The world population has just hit a new record: 8 billion.
As is often the case, there are heated debates about the planet’s so-called “carrying capacity” – the total number of people who can live on Earth sustainably. Experts are generally divided into two camps.
There are those who argue that we need to drastically reduce the human population to avoid ecological catastrophe.
And then there are those who believe that technology will find smart solutions without any need to actively tackle the issue head-on.
Scientists have been debating such demographic issues at least since the 18th century, when Thomas Malthus published An Essay on the Principle of Population, arguably the first global treatise on the relationship between population growth and scarcity.
A few decades later, however, the Industrial Revolution (which the British economist had failed to anticipate) ushered the world into an era of abundance, relegating Malthus’s grim predictions about the inevitability of scarcity to the margins of scientific debate.
In a bestselling book published in the late 1960s, The Population Bomb, Stanford professor Paul Ehrlich brought the topic back, advocating for immediate action to limit population growth on a finite planet.
This recommendation was reiterated a few years later by the Club of Rome, an international network of scientists and industrialists.
Its 1972 report The Limits to Growth aptly demonstrated the dynamic relationship between increasing consumption and the idea of “planetary boundaries” which cannot be crossed without risking severe environmental change.
It’s true that some technologies have made production more efficient (think of fertilisers), thus alleviating the impact of population growth on resource use.
A smaller population could still be more destructive
It is difficult to estimate just how many humans the planet can carry sustainably, however.
This is often overlooked in policy debates, which generally deal with the issue rather simplistically, resting on the assumption that increasing living standards will lead to lower birth rates.
Therefore, the argument goes, the global population will decline as soon as continents like Asia and Africa reach similar development levels as Europe and North America
The fallacy here is to assume that only technology and population matter. These days environmental scientists generally agree that the overall impact is also a function of affluence (the so-called I=PAT equation).
This can easily generate a paradox. Countries continue increasing their living standards by pushing up per-capita consumption, thus resulting in smaller populations but much bigger ecological impacts.
Take China. Its population growth rates have gone down significantly from 2.8% in the 1970s to the first decline in absolute terms this year.