Original subtitles

(dramatic music)

Narrator: Freezing cold,

(wind blows)

oppressive heat, devastating drought.

(thunder)

Extreme climate change may have contributed

to the extinction of the Neanderthals

and allowed modern Homo sapiens to dominate the earth.

(dramatic music)

All life on earth is subject to the power of climate.

Civilizations evolve or vanish forever.

(wind blowing)

Favorable climatic conditions support the rise

of great empires and promote trade, prosperity,

and artistic achievement.

Adverse climatic events often lead to war

and other human catastrophes.

(storms and thunder)

(dramatic music)

(explosion)

Almost 14 billion years ago.

Immense forces created the universe.

The Big Bang spawned vast galaxies.

Each with millions and billions of stars, moons and planets.

Among these, is one small blue planet.

Our earth.

Water, warmth, and the earth's protective atmosphere

create something that may be unique in the universe.

A climate that makes life possible.

As the oceans formed and the continents drifted apart,

the earth developed seasons.

Temperature differences between land and water

produced winds and land bridges shaped the ocean currents.

But climate has always been prone to sudden change.

Often with dramatic consequences for life on earth.

65 million years ago, the dinosaurs were the unchallenged

masters of the prehistoric world, until their sudden demise.

A meteor strike triggered volcanic eruptions

and earthquakes.

The ensuing climatic chain reaction wiped out

the giant reptiles.

(dinosaur roars)

(explosion)

After the age of the dinosaurs the earth cooled.

Climate change also affected our ancestors.

Early hominids had to survive

periods of both extreme heat and extreme cold.

Most were unable to adapt and died out.

Then over thousands of years, the polar ice caps expanded.

As did the earth's alpine glaciers.

(wind rushing)

Around 60,000 BC, average temperatures

were about five degrees colder than they are today.

This had a huge impact.

(wind blowing)

Arctic sheet ice extended all the way to Europe.

(whimsical music)

So much water was frozen

that sea levels became up to 100 meters lower.

(foreboding music)

The icy temperatures also affected the land.

The ground was not only frozen solid

but also extremely dry.

Where the ice ended

there were stretches of tundra and taiga.

-: If you look at Western Europe as a place to live,

you find that there are two challenges.

One, you find that you have very cold conditions,

particularly in winter.

But during the summer because the ice is so far South

you have this wonderful,

sort of like high energy environment.

So it doesn't stay stable for a very long period.

And you have this sort of oscillating extremes

going through the ice age.

Which then stress any creatures that are living there

at that time.

(wind blowing)

Narrator: But one homogenous was resistant

to these stresses.

(wind blowing)

The Neanderthals were suited to these extreme conditions.

They not only survived the climatic variations

but developed an impressive range of skills.

(wind whistling)

Neanderthals were adept at hunting large animals

and knew how to light fires.

They were the first hominids

to develop successful strategies for coping

with climatic variation.

(Frank speaks foreign language)

(drums beating)

Narrator: In the Neanderthal's caves,

fires kept temperatures constant.

They made warm clothes from animal skins.

-: The key thing for surviving cold climates

is to avoid frostbite.

So the key things that you want to actually protect

in cold climates, of course your fingers,

your toes, your nose, and of course genitalia,

if you happen to be a male.

(wind blowing)

Narrator: Neanderthals we're short and stocky.

Their body surface area was quite small

relative to their body mass.

But they had lots of muscle which generates heat.

They had the perfect anatomy for surviving in an ice age.

(wind blowing)

The Neanderthals main problem was their diet.

They needed to consume large quantities of meat

to sustain their muscle mass.

So they preferred to hunt large animals.

In summer when the ice receded for a few weeks

they hunted mammoth and other big game.

Hunting was physically demanding and dangerous,

but Neanderthals needed animal protein and vitamins

to survive the long winters.

They often tracked their prey over long distances.

-: When you look at a Neanderthal, they are tough,

they are cold adapted.

