I remember being taught in geography classes about the environmental dangers of overpopulation. Our kids, we have heard again and again in recent years, are going to be a blight on the environment. Article after article has agonised about whether we should have children at all. Would it not be a kindness to the planet if we just stayed childless? Thus antinatalism has acquired a very modern shade of green.
Unfortunately, following years of doom-mongering by groups such as Population Connection, as well as climate activists, many now reference the environment as a major reason for not expecting to have kids. People debate the extent to which this is a reason or an excuse. However, even if the true number of people who would want kids if not for environmental worries is a tenth of that reported, that’s still about 1 in 100 people. For context, in the UK alone that would mean 700 thousand people across the course of their lifetime choosing not to become parents because of these environmental concerns.
But people’s concerns about the environmental costs of having kids are wrong on their own terms. A lot of rhetoric around the climate costs of childbearing is based on pessimistic projections from old data when carbon emissions per capita were a lot higher. Many figures bandied around also use US carbon emission rates — which are multiples of European emissions per capita.
A 2017 study (Wynes & Nicholas) is often cited to say that having a child is the single worst thing one can do for the environment. Their research solely relied on a 2009 study (Murtaugh & Schlax) for its figures on the carbon costs of having children. The 2009 study uses 2005 data, from a time when per capita emissions were highest in the developed world. They have since come down substantially.
Raising the fertility rate today would have a slow effect on population growth
Another way Murtaugh & Schlax obtained such high figures was by including “carbon legacy” for grandchildren, forecasted by conventional fertility rates at the time. But fertility rates have come down in most of the developed world since then and even back then had shown a downward trend. By counting grandchildren, Murtaugh & Schlax were really estimating the carbon cost of both your and your children’s decision to procreate — but they could not predict the sort of world that we would live in any more than you can predict what sort of world your children will live in.
European emissions have kept falling. The only paper that integrates downward trends in carbon emissions into the carbon cost of procreation was published in 2023. This makes it far more realistic than estimates that take current carbon emission levels as fixed. This paper predicts that under pessimistic forecasts of carbon emission reductions, a shift to replacement level fertility would raise warming by just 0.05 degrees Celsius by 2200.
How did it get a figure so different in its implications than the sensationalist ones? Carbon emissions have been falling as alternative technologies get better and better. Hydrocarbons are still very important for our prosperity today and in the near future, but as arc steel furnaces become more efficient, electric car batteries last longer and electric power to ammonia becomes a viable alternative to Haber-Bosch fertiliser, this importance will continue to fade. Meanwhile, raising the fertility rate today would have a slow effect on population growth. It will take 15 years to make a full new replacement-fertility generation, and another 20 years to take them to adulthood. That is a long time before they have the chance to significantly contribute to carbon emissions, by which time carbon emissions will be even lower than they are today.
Therefore, the latest evidence suggests that the marginal effect of a higher fertility rate in Europe on long run global warming is negligible. Achieving replacement fertility in Europe will not affect whether there is a climate disaster. Those who try to save the planet by having fewer children are sadly misguided.
Since having more children does not bring a significant carbon cost anymore and does help with ageing population, having children is a clear-cut social good. The more that we tell people otherwise, the higher the number of people who want children will be put off by incorrect information about the environmental effects.
Have babies, if you want to. It will change your life, it will give them life and it won’t do a lot of harm to the planet.
