EARLIR THIS MONTH, it was reported that Elon Musk, the unelected head of the Department of Government Efficiency (DOGE) in the US, had become a father again:

“The biggest problem the world will face in 20 years is population collapse,” Musk said in 2019, referring to the evidence of multiple countries around the world experiencing an accelerating decline in birth rates.

Musk believes that “people are going to have to revive the idea having children as a kind of social duty otherwise, civilisation will just die,” he said in a 2014 interview, per biographer Walter Isaacson.

Vice-president JD Vance agrees.

“I want more babies in the United States of America,” he said in his first address to the United States after becoming vice president.

In late January, a Department of Transportation memo directed the agency to prioritise projects that ‘give preference to communities with marriage and birth rates higher than the national average’.

A new concept of ‘pronatalism’ is gaining momentum. But it is a false god.

What is pronatalism?

Pronatalism can be defined as the belief that having children is important to the greater good whereas declining birth rates are a threat to national stability and growth.

While the United Nations reports that the rate of new people being born is definitely slowing down, the global population is expected to continue growing for many more decades.

The real question that is not being asked by pronatalists is whether the global population has already surpassed the ability of the planet to sustain it.

The reality is that growth always ends. There will come a point where the population grows beyond the ability of the planet to sustain it, and there are clear warnings that we have already passed that point.

Population

The UN expects the global population to reach 8.5 billion in 2030 and 9.7 billion in 2050. By 2100, the organisation expects there will be 11.2 billion people on the planet.

These figures take into account births and deaths. What is not being fed into the equation is the way in which human growth is finally bumping up against the physical limits of our biosphere. Sooner or later, one way or another, these limits will drive a radical transformation of human civilisation.

Many people assume that the human population can continue to grow exponentially forever. Musk in particular seems to think that we will soon be populating Mars and that will solve the problem of a trashed planet as we move onwards and upwards.

Greenhouse gas emissions

But not only is the population growing exponentially – so too are human greenhouse gas emissions, at a rate of 2.2% per year. Before James Watt patented his steam engine in 1781, the atmosphere’s CO2 concentration was 280 ppm, with a climate that was stable.

At 2.2% annual growth, the cumulative growth of CO2 dumped into the atmosphere is doubling every 30 years. By 2014, CO2 concentrations had risen to 400 ppm and three decades later in 2044 are predicted to reach 520 ppm.

In other words, growth starts slowly, but the early 21st century has seen a sea change in growth of greenhouse gas emissions that continues on an explosive trajectory of doubling approximately every three decades.

Peter Kalmus, climate scientist and author of Being the Change (2017) sums up the reality by saying this is why he is ‘certain that global fossil fuelled industrial civilisation will soon end, one way or another.’

The global population growth peaked at 2.2% per year in 1963, the year I was born when there were 3.2 billion people, equivalent to 190,000 new humans per day. By 2014, growth had decreased to 1.1% per year, but because there were now 7 billion people, this translated to 217,000 additional people each day.

Scarce resources

The main reason for the slowing of birth rates is the empowerment of women with improved access to both education and contraception. When women gain control over family planning and have career options, they tend to delay having families and have fewer children.

However, the UN predicts population growth to 9.7 billion by 2050 and 11.2 billion by 2100 with growth of about 0.1% per year. The global replacement rate is 2.3 children per woman: if no person had more than two children, the global population would steadily come back down to earth.

At this point, there is a systemic problem. Falling fertility rates challenge the global economy, but continued population growth is unsustainable.

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The system that supports continued existence on the planet is called the biosphere. The biosphere provides food, water, oxygen, waste removal, a stable and temperature climate and protection from harmful solar radiation. These systems do not exist in isolation but are powerfully interconnected. You can’t grow food without water, and the distribution of water across the globe, as it is becoming increasingly apparent with the increased frequency and intensity of droughts and floods globally, is dependent on a stable climate. The population has already grown to a point that has put these life-supporting systems under pressure.

Kalmus questions whether we can sustain the amount of food we grow indefinitely. “Nonhuman animals are quite literally under relentless systematic attack from a mechanised and militarised global economy of nearly 8 billion humans; but ultimately the only way to avoid the sixth mass extinction is to address the underlying causes.”

If eight billion humans (living and eating as we’re actually living and eating today) is beyond carrying capacity, what is the sustainable limit?

How many people can the planet sustain?

Kalmus states that some evidence supports the Earth’s carrying capacity at about 4 billion. This is based on the average land required to support one average person globally, including ecosystem services. A paper in Population and Environment (1994) suggested that the 1994 global population of 5.5 billion “clearly exceeded the capacity of the Earth to sustain it.”

Obviously the carrying capacity would increase with more people being vegetarian. Eliminating meat consumption would double the carrying capacity to 8 billion and eliminating food waste (about a third of food is wasted) would potentially increase carrying capacity by another quarter – about one or two billion people.

Exponential population growth in the last century has been intrinsic to intensive agriculture that involves high yielding crops, irrigation, nitrogen fertiliser and chemical pesticides.

Now genetically modified organisms have been added to the mix. But intensive agriculture comes at a cost, with the biosphere under increasing threat.

The real question about global fertility rates is not the threats to national economies and society from falling births, but the absolute imperative for the fertility rate to fall exponentially- particularly in countries with the highest carbon footprint.

Countries such as China, the US, India and Russia need to reduce both their populations and their carbon footprint if we are to have the remotest chance of preventing a global economy that is based on exponential growth from eating the planet alive.

Rather that focusing on ways to maintain consumerism and endless growth maintained by high fertility rates, Trump and his allies would do well to focus all their energies on searching for ways that societies can live on Earth in alignment with the fantastically complex biosphere we were born into.

Dr Catherine Conlon is a public health doctor in Cork.