Original subtitles

The kitchens of today can be more beautiful,

because this year, there's a better...

♪ Oh, what a relief it is... ♪

Charlie!

On July 5, 1946,

French designer Louis Reard paraded a model

down a Paris runway in a two-piece bathing suit

that he called a bikini.

Reard spontaneously dubbed it "bikini"

during a week in which world headlines were occupied

by nuclear tests conducted by the United States of America

off the Bikini atoll in the Pacific.

Wearing a bikini actually created

more cries of outrage and scorn

than the act of exploding an atomic bomb.

It's a new era of undersea exploration,

with the self-contained underwater breathing apparatus.

If the bikini won't get you into the water,

perhaps the aqualung will do the job.

Those denizens of the deep had better watch out,

as man's dominion now extends both above and below the waves.

In 1946, in the waters

around the remote Pacific island of Bikini,

coral reefs were demolished and pulverized

by the test explosions of multiple nuclear bombs.

Since radioactive fallout contaminated the island,

the reefs of Bikini were to be left to their own devices,

with no human contact for over 50 years.

But in that time, something wonderful happened.

The reefs returned.

The reefs of Bikini are testament

to the resilience of nature.

But the reefs of the world now face a far greater threat.

Think of a reef as a city,

a city beneath the sea.

Like our cities, reefs offer sustenance and shelter

for their diverse communities.

They protect an incredible variety of creatures.

But our cities are altering the chemistry of the ocean,

the very chemistry the reef-builders rely upon.

Coral comes in so many different shapes and forms.

For years, people were confused

as to whether it was a rock formation

or a plant.

In fact, coral reefs are colonies

of thousands of tiny animals called polyps,

each colony sharing a communal skeleton.

Living within the coral polyp is a kind of algae.

Like a plant, the algae absorbs the sun's energy

and passes it on to the coral.

In this way, coral can get

as much as 90% of its energy from sunlight.

But we need more than energy to build our cities.

We need bricks and mortar, stone and cement.

The reef's building blocks are the carbon, calcium,

and other minerals dissolved in seawater

or trapped in organic matter.

They absorb these elements and create calcium carbonate.

It's not unlike the way we grow our bones and fingernails.

It's an organic factory,

using the sun's energy and carbon

to build the reef cities.

We may think our cities diverse and well populated,

but the reefs of the world rival tropical rain forests

for their wealth and variety of life.

If we look closer, we soon realize how alien,

how beautiful these cities really are.

Nudibranchs, the slugs of the sea,

are just one of an incredible number of creatures

that depend upon the reef.

They come in an amazing array of shapes and colors.

And they're no bigger than your little finger.

Flatworms have no respiratory organs.

They absorb oxygen and expel carbon dioxide

by a process of diffusion,

so their bodies are paper-thin.

Elsewhere on the reef,

clownfish shelter within the poisonous tentacles

of a giant sea anemone.

Unlike other reef fish,

they are immune to the anemone's sting.

Away from this protection,

a clownfish might quickly be devoured by predators.

In return, the clownfish eats

the anemone's waste and leftovers.

And by being fiercely territorial,

it even helps ward away the anemone's predators.

This is one of the reef's many examples of symbiosis,

a relationship between two different creatures

that benefits each of them.

There are other methods of defense on the reef,

equally creative.

Camouflage, for example.

The crocodile fish almost completely disappears

amongst the sand and stones in the shallows

as it waits for unsuspecting prey to pass by.

Other fish blend in with the coral,

like the scorpion fish,

or hide beneath the sand.

Coral reefs support over one quarter

of all the world's marine species,

and that includes a vast array of mollusks.

There are more species of mollusk

than all species of bird, reptile, and mammal combined.

Grooming may have become

something of a ritual in our cities,

but is a vital part of our lives

as far as health and hygiene is concerned.

We even use a form of grooming

that directly mimics life on the coral reef.

Cleaning stations attract much larger animals

to the shallow waters of the reefs.

Small fish operate the stations.

They groom the larger ones

by nibbling away parasites or dead skin.

These manta rays approach the reef at high tide,

in search of the cleaning station.

It's a predictable timetable that can attract other visitors.

Coral grows and builds upon its own skeletal remains

in whichever direction will give it light and warmth.

As a result, reefs can take many different forms.

They follow coastlines.

They surround rising or falling mountains.

They can become atolls around sunken peaks.

Reefs offer protection for the islands within,

sheltering them from the ravages of the open sea.

Throughout time, reefs have created

these sheltering cities beneath the sea,

in tune with the slow-moving geology of our planet.

And they have helped shape it.

Both cities have transformed our planet--

the reefs over millions of years,

our cities in merely hundreds of years.

As our cities sprawl and expand,

it's possible to see them from space.

But the coral cities have been building for millions of years,

creating the largest living structures on the planet,

also visible from space.

As sea levels change, exposed reefs quickly turn to stone,

outcrops become rock islands,

or over time, they become cliffs or mountains.

Limestone formations all over the world

were mainly created by reef-builders.

Reef limestone even covers the exterior

of the Empire State Building.

500 miles east of the Philippines, in Palau,

ancient reefs have created an archipelago of rock islands.

Some of the islands have formed marine lakes,

completely cut off from the surrounding ocean.

The lakes have trapped whole populations of jellyfish,

uniquely separating them from the open sea

and their principle predators,

so they no longer need their sting.

They simply drift around the lake, tracking the sun--

just as dependent upon its energy

as their relatives on the reef, the coral polyps.