And you would expect them to survive

and thrive in the ice ages.

Narrator: And they did thrive

while the climate was stable.

But then quite suddenly it changed.

(dramatic music)

The climate has always been subject to large

but predictable fluctuations.

Most of these are caused by the sun,

the center of our solar system.

As the earth revolves the sun's rays strike its surface.

At some times its orbit is more circular.

At others, more elliptical.

One orbital cycle takes 100,000 years.

The angle of the earth's axis

also moves in a 40,000 year cycle.

These changes cause regular climatic variations on earth

as the intensity of solar radiation increases and decreases.

Other influences on the earth's climate

such as fluctuations in sea currents are irregular.

The Gulf Stream, for example, works like a giant heat pump.

(water rushing)

Moving warm water towards Europe.

(Frank speaks foreign language)

Narrator: Climatologists are investigating

how changes in the Gulf Stream effected the Neanderthals.

The answers lie hidden in Germany's Eifel mountains.

Deep in the lakes that have formed in Maar,

the craters of extinct volcanoes.

These scientists are doing pioneering work.

They use sophisticated technology

to reconstruct the earth's prehistoric climate

from its own natural records.

Using a special drill,

they're taking core samples from the sediment of Maar lakes

and the Eifel Maars region.

(boat creaking)

For thousands of years

pollen has settled in these oxygen poor waters

and have been perfectly preserved.

For scientists, the lakes provide a unique climatic record.

The core samples are fragile.

They have to be frozen with liquid nitrogen

so they don't disintegrate on their way to the surface.

(water bubbling)

Every sample that's brought up in tact

opens a door to the past.

The pollen layers allow the scientists to draw conclusions

about climatic conditions thousands of years ago.

(water bubbling)

The earth never forgets.

And the climate leaves a unique footprint.

(determined music)

(scientists speak foreign language)

(water and mud trickling)

Narrator: Now the research team

from the University of Mainz

can start reading the climate chronicle.

(scientists speak foreign language)

Narrator: The older the period they want to investigate,

the deeper the scientists need to drill.

One millimeter of the sample equals one year.

A meter long sample takes them back in time 1000 years.

At a depth of 40 meters

the researchers reach the era of the Neanderthals.

(machinery whirring)

The Eifel Maars are an ideal location for this research

because the Neanderthals lived in this region.

The Neander Valley,

where the first Neanderthal skeleton was found

is just 150 kilometers away.

The core samples reveal what conditions were like

for the Neanderthals

when the Gulf Stream became erratic.

The dark layers of earth indicate periods with mild climates

and extensive forest cover.

Lighter layers indicate periods

when barren steps covered the area

and summers were four degrees colder than today.

(metal scrapping)

About 60,000 years ago, the climate changed suddenly

with dramatic consequences for the Neanderthals.

(scientist speaks foreign language)

(foreboding music)

Narrator: There were 10 cold and hot phases

in quick succession.

The landscape and the vegetation changed rapidly.

Humans and nature were under constant stress.

(various nature sounds)

This climate chaos pushed the Neanderthals to their limits

and threatened their very existence.

(scientist speaks foreign language)

(water rushing)

Narrator: First, the Neanderthals prey disappeared.

Many animals were unable to find enough food and starved.

(wind blowing)

Others migrated away.

Suddenly the Neanderthals were hunters with no prey.

At the same time, a competitor moved into their territory.

Homo sapiens evolved in the warm climate of East Africa

and slowly migrated all the way to Europe.

(hopeful music)

The newcomers seemed completely unsuited

to these harsh and changeable climate.

Homo sapiens was tall and slender

with long arms and legs.

This build made them extremely susceptible to cold.

But they overcame this disadvantage thanks to a new skill.

-: It's been argued that Homo sapiens

had a very different shoulder,

so they could actually throw spears.

Whereas if we look at the shoulders of Neanderthals

they're so big and chunky

that actually that ability to throw probably wasn't there.

And actually they were much more likely

to be thrusting spears.

