Overpopulation in the Era of Climate ChangeOverpopulation in the Era of Climate Change

Overpopulation in the Era of Climate Change


[Editor's Note: This article originally appeared in November 2018. It was reposted as part of MagellanTV's Earth Day 2020 observance.]  


Overpopulation is a root cause of climate change. The links between the two problems are undeniable, and reducing the rate of population growth is crucial to bringing global warming under control. But governments and international organizations are reluctant even to acknowledge overpopulation as an important factor in diagnosing the problem. Without concerted action on population issues, the dire predictions of Thomas Robert Malthus are likely to come into play.


Talking about global climate change without acknowledging the role played by overpopulation is a waste of time. It’s like talking about gun violence in the United States without taking into account the millions of military-style firearms held by private citizens. Any serious effort to solve the problems is undermined by a widespread unwillingness to address the root causes.


When it comes to guns, we can compare rates of their criminal use in different countries and draw applicable conclusions. Unfortunately, we know of no other planetary civilizations to which we can compare our world’s population problem. But we can be certain that our little third rock from the Sun is in trouble. Big trouble. Too many people consuming too many resources – and releasing too much carbon dioxide (CO2) into the atmosphere – are primarily responsible for the fix we’re in.


Consider this:  According to a 2009 Oregon State University study, a single child born in the U.S. can, over the course of her or his lifetime, leave a “carbon legacy” of approximately 20 times what would be saved by measures such as reducing consumption via recycling, high-mileage vehicles, conservation of resources, and use of fuel-efficient light bulbs and appliances.


More People = More Greenhouse Gases

I am mindful of Mark Twain’s famous displeasure with statistics (“Lies, damn lies, and statistics!”), and I know that thoughtful people on opposite sides of an argument often marshal competing data to prop up their views. But bear with me as I lay out a few more simple facts that should make clear, even to the non-scientifically inclined, the relationship between overpopulation and the increase in greenhouse gases in the atmosphere.


In 1950, there were about 2.5 billion people scattered around the globe. Now, there are approximately 7.6 billion. By 2050, according to the U.N., that number will grow to 9.8 billion on the way to 11.2 billion at the end of the century.


Now, let’s compare the level of CO2 in the atmosphere. Back in 1950, the carbon dioxide level was in the range of 300-310 parts per million (ppm). The seasons progressed, fishermen fished, farmers farmed, permafrost was permanent, the poles were frozen, and there was, at least theoretically, enough food to go around. Planet Earth’s climate was pretty stable.


Flash forward to 2018, and the CO2 level is over 400 ppm. (It hasn’t been that high in 3 million years, and the human population back then was exactly zero.) Weather is erratic and often downright scary. Seas are rising, and fisheries are collapsing. Farms in formerly fertile areas are under stress from limited freshwater supplies and from insects. Permafrost is melting, glaciers are in retreat, and the waters around the North Pole are navigable in the summer. And don’t forget: There are over 5 billion more mouths to feed than in 1950.


If the current situation seems alarming to you, consider this:  According to the Association for Canadian Educational Resources, the CO2 level will rise to between 540 and 970 ppm by 2100 (depending on which of several scenarios bear out). If the worst-case forecast comes to fruition, we are likely heading for a “Hothouse Earth” similar to the world the dinosaurs dominated 100 million years ago.


So, what’s a poor planet to do when its dominant species refuses to restrain its population growth and, adding insult to injury, insists upon turning the thermostat up? Well, one answer might be for the planet to get rid of a large portion of those unwanted guests.


What Malthus Got Right

Robert (“Don’t call me Thomas”) Malthus (1766–1834) was a minister in the Church of England who had a flair for scholarship in the nascent fields of demography and political economy. I will readily concede that he got some things badly wrong, notably his theory that human population would double with each generation. But, while he may have wildly miscalculated the rate of population growth (and also the increase in available food), he might also have gotten some other things chillingly right.


“The power of population is indefinitely greater than the power in the earth to produce subsistence for man.” – Thomas Robert Malthus


Malthus’s most influential work was his book, An Essay on the Principle of Population, published in 1798. In it, he argued that increases in food production were beneficial to a nation’s people, but that those increases also stimulated population growth. With a larger populace, the benefits of the additional food were negated. Why? Because people had a tendency to use the abundance of food to support larger families (and thus a larger population) rather than to maintain an improved standard of living. When population outstripped increased food production, bad things were bound to happen. This is what is termed the “Malthusian Catastrophe.”


Graph shows population growth exceeding food production in a Malthusian Catastrophe.


Balances and Checks

As long as the balance between food production and population was maintained, things would be fine. But what would happen when they fell too far out of balance? In An Essay on the Principle of Population, Malthus asserted that there were two types of “checks” on population growth:  “Preventive” and “Positive.”


The Preventive Check would come into play when a population crisis was created by overconsumption of food resources. Because humans are uniquely capable of responding rationally to such a crisis, their best move would be to forgo childbearing until the balance between population and available food resources was restored. In this regard, I think we can safely say that, despite his reputation for being a “gloomy Gus,” Malthus was a cock-eyed optimist.


