Life After People Page #7

[music]

I think our dogs,

As placid as they may seem

When they're in our homes

Lying on the living room floor,

Still posses the instinct

To survive,

Enough that they would be able

To do whatever it took

In bringing down prey

In order to live.

[music]

150 years after people,

The oceans are teeming

With life.

The creatures of the sea

Have welcomed

The disappearance of mankind.

historically,

We've treated the oceans

In two strange ways

At the same time:

A pantry and a toilet.

And over time,

Our ability to damage the ocean

Has grown and grown and grown.

with humans no longer fishing

And polluting the sea,

The path was cleared

For this astonishing recovery.

It has happened before.

During World War II,

Allied fishing trawlers

Avoided the north Atlantic,

And populations of fish there

Skyrocketed.

in here, the basic biology

Of these kinds of animals

Is working in our favor

Because animals

Like this sunfish

Can produce millions

Of offspring in a year,

Much more

Than an equivalent-sized

Terrestrial animal like a cow.

And because of that

Prodigious potential

To reproduce,

The oceans could come back

Pretty quickly

If the human population

Were suddenly to disappear.

research has shown

That in the 18th century,

Before the havoc

Caused by humans,

The oceans were capable

Of sustaining

Massive amounts of life.

so many whales

That they stink up the air;

So many tunas

That they froth the ocean;

So many turtles

That you could walk

Across the sea on their backs.

So, if people were to vanish

Off the face of the earth,

Then that's the kind of ocean

It could be.

[music]

seagulls are also

Flourishing, but it has been

A treacherous flight.

The abundance of food

From humans

Had allowed gull populations

To explode beyond what nature

Could normally support.

we humans

Are pretty messy species.

And for a very long time,

We had open landfill dumps

Where, as far

As we were concerned,

All the stuff

That wasn't fit to eat

Was just thrown out.

But from the gulls'

Point of view,

This was an amazing

Free lunch counter.

So, you had a lot of birds

That probably

Wouldn't have made it through

Their first winter

If they've had to feed

For themselves.

Suddenly, they had

All these free food

Available to them.

An immediate consequence

Of a world without people

Would be some very hungry gulls

Who would be very voraciously?

Looking for other things to eat.

after an initial die-off,

The remaining gulls

Took advantage

Of the recovering oceans,

Where plentiful schools of fish

Erased any memories

Of the human-manufactured feasts

They used to enjoy.

Two hundred years after people,

From New York to Chicago,

Seattle and Paris,

Our iron and steel icons

Are on the verge of collapse.

While it has outlived

Our great suspension bridges,

The Eiffel tower

Is not invincible.

In the time of humans,

Its iron superstructure

Was painted

Once every seven years

To protect it from corrosion.

In both age and structure,

The Eiffel tower

Has a lot in common

With the 300-foot high

Kinsman railroad viaduct

In Pennsylvania.

was a bridge

That was wrought iron

Originally.

It was reconstructed

About the turn of the century

In steel.

And what happens here of course

Is that unless it's maintained,

Corrosion occurs.

And what happens

With the corrosion?

The connection points freeze up.

They are not allowed to move.

And here are some pieces

From that viaduct.

You can see

That there's corrosion

All over the place.

That's no longer steel.

a structure

With frozen connection points

Can't absorb the stress

Of high winds.

eventually,

In this strong wind storm,

It literally fell over.

Section by section,

Piece by piece,

It fell over into the valley

Where it had spanned the valley

For over a hundred years.

Just not maintained.

You can think of many structures

That is coming

From that same era

Like the Eiffel tower,

Its iconic structure.

That doesn't shield it

From the fact that's it

In a corrosive environment.

And so in time

If you do not do anything

For that structure,

It will fail.

And it will come down.

the time between one

And 300 years after people

Will likely be the era?

Of the great collapses

Worldwide.

In Seattle,

The iconic space needle

Was designed to sway

One inch for every 10 miles

Per hour of wind,

But with its steel

Weakened by corrosion,

It takes little more

Than a strong breeze

For the symbol

Of the 1962 world's fair

To crash down from the skyline.

When humans disappeared,

Sea levels were already

On the rise.

In Manhattan,

Over the centuries,

Saturated soil

Around the empire state

Building's foundation pilings

Have allowed the building

To lean.

once a building strays

From the vertical,

Then gravity forces

Are also acting

Against the structure,

Increasing the stresses

At the base of the building,

Now we're unlikely to see

A skyscraper fall

Like a tree in the forest.

Once it does start to incline,

Gravitational force will cause

The top of the building

To collapse downward

On top of itself.

decay has also overtaken

The city of Chicago,

The birthplace

Of the skyscraper.

The sears tower,

The tallest man-made structure

In North America,

Has reached

The end of its reign.

The first 500 years

After people has been an era

Of decay and destruction.

Our concrete structures

Have lasted the longest.

The ancient Romans

Invented the first form

Of concrete.

And some of their structures

Remained intact

For over 2,000 years.

But modern concrete

Isn't nearly as durable.

It has higher water content

And is more loosely packed,

Which leads to more?

Air pockets and cracks.

Modern concrete structures

Have another fatal flaw.

below the surface

Of reinforced

Concrete structures,

There is a mesh

Of steel reinforcing bars

And they don't corrode

Because the concrete maintains

An alkaline environment

Around them.

Now, when that alkalinity

Breaks down,

As it will in time,

Then the steel

Will start to corrode.

as the steel rebar rusts,

It expands to three times

Its original volume

Creating an outward pressure

That causes the concrete

To crumble.

in very broad terms,

After 50 years

We'd start to see

Surface cracking on concrete.

After a hundred years,

Flaking of the concrete surface.

After maybe 500 years,

Most reinforced

Concrete structures

Will be gone.

we look at these images

Of our fallen civilization,

It helps us to identify

With the past,

With the Greeks and the Romans,

With the crumbled

Mud brick cities of urn.

Each of us knows

That our bodies

Are going to fall apart;

Why not our cities too?

a thousand years ago,

6 1/2 billion people

Called this planet home.

At the early 21st century,

More than half of them

Lived in cities.

Now those cities

Are unrecognizable.

after maybe a thousand years

Or so, the scene behind me

Would be very, very different.

There'll be very little evidence

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