In November 2022, the Earth’s human population reached 8 billion.

More than 8 billion humans are alive, and our population is growing exponentially. How did we get here, to the point of such rapid population growth and expansion? And, more importantly, is this growth sustainable?

Increasing populations throughout nature always come with challenges, but the ones faced by humans are especially unique. From issues of health equity and happiness, to balancing economic progress and environmental protection, there are many challenges the human race will have to face as we expand and transgress the boundaries we usually see on populations in nature.

But is it all bad, and is the human race equipped to handle these challenges?

The story so far

A bit over two centuries ago, during the industrial revolution, mortality rates started to drop dramatically — particularly among infants and young children — as we developed modern medicine and sanitation methods. Until then, population levels had been relatively stable. According to the UN, it took all of human history until 1804 to reach the point where even one billion humans were alive on our planet.

But as mortality rates dropped, birth rates also increased. More and more people were living till adulthood and having children, and it wasn’t until 1960 that researchers developed reliable methods of birth control. Following that first milestone of one billion people, we took only 123 years to reach a population of two billion, followed by 33 years for three billion, and less than 15 years for each subsequent billion. If current trends remain unchanged, the United Nations Department of Economic and Social Affairs (UNDESA) estimates that the human population will grow to 11 billion by 2,100.

Today, even as we reach new heights, things are starting to slow down. It took us 13 years to go from four to five billion people and a further 11 to reach six billion, but it’s taken a full 12 years each to get to seven and eight billion people, and it might take even longer to reach nine billion.

But even though populations have grown with human progress, continued growth can also be linked with slow social progress. One factor associated with population growth, identified by the UNDESA, was increased birth rates in certain regions, caused primarily by a “lack of autonomy and opportunity among women and girls.”

Health inequities

One concern with population growth is that more people needing the same resources and public services will worsen existing inequities, particularly in health.

In an interview with The Varsity, Carmen Logie — Canada research chair in global health equity and social justice with marginalized populations and a professor at the Factor-Inwentash Faculty of Social Work — defined health equity as “a stance that all people deserve access to well-being,” which focuses on “how resources and social processes produce a type of health inequality.” When social structures do not allow everyone to benefit from resources and programs, we end up with unequal access to services and resources such as health care, ultimately impacting health outcomes.

When we look at health risks related to obesity, for example, public health communication tends to focus on the individual. Still, Logie explains that because our social environment “has so much influence on our ability to access healthy food, walk around our neighbourhoods, and access a range of health clinics,” reasons behind health factors like obesity are more systemic than they may appear. 

Logie explains that these disparities in equity can exist across several dimensions — including gender, sexual orientation, and race, as well as the intersections between these. 

And as populations grow, there is a risk that these disparities will only get bigger.

We’re already seeing the impacts of this in the realm of climate change. Logie and her colleagues recently found that when girls and women face increased water scarcity, they may also face increased gender-based violence.

Gender-based disparities already exist before water scarcity becomes an issue, but the added psychosocial stress of lack of water further amplifies these disparities.

Instead of populations increasing across generations, we’re now also seeing ageing populations. Nations are worried that ageing populations may result in slower progress, potentially leading to a lack of resources as populations grow. Still, it seems as though this trend will continue in most of the world besides sub-Saharan Africa.

So, what can we do? To create a more equitable society, Logie mentions we should focus on social determinants of health and ensure people have equal access to basic needs. We also need to focus on bridging the gaps and disparities between genders, races, and other axes where these issues occur. Only through holistic, intersectional approaches will we progress in this realm.

Happiness

As populations grow and cities get denser, changing circumstances could impact individuals’ happiness and satisfaction levels. In an interview with The Varsity, Felix Cheung, Canada research chair in population well-being and assistant professor of psychology at U of T, discussed the potential impacts on well-being we might face as society changes.

Cheung’s lab at U of T, the Population Well-Being Lab, focuses on better understanding the determinants and consequences of satisfying and purposeful lives. They use interdisciplinary approaches to explore population well-being in different global contexts.

Cheung mentioned that, while population growth may not directly impact well-being, “population density has a detectable but small negative effect on happiness.” Since urban areas are able to accommodate more people, it is reasonable to expect that population densities in these areas will increase across the globe. Therefore, indirectly, increasing populations may have consequences on the happiness and well-being of individuals in cities.

But there are ways to mitigate these issues. “We need to think about development from a human-centred way informed by well-being or happiness research,” Cheung argued. We can use the knowledge we get from happiness research to create better policies and cities.

While we look for solutions and means to improve population well-being, it is essential to understand that happiness, like health, is not just an individual responsibility. Many health and wellness programs put the burden on individuals by prescribing gratitude journals or meditations. While these practices can be beneficial, they may also often backfire by making people think they should be happier than they are. Instead, individuals, organizations, and governments need to work together to achieve satisfaction in our lives and happiness, especially as populations increase.

Is this growth sustainable?

Whenever there are discussions on population growth, one line of questioning always arises: how much longer can we keep going? How long will it be before nature takes its course and human populations collapse, unable to sustain the level of growth we’ve maintained since the industrial revolution?

The rationale behind these questions is simple and based on general ecology principles. Every population in every species has a carrying capacity — an upper limit for the number of individuals a particular environment can support. As a population approaches this point, provided there are no predators to limit its growth, resources become more scarce and harder to come by, reducing the population’s growth rate until its size declines or remains constant around the species’ carrying capacity.

If every other species has this, it seems intuitive to assume the same of humans.

The argument puts forth that, in a finite world like ours, continued demographic and economic growth is impossible. Technological innovation may also never be able to replace natural resources fully, which could limit population growth. To avoid resource depletion catastrophes, proponents of this argument claim we should control human populations to reduce humanity’s drain on natural resources.

Arguments around carrying capacity are known as the pessimistic side of the population growth question. But many individuals, including Pierre Desrochers, an associate professor of geography, geomatics, and environment at U of T, favour the optimist’s position more.

When talking about population growth, optimists argue that larger populations lead to more individuals engaged in trade, creativity, and progress, creating more prosperity than individuals working alone would experience. One part of Desrochers’ argument is based on trade — animal populations are limited to resources within their region, but humans seem to have evolved past that with the ability to trade.

Another essential aspect of this argument is human creativity. In an interview with The Varsity, Desrochers points out the brain’s powerful ability to “recombine existing things in new ways, solving problems, and the more we advance, the more we can advance.” Innovation then seems more exponential than linear as more people from our growing society build upon past creations to keep up with the rate of human population growth and needs.

According to Desrochers, pessimistic perspectives on population growth have been proven wrong throughout human history. From Catholic priests in the 1600s to economist Thomas Malthus, who popularized the pessimist perspective in the eighteenth century, the pace of human innovation has outstripped all predictions. “The limits argument does not apply to human beings,” Desrochers claims.

Despite the fact that human population growth doesn’t seem to currently be limited by environmental factors, we are seeing a steady decline in growth rates across the world. Many nations, including most of Europe, Canada, Brazil, and Singapore, are now below ‘replacement-level fertility,’ since each new generation is less populous than the previous. Despite this, these nations have increasing populations, potentially due to immigration and increasing life expectancy.

Overpopulation, at least on a global scale, is not a concern in the way many think it to be. Humanity and its technological innovations have the power to keep us going for a long time. But there are still factors that are limiting us — our social and cultural priorities, which inform policy and shape the world we experience, are also going to have to adapt as human populations change and grow. The mismatch between our priorities and what we actually see in the world today creates dangerous inequalities — and that will only get worse until we address them properly.