Coral atolls create calm lagoons within the circle of the reef,

a perfect environment for mangrove forests.

Just a few species of tree, adapted to the high density

of salt in the warm shallow waters,

make up these dense forests.

Mangroves harbor nurseries for a variety of marine life.

Juvenile lemon sharks shelter within the mangroves,

where there is also an ample supply of food,

venturing further away from the mangrove roots

as they grow in size.

So coral reefs can both protect

and connect different ecosystems.

The lagoons are quite different environments to the coral reefs,

with their sandbanks and sea grass.

When the sharks reach 12 to 15 years of age,

they leave the mangroves and the lagoons behind

to assume their role in a complex, interlocking food chain

that connects the creatures of the reef

to creatures of the open sea.

Reef fish tend to grow slowly

and live longer than oceanic fish,

but their eggs are spawned directly into the open sea,

with a less than one percent chance of survival,

since they immediately join the ranks

of the ocean's greatest food source: plankton.

Plankton drifts freely in the water,

swept away by the currents flowing in and around the reefs.

It's here that feeding stations form.

Manta rays and huge shoals of fish gather at these stations

to filter the plankton and nutrients from the water

as it flows through the channel.

The whale shark is one of the largest filter feeders

to visit the reef.

Out beyond the reef,

there is fierce competition among the predators,

and yet, they are all still dependent

upon the reef in some way.

These Atlantic spotted dolphins

use the shallows close to the reefs as a place to rest, play,

and to teach their young survival tactics

for the open sea.

So reefs can be seen as a primary source

of food in the ocean.

They also filter the surrounding water,

helping keep a balance of nutrients, minerals,

and chemicals beneficial to local fish populations.

Without this filtration,

disease can quickly spread through the food chain.

In the years since the invention of scuba,

technology has transformed our lives,

but reef life has deteriorated all over the world,

for many different reasons.

The pollution from our cities, bacteria in our sewage,

the removal of mangrove forests, the increasing pressure

on local people to find new sources of income

has led to the dynamiting of reefs.

Even the sun cream we use to protect ourselves while bathing

can have a harmful effect on reefs.

And then there's bleaching.

The algae that lives within the coral

and is responsible for much of the coral's energy,

also gives coral its color.

When sea temperatures rise,

the algae is forced to abandon the coral,

taking with it the coral's color.

This is what is known as "bleaching."

Without the algae, the coral can die of starvation.

The impact of these combined threats

can be fatal for coral,

and many reefs around the world have already been lost.

Reefs have so much more to offer.

We still have so much to learn,

secrets to unravel.

They are as much a potential source of new breakthroughs

in medical science as the world's rain forests.

Yet reefs are vanishing five times faster than rain forests.

And there is another, much greater threat.

At night, the light that glows from our cities

requires an enormous amount of energy.

And where energy is concerned,

there's always a price to pay.

Every second, we pump 761 tons

of carbon dioxide into the atmosphere

in our unquenchable thirst for energy.

A third of that amount

dissolves into the ocean.

Carbon is an essential building block of life.

It is locked in rock,

buried in fossils,

circulating in the atmosphere,

dissolved in the ocean.

The transition from one form of carbon to another

can take millions of years

or can be burned in an instant.

As CO2 dissolves in seawater,

the ocean becomes more acidic.

Every aquarium keeper knows that the pH value--

the measurement of water's acidity--

is vital to the health of any fish tank.

So it's easy to understand

that a change on a global scale

would have a catastrophic effect on life in the oceans.

As the sea becomes more acidic,

any creature that absorbs carbon

to manufacture a new shell,

a new skeleton,

or a new coral structure,

finds it more and more difficult,

to the point that growth slows down,

and the strength of the shell or skeleton weakens.

Entire coral reefs will simply soften,

crumble, and disappear.

Imagine the outcry

if science were to predict the complete extinction

of trees everywhere

by the middle of the century.

This is what the ocean is faced with:

the complete destruction of all reefs, everywhere,

within our lifetime.

And some say the point of no return is already upon us.

Losing reefs would have a disastrous effect

on the food chain

and the rest of the marine environment.

Consider, for a moment,

how much our lives depend upon life in the ocean.

Remember, however, that nature is resilient.

Coral spawns its eggs into the sea.

The larvae drifts on the ocean currents,

some finding their way back to the reef of their origin.

Others, however, find new homes,

new rocks, new starting places.

By spreading to new areas,

as the world changes around them,

coral has survived over millions of years.

Coral will take advantage of any structure.

So long as the water is clear and clean

and has ample sunlight,

they'll create a whole new environment.

Relics of war in the Pacific

are now home to the reef-builders,

slowly transforming them over time.

Decommissioned ships are now regularly sunk

to encourage the development of new coral reefs.

Even statues can form the basis of a new habitat,

a new city.

All over the world,

people are trying to lend the reef-builders

a helping hand.

But reefs cannot rebuild in an acidified ocean.

The very simple chemistry,

whereby CO2 raises water's acidity,

is unarguable.

The call for cutting our carbon emissions,

finding greener sources of energy,

greener forms of transport,

becomes more vital than ever.

It's the one way we can all contribute,

however indirectly,

to the recovery of the world's oceans.

The reef-builders will return.

They will create new hot spots of diversity in the oceans,

new cities beneath the sea...

if we let them.

Perhaps we can learn from the lessons of Bikini.

Coral reefs have an amazing ability to rebuild,

and their influence reaches far across land and sea.

The last reef is now our responsibility...

a responsibility that we cannot ignore.

Its future is in our hands.

The last reef...

is in our hands.