Narrator: Throwing spears allowed Homo sapiens

to kill much faster animals from a distance.

The revolutionary invention made hunting for meat

much easier.

(dramatic music)

The Neanderthals who'd been the masters of Europe

lost their fight for survival.

They weren't adaptable enough to save their species.

The last of them died on the rock of Gibraltar

about 24,000 years ago.

The clear winner in this time of climate change

was Homo sapiens.

We still share about 99% of our genetic material

with these ancient humans.

After migrating to Europe from Africa, Homo sapiens

spread to India and Asia,

then via land bridges to Australia and America.

During this mass migration,

they settled in some of the most remote corners

of the earth.

-: The key to that was the adaptability.

The ability to understand the environment,

how it's changing and to work with large social groups

to be able to actually deal with that changing landscape.

And for me,

this is the point where humans first started to adapt

to the climate and use the climate for their own good.

Narrator: During a time of unprecedented climate chaos

humans developed a unique ability.

Surviving in changing climates.

This allowed them to withstand the last millennia

of the ice age.

A time of extreme cold.

The ice age gradually came to an end around 17,000 BC

due to changes in the earth's orbit.

As the earth moved closer to the sun,

life changed dramatically.

The sunlight grew stronger, particularly in summer.

The icy planet was about to experience a global spring.

It took several thousand years

for the sun to warm the entire globe.

As the earth's climate became much milder,

a new era began and has continued until the present day.

(dramatic music)

Warmer temperatures lead to changes in the environment.

(water dripping)

(ice cracking)

First, the ice sheets in the Arctic and Antarctic

began to melt.

The oceans also began to warm

and the Gulf Stream began to flow again.

(water rushing)

As temperatures rose,

more and more moisture evaporated into the atmosphere.

This led to regular rainfall,

which triggered a burst of plant growth.

(birds chirping)

There was increased biodiversity.

Mixed forests spread across Europe and North America.

And sub-tropical forests flourished closer to the equator.

New animal species started to populate the fertile plains.

(elephant trumpeting)

(Detlef speaks foreign language)

Narrator: Along the Tigris and Euphrates rivers,

and in the Eastern Mediterranean, abundant natural resources

created ideal living conditions.

(swooshing sound)

At the ancient site of Gobekli Tepe,

are 60 stone steels, engraved with the images of animals,

including foxes, wild boar, and waterbirds.

(fire whooshing)

Nomadic peoples may have worshiped these figures

because wild animals supplied them with meat and skins.

(fire whooshing)

(mystical music)

(Detlef speaks foreign language)

(swooshing sound)

Narrator: Also of great benefit to humans and animals,

were the wild grains growing in the warm sunshine

of the Fertile Crescent.

(crickets singing)

Einkorn, spelt, and emmer grew all across the Middle East.

They're among the oldest grain varieties on earth.

Easily stored, these grains could be eaten all year round.

And so provided humans with a reliable food source.

(hopeful music)

As the seasons became more regular,

humans began to cultivate these wild cereals.

They observed the cycles of nature

and by experimenting soon learned the best times

to sow crops.

Agriculture revolutionized prehistoric societies.

(pensive music)

Many abandoned their nomadic lives

and became farmers and cattle breeders.

For the first time,

humans began to settle down and build villages.

They no longer needed to travel, to find food.

(hay crinkling)

-: Prior to agriculture, people were hunter/gatherers

and moving around.

And everybody from the very eldest to the very youngest

were all concentrating on collecting and hunting for food,

because that was essential.

As soon as you have the agricultural revolution

and agriculture starts, suddenly,

not everyone is involved in food production.

And allowing people to have the freedom

to actually do other things, allow society to build.

(sheep bleating)

Narrator: Once they'd settled in villages

people began to specialize and develop their skills.

They invented techniques that allowed them

to make new valuable objects for their communities.

(birds chirping)

-: You have specialists who are then farmers,

you have specialists who are then looking after cattle

and goats and other domesticated animals.

