In July, Resilience.org published an opinion piece by Chris Smaje titled Population: What’s the Problem? As sustainable population advocates, we at World Population Balance thought we should help the author answer that question. We felt it essential to point out several reasons why population – and specifically overpopulation – is a huge problem if we hope to build a sustainable future. We have a lot of respect for the Post Carbon Institute’s work, including the content published at Resilience.org. Unfortunately, the editors at Resilience.org declined to publish our response. We offer it here and thank MAHB for its dedication to informed debate.

Smaje apologizes at the outset for the “clickbait-y title” and “doesn’t doubt” that population levels are a problem. And Smaje notes that “it would be a good thing if human population was lower than it is.” We and many other population-concerned people around the world would argue that it’s not just a “good” thing. It’s an essential thing if we hope to have a viable ecological habitat for us humans and other species for the long-term. Smaje asks what “kind of problem” these population levels are. We’d respond that current human numbers are an existential kind of problem, and the evidence keeps piling up.

Twenty thousand scientists from around the world have now signed the World Scientists’ Warning to Humanity: A Second Notice, issued in 2017. This Second Warning comes 25 years after the 1992 World Scientists’ Warning to Humanity in which they called for stabilizing global population. Since 1992, we’ve added another 2 billion passengers to the planet while further depleting resources and polluting the planet.

In the Second Notice the scientists caution that “We are jeopardizing our future by not reining in our intense but geographically and demographically uneven material consumption and by not perceiving continued rapid population growth as a primary driver behind many ecological and even societal threats [italics ours].” The scientists note that one of the main actions we can take as individuals includes “limiting our own reproduction.”

Twenty thousand scientists aren’t the only experts issuing existential warnings to humanity. The Global Footprint Network, whose Earth Overshoot Day fell on the earliest-ever date of August 1st in 2018, has concluded we’re consuming the renewable resources of 1.7 Earths – a 70% overshoot.

The facts of our overshoot should cause alarm. The 20,000+ scientists who signed the Second Warning are alarmed. The Global Footprint Network is alarmed. The World Wildlife Fund – which estimates that mammal, bird, amphibian, and reptile numbers have been halved since 1970 – is alarmed. And behind the sounding of all these ecological alarm bells lies the fact that global population has more than doubled since 1970. And we’re still increasing human passengers on the planet by over 220,000 per day – about 80 million per year.

It is true, as Smaje notes, that many contemporary problems such as plastics in the ocean should be dealt with – regardless of whether sustainable population is achieved. But growing population and consumption are the ultimate causes that make many current problems worse and build ever-larger problems for the future. A declining population would provide enormous leverage in addressing the major problems of our age – topsoil and groundwater depletion, species loss, deforestation, ocean acidification, sea level rise, and climate change. In fact, most of these problems will not be solved as long as human population remains far above a sustainable level.

In one critical area of concern, climate change, it’s clear that population numbers – especially in richer, developed countries – are critical. A 2017 study from Lund University in Sweden found that an individual having one fewer child in a developed country would reduce their carbon emissions over 7 times the level of several other “green” actions combined: including living car-free, avoiding airplane travel, buying green energy, and eating a plant-based diet.

Species loss and animal population declines show that high levels of human population do not, as Smaje states, “lurk somewhere behind the numerous environmental crises of our age.” Instead, hiding in plain sight, human numbers expanding by an additional 80 million per year are destroying animal habitat to expand cropland, pastureland, and cities. The UN estimates that by 2050 we’ll have to increase food production 60% over 2009 levels in order to meet the demands of our swelling population. Assuming such a huge increase in food production is even possible, the attempt will surely mean the destruction of more farmland, creation of more ocean dead zones, depletion of more aquifers, and further disruption of the climate.

Smaje claims as fact that it’s what populations do that matters most. We certainly agree that what populations do matters, but if what we’re doing is a problem, then the number of us doing it compounds the problem.

And the sad fact is that we’re very stubborn about changing what we do. We’ve so far NOT demonstrated a willingness to consume less and reject the worship of economic growth in the interest of stabilizing the climate or preventing further destruction of ecosystems. This doesn’t mean we should give up on this solution. But it also doesn’t mean we should ignore a solution we HAVE demonstrated a willingness to do – choosing smaller families.

There’s evidence that for all 7.6 billion of us to live a life we consider “decent” and “dignified,” the level of consumption required far exceeds most of the ecological “planetary boundaries” that many scientists believe should not be crossed if we hope to stick around for a while. The University of Leeds study, A Good Life for All Within Planetary Boundaries, concluded that not a single nation is currently delivering a high standard of living to their populace while staying within all nine planetary boundaries. Globally, we’re currently exceeding four of the nine identified boundaries: climate change, loss of biosphere integrity, land-system change, and altered biogeochemical cycles like phosphorus and nitrogen runoff.

