from BBC Learning English.

I'm Neil.

And I'm Sam.

We're talking about the environment

in this programme, specifically climate change.

Now, Sam, what do you think is

the biggest cause of climate change?

An obvious answer would be that

climate change is the result of

carbon emissions caused by humans.

It's about people's carbon footprint –

the measurement of how much carbon

dioxide is produced by someone's

everyday activities.

That makes sense.

But recently some

scientists, especially in the west,

have been focusing on another issue:

the increasing number of people

in the world, something known as

overpopulation.

In this programme,

we'll be discussing the controversial

link between overpopulation and

climate change.

And as usual

we'll be learning some new

vocabulary, as well.

Sounds good, Neil, but first I

have a question for you.

Over the last 100 years,

within one lifetime, the world's

population has soared.

At the

start of the 20th century,

it was around one-and-a-half billion,

but how many people are there

in the world today?

Is it:

a) seven billion?

b) eight billion?

or c) nine billion?

I'll say around eight

billion people live on the planet today.

OK, Neil, I'll reveal the

answer later in the programme.

Since climate change is caused

by human activities, it seems

common sense that fewer people

would mean lower carbon emissions.

But in fact the connection isn't

so simple.

Not everyone emits

carbon equally, and people in

the western world produce far

more than people in sub-Saharan

Africa or Asia.

Arvind Ravikumar is professor of

climate policy at the University

of Texas.

He's made the

surprising calculation that

an extra two billion people born

in low-consuming countries,

would actually add very little

to global carbon emissions.

Here, Kate Lamble and Neal Razzell,

presenters of BBC World Service programme,

The Climate Question, discuss

Professor Ravikumar's findings.

What he's saying is kind of

astonishing, right?

Two billion

people is, to say the least,

a lot.

It's the combined population

of Europe and Africa.

He's crunched the numbers and

found that an extra two billion

low-income people as defined by

the World Bank, these are people

without cars, without electricity

often, would see global emissions

rise by just 1.5%.

Add two billion high-income earners

- that's people with cars and

power and all the mod cons,

and Arvind reckons emissions

would rise by more than 60%.

So when it comes to climate change

and population, where you were

born matters.

Professor Ravikumar made his discovery

after crunching the numbers,

an idiom meaning performing many

mathematical calculations involving

large amounts of data.

He concluded that whereas two billion

low-income people would increase carbon

levels very little, two billion

high-income people would increase

it a lot.

That's because high-income

populations have mod cons, which is short

for 'modern conveniences': technology

and machines like cars, fridges

and air-conditioning that make life

easier and more pleasant.

According to this view, the

real problem is not overpopulation

but overconsumption.

Affluence – that's having

lots of money and owning many things,

has become a big factor in climate change,

and that's true in poorer countries

as well as richer ones.

Listen to Rajesh Joshi, reporter

for BBC World Service's, The Climate

Question, interviewing a rich

Indian housewife, Priti Dhagan,

in her luxurious home in New Delhi.

I need everything that I buy.

You cannot be judgmental about

anybody's needs, and I derive a

lot of happiness out of being very,

very drawn towards consumer things,

and I love it.

And I'm not

apologetic about it.

So if I tell you that poor

people have a smaller carbon

footprint as compared to their

richer counterparts, do you feel

apologetic about it?

So the brain says yes, we should

be apologetic about it, but the heart

does not agree.

Yes, poor can't

afford lots of stuff so their

carbon imprint is small, but here

my heart wins over my brain

because it gives me happiness.

Priti does not feel apologetic

about her shopping – she doesn't

think that she should feel sorry.

Shopping makes her happy and she

lets her heart rule her head –

an idiom meaning that you do

something based on emotions

rather than reason.

Priti is being very honest.

She is consuming and looking for

happiness in a way that people

in the west have been doing for decades.

It seems overconsumption is

a bigger cause of climate change

than raw population numbers.

Speaking of which...

what was

the answer to your question, Sam?

Ah yes, I asked about the

current global population.

You guessed it was around eight billion

people which was... the correct answer!

According to the United Nations,

the world's population reached eight

billion on November 15, 2022.

Right, let's recap the

vocabulary we've learned,

staring with carbon footprint –

a measurement of how much carbon

dioxide someone's activities produce.

If you crunch numbers, you perform

many mathematical calculations involving

large amounts of data.

Mod cons is short for 'modern conveniences'

- machines like cars, washing-machines,

and fridges which make life easier

and more pleasant.

Affluence means having lots

of money or material possessions.

If you are apologetic, you show

that you feel sorry for something

harmful you have said or done.

And finally, the idiom let your

heart rule your head means to do

something based on emotion and personal

desires rather than for logical or

practical reasons.

For now it's goodbye!

Bye bye!