Beyond the Population-Consumption Dichotomy

Most of my research and writing these days is about land use and agriculture, but every so often, I put on my think tank hat and tackle a different issue. This post, which I wrote together with Dr. Jennifer Bernstein, is an example of that. As always, comments are welcome.

In general, a large human population leads to less non-human life. Unless you are at the extreme end of the induced innovation spectrum, where larger human populations create such technological progress as to lower impacts, this is hard to argue with. But the following two statements are simultaneously true: a large human population is detrimental to non-human life, and the concept of overpopulation is both scientifically and ethically problematic. Many have understood these problems, but the most common retort today — that the culprit instead lies in overconsumption — is also an idea fraught with issues. There needs to be a different way of thinking about population and consumption that goes beyond this tired dichotomy.

An example of this dichotomy is two articles recently published in the journal Biological Conservation. The opening salvo came from Philip Cafaro, Pernilla Hansson, and Frank Götmark in their piece “Overpopulation is a major cause of biodiversity loss and smaller human populations are necessary to preserve what is left.” The response, titled "Shifting the narrative from overpopulation to overconsumption," was authored by Aalayna Green and others. Since these represent much of the broader debate, they are worth unpacking.

Cafaro et al. use the term overpopulation as if it were a scientific concept, but it is not and never will be. This is due to the tenuousness of what population level merits the prefix “over.” The authors propose the following definition:

Here we stipulate that overpopulation exists where 1) people are displacing wild nature so thoroughly that they are extinguishing numerous species; 2) people are degrading ecosystems so thoroughly that future human generations likely will have a hard time living decent lives; and (3) one or both of these environmental catastrophes cannot be avoided without significantly decreasing the size of the human population.

The definition is rife with imprecise terms — “displacing,” “extinguishing,” “degrading,” “catastrophe,” and “decent lives” — that the authors treat as settled. But a population level considered too high by one person might be just fine for another. Values, not objective facts, underlie any given definition.

There's an entire academic cottage industry attempting to scientifically determine what constitutes an ideal or maximum sustainable population, including prominent scientists like Gretchen Daily and Partha Dasgupta. But the planet’s carrying capacity is not fixed. In prehistoric times — when the human population was, say, 100 million — it would have been hard to support much more with the technologies of the era. Today there are nearly eight billion people and food production that would be enough for everyone — and then some — had its distribution not been unequal and had not so much of it been diverted to livestock feed and biofuels.

Let’s think about what’s possible. In 1979, Cesare Marchetti presented a vision of the future where the earth supports a trillion people. In this scenario, people live in dense cities, food is produced in vats, virtually unlimited energy is provided with nuclear power, and the per-capita land footprint is minimal. We are not advocating for this world, nor are we saying that this scenario is on the horizon (according to the latest UN projections, the world's population will peak at 10.4 billion around 2080). But scenarios like this are worth mentioning because they show that we are not running up against hard environmental limits. With the appropriate technical, economic, and political arrangements, some futures could provide for dramatically more people than we have today. Our technology and institutions ultimately redefine the concept of “carrying capacity” from one bound by static planetary limits to one that is ever-changing and can never be defined without values-based judgments.

The concept of overpopulation is not only problematic scientifically, but it is also problematic ethically, as Green et al. rightly point out. The conservation biology community and most readers are aware of the dark history associated with calls for population control — including statements about which populations are excessive, where control needs to take place, and what policies should be enacted to reach this goal.

Cafaro, in a solo-authored paper, states that "My own view is that every competent adult couple that is willing to take on the burdens of raising a child should be able to do so, as a basic human right. However, that right should be limited to one child."

This is a chilling statement. Take the term “competent.” Who decides who is “competent”? Is there an application and a committee evaluating “competency”? Nearly 75 years ago, known eugenicist (and former Planned Parenthood director) William Vogt wrote that since a “sterilization bonus” would “appeal primarily to the world’s shiftless, it would probably have a favorable selective influence.” One cannot escape the conclusion that only some people have the right to have children and, equally terrifying, that there is a group of people who decide who has that right. To their credit, many who caution against overpopulation don't go as far as Cafaro's implying who gets to have children.

Cafaro and the other authors of the recent piece are, at least on paper, for women's rights, but only when it serves the population control agenda. In their view, women’s rights are a means to an end, rather than an end in itself. The authors argue that women’s rights without a population component are not in women’s best interest, stating, "the campaign to disavow overpopulation and refocus birth control efforts exclusively on women’s reproductive health and rights has not served women’s rights well." This sentiment is not limited to these authors. In Colombia Magazine, David Craig suggests that "the days of promoting birth control purely as a way to empower women … may be ending."

We shouldn’t have to remind anyone that women should have every right to choose their family size, small or large. Women’s rights can’t be invoked only when they serve the ends of the conservation biology community and revoked when they do not. Autonomy, and the right to make one’s own reproductive decisions, are just that.

Consider, for example, the inconvenient fact that fertility rates are higher in the wealthiest countries, notably those with progressive social policies, like the Scandinavian countries and France. Here, having children is less of a sacrifice, especially for women, as parental leave is generous and childcare is heavily subsidized. How does that fit with the population control agenda? Not very well, according to some commentators, who argue that pro-natalist policies are coercive and impinge on women's rights or that they are incompatible with climate goals.