The researchers conclude that elements of a “good life” that most of us in developed countries consider basic such as secondary education, decent health care, and democratic forms of governance are associated with consumption 2 to 6 times greater than a sustainable level at our current global population. The fact is, as billions of people strive to live the “good life” they deserve, they will consume much more. For all of us to enjoy the basics of the “good life” without also trashing the planet, there needs to be far fewer of us humans on the planet.

This is surprisingly within our reach. An average family size of one-child per couple for 100 years could lead to what some experts posit as a sustainable population of around 2 billion people living at a European standard of living. Even an average of 1.5 children per family could, in 100 years, lead to a population smaller than today’s – instead of the 47% growth to over 11 billion projected by the UN.

Our goal should be smaller families in countries all over the planet – rich and poor alike. Rich families consume the most, and poorer families are rightly aspiring to consume more. And neither rich nor poor seem willing to voluntarily and dramatically lower consumption.

As Smaje notes, most of the world has had fantastic success at lowering birth rates over the past 50 years. The world’s average family size has fallen from about 5 in the 1960’s to around 2.45 children today. And, as Smaje rightly notes, the globe has achieved this fall in fertility voluntarily. He rightly asks, “what realistic policy measures… could have been implemented over the last fifty years that could have improved on this 50% fertility decline?”

And we answer that we could have had fertility reduction campaigns in place in every nation. Countries such as Thailand and Iran achieved dramatic fertility rate reductions in a short time using multi-faceted, coordinated, and socially just campaigns designed to encourage smaller families. Had we embarked on such a path fifty years ago, how much less plastic would we have in the oceans today? Might CO2 in our atmosphere still be below 350 ppm?

We can still do this. Better late than never. We can continue on this fertility rate reduction course, and even accelerate it, without disrespecting human rights. The only “population control” we need is awareness, public commitment, and self control. The good news is there are many ways of helping people voluntarily choose smaller families: more widespread contraceptive availability and education of girls are two tried and true pathways of lowering birth rates. But for more of this to happen, we need to acknowledge the problem: that our huge and growing human numbers are unsustainable.

Smaje parrots conventional economists when he refers to the social problems coming to many countries this century that will be facing “demographic collapse.” Is he arguing for us to stabilize our population at today’s totally unsustainable level of 7.6 billion? While it’s true that some countries will be facing some social and economic problems due to declining population, those challenges can be managed. They are minor compared to the challenge of meeting the needs of over 11 billion people without extinguishing other species, irreparably damaging the Earth’s life-supporting ecosystems, and rendering the climate inhospitable if not downright uninhabitable.

Smaje states that “the problem isn’t really ‘population’…‘capitalism’ gets a bit closer to the mark, perhaps.” We certainly agree that it’s essential to begin transitioning to an economic system that’s ecologically sound. Alternative economic systems could help us better differentiate needs and basic requirements of human flourishing from wants and superfluous status-seeking consumption. We must go there. But let’s not forget that living a decent life – whether done under a capitalist system or an ecologically-enlightened system – requires some consumption of resources and production of wastes. Our numbers do matter. We must find a reasonable balance – between our lifestyles and the number of lives – that will leave future generations a planet worth inheriting.

Choosing to have a smaller family is a decision many people can make right now that has huge benefits to the planet. We don’t have to wait for policymakers to do something. Changing an entire economic system is going to take some time. History shows that we’ve had much more success in voluntarily reducing family size than we have in voluntarily reducing consumption. Throughout the long sweep of history – so far – dramatic reductions in peoples’ consumption has happened only involuntarily – in times of economic depression or war.

We believe you can promote smaller families and deal with environmental impacts “directly” as Smaje suggests. In fact, the biggest problem we have with his commentary is his notion that we have to choose – that we have to prioritize either reducing each individual’s consumption or reducing the number of individuals doing the consuming. We don’t have to choose just one. We can do both. The 20,000+ scientists who signed the second Warning to Humanity certainly think we can. And, for the sake of a habitable planet and sustainable human civilization, we must.

Alan Ware is Research Associate and Dave Gardner is Executive Director at World Population Balance. Hear their roundtable discussion of this topic on episode 18 of The Overpopulation Podcast.

The MAHB Blog is a venture of the Millennium Alliance for Humanity and the Biosphere. Questions should be directed to joan@mahbonline.org