Whether residents of high-income countries are morally obligated to have fewer children is a growing debate in climate ethics. Because of the high projected carbon impact of future population growth, some climate ethicists are expressing support for non-coercive population manipulation policies, such as reduced tax credits for children.
This debate has attracted wide public attention, making family planning an important topic in climate change prevention.
Much of the debate is supported by an influential US study published in 2009 by Oregon State University. The starting point of the research is that a person is responsible for the CO2 emissions of his descendants, weighted according to their relationship. A grandparent is responsible for a quarter of each of their grandchildren’s emissions, and so on.
Having a child sets in motion a cycle of continuous reproduction over many generations. The emissions of future generations are included in the carbon legacy of their ancestors.
Children’s CO2 impact
Using this logic, the authors found that having one child adds 9,441 tons of carbon dioxide to each parent’s carbon legacy. This corresponds to more than five times their own CO2 emissions over the entire lifetime. The potential savings from reduced reproduction are therefore dramatic.
This result is usually considered obvious in both academic debates and popular discussions, while its details and assumptions are rarely scrutinized. However, the result depends on the assumption that all future generations will emit at 2005 levels indefinitely, an assumption that is not quite right now.
For example, from 2005 to 2019, before being artificially suppressed by the COVID pandemic, per capita emissions in the US fell by 21%. And in the future, they are likely to fall even further.
Major public investments accelerate the transition to carbon neutrality. The recent US Inflation Reduction Act allocated US$369 (£319) billion to fight climate change.
Net zero has also become a legally binding target in many countries. The European Climate Act, for example, aims to achieve net zero carbon emissions across the EU by 2050.
Rethinking children’s carbon impact
Given these efforts, the central assumptions underlying the study need to be reconsidered.
Using the same reasoning that yielded large CO2 impact figures for reproduction, we instead suggest that having a child today may be much less damaging to the environment than is commonly believed.
If countries with high per capita emissions reach net zero by 2050, a child born in one of these countries in 2022 would only generate emissions until they are 28 years old. After 2050, they and their descendants would no longer cause additional emissions. Adding up their lifetime emissions therefore yields a much lower CO2 inheritance.
Assuming emissions decline linearly to zero until 2050 and the child is not reproducing during that time, a child born in 2022 will add seven years of carbon emissions to each parent’s lifetime carbon footprint. This is because in the 28 years to 2050 a linear decrease can be modeled as half of the total amount on average (14 years) with each parent responsible for half of their child’s footprint (seven years). Subsequent generations add zero emissions to this.
The difference between this potential scenario and the accepted “constant emissions” scenario is large. But even this much lower result may still overestimate the CO2 impact of having a child.
This figure assumes that a child will cause additional emissions at the per capita rate of the country of residence. However, children generally do less high-emission activities than an adult. They share a household with their parents and will not drive or go to work for much of the period until 2050.
Especially in the near future, where per capita emissions are highest, a child is likely to cause far fewer emissions than the average per person in their country.
Net zero obligations must be met
Aiming for net zero can significantly reduce the climate impact of having children in countries with high per capita CO2 emissions. However, this remains dependent on the fulfillment of this commitment.
Progress towards net zero is faltering, while current climate policies in many countries are falling short of their commitments.
Despite having a net-zero strategy, the UK’s progress towards carbon neutrality is limited. Emissions in the UK rose by 4% in 2021 as the economy began to recover from the pandemic – and many other countries with high per capita emissions are in a similar situation. Prime Minister Liz Truss’ cabinet appointments have also cast doubt on the UK’s commitment to climate goals.
So delivering emphatic reductions on the carbon impact of reproduction remains a long way off, despite our reassessment of the 2008 study.
Read more: ‘Too scared to have kids’ – how BirthStrik for Climate lost control of its political message
As a society, it is in our power to set ourselves on a credible net-zero path. This also means rejecting the popular tendency to assume that climate change should be addressed through individual lifestyle changes, rather than institutional and structural changes. If net zero is reached, it would be possible to have children without being saddled with environmental debt.