Just population policies for an overpopulated world

By Philip Cafaro | 16 November 2021
The Overpopulation Project

(Photo by Nikita Vasilevskiy on Unsplash)

After three decades of neglect, more environmentalists are waking back up to the need to limit human numbers. But like Rip Van Winkle, we find that the world changed while we were asleep. There are now billions more people, consuming more than ever, while our world has grown warmer, tamer, and more polluted. A new article in The Ecological Citizen discusses what just population policies might look like in an overpopulated world.

Like other sustainability advocates promoting reforms that run counter to mainstream economic boosterism, population advocates have learned to carefully police our language and temper our proposals. Given how far our societies are from sustainability, just slowing down their enthusiastic charge in the wrong direction can look like a reasonable goal. For instance, “population stabilization” sounds less threatening to our fellow citizens than “population reduction,” so that’s what we often end up arguing for. But as Karin Kuhlemann observes, “that a population’s size is stable in no way entails sustainability. It may be sustainable, or it may be far too large.”

There’s the problem. Globally, current human numbers appear nowhere near compatible with long-term human wellbeing and the flourishing of other species. In their article “Sustainable welfare and optimum population size,” Theodore Lianos and Anastasia Pseiridis calculated that the world could safely accommodate 3.1 billion people living on an average annual income of $9000 per person, an amount deemed sufficient for a satisfactory life. They then calculated sustainable populations for the world’s 52 most populous nations, on the premise that each country was entitled to a share of the sustainable global population equal to its share of global cropland. Graph 1 below shows the difference between recent, future, and sustainable populations for the world’s five most populous countries based on these stipulations.

Graph 1. Population and overpopulation in the world’s five most populous countries. Data in first two columns from Lianos and Pseiridis (2016), last column from United Nations (2019).

These sustainable national population estimates assume a willingness to limit or reduce average annual income to $9000; at higher average incomes, the sustainable population decreases proportionally. Of course, income is only a crude measure of our use of natural resources and generation of wastes, and many other things besides the availability of agricultural land factor into sustainability. Still, these rough calculations give some idea of the amount of population decrease these five countries would need to achieve sustainability.

Clearly that amount would be immense. China would have to cut its population by nearly 1.15 billion people to reach sustainability: from 1.4 billion today to approximately 250 million. India would need to reduce its population by nearly as much, down from 1.4 billion today to about 340 million. At first glance, America looks in better shape, but only if we ignore the need to drastically cut income and consumption to sustain 325 million people. Americans’ average annual household income in 2020 was around six times greater than $9000, so unless we were willing to cut our incomes substantially, a sustainable U.S. population would need to be a small fraction of our current numbers.

Looking at the UN’s projected populations for 2100, none of these five countries are anywhere close to achieving a sustainable population under current demographic and economic trends and policies. Nor are most other nations, whether overdeveloped or underdeveloped. This is shown, for example, by Lianos and Pseiridis’ calculations for sustainable populations for the seven most populous European nations, shown in graph 2 below.

Graph 2. Population and overpopulation in Europe’s seven most populous countries. Data in first two columns from Lianos and Pseiridis (2016), last column from United Nations (2019).

Leaving aside Russia as a continent-sized outlier, the six other most populous European countries would all have to cut their populations substantially to achieve sustainability: France by 40 per cent, Italy by 66 per cent, Germany by 70 per cent, the United Kingdom by a whopping 81 per cent – down from 63 million to 12 million people. All this, remember, with the stipulation of an average annual income of $9000. With the extra income that most Europeans probably would want to retain, sustainable population sizes decrease proportionally.

Developing nations, meanwhile, face demands for more consumption by the poor, rising consumption by a burgeoning middle class, and the same excessive consumption by the wealthy seen in the developed world. Here, too, sustainability demands decreased human numbers, to free up ecological space for the poor to increase their consumption. Instead, many developing nations are moving rapidly in the opposite direction, as shown in calculations for sustainable populations for the six most populous sub-Saharan nations (graph 3 below).

Graph 3. Population and overpopulation in sub-Saharan Africa’s six most populous countries. Data in first two columns from Lianos and Pseiridis (2016), last column from United Nations (2019).

According to Lianos and Pseiridis’ calculations, Nigeria would need to decrease its population of 206 million to 38% its current size, 79 million, to achieve a sustainable population at an average annual income of $9000. Instead, it is on track to increase more than 250% by 2100, to 733 million people. Ethiopia’s current population of 115 million would need to shrink to 31 million, 27% its current size, to achieve a sustainable population. Instead, it’s currently projected to increase by 155% to nearly 300 million. And so it goes throughout the region. Comparing these three graphs shows us that for all their differences, richer and poorer nations today share a key characteristic: they are both massively overpopulated relative to the income and consumption they engage in or aspire to.

Population policies for an overpopulated world

Around the world today, overpopulation contributes significantly to unemployment, malnourishment, crowding, poverty, disease, and other harms afflicting hundreds of millions of people. In this century, it threatens billions with such suffering. Overpopulation has also contributed to massive biodiversity loss over the past century and threatens to extinguish millions of species if not reined in. Arguably these facts don’t merely justify stringent efforts to reduce human numbers as quickly as humanely possible. They require them, as a matter of justice between current and future generations, and between people and other species.

That’s the premise of a new publication I recently published in The Ecological Citizen as part of their special issue on overpopulation. “Just population policies for an overpopulated world” tries to strike the proper balance between protecting reproductive rights and promoting reproductive responsibility, and between human interests and the well-being of Earth’s many other life-forms. In it, I claim that overpopulation justifies a new ethical imperative:

  • would-be parents should restrict themselves to one child

Larger families are socially irresponsible at this point in history, whether in rich societies or poor ones. There simply isn’t room for them. The paper further argues that urgent environmental threats also justify stringent public policies designed to rapidly, yet humanely, decrease national populations. In particular, it maintains that national governments should:

  • guarantee their citizens universal, affordable access to family planning services, modern contraception, and abortion on demand.
  • encourage their citizens to have only one child and discourage them from having more: through widespread information-sharing, tax and benefits policies, and direct advocacy to change patriarchal norms.
  • strictly limit immigration, as part of comprehensive efforts to reduce their populations to sustainable levels as quickly as possible.

Together, I claim, such measures can reduce national populations rapidly, yet fairly. This in turn could make possible genuinely sustainable societies and allow people to share the landscape generously with other species.

Of course, I do not argue that societies should average only one child per couple forever. That would lead to permanently decreasing populations and, eventually, human extinction. In time, once they reach a sustainable population size, societies can transition back toward averaging two children per family. But that time is several generations in the future. For now, we need to average one-child families—on pain of potential ecological disaster.

Many people will disagree with the need for prescriptive policy measures to reduce human numbers, which, to be clear, is my own position, not necessarily TOP’s. But before dismissing such proposals, we need to be open and honest about what is at stake and whether unprompted voluntary restraint can be sufficiently effective. We invite you to read “Just population policies” and express your views by posting comments below.

Other articles in The Ecological Citizen’s special issue on overpopulation include:

Reprinted with permission from Frank Götmark – Project leader of The Overpopulation Project (TORP); Professor, Animal ecology and Conservation Biology, University of Gothenburg.

Sir David Attenborough on overpopulation

World Population to hit 11 Billion in 2100 Full Documentary

8 Billion Angels – OFFICIAL TRAILER

World Scientists’ Warning of a Climate Emergency


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