Population is a planet emergency but … | Brussels Blog

Population is a planet emergency but …

posted by on 3rd Aug 2018

Population is a planet emergency but …

Whataboutery and the carbon cost of children

I do not sneer at ‘whataboutery’, the practice of responding to an accusation by making a counter-accusation. An example:

Diesel cars kill tens of thousands due to pollution – but what about driving petrol cars. That is worse because they cause greater CO2 emissions, which will kill many more through climate change.

There is an excellent piece by Peter Hitchens defending whataboutery. He quotes The Gospel according to St Matthew Chapter 7, vv 3-5, where:

Our Lord says : ‘And why beholdest thou the mote that is in thy brother’s eye, but considerest not the beam that is in thine own eye?

However, grossly exaggerated claims about the carbon cost of having children can cause a dangerous form of whataboutery:

I’m OK trashing the climate but you have children and that’s much worse.

Here is the example that I came across recently:

A teacher with no children goes on several big flights a year. She has a lifestyle far more sustainable than a family of 5, no matter how little they travel.

The MSM reporting

This shocked me – but the what shocked me more was that the Main Stream Media (MSM) passed on this idea – without a basic level of fact checking. It started with a press release from Lund University, The four lifestyle choices that most reduce your carbon footprint, which said “having one fewer child would save 58.6 tonnes per year.”

Many of the MSM picked up this story. A typical report, Want to fight climate change? Have fewer children was in the Guardian:

The new study, published in Environmental Research Letters, sets out the impact of different actions on a comparable basis. By far the biggest ultimate impact is having one fewer child, which the researchers calculated equated to a reduction of 58 tonnes of CO2 for each year of a parent’s life.

In the MSM reports allowed conclusions like these: Avoiding having children allows you to screw the climate.

–1– This is evident in the ‘flying teacher’ example above.

Any reduction of world population is as good as any other.

–2– None of the reports in the appendix cite the original work by Murtaugh & Schlax, which estimates carbon emissions for different countries. Although this work is flawed, it does note that the impact of children is very, very much higher in richer countries than in poorer ones.

–3– The carbon cost of children is independent of parenting.

The assumption in the reports is that parents have little influence over the carbon emissions of their children. However, if you have a child now but don’t have a car, don’t fly and don’t each much meat (especially beef and lamb) then the carbon cost of your child will be much lower than average – at least until they are in their teenage years.

There are samples of the way the MSM reported this issue in the Appendix. Skip to there to avoid the rather laborious detail of the argument.

Before analysing the detail a prelude is necessary.

Prelude. The Individual Remaining Carbon Budget

The science isn’t exact but it is reasonable to say:

Humanity can emit about 100 tonnes CO2-equivalent (CO2e) per person before we have a climate disaster. This will cause the deaths of billions of people and the extinction of many other species.

This number of 100 tonnes is an Individual Remaining Carbon Budget found by dividing the total Remaining Carbon Budget (770 billion tonnes of CO2-equivalent) by the number of people in the world (7.6 billion).

(CO2-equivalent is CO2 plus an allowance for other greenhouse gasses such as methane and nitrous oxide.)

Is that extra child costing the earth?

The word is going round that having that extra child leads to enormous increases in your carbon footprint. With some other clues, I estimate the teacher in the example above has a lifestyle that causes the emission of at least 50 tonnes of CO2e per year, five long-haul flights is a substantial part. 50 tonnes of CO2e is more than three times the CO2 emissions of an average US citizen.

The example depended on a paper by Wynes & Nicholas published in 2017. This claimed that, for devloped economies, each child caused an extra 4,688 tonnes CO2e. For an average lifetime of 80 years thats 58.6 tonnes CO2e per year added to each parent’s carbon emissions. So avoiding that extra child saves 58.6 tonnes CO2e per year. Wynes & Nicholas give other possible ways of cutting carbon emissions:


Savings per year in tonnes CO2e

One fewer child


Live car free


Transatlantic flight


Green Energy


Increase fuel economy


Electric car


Plant – based diet


Laundry in cold water




Hang dry clothing


Upgrade light bulbs


This means that the carbon footprint of one extra child is worse than driving an average car a distance of 1000 kilometers every day of the year. All your life.

The estimates of the emissions from having an extra child used a method developed by Murtaugh and Schlax. This is the method:

–1– Assign half of a child’s emissions to each parent

–2– Add one quarter of the emissions of each grand-child

–3– Add one eighth of the emissions of each great-grand-child

–4– …and so on.

As the number of descendants increase the carbon emissions add up to a very large amount – even though for each descendant the share of their emissions is diminishing. Wynes & Nicholas considered carbon emissions in ‘developed’ nations (average lifetime 80 years), it is possible to see that their estimate of the carbon cost of having an extra child is about 4,668 tonnes CO2e – over 46 times the individual budget (100 tonnes CO2e) for avoiding “dangerous climate change”.

One flaw in this argument is the assumption made by Murtaugh and Schlax that future generations will have carbon emissions similar to the initial parents. It ignores these two possibilities:

Option 1: Greenhouse gas emissions are be reduced to zero or below, as outlined by several IPCC reports, so that future generations can avoid dangeroous climate change.
Option 2: Greenhouse gas emissions continue to be high bringing on a sixth mass extinction where future generations – and most life on Earth – die.

