One child fewer per family worldwide could be necessary to save Earth from overpopulation

The scientific evidence is already amassing that the Earth has far more humans, living at far higher levels of consumption and pollution, than it can possibly carry in the long run.

Overpopulation is not a matter for individual or group opinion, or for ideology. It is defined as the point when a creature begins to exceed and then to destroy the resources that support and give it life. It can be measured. In countless ways, the evidence is accumulating that humans have overpopulated planet Earth by exceeding the boundaries that ensure the renewal of life.

Early warnings of this danger were uttered by Professor Paul Ehrlich in The Population Bomb (1962) and Club of Rome in Limits to Growth (1972). Then in the 1990s Matthis Wackernagel developed the Global Footprint Network whose work now shows we exceed the Earth's renewable carrying capacity by July each year, making the world economy nothing more than a giant Ponzi scheme.

Yet these well argued, firmly-evidenced warnings have all been dismissed or belittled by various vested interests - political, religious and commercial - who care not about the survival of humanity, but only what they can gain from it in the short run. Overpopulation is the word no politician, priest, economist or business executive dares to utter. It is the unmentionable - but inescapable - elephant in the room of the human future.

The advent of the eight billionth little human gives us sober reason to reflect on the dangers of overpopulation.

In the space of a single lifetime our numbers have swollen from 2 billion to 8 billion and continue to burgeon at a rate of around 80 million (1 per cent) a year. Anyone who considers the matter soon realises that the resources needed to support such gigantic numbers will run out - and there will be an exceedingly painful crash.

While our numbers were quadrupling, our consumption has also run off the rails and is generating the resource and environmental crises that now loom. Since 1972, human consumption of material resources has tripled from 29 billion tonnes a year to 101 billion tonnes in 2021 - and is on track to reach 170 billion tonnes by 2050, as documented in The Circularity Gap report.

The other thing that has run off the rails is pollution. All told humans release over 200 billion tonnes of waste into the biosphere every year, including 2.5 billion tonnes of chemicals, mostly toxic. This is having a dire impact on the ability of all forms of life, ourselves included, to survive in the long run. The universal vanishing of insects, bees, frogs and birds is almost certainly related to this uncontrolled toxic avalanche.

So yes, the bomb has already exploded, though the full impact of the blast is yet to be felt.

This raises the essential question of how we can take deliberate, voluntary, steps to reduce the human population - along with its consumption and pollution - back to a size the Earth can sustain.

The central issue of human population growth is not whether it is good or bad. It is: can we avoid a devastating crash, caused by our outrunning the planet's ability to support us? Voluntary population reduction is therefore about sparing billions of people needless and agonising deaths by starvation, war and disease, which will otherwise result from a collapse in our resources. To prevent the crash, we have to prevent and reverse the growth.

Those who advocate a larger population, for either the planet or country, are calling for disaster. Whether they admit it or not, in the same breath they are advocating:

Every person who insists on their 'right' to have more children, diminishes the right of all children - including their own - to live on a safe, habitable planet.

Fortunately, a growing number of thinking people are embracing the idea of 'one child fewer' per family, and many are even taking the decision to remain childless - because they foresee what a fearsome world a child born today will face. The 'one child fewer' proposal means each family deciding to have one less baby than they otherwise might have had - and idea proposed by Seth Wynes and Kimberley Nicholas in 2017, based on a study of the best ways an individual could reduce their carbon footprint.

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If universal family planning is made available, and 'one child fewer' becomes an accepted global norm, then UN projections suggest it is possible to reduce the human population to 6.5 billion by 2100 - and lower still beyond that.

However, the scientific evidence suggests that this is still three times more than the Earth's carrying capacity, which is estimated at 2-2.5 billion people, living at advanced living standards.

For human civilisation to survive in the longer run, the global conversation now needs to turn on the best way to reduce our numbers, in the least painful way, and without coercion.

Because - let there be no doubt - if we don't do it ourselves, then nature will do it for us.