And then other people can then develop specializations.

So for example, if you're settled in one place

then you will want people who are specialized in building.

So you can actually then have houses built

or you can have buildings built.

And so you then start to free up people

from the manual labor of just producing food.

(birds chirping)

Narrator: Pottery, metalwork, and weeding

changed people's lives.

So did more humble inventions, like bread and beer.

(birds chirping)

Over the centuries,

villages grew into towns.

One of the oldest is Jericho,

on the banks of the river Jordan.

Other cities in the area,

were Catalhoyuk, Eridu, and Ur.

This cradle of civilization benefited from a long period

of favorable climatic conditions.

(triumphant music)

(Detlef speaks foreign language)

(foreboding music)

Narrator: Around the same time,

a disaster was looming in North America.

Part of the continental ice sheet melted

and created a vast Lake.

It continued to grow until it covered an area

of 440,000 square kilometers.

Far bigger than any lake existing today.

The intense sunlight caused the lake to grow

as more and more meltwater flowed into it

from the mountains.

(swooshing sound)

(ice cracking)

At first ice barriers held back this huge volume of water.

(ice sheets collapsing)

But around 6,200 BC, they too began to melt

and disaster was inevitable.

The barriers around Lake Agassiz collapsed.

(water rushing)

A huge amount of icy water was released.

It flooded large parts of North America

and eventually drained into the Atlantic.

The immense inflow of cold water

upset the currents in the Atlantic.

It disrupted the Gulf Stream

which ceased to have a warming effect.

Temperatures dropped all across Europe.

In the Fertile Crescent

where agriculture had so recently allowed humans

to make enormous progress,

the weather suddenly became cold and dry.

This led to devastating droughts and crops failed.

(wind blowing)

The new agrarian societies lost their livelihoods.

(Detlef speaks foreign language)

Narrator: The first ever climate refugees,

came from the Eastern Mediterranean.

Many thousands left in search of a new Eden.

(birds chirping)

Some ventured, as far as Europe,

where temperatures were still relatively mild

and fertile soil promised ideal conditions for settlement.

Others stayed in the Middle East,

but moved further south.

Everywhere they went, these migrants introduced agriculture.

They preferred to settle along rivers or on the coast.

Anywhere they had a reliable supply of fresh water and food.

But even in moderate climate zones,

the settlers were not safe.

The dangers caused by the North American meltwater

were far from over.

Sea levels rose 120 meters.

(foreboding music)

All over the world

humans found their very existence threatened.

(water rushing)

Gradually the sea reclaimed vast tracks of fertile land,

and rising sea levels flooded settlements

in river deltas and along coasts.

The Bible tells of these events

in one of its best known stories.

God told Noah to gather all the world's animals on his Ark,

two of each kind and take them to safety.

The rest of humanity was to be punished

in a devastating deluge.

(lion roars)

(people screaming)

Noah did God's bidding.

-: If you look into almost all human societies

there are stories about the great flood.

And the reason for this is because key period of time

between 10,000 and 5,000 years ago,

after the last ice age, sea levels continue to rise.

And that flood, all those societies that are affected

by that sea level rise has really impinged upon our psyche

and has embedded itself in our stories

about the end of the world.

(water rushing)

Narrator: The Bible is not the only book

that tells of a great flood and an ark.

(waves rippling)

The mountainous waves and the deluge

that destroyed everything in its path

are also vividly described in the Epic of Gilgamesh

from ancient Mesopotamia and the Quran.

(water rushing)

Tribal peoples in South America

also tell of a vast flood that covered the entire earth.

It is said that people only survived

by fleeing to the mountain tops.

Indigenous Australians also refer to a great flood.

The dramatic rise in sea levels

thousands of years ago

has become part of our collective memory.

-: All around the world where people were

sea level rose and rose and rose until about 5,000 years.

And we know that there are lots of areas

that are completely flooded now that had society.

So you can see cities underneath the sea close to mortar.