The first case, possibly optimistic, reduces greenhouse gas emissions enough to save the climate. Let us consider a specific case, where emissions are reduced from the present level of 6.2 tonnes CO2e per person to zero in equal yearly steps. The question arises: How soon must we reach zero emissions to stay within the 100 tonne CO2e limit?

Answer: 33 years.

In other words, a steady reduction to zero emissions will just exhaust the Individual Remaining Carbon Budget over a period of 33 years – sooner if cuts in emissions are too slow. In short: Climate disaster in 33 years (probably less).

If the “flying teacher” were to keep with this individual budget, she would have just 3 years to reduce from 50 tonnes CO2e to zero. As this is extremely unlikely we must count on other people having much lower emissions. Fortunately the poor of the world emit much lower amounts as this infographic from Oxfam shows.

It is probable that, in the real world, neither Option 1 or Option 2 above will happen. It will be somewhere in between with many climate related deaths among the poor. We should note that killing off the poor will of limited help in saving the climate. Kill the poorest half of the world and emissions are only reduced by 10%.

What is the carbon cost of an extra child?

A rough method of estimation might be this:


–1– Your remaining carbon Budget is 100 tonnes CO2e

–2– Your yearly emissions are the world average of 6.2 tonnes

–3– World carbon emissions will reduce to zero over the next 33 years.

–4– Fertility of 2 children per couple.

–5– Children are born when you are 25.

–6– Children cause similar emissions to their parents as soon as they are born


–1– Today: Have 2 children. Count one child to you – the second to your partner.

–2– 25 years time: Your children have 4 offspring. Count one grand-child out of four.

In this crude model of reproduction, the extra emissions in 33 years time for the descendants assigned to one parent is 106.8 tonnes of CO2e. Over the 33 years that is 3.23 tonnes CO2e per year. If the parents have just one child, the emissions of the descendants that is assigned to one parent is 53.4 tonnes CO2e.

So avoiding one child cuts your carbon emissions by 53.4 tonnes CO2e. That’s rather less than the estimate of 4,668 tonnes CO2e from Wynes & Nicholas.


For frequent reminders on the problems of over population, I do follow the Twitter feeds of @PopnMatters, @RichardLAshwell and @soupypeas. Having children in a ‘developed’ country causes many tonnes of CO2e. Nowhere near the 4,668 tonnes CO2e that Wynes & Nicholas calculate – but it will be more than enough to severely damage the climate.

Final conclusion

Don’t trash the climate because your neighbour has a child.

Appendix: Reports in the Main Stream Media

The Independent: Having children is one of the most destructive things you can to do the environment, say researchers

Eating meat, driving a car and travelling by aeroplane made up the list of the most polluting things people can do to the planet.

But having children was top, according to the new study, published in the journal Environmental Research Letters.

The Guardian: Want to fight climate change? Have fewer children

The new study, published in Environmental Research Letters, sets out the impact of different actions on a comparable basis. By far the biggest ultimate impact is having one fewer child, which the researchers calculated equated to a reduction of 58 tonnes of CO2 for each year of a parent’s life.

The Telegraph: How to save the planet: cut holidays, sell the car and don’t have as many children, say scientists

Having multiple children was found to have the largest impact on climate, with each child creating nearly 60 tonnes of CO2 each year. Avoiding a one-way transatlantic flight could save around 1.6 tonnes of carbon dioxide emissions, while a round-trip to Australia would prevent 4 tonnes – 20 times the saving made by a year’s recycling, which is around 200 kg a year.

Mail Online: Want to save the planet? Don’t have children!

Recycling, washing clothes at 30°C and switching to energy saving bulbs are all touted as ways to help the environment.

But if you really want to save the planet, one of the best ways is to not have children, according to a study.

USA, Science Magazine: The best way to reduce your carbon footprint is one the government isn’t telling you about

Foregoing one round-trip transatlantic flight each year would cut a person’s emissions of CO2 by 1600 kilograms. Getting rid of their car would reduce emissions by 2400 kilograms, or 2.4 metric tons. And by choosing to have one fewer child in their family, a person would trim their carbon footprint by a whopping 58.6 metric tons.

Sweden, The Local: Want to save the planet? Have fewer children, Lund University researchers say

“We found there are four actions that could result in substantial decreases in an individual’s carbon footprint: eating a plant-based diet, avoiding air travel, living car free and having smaller families,” said lead author Seth Wynes of Lund University in Sweden.

“For example, living car-free saves about 2.4 tonnes of CO2 equivalent per year, while eating a plant-based diet saves 0.8 tons of CO2 equivalent a year.”

Avoiding airplane travel saves about 1.6 tonnes of CO2 equivalent per trip.

By far the biggest action was having one less child, which saves an average of 58.6 tonnes of CO2-equivalent emission reductions per year, the report said.

Germany, Deutsche Welle: Having fewer children: A solution for climate change?

In industrialized countries, one person could save 2.4 metric tons of CO2 a year living car-free, 1.6 from avoiding a single trans-Atlantic flight and 0.8 by changing to a vegetarian diet, researchers have found.

But having one fewer child blows those figures out of the water, with a reduction of more than 58 tons of carbon emissions per year.

This might be an uncomfortable result for many – but the data doesn’t lie.

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