Mother Pelican
A Journal of Solidarity and Sustainability

Vol. 17, No. 8, August 2021
Luis T. Gutiérrez, Editor
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What Does It Take to Raise the Alarm
About the Danger of Overpopulation?

Christopher Bystroff

August 2021


Way back when, it was much easier to draw attention to danger. If you were the alpha male and you saw a lion creeping towards the troop you would just bark loudly and the whole troop would jump to attention, no questions. But today, the bark first has to pass peer-review. After that, in order to get the message of alarm into the main stream of living room conversation, it has to be dumbed down so that the average reader can understand it. Even then, the dumbed down alarm bell has to compete with a fireworks display of daily headlines that demand our attention. Meanwhile the lion is already picking off the folks on the margins.

This scenario played out with climate change over a period of thirty years. In 1990, when I was a young scientist, I enlisted with the Union of Concerned Scientists and helped organize a week-long event to bring awareness to global warming. At that point, climate change had passed peer review many times in the primary literature of science but the message was not yet dumbed down enough even for scientists outside of the climate field. I remember talking with a professor of biophysics on the topic. He believed the atmosphere was too big to be affected by pollution. It took many years. Long after the first CO2 data came out, several years after the call-to-arms that was Al Gore's "The Inconvenient Truth," at last technology and public opinion are, finally, slowly, pushing the shift from fossil fuels to renewables, with aches and pains and pull-backs like a global physical therapist that is force-stretching humanity's sore technology muscles.

But today's call to alarm is more serious. It's like looking past the approaching lion and seeing something much worse, like a raging fire on the horizon. Maybe that's why the lion was running towards us. The raging fire is over-population. When I try to bring it up these days I feel like I did bringing up climate change in 1990. People are dismissive. It isn't that they disbelieve the mathematical truth that there is a limit to how many people can live on this planet. They just don't think the problem is important. Not yet. Not today. It's not a raging fire yet, not even an approaching lion. It gets the reaction the alpha male would give, if a member of the troop were to tell him there are lions in the woods. Yeah, I know, the alpha would say, and yawn. Wake me up when they are nearer.

Scientists like me are not the alpha males of society, except in one respect. Like the alpha male who sits on a high prominence, giving him a clear view of the horizon, so, we, the scientists of the world, give attention to our surroundings. From our cloistered labs we enjoy an unfettered view of the natural world through microscopes, telescopes, fluorometers and centrifuges. We believe no one, but get our opinions directly from the world around us through our chosen instruments of observation, like the alpha male who responds to the barks of no one but instead reacts only to what he sees with his own eyes.

My instrument of choice is computational modeling. Using it I have seen that the raging fire of a population crash is closer than we previously thought, just 5 to 10 years out in the business-as-usual version of the simulation, not 20 to 50 years out as an earlier model predicted. The population decline is predicted to be sharp, peaking at a downward rate of 30 to 200 million souls lost per year and continuing to decline for 20 to 40 years before bottoming out at 1 to 5 billion. Contrast this steep decline with the 3 million dead from COVID-19 over the course of one year. The modeling recognizes a vicious cycle of feedbacks involving food supply and deforestation, deforestation and climate, climate and the food supply, circling back and spiraling out of control. These concepts are not new. They just weren't translated into a computational model.

Figures 1 and 2 summarize the structure of the model and the simulation results:

Figure 1. World4, a system dynamics model that reproduces world population numbers up to the year 2010 and projects forward. Stocks (rectangles) and flows (solid arrows) form two interacting closed systems, one for Technology and one for Environment. Input variables (ovals) are colored and grouped by function. Output variables (white) are the global carrying capacity (CC) and population. Dashed lines indicate variable dependencies.

Figure 2. World4 simulations superposed on 20th century population numbers (thick cyan line) and UN population projections (dashed blue line is the median projection and light blue are 95% confidence region). The program hyperfit carried out 1 million World4 simulations using randomly selected parameters. Shown are the 184 trajectories that deviate from true 1970-2010 population data by less than 1%. Simulations are colored by their E0 value (total ecosystem size in gha). Counterintuitively, a lower estimate of the ecosystem size means a higher population is sustainable.

In contrast, the word from the United Nations Department of Economic and Social Affairs, vouching for economists and demographers who, truth be told, don't know much about ecology, is that the population will continue to grow for another 70-80 years, leveling off towards the end of the century, perhaps subsiding slightly but not much. But the error bars are huge, which is telling. Also telling is the fact that the UN population projections have not budged in the face of new climate science projections of massive draughts, fires, storms and floods coming in the near future, events which will most certainly impact agricultural productivity. It would be logical to assume a decrease in the food supply would affect population, would it not? But demographers don't go there.

This is not a hair-splitting academic turf tiff between ecologists and economists. Not at all. This is an asteroid-heading-our-way, who's-in-charge, academic turf tiff between ecologists and economists. The consequences of sticking to a misplaced worldview are huge. Come over to our telescope, people, and you will see the shape and trajectory of what is heading our way much more clearly. It is not going to miss us.

I am not the only one who has noticed this danger. There are many books on the subject. For an easy, no-nonsense overview, I recommend Karen Shragg's "Moving Upstream". The warnings go all the way back to 1798, to Thomas Malthus, whose name became an adjective, and to Nobel Peace Prize laureates in the 1960's, Norman Borlaug and Martin Luther King, who saw beyond their respective social causes and noticed the warning signs of an approaching population problem. But the warning signs challenge us, testing our ability to fathom a slow-onset existential threat and a danger that emanates from self. The occasional alarm bells of academics and do not easily translate to the collective alarm that is needed.

If it did, or if it eventually does, then the actions to control population overshoot are fairly easy to conceive and implement, certainly easier than repairing our climate. Easy access to contraception world-wide would probably do it, as long as it is a globally shared responsibility. Eliminating all unplanned pregnancy -- 44% of all pregnancies are unplanned according to the Guttmacher Institute -- would by itself decrease population growth by 78%, with the happy side effect that every child would be a wanted child. And please add to that a decrease in abortions to zero, since only unwanted pregnancies are ever aborted. It is almost enough, but not quite. In a world of climate-induced food shortage, peaceful population growth will have to be negative, not just zero. But it is the only way. The alternative [do I have to say it?] is a non-peaceful decline.

A peaceful solution to overpopulation is tantalizingly possible, if we reach collective awareness of the danger. But we are not there yet. Until such collective awareness arrives, the proverbial alpha males of the world have a job to do. Keep barking.


Bystroff, Christopher, Footprints to singularity: A global population model explains late 20th century slow-down and predicts peak within ten years, PloS One, 20 May 2021.


World4: Footprints to Singularity, Chris Bystroff, 31 July 2021


Chris Bystroff, PhD, is Professor of Biological Science and Computer Science at Rensselaer Polytechnic Institute. He has published over 70 peer-reviewed papers in biochemistry and bioinformatics. When not designing a contraceptive vaccine, he teaches a course called Human Population. For more information about Professor Bystroff and his research, see his website.

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"Small-minded people blame others.
Average people blame themselves.
The wise see all blame as foolishness."

— Epictetus (ca. 50-135 CE)


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