And in Japan.

We know that off the coast

of the United Kingdom in the North sea is Doggerland.

And when you actually survey Doggerland,

it has the imprint of villages of neolithic tribes

that used to live there that were flooded out.

(dramatic music)

Narrator: The rising sea levels

change the map of the world.

In North America, Hudson Bay and the Great Lakes

came into being.

In Northern Europe, the Baltic Sea was formed.

Japan, Indonesia and Australia became islands.

The great glacier melt did not always bring devastation.

One place that benefited was the Sahara.

(sand blowing)

Today it's a hot, arid and inhospitable region.

But the Sahara may once have been very different.

(sand sifting)

At an ancient site on the (indistinct) plateau in Egypt,

archeologists have uncovered surprising scenes

from prehistoric times.

(dramatic music)

They found stenciled hand prints

which were probably made by nomads or traders.

An adjacent cave has rock paintings of humans

standing alone and in groups.

All this art

was produced during the time of the great flood.

While much of the world suffered,

the Sahara appears to have been teeming with life.

Many people lived here and animal life was abundant.

There were antelopes and lions.

And even giraffes.

What is now the world's largest sandy desert

was once a fertile savannah.

(water trickling)

It was home to herds of animals that roamed rich pastures

fed by a vast network of rivers and lakes.

Change in this region's climate

was influenced by another factor.

Monsoon winds.

The Northern hemisphere was receiving more heat from the sun

because of a change in the tilt of the Earth's axis.

Land masses store more heat than oceans,

creating temperature differences that produce monsoon winds

which carry cool, moist air inland.

These winds brought rain and abundant life

to what is now desert.

-: If we look at the Sahara,

we find that there is a huge period of time

between about 12,000 years ago

and 5,500 years ago

where the Sahara was green.

And by that we mean that people were able to live there.

And so we find archeological finds

all the way through the Sahara,

showing that people thrived there,

there was clearly enough food,

agriculture was actually developing there.

And then slowly from about 7,000 years onwards

the Sahara started to expand.

(gentle music)

Narrator: But this flowering of the Sahara

and the abundance of water, wildlife and food plants

was fated not to last.

The fertile savannah land became a sandy desert.

Harsh, barren and largely uninhabited.

(wind blowing)

The subtropical monsoon winds

lasted only a relatively short time,

until the earth's axis shifted again.

As the sun's heat decreased, the monsoons lost their power.

(wind rushing)

When plants die from drought,

less moisture is retained in the soil.

This accelerates the degradation of the land

and deserts form surprisingly quickly.

(Frank speaks foreign language)

Narrator: We know when the Sahara became a desert

thanks to this ancient burial site in Niger

on what was once the shores of Lake Obero.

For many generations, the dead were buried here

along with objects, such as bone fish hooks

and jewelry made from hippopotamus tusks.

But the burials seem to have ended quite abruptly

in around 3,500 BC.

When the lake dried up,

the inhabitants abandoned the burial site

and all trace of them disappears.

When the rain stopped, they had to leave.

Drought had completely transformed the landscape

and this didn't just happen in the Sahara.

All over the world, deserts began to form.

The (indistinct) in Central Asia,

Australia's Red Centre

the Namib and the Kalahari deserts in Southern Africa.

(dramatic music)

This was the last major shift

toward the earth's current climatic patterns.

That small change in the tilt of the globe

caused the rains to stop in many subtropical regions.

(wind blowing)

Once again, climatic change forced thousands to migrate.

There was an exodus from the Sahara

towards a fertile region in Northern Africa.

While inland rivers had dried up, the Nile in lower Egypt

was still a reliable source of water.

On its banks, the migrants found fertile soils.

The Nile Valley is Egypt's green heart.

A verdant floodplain over 1100 kilometers in length.

The great river provides ample water to irrigate the valley,

which is surrounded by desert.

Every summer, heavy rains in the Ethiopian Highlands

cause the river to break its banks.

