Is emergent pro-natalism a threat to a sustainable future?

The most recent (2024) World Population Prospects data from the UN suggests that peak global population estimates have eased.  The central projection for peak population, expected to occur in the 2080s, has dropped from 10.4 billion to 10.3 billion, (compared with the current population of 8.2 billion).   

There are still large uncertainty ranges around those central estimates.

This chart from the same report summarises the component demographic drivers of global population, and how they interact over time as countries pass through what is called "the demographic transition".

This curve broadly plays out to determine what the peak population is going to be, once all countries have arrived at "post-transition" stage.

An earlier (and smaller) global population peak would be good news (eg if it translates into potential reduction in future pressures on the environment in some post-transition countries), which should generally please most environmentalists.

However, some pro-natalists have seized upon this reduction in the peak population estimate to strengthen their arguments for encouraging fertility rates in countries currently experiencing falling or low fertility rates (below replenishment rate).

They point out (quite rightly) that where some countries now have falling populations, that creates some problems and challenges (eg ageing populations and fewer people of working age to pay taxes to support social provisions including those for the elderly), even though at the same time it can potentially reduce total environmental impacts generated by such a country's aggregate population. 

​However, even in that complex post-transition situation, it's an over-simplistic response to say that such countries should take public policy steps to increase their populations through "growing their own" (eg instead of allowing inward immigration to address the problems and challenges).

I think it's helpful to return to one of the first equations people are taught in the subject of environmental studies - the IPAT equation.  This equation was created by Paul Ehrlich and John Holden in 1971, to describe the key factors driving the aggregate environmental impacts of the human population.  

Most terms in the equation are self-explanatory.  

The least intuitive is the "T", so I'll explore that a little.  Some people describe this factor as "Technology".  But it's better described as "resource and waste efficiency", ie a measure of the environmental impact per unit of product or service consumed.  The "environmental footprint" per unit consumed.  Technology clearly has a part to play in that metric, but it's not the only driver of the value of that factor in the equation.  

​Of the various factors making up the IPAT equation, global population is generally the most stable, slow-moving and predictable over quite long timespans (several decades). The other factors vary more significantly and unpredictably, eg by the average affluence in countries and paradigm shifts such as global net zero, the switch from fossil energies to renewable energies, the switch of mass transport from fossil fuels to electric transportation etc.

So, to some extent, focussing on population (as pro-natalists do) is an unnecessary distraction.  An exception to this is to note the relationship between peak population, environmental impacts at peak and environmental tipping points.  We need to do our best to avoid triggering such tipping points, so knowing what the peak population will be is very important.  But the other factors in the IPAT equation have bigger potential for yielding improvements in environmental sustainability through public policies. 

At the current time, it's not at all clear that we will avoid tipping points, so it doesn't make sense to increase peak population, through pro-natalist policies, at the global level, and this is in accordance with the Precautionary Principle.

It seems to me that, where we are currently in the early stages of dealing with unsustainability crises such as Anthropogenic Global Warming and climate change, the risks are asymmetric.   The risks associated with triggering climate tipping points are far greater than the risks associated with falling fertility rates.  Also, it's much easier to enact pro-natal public policies in future (if needed) than it would be to tackle runaway climate change in the event of triggering one or more climate tipping points.  

We just need to consider if the problems associated with falling populations in specific countries in "post-transition" are serious, and whether or not they are solvable without adopting pro-natalist policies.

​But that's a subject for another day...

    

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​References:

United Nations Department of Economic and Social Affairs, Population Division (2024). World Population Prospects 2024: Summary of Results