"In fact," writes Jonathon Porritt, "50 countries now have pro-natalist policies of one kind or another, all impinging (directly or indirectly) on a woman’s right to determine for herself whether or not she wants to have children." "State-sanctioned pro-natalism — a form of nationalism — is at odds with the reality that population remains a significant driver of global greenhouse gas emissions," according to Robert Proctor and Londa Schiebingert of Stanford University. But countries like Sweden have had policies that are essentially pro-natalist for over half a century, and they can scarcely be said to be detrimental to women's rights. What gives?

Overpopulation, according to Cafaro et al., also motivates anti-immigration policies.

"Reducing immigration in order to stabilize or reduce populations thus can help EU nations create ecologically sustainable societies, while increasing immigration will tend to move them further away from this goal."

This amounts to saying that poor people should stay in their poor countries so that rich countries can remain, within their geographical borders, "sustainable." (Ironically, immigration to higher-income countries would reduce birth rates.) Cafaro et al. are not alone in this view. Other examples include Colin Hines, environmentalist and former Greenpeace coordinator, who writes, “controlling population growth and its main engine in rich countries — namely, immigration — must be central to future environmental and social campaigning.”

We are far from the first ones to problematize overpopulation. It has been done since the time of Malthus himself. The most common retort for those aware of the problematic nature of the term overpopulation is to instead lay the blame on consumption for its role in biodiversity loss. This is what Green et al. do in their response to Cafaro et al. There is no question: consumption and the associated resource extraction, distribution, consumption, and disposal, have adverse effects on wildlife populations. However, as with overpopulation and carrying capacity, the concept of overconsumption is fraught with problems and is subject to drawing the same type of line in the sand as to what level of consumption is ideal and the associated issues with who determines those metrics.

Let's say that consumption, at least in rich countries, should be reduced. What exactly is the plan? There's no lack of proposals, and entire books have been written on the topic. However, it's hard to know what this would look like in practice since no explicitly degrowth-oriented policy has ever been attempted at scale. As a recent article noted, with a good deal of understatement, "So far, calls for degrowth have been limited to activists and academics rather than policymakers in countries suffering most from climate change."

Some policies perceived as furthering degrowth are perfectly sensible. For example, public transit and bike infrastructure investments reduce material inputs and greenhouse gas emissions. To the degree they can be successful, campaigns to moderate meat consumption lessen the need for resource-intensive livestock feed and pastures. Taxing the richest might dampen exorbitant consumption while raising money for climate mitigation investments. However, how far will voluntary and relatively modest policies like this go? Will they lead to the drastic cuts in consumption that degrowth advocates envision? If they don't, what comes next — and can it avoid being to some degree coercive or against the wishes of large swathes of the population?

Let's imagine an "ideal" level of consumption is achieved by reducing consumption in rich countries and at the same time lifting poor people out of poverty. Max Roser noted that if the income of everyone in the world was at the US poverty line — that is, rich countries go down to this level, developing countries go up — the world economy would double in size. What then? Who wants to argue that the US poverty line — the poverty line! — is too much to ask for? Then there's the fact that lower economic growth in the rich countries might hurt poorer countries' development, as they would have less income from exports and thus less of a basis for increased living standards. Few countries have gotten richer without a large export sector.

Another reason the idea of overconsumption needs to reckon with a large economy is that population and consumption are tightly coupled. In most cases, slowing population growth has only been achieved in tandem with economic growth. Economic growth — along with strengthened rights of women, girls’ education, and other facets of modernization — shifts women towards formal employment and the incentive of families to invest more heavily in a smaller number of children rather than a large number working the farm. So if you want a smaller population, the reality is that consumption will grow.

Many are familiar with the IPAT formula, which decomposes trends in environmental impacts into three drivers: Impacts = Population * Affluence * Technology. It has a brutal logic: both population and affluence (the latter related to consumption) contribute to environmental impacts. In this sense, those pointing to overpopulation and those pointing to overconsumption are both right. But the back and forth illustrated by Cafaro's piece and the response to it is getting us nowhere. We need to speak and think differently about population and consumption and their associated environmental consequences.

Most importantly, the concept of overpopulation has to die. It is laden with rhetorical baggage and cannot be objectively defined.

The next is to stop treating women’s rights as a means to an end, with those rights contingent on the particular end imagined by population control advocates — or any types of advocates. Rights are rights. Supporting those rights might lead to lower populations, but that is a side effect and cannot be the motive.

With the arguments about population and consumption, another important factor is less discussed — technology, the T in IPAT. But reducing the per-capita impact of the human population with innovation and deployment of better technologies has to be part of the way forward. We will have a large and increasingly wealthy population for a long time to come, so we need to deal with it, and technology — renewables, high-yield farming, pick your favorites — can be part of that. Relying on technology — just like relying on concepts of overpopulation and overconsumption — is not unproblematic; people have rightly noted that historical progress is not fast enough to keep us below 1.5C of global warming or halt biodiversity loss in the immediate future. But it might be the most powerful tool in the toolbox.

In sum, the way forward lies in abandoning the concept of overpopulation, valuing women’s rights for their own sake, enacting modest and democratic policies to moderate rich-world consumption while supporting developing countries in achieving higher levels of material well-being, and investing heavily in environmentally-friendly technologies.