In September and October, the flood waters recede,

the soil dries out and the fields can be tilled.

While they follow a regular yearly cycle,

the Nile floods can be extreme.

The early settlers had to adapt to these conditions.

The climate refugees became skillful farmers

and hydraulic engineers.

(birds chirping)

The ancient Egyptians knew how to use every drop

of the precious monsoon rains for their fields.

(water flowing)

Water flowed through a system of canals.

To direct the water to where it was needed

they used lochs and counterweighted buckets.

(water rippling)

This sophisticated irrigation system

helped create an economic boom.

The Nile made the region prosperous

and fed increasing numbers of people.

(cow moos)

Egypt's first cities sprang up along the banks of the Nile.

(birds chirping)

(Gunther speaks foreign language)

Narrator: Simple settlements soon evolved

into Egypt's first kingdom.

But the social and political system continued to revolve

around safeguarding and managing the water supply.

(hopeful music)

(swooshing sound)

This was done with the help of an ingenious invention,

the nilometer, a step structure used to measure the level

of the Nile flood borders.

The measurements were used to predict the effect

of the flood each year.

(water rushing)

The Egyptian calendar was also based

on this annual flooding.

Akhet was the season of inundation,

Peret was the season of emergence,

and Shemu was the harvest season.

(grain sifting)

(Gunther speaks foreign language)

Narrator: This most famous of ancient civilizations

was the product of favorable climatic conditions

in the Nile Valley.

The pharaohs were able to build and maintain

the Egyptian empire over almost 3000 years

because the Nile provided all the necessary resources.

-: The fundamental resource you need

to build an empire is food and water.

If you actually want artisans to build temples,

you want soldiers to go off and fight wars for you,

you have to be able to feed them and to water them.

If you can ensure and protect your food supply

and your water supply for all of your people

then you can start to build a large civilization

Narrator: With key resources secured,

the pharaoh's oversaw a long period of stability.

These powerful leaders were able to bring prosperity

to their people.

(Gunther speaks foreign language)

Narrator: It wasn't just Egypt that flourished.

Other civilizations arose between the latitudes

of 20 and 40 degrees North.

In Mesopotamia and Persia,

in Northern India,

in Karakorum,

in China,

in Mexico and Peru,

and in the Mediterranean,

the Mycenaeans, Minoans, Thracians and Etruscans.

All these cultures had similar climates.

(triumphant music)

The kingdom of Katna in modern day Syria

also blossomed during this period.

And established itself as one of the ancient world's

most important economic centers.

It controlled the major trade routes connecting North Africa

and the Middle East.

Bronze Age cultures had something else in common.

Again, it was related to the climate.

Sun worship.

Egyptians venerated the sun god.

In Southern England, the stone circles of Stonehenge

marked the summer and winter solstices

and may have been associated with sun worship.

This structure in the German town of Goseck

is a solar observatory.

This sky disc found in nearby Nebra

is thought to be an astronomical instrument.

Many Bronze Age societies revered the sun

as the giver of life.

2000 years later, all this changed

as the entire Mediterranean region entered a period

that is sometimes called the Dark Ages of antiquity.

(fire whooshing)

From about 1200 BC, civilizations collapsed

one after the other.

Sources refer to seafaring people

who launched raids around the Aegean.

Little is known about them,

only that they always attacked from the sea.

(raiders screaming)

They ransacked towns and cities.

Leaving a trail of destruction wherever they went.

From Greece to Gaza, no one was safe.

Their raids marked the end

of the Mediterranean civilizations of the Bronze Age.

(fire roaring)

Researchers are still investigating

the reasons behind the collapse of these kingdoms.

They suspect that climate change may have played a role.

(foreboding music)

But one of the reasons that these are called the Dark Ages

is that there are so few written records

dating from this time.

Paleoclimatologist Dominik Fleitmann

hopes to shed light on this period using geological data

from the (indistinct) cave in Southern Turkey.