Or maybe not. What would happen if people couldn’t restrain themselves from churning out more little bundles of joy? In that case, Malthus suggested that Positive Checks on human life spans would kick in – and by “positive” he famously meant three particularly negative consequences:  war, disease, and famine. Put another way, if too many humans were coming into the world, then more of them would have to depart into the not-so-sweet hereafter sooner rather than later to mitigate the consequences of overpopulation.


Rushing Headlong to the Promised Land

Of course, Malthus lived almost two centuries before remarkable advances in agricultural production such as the Green Revolution of the late 20th century. These great leaps forward in food production have supported a massive increase in global population along with an undeniably improved average standard of living worldwide. So, Malthus just couldn’t see far enough ahead to realize that humanity could solve the dilemma he described, right? Well, hold your horses.


During the lifetime of the Reverend Mr. Malthus, a magnificent storm was brewing, a tempest that would change the world dramatically:  the Industrial Revolution. Fueled by coal and, later, petroleum, previously unimaginable industries, transportation systems, international trade, and jobs jobs jobs sprang up like weeds in a fallow field. Population growth was no longer a problem to be restrained but, rather, a necessary foundation for national and international economic growth. Surely, the biblical imperative to “be fruitful and multiply” was, well, imperative.


And wow, did the population multiply. Not as fast as Malthus imagined, but plenty fast enough to provide the needed workers to build the promised land of prosperity – if only we could figure out how to distribute the benefits evenly around the world. Legions of good people are hard at work on that challenge today, as well they should be.


But what no one understood as humankind embarked on rapid industrialization was that the byproducts of the fossil fuels that powered the factories, the transportation, and the electrical grids were insidiously rising into the atmosphere. Soon enough, cities like London, Frankfurt, and Pittsburgh were choked with smog, but worse was what could not be seen, smelled, or yet understood: greenhouse gases collecting and expanding around the planet.


Now the 21st century has arrived, and there may be a Malthusian bill to pay.


A Problem Spiraling Out of Control

Before the Industrial Revolution, nature itself set effective limits on population growth. When people consumed more food than could be produced reliably, their numbers dwindled. But with advances in producing, obtaining, and distributing food, we have run through the barriers that nature used to erect to keep our population in check. Worse still, through global warming we have set in motion processes that are beginning to wreak environmental havoc on our one-and-only home planet and its ability to sustain us.


“Over the last few centuries, human scientific knowledge and technology have become so effective at thwarting nature’s attempts to control our rising populations, countering disease outbreaks, and altering food and water supplies, that our human population has spiraled out of control. . . . Our success has put our world . . . on a rollercoaster toward crisis. Malthus had it right long before his warnings became a global reality.” – Sean Palfrey, Professor of Pediatrics and Public Health, Boston University


In just a few hundred years, as previously noted, carbon dioxide in the atmosphere has rapidly risen to levels not seen in three million years! We are no longer wondering when we might begin to experience the effects of climate change – they are already happening. We see it in the frequency and intensity of major storms, unprecedented rainfall in some areas and desertification in others, dying coral reefs, the retreat of glaciers, huge chunks of ice breaking free of Antarctica, and rising seas. And, all the while, approximately 131.4 million people are born annually, while only 55.3 million die. The arithmetic isn’t all that complicated, folks.


Swedish professor and statistician Hans Rosling discusses population growth (Source: Open Knowledge Foundation Deutschland, via Wikimedia Creative Commons)


So, the United Nations must be working assiduously to get the word out about the relationships among overpopulation, economic development, resource depletion, and climate change, right? Uh, not exactly. The U.N. lists 17 important areas in which “progress must accelerate” in its Sustainable Development Goals Report of 2017 if we are “to eradicate poverty, address climate change and build peaceful, inclusive societies for all by 2030.” It is appalling to note that reducing the rate of population growth is not among them.


Recycling Ain’t Enough

Humans are using up natural resources at a rate that far exceeds the planet’s ability to keep up.  Reporting on research by the World Wide Fund for Nature (WWF) and the Zoological Society of London, The Guardian states that humans are “cutting down trees faster than they regrow, catching fish faster than the oceans can restock, pumping water from rivers and aquifers faster than rainfall can replenish them and emitting more climate-warming carbon dioxide than oceans and forests can absorb.” The WWF’s Living Planet Report calculates that we would need 1.6 Earths to sustain our current worldwide rate of consumption. But, alas, we have only one Earth.


It is true that around the world people are making serious efforts to reduce consumption and environmental degradation. More power to them. But to have a fighting chance to stave off the worst effects of global climate change, we need to seriously address the problem of overpopulation. As the Oregon State study mentioned above points out, “the potential savings from reduced reproduction are huge compared to the savings that can be achieved by changes in lifestyle.”  


If the climate is changing as a result of global warming; and if global warming is largely attributable to human activity; and if that human activity has included polluting the atmosphere with greenhouse gases and over-consuming natural resources by an ever-increasing population – why not connect the dots and accept the obvious? Overpopulation is not just a contributor to climate change, but a root cause of the problem.


Yes, we all need to reduce our carbon footprints, but time is running out. As the Center for Biological Diversity states, in the quest to survive climate change “we not only need smaller footprints, but fewer feet.”






Title image; International Space Station image of Nile River at night (Source: Scott Kelly, via NASA)




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