It's clearly never going to leave us.

If our population is to hit ten billion,

we need to look for new solutions.

We are like nothing else that's ever lived on this planet

that we know of.

We are highly intelligent, remarkably adaptable,

incredibly inventive, and we're really good when it comes to

dealing with catastrophe.

And when ever we've been faced with problems in the past,

we've come up with solutions.

For many, the answer to our problems lies in new technology.

Hidden 100 feet below the streets of London in an abandoned

World War II bomb shelter, something extraordinary is happening.

They're growing salad.

This is pretty futuristic when it comes to growing food, isn't it?

I mean, the whole lot is underground.

The garlic chives, the watercress,

the sunflower, the coriander all look remarkably healthy.

The whole place oozes fertility.

But it's a somewhat bizarre place

to think that food might be grown, isn't it?

Goodness, it goes on and on.

A traditional farm might yield several crops a year.

By precisely controlling the environment

this farm can produce 60 harvests a year

stacked across four levels.

It's good, actually. It is good.

It's sort of perfect.

That's good, good to hear. That's what we aim for.

Yeah, except that when I'm eating my salad, I always like to see

those leaves with a little bit missing

where a caterpillar's had a nibble.

There's not going to be any of that down here, is there? Not down here.

Food production here is only on a micro scale.

So do we need to think about bigger solutions

to feed the world's growing population?

How much more of the world's land surface,

if we ignore the damage it does to biodiversity, could be productive

for growing human food?

Erm, quite a bit more.

I think that's, that's the problem.

It's, in a way, the same problem that we have with oil.

We have enough oil to cause yet more catastrophic damage,

so it's not a finite limits issue to quite the same extent.

It's about the damage that we cause by continuing to use it.

We've got a population of a little over seven billion people now.

What's going to happen when we get to ten billion?

Can we bioengineer our way out of this problem

just using the space and the soils that we've got at the moment?

SHE SIGHS HEAVILY

That's one of the biggest sighs... There's no...

That's one of the biggest sighs that we've had making this programme.

I think, I think we have the knowledge to change

the way we produce.

It's the, will we do it and can we do it,

and that sense of urgency and that sense of...

Well, what do you think?

Erm...

I don't know.