Widgets Magazine


Human overpopulation: When no news is bad news

Last week, a high-profile study using the latest United Nations data revisited predictions of global population size. The news wasn’t good: Updated estimates using new statistical analyses suggest the world’s population will hit nearly 11 billion by 2100. There’s some uncertainty in this measure because birth and death rates may be changed by political and social dynamics. Still, the study’s authors wrote that there’s a four in five chance the world’s population will be between 9.6 and 12.3 billion by the end of the century.

I was glad to see several media outlets pick up the story. But while most of the reports alluded to the challenges of feeding and employing additional billions of humans, almost none acknowledged the fundamental issue with human population size.

There are already too many people on the planet, and this overpopulation drives the ongoing environmental crisis.

It’s no wonder we shy away from open discussion of this issue. First, “overpopulation” is hard to quantify. It’s obvious that the present-day human population is too large to sustainably support on the planet. For example, modern agriculture relies on the chemical fixation of nitrogen for fertilizers, which experts believe allowed Earth’s population to grow beyond 4 billion. Yet this fertilizer production requires energy from fossil fuels, a non-renewable resource. In other words, more than 3 billion people on the planet survive because of an unsustainable energy subsidy.

But how many is too many? Experts struggle to quantify the maximum sustainable human population size (called the “carrying capacity”) of the planet. Their calculations are limited both by uncertainty about Earth’s capacity to maintain its human life support systems (e.g., freshwater, breathable air and so on) and by the lifestyle each person chooses to maintain. For example, Americans have relatively high-impact habits that consume more natural resources than sub-Saharan Africans living below the poverty line. Ethically, we can agree that every human deserves a certain standard of living. But the higher that that standard rises in terms of energy and other resource consumption, the fewer people Earth can support indefinitely.

Meanwhile, our global population continues to swell, as do our environmental impacts. Each individual requires sustaining resources including food, housing and energy. No matter how small the average person’s resource demands are, each additional person adds to the human burden on the Earth. In the past 40 years, the human population has increased by 40 percent, while, as a consequence, the world’s wildlife population has been cut in half.

Indeed, the Intergovernmental Panel on Climate Change notes that population growth and economic development are the two most important drivers of increasing carbon dioxide emissions. In the United States, every child born increases a mother’s carbon legacy more than sixfold. Worse, present day population growth is occurring in impoverished areas where large families, though themselves contributing relatively little per person to global emissions and climate change, are more likely to be vulnerable to its impacts as well as the usual suite of natural disasters.

Why, then, do we fixate on technological fixes like solar power and carbon capture, rather than addressing global population growth?

According to former United Nations Population Division officials, the reasons stem primarily from political fear. Talking about population control necessarily brings up contentious moral issues like birth control and reproductive rights. Policymakers and government officials shy away from these thorny topics: Even the UN has spent the last 20 years focusing on women’s reproductive health and rights while ducking larger questions about population size.

Still, sociology tells us this is not a bad strategy. Educating women, and providing them with access to reliable birth control methods, is perhaps the most reliable way to reduce population growth. Educated women add value to families as breadwinners: the cost of having children now includes not only the infant’s direct expenses, but also the mother’s lost wages. As a result, these women are choosing to have fewer children.

The UN, which is about to miss its 2015 Millennium Development Goal of universal access to reproductive health, notes that 25 percent of sub-Saharan African women of reproductive age want to delay or avoid pregnancy but still have no access to reliable birth control.

This statistic should tell us something: Here is a need that we can fill, with a big impact on human population growth. The greatest uncertainties in population projection estimates center around sub-Saharan Africa, where investments in female education and family planning can make the biggest difference both in the lives of the individual women and in the sustainability of the global human population. Additionally, economic analyses show that these investments are more cost-effective at reducing carbon emissions than technological fixes like cleaner, greener power plants. So many birds can be killed with the same stone.

Rather than fearing discussion of human overpopulation, we should embrace it. That’s a lot less scary than rocketing blindly towards 10 billion with no plan for the environmental consequences when we get there.

Contact Holly Moeller at hollyvm ‘at’ stanford.edu.

About Holly Moeller

Holly is a Ph.D. student in Ecology and Evolution, with interests that range from marine microbes to trees and mushrooms to the future of human life on this swiftly tilting planet. She's been writing "Seeing Green" since 2007, and still hasn't run out of environmental issues to cover, so to stay sane she goes for long runs, communes with redwood trees and does yoga (badly).
  • Abby

    I agree that the growth of the human population can be scary at first. The article mentions that the US consumes more than most of the rest of the world. In fact, countries that are the most populated are often actually relatively low consumers. According the The Guardian, a child born in the US produces a carbon footprint 55 times that of an Indian child and 86 times that of a Nigerian child. This goes to show that merely handing out birth control in sub-Saharan Africa will not make the difference needed to restore the planet’s resources for future generations. Reducing the consumption of “developed” countries such as the US and other Western nations is the only way to avoid the depletion of the world’s resources.

  • Realist

    There is another solution… A man made killer virus with an antibody but the people at the top won’t tell us about the solution until this population problem is solved. Think Bill Gates and his ‘foundation’. They will find a cure and look like saviors when in fact it was them who sicked the disease on us in the first place

  • Ang


  • Ang

    It will take both greener living and birth control to tackle this problem

  • GnomeCoach

    I’m now almost 69. Back in the late 1960’s there was a strong movement of people in this country that were far more adamant about greener living and especially easily available birth control. Then discussions, of overpopulation became taboo. In other words, this concept is not new and world population kept growing. During my life the world population has trippled.

  • Watch it

    Excellent commentary. Holly Moeller lays out common sense that the liberals will never experience.

  • William Santos

    I shearched for this article after reading Dan Brown’s Inferno…..

  • JohnTaves

    “Experts struggle to quantify the maximum sustainable human population size (called the “carrying capacity”) of the planet.” Yes, they do and this shows us a significant problem with our understanding. It is not necessary to quantify the maximum sustainable human population size. It is blatantly obvious that it is significantly less than our current numbers.

    The definition of “overpopulation” is the condition where the species numbers exceed the “carrying capacity” and “carrying capacity” is defined as the maximum population size that can be accommodated indefinitely (see wikipedia for example). Notice what this means. It means the maximum that can be kept alive without consuming resources faster than they renew. Humans are obviously way overpopulated. We consuming ridiculous quantities of non-renewable in order to keