long it will take.

The last time Greenland lost a
significant portion of its ice,

White suspects it happened
over thousands of years.

But this time,
it could happen much faster.

SERREZE:
And here we are now,

fiddling with the dials
of the climate machine,

not quite knowing
what's going to happen,

and we know
from these past records

that the climate system
can come up and bite us hard.

NARRATOR:
So far, global warming
is biting hardest

at the fringes
of Greenland's ice sheet.

Ringing the island are hundreds
of outlet glaciers

that act like pipes,
draining the interior ice sheet

out to sea
through narrow fjords.

In the late 1990s, many of these
spigots began gushing more ice.

One of the largest, Jakobshavn,
is now pumping out

over 40 billion tons
of icebergs each year,

more than any other glacier
in the Northern Hemisphere.

These icebergs reach
the open ocean at Disko Bay.

In this deceptively
peaceful icescape,

James Balog is on the hunt
for giant bergs.

Some of these blocks of ice rise
over 300 feet

above the waterline, but 90%
of their mass is hidden below.

BALOG:
Oh, my God, these things
are gigantic.

If they roll over, we'll be
swimming with the fishes.

Right in here, there is
this line of jewels

as you come around
the arc of this berg,

and all the water drops are
coming in,

and the sun makes this fantastic
necklace-- jewelry

along the edge of this.

Aw, man, let's do it again.

There's something in there.

It's making me crazy, actually,

because there's a picture
in here,

there's definitely a picture
in here.

Wow! That was amazing.

NARRATOR:
35 miles up the fjord
from Disko Bay,

Balog's time-lapse cameras are
stationed above the calving face

to capture Jakobshavn's
every move.

Balog has teamed up
with glaciologist Jason Box,

who has been keeping a close
watch on Jakobshavn

and other glaciers along
the coast for the past 14 years.

The Jakobshavn glacier is the
king of glaciers in Greenland.

It produces by far more icebergs
and more ice flow

than any other single glacier.

This is really where
the rubber hits the road

in terms of sea level rise.

Glaciers are, of course,
very dynamic systems,

but you don't really see that

when you sit there
and stare at them.

We're able to observe
with the time-lapse cameras

at a much higher frequency,
like every hour,

whereas from satellite,

you can only observe the glacier
every ten days or so.

NARRATOR:
What they are finding
is that the ice

is far more sensitive
to temperature changes

than they thought.

During the summer melt season,
Jakobshavn is now moving

at a clip of 130 feet per day,

almost twice as fast
as a decade ago.

The faster it goes,
the more pressure builds up

behind the glacier
400-foot-high calving face.

This triggers more frequent
and explosive calving events.

In the spring of 2008,

Balog's team was staking out
Jakobshavn and got lucky,

capturing the largest
calving event ever filmed.

In the space of about an hour,

a section of ice
as wide as Manhattan

sheared off the glacier.

BOX:
We've underestimated the
sensitivity of these systems.

We are approaching

the threshold of viability
for the Greenland ice sheet,

and that's when
the melting occurs

high enough on the ice sheet

that no matter
how much snow accumulates,

there's net loss every year.

NARRATOR:
Greenland is already losing

150 billion tons
more ice every year

than it gains in snowfall.

As temperatures go up
in the coming decades,

even more ice will be lost.

The hard part is figuring out
how much and how fast.

There's big questions now

that we didn't think we were
going to have to solve.

They're hard questions.

Ultimately, you crank up
the temperature in the air,

and the ice sheet notices
and it flows faster

and it raises sea level.

But how fast and how much

are questions that really
we don't have answers to.

NARRATOR:
Some of those answers may be
hidden, deep under the ice.

The summer melt season
on the Greenland ice sheet

has grown hotter
and is now two weeks longer

than it was only a decade ago.

Rivers of meltwater cut
deep into the ice,

creating a serpentine canyon
that winds for miles.

BALOG:
This is one of the most
exceptional landscapes

I've ever seen in my life.

You know, this looks so much
like those incredible canyons

out in the sandstone country
in Utah,

and you have that, except
it's sculpted out of ice.

It's like this huge,
incredible cake,

sculpted by this river in here,

and it's, like...

the world isn't
supposed to look like this.

NARRATOR:
As the summers heat up,

features like this ice canyon
are becoming more pronounced.

But for all its beauty, it
raises perplexing questions

about the effect this water
is having

underneath the skin
of the ice sheet.

The strangest phenomenon is the
mystery of the meltwater lakes.

As the ice sheet cooks down,
the meltwater collects

in depressions in the ice,
forming thousands of lakes,

some over several miles wide
and nearly 50 feet deep.

From satellite images,
scientists noticed

that in mid-summer, many of
these lakes vanished overnight,

leaving bright circles
where the water once stood.

Until recently, it was assumed
that the water was absorbed

and re-frozen
into the ice sheet.

But Ian Joughin and Sarah Das
have a hunch

that the water could be having
a deeper impact.

These events are
so unpredictable,

nobody has ever observed them,

but Das and Joughin
just came close.

A few days ago, a big lake by
their camp suddenly drained out.

SARAH DAS:
We were in the fog, so we
couldn't see the whole lake.

While standing right
on the shore of the water,

we started to hear
some really loud booms and pops

and it was
just extremely spooky.

Cracks would run across
the ground beneath your feet.

It was all around you.

It was a strange experience.

NARRATOR:
Frightening,
but also fortuitous.

They had placed a device
that measures water pressure,

called a pressure logger,
in the bottom of the lake,

hoping it might drain.

If they can find the logger,
their bet might pay off.

DAS:
The fish line
that we are following,

it's tied at one end
to our stations,

and it's tied at the other end
to an old plastic bottle

that has a pressure logger
attached to it,

and that's sitting
in the lake basin.

And so we're following the line
out, hoping that at the end,

we'll find it tied off
to our loggers.

NARRATOR:
The loggers should reveal

exactly when and how fast
the lake drained.

ywre, truck-sized blocks
of ice litter the lakebed,

evidence of the violent forces
uncorked

as the water rushed out.

DAS:
I see it!

JOUGHIN:
There it is!

In there, under the ice.

Watch your fingers.

NARRATOR:
With the loggers in hand,

they can now plot out
the minute-by-minute account

of the mass draining
of the lake.

So what you see here
on the left is early June,

when there's no water
in the lake,

and as more water fills
the lake, the pressure goes up,

the height of the water column
goes up, and up and up,

continues to fill, fill, fill,

until about this point,
and then on July 10, boom,

you see the lake drop in
a matter of about 40 minutes.

NARRATOR:
GPS data reveals that so much
water drained out so quickly,

the surrounding ice was pushed
up by several feet.

JOUGHIN:
Well, as you can see from
the blocks all around us,

this was
a tremendously violent event.

You have a lake that's
two miles wide, 40 feet deep,

and all of a sudden, it drops
3,000 feet through the ice.

It would have basically been
one of the tallest waterfalls

in the world.

The flow into these cracks
in the lakebed

is greater than the flow
over Niagara Falls.

NARRATOR:
Instead of being absorbed and
refrozen into the surface ice,

they discovered that
the water dropped

all the way to the bedrock.

There, it lifts and lubricates
the ice sheet

and accelerates its slide.

DAS:
And if you have increased
warming,

especially in the summertime,
over the ice sheet,

you're going to just increase
the supply of meltwater

to the bed, and potentially that
could escalate the speedup.

NARRATOR:
Their breakthrough solves the
mystery of the meltwater lakes.

They'd measured it,
but because of the fog,

they hadn't seen it happen.

By sheer chance,
the very next morning,

Balog and the scientists would
witness it firsthand.

About a mile away from his camp,
a smaller lake

that was full only hours before
suddenly starts to drain.

Balog heads for the water line

to try to find
where the water is going.

BALOG:
This is the world's
most treacherous footing.

These wave cups are hard walking
as it is,

and with them just emerged
out of the lake,

they're slick as can be.

There's so much water packed
in there,

it's just like grease
on top of glass.

BALOG:
Ah! Oh, my God!

Not being roped up here

is one of the scariest, dumbest
things I've done in my life.

Where I'm laying right now was
underwater just six hours ago.

And I can see maybe 250,
300 feet down there.

I'm not feeling real comfortable
out here.

DAS:
This is really the first time

that we've been able to observe
these things firsthand,

actually happening,
and it's really nice to see

that our theories
that we've pulled together

from our instrumental records

match our observations
on the ground very nicely.

NARRATOR:
Now they know, these billions
of gallons of water

are finding a route
under the ice and out to sea,

lubricating the outlet glaciers
and making them speed up.

Das and Joughin calculate
that this lubrication effect

accounts for about 10%
of the increase in speed.

So there must be
another powerful force

behind the surge of ice
from Greenland.

The latest ocean research
may have found it.

Around 1997, there was an abrupt
three-degree Fahrenheit jump

in coastal water temperatures,

exactly when the outlet
glaciers began to speed up.

At the foot of Jakobshavn
Glacier, in Disko Bay,

Ian Howat is investigating
how the warming ocean

could be eating away
at the edges of the ice sheet.

HOWAT:
We're trying to get a handle

on how the ocean
and the ice interact,

and so by that I mean

how heat is transferred
from the ocean,

which is this huge source of
heat, up against this ice sheet.

NARRATOR:
To figure it out, Howat is using
a capsule packed with sensors

that record temperature,
salinity and depth,

at intervals going down
1,000 feet to the ocean bed.

The measurements give Howat
an immediate picture

of how the meltwater streaming
off the glacier

and the denser saltwater below
stack up like a layer cake.

HOWAT:
So this plot is showing

the increase in temperature
with depth.

What we see here is very cold,
nearly freezing water

at the surface,
and then as we go down,

it increases its temperature
as it mixes

with the warmer
ocean water below.

So this transition zone,
this almost flat line,

shows us that there is
a very sharp transition

between that fresh water
and the salty ocean water below.

NARRATOR:
Howat thinks the rush
of cold meltwater

and you increase the force
of this conveyor belt

of fresh water going out
of the fjord,

you're bringing more heat
from the ocean into the fjord

to melt more ice, and that would
be a strong feedback

that could actually lead
to more glacier melting.

It's a much more dynamic
environment

than we thought in the past.

NARRATOR:
The story of the mountain
glaciers and the ice sheets

shows that abrupt changes in
the ice aren't the exception,

they are the rule.

SERREZE:
There are concerns
that we get to some point

beyond which strong feedbacks
in the climate system kick in

and cause changes that we're
really unprepared to deal with.

NARRATOR:
The ice may have
more surprises to come,

but based
on the latest research,

the best guess for
future sea level rise

comes down
to a simple calculation.

In the next hundred years,

the oceans will expand
on their own as they warm,

accounting for about a foot
of sea level rise.

Another foot will likely come
from the loss

of the world's mountain glaciers
as they melt away.

The ice sheets of Greenland
and Antarctica won't disappear,

but their combined melt
is expected

to add about another foot.

The total equals
an estimated sea level rise

approaching three feet,
or one meter, by about 2100.

It may not sound like much,

but over 100 million people live
within three feet of sea level.

Cities around the world
will spend trillions

building up coastal defenses.

Low-lying regions
such as Florida, Vietnam

and Bangladesh
will be devastated.

Many island nations
will cease to exist.

The consequences will test
our ability to adapt

like never before.

But it doesn't stop there.

ALLEY:
If we look beyond 100 years,

the biggest questions
might even be what we do.

There's huge things we don't
know about the ice sheets.

But our uncertainty about
what we decide to do

may be bigger than that.

But if we make it really warm,

I think a whole lot of us
get really nervous

about what the ice will do.

WHITE:
This is going to be

one of the pivotal moments
in human history.

Ice is too important for us in
terms of climate of the planet,

in terms of sea level,

in terms of the fundamental
operating systems of the planet,

for us to continue to ignore it.

NARRATOR:
The final chapter
of Balog's story plays out

on the southern coast
of Iceland,

where he discovers
an unrivaled confrontation

between the ice and the sea.

8,000 years ago, the island
was encased in ice.

But now, the last remnant of its
ice cap is quickly disappearing.

As the ice seeps down
towards the sea,

it discharges
into a meltwater lagoon.

Each day,
the tide draws the icebergs

out into the North Atlantic.

BALOG:
I'm not aware of any other place
in the world

where you can see this dynamic

between the ice and the surf
in the same way.

What I see in this ice is
a unique sculpture by nature.

Each one is a Hope Diamond--

you know, some really perfect,
pure manifestation

of form and color and texture.

They come up here on the waves,

they sit here for 12 hours
after the tide goes out,

then the tide comes back in,
takes them away

and they're gone for good,

and in that transitoriness,
I see extinction.

BALOG:
Our brains are programmed

to think that geology
is something that happened

a long time ago or will happen
a long time in the future.

We don't think
that that can happen

during these little years that
we each live on this planet,

but the reality is that it does.

On NOVA's "Extreme Ice" Web
site, see dramatic graphics

that show how the world's
coastlines would change

if all of Greenland's ice
melted.

Find it on pbs.org.

Captioned by
Media Access Group at WGBH
access.wgbh.org

This NOVA program
is available on DVD.

The companion book,
Extreme Ice Now,

is also available.

To order, visit shopPBS.org,

or call us at 1-800-PLAY-PBS.