Horizon

Just take a look at the number of people that have been living

on planet Earth.

We start about 10,000 years ago.

At that point there were roughly five million people

living on the planet,

and they slowly increased in number

for some considerable time, up until we get to 1800.

Well, then we get one billion people on the planet.

And by the time we get to 1960, we get three billion.

And then things go wild and it escalates massively

up here, to the 7.7 billion people

that we've got on planet Earth right now.

The UN predicts that by 2050

there'll be almost ten billion humans on planet Earth.

We all know about the pressures our planet is under from climate change.

We exist because of nature,

and that nature is really falling apart.

But I believe we're facing another challenge

which is just as fundamental.

Within the last six generations

we've gone through the biggest population explosion of our species.

I'm going on a personal journey around the world to find out

what effect our growing population is having on the planet right now.

This is Earth, vast consumption.

We honestly think that we can carry on doing this?

And to find out if there's any limit to the number

of people our Earth can sustain.

Things are probably going to get fairly uncomfortable and pretty ugly

before we fix it, aren't they?

I think there are systems in place.

I just think we've rather lost the plot.

If, as I believe, our ever increasing numbers

may in fact be a threat to our own survival,

could we find a way, as a species,

to reduce our own population?

Someone's got to talk about this issue

whilst there's still some chance that we can solve the problem.

Hey, come on.

Yeah, let's go. Come on, hurry up.

All right, come on, come on, come on.

I live on my own in the middle of the woods with my dogs.

Scratchy fell down the stairs a couple of days ago

and I've been told that I mustn't appease his limp or carry him

or anything like that.

Come on, Scratch.

Ever since I can remember, I've dedicated my life to one thing.

I have a profound love for every last thing that

slimes, creeps, crawls, stings, bites and slithers.

I fight really hard against injustices

that are wrought upon the natural world.

They're incendiary to me.

I'm a patron of a charity that campaigns to achieve

a sustainable human population.

If I'm very honest with you, most of the time I don't hold the human

species in terribly high regard because of the enormous damage

that it's done to the natural environment

and it's still doing to it.

But at the same time, I am a human and there are lots of humans

that I have an enormous admiration for.

When you think about what we're capable of in terms of art,

music, technology, we are remarkably adaptable,

resourceful and intelligent.

Nothing else comes close to us.

But there are 7.7 billion humans on the planet at the moment.

So what's the impact of that?

Is that a sustainable number of people?

Or do we need to be considering how we adapt our behaviour

to make that sustainable, or even going as far as to stopping

the population growing much more?

And there, I've said it.

That's the controversy, isn't it?

For me, it's been THE most important thing

to think about for a long time.

It is undeniably the elephant in the room.

So how did we get to 7.7 billion in the first place?

And what's going to happen if by 2050

there were ten billion humans on planet Earth?

One of the biggest changes that's occurred in my lifetime

is the sheer number of people living in urban centres.

There are now more than 30 so-called mega cities in the world

with ten million people or more,

not just New York, Shanghai and Tokyo,

but also Kinshasa, Lima, Mumbai.

Such concentrations of people places a major pressure on resources.

We definitely are at a turning point, a tipping point,

and I think all sorts of factors are coming together.

We have obviously huge climate change issues,

environmental resource issues.

And I think the next two or three decades,

yes, are going to be crucial.

Look at it, just endless sprawl to the horizon.

I'm starting my journey in one of the world's

most populated megacities.

Land, a carpet of concrete blocks

filled full of millions and millions and millions of people.

In 1960, Sao Paolo was home to roughly four million people.

Today, as the city's grown, it's more like 22 million.

You can see here on the right side how many buildings we have.

It's the financial capital of Brazil and one of South America's most

important economic and cultural centres, a bit like London,

only five times the size.

These mega cities, you think of the impact and the consumption,

the hunger and the thirst and the dependent need

of all of these people living in one place at one time.

The prediction is that by 2050, nearly 70% of the human population

are going to be living in these areas.

What's going to be the impact of that?

Cities are associated with higher levels of consumption

because they have higher levels of productivity

than rural areas.

And it's very clear that the richer countries actually have...

...levels of consumption that really outweigh everything

that the planet can sustain.

But on the other hand, the cities themselves have the potential

to make that consumption more efficient.

Although Sao Paulo's levels of consumption aren't as high

as some places in the world, the traffic here is so notorious

that the city's wealthy businesspeople

often get around by helicopter.

But Sao Paolo has a more fundamental problem -

it's running out of water.

Starting in 2014, reservoirs almost ran dry

as the city suffered one of its worst droughts since records began.

Now, some residents are taking matters into their own hands.

Hello. Hola. Chris.

How do you do? How do you do?

Is that a purifier? Purifier, yes, it is.

And does all of the water here need to be purified?

You can't trust it out the tap, no? No, we can't.

We can't trust the water that comes from the pipe.

You have a family.

Many parents worry about whether their children will go out

and get an adequate education or whether they will find employment

and some sense of fulfilment and contentment in their life,

but here in Sao Paulo, you've got to hope that your kids

are going to grow up and be able to get a drink of water,

which is fundamentally different.

That must be a real concern to you.

Yes, it is. Yes, it is.

The population will be bigger

in some years with the same amount of water.

So the problem, er, will be worst

in a few years, in a short period of time.

So... It's not good?

No, no, it's terrifying.

It's terrifying.

Maria and her neighbours are paying to secure their own private water

source, drawn directly from the ground outside their block.

Hola. Hola.

Chris. Chris, Emerson. Emerson.

Are you well? Yes. Good, good.

It's a bit like Texas, when they were digging oil wells everywhere

in that mad rush for the oil.

And now it's not the oil business, it's the water business,

it's a water boom.

Across Sao Paolo, over 13,000 private wells have already been dug.

But with the poorest parts of the city often suffering the most

from the droughts, protests have erupted in the streets.

Unless you reduce consumption, the original aquifers,

the original source of water is going to run dry.

Climate change doesn't help.

You know, in some regions, rain is becoming more and more scarce.

It is a major, major problem of mixture of climate change

and individual consumption levels.

In Sao Paulo, they're digging their own wells.

We've already seen water riots where people without water

are clearly upset with this disparity. Yes.

When the fundamentals of life, like water, are decided

by whether you're rich or poor,

that's not going to be sustainable, is it? I agree.

The trouble is, we don't have control over climate change.

So the minute the rivers dry up or there's, there's a drought

that lasts for years, then you have to resort to major measures

like desalination, like bringing water even further out,

as Los Angeles does.

Los Angeles brings in water from hundreds of kilometres away.

And therefore, there's an issue of justice.

You're depriving local people from the water that is theirs

in a region because you're feeding this large city.

So it's a very difficult problem.

All over the planet, cities like Los Angeles, Cape Town

and even Tokyo have faced severe water problems.

And it's predicted that within 25 years, London could be next.

Erm.. Wow, it's very impressive.

We're monitoring here, all Brazil.

In Sao Paolo, the droughts have become so serious that a team

of government scientists now continuously monitor rainfall.

This is fabulous, isn't it?

I love data, and this is real time data on a continental scale. Yeah.

But this presumably is also the interface

where you look at a shortage of rain.

This is for the short term rainfall.

But, for example, for drought, we use this for infrastructure also.

So this is effectively the emergency room.

Yes, we now have a mapping for all Brazil

to see where regions of Brazil

are suffering with droughts.

For the drought, we are concerning about this region

and the north-east. The north-east too?

Yes, north-east too.