People have been visiting the cave for thousands of years

because it provides not only shelter, but also water.

Large pools were built in ancient times

to collect the rain water that seeps into the cave.

Deeper inside the cave,

this water has created a fascinating climate record.

which Fleitmann is researching.

(boots creaking)

The cave contains huge rock formations,

including stalagmites up to 20 meters tall.

Most are millions of years old.

A walk in this cavern is also a journey

through the area's climatic history.

(Dominik speaks foreign language)

(foreboding music)

Narrator: The problem is that he needs to find

just the right sample

from among all these stalagmites.

Many of these ancient formations

stopped growing at the end of the Bronze Age

when water stopped entering the cave.

Stalactites and stalagmites need a constant supply of water

if they are to grow.

(water dripping)

They're formed by rain water

seeping through soil and dripping off rocks.

The water leaves behind deposits of calcium carbonate

which accumulate over time.

These fragile structures

allow researchers to analyze rainfall patterns

over millennia.

The samples from (indistinct) cave

indicate that the climate changed abruptly

during the Bronze Age.

(Dominik speaks foreign language)

Narrator: This increase in dust layers

shows that during the late Bronze Age,

the climate became dryer.

This is confirmed by the rate of which the stalagmites grew

which slowed noticeably during the period.

In contrast to preceding centuries,

almost no new layers of limestone were added.

This suggests a decrease in rainfall

around the Mediterranean from about 1200 BC.

The whole region was in the grip of drought.

(Dominik speaks foreign language)

Narrator: A recipe for disaster indeed,

as recurring droughts affected

the entire Mediterranean region.

(bell tolls)

Soon soils were depleted.

Fields could no longer be tilled.

The mysterious seafarers who raided kingdom after kingdom

were actually climate refugees.

Huge numbers of migrants overran Egypt.

Word had spread that it was rich in resources

and that the pharaohs granaries were well stocked.

(crowd shouting)

Ramesses the third eventually won a resounding victory

over the raiders.

(crowds shouting)

But their invasion of Egypt was the beginning

of a prolonged gradual decline.

(mournful singing)

-: So the old kingdom ruled

for hundreds and hundreds of years.

And then a cold snap produced drought

across the Middle East.

The key problem with drought

is it means that your food supply stops.

If you don't have enough food, you can't feed people.

Those people then either migrate to other places

where there is food,

or they actually start trying to produce food themselves.

So what you have is every layer of government

starts to collapse because you can't feed people

that are trying to run the country.

And you see that the old kingdom collapses.

Egypt shows us the power of climate.

Narrator: So kingdoms fell because of a climate anomaly.

(dramatic music)

Rainfall drops substantially,

and temperatures were the lowest they'd been

since the end of the ice age.

It wasn't until about 300 BC

that the earth's alignment

again made the climate more favorable,

with milder temperatures and regular rainfall.

(wind blowing)

In the mountains,

glaciers receded.

The balance of nature was restored in the Mediterranean

and beyond.

(thunder roars)

The changes brought an end to the climate crisis

and much needed relief to ecosystems all over the world,

including Africa.

(rain pours)

Abundant rainfall replenished groundwater levels.

Soils became fertile again

and crops thrived in Northern Africa.

Emmer, the most sought after export of the time

grew as far as the eye could see.

(Frank speaks foreign language)

Narrator: This abundance

attracted the attention of an emerging power,

which obtained access to Africa's granaries by force.

It subjugated its archenemy Carthage in the Punic Wars

and secured its food supply for centuries to come.

The rising imperial power was Rome.

During its golden age,

more than 800,000 people lived in it's busting capitol

on the river Tiber.

(people having conversations)

Famous for both its efficient administration

and its extravagant lifestyle,

the Roman Empire outshone all that had come before it.

(Gunther speaks foreign language)

(crowd cheers)

Narrator: At home, Rome kept its people content

with bread and circuses.

Abroad, it expanded its empire.

The climate favored Rome.

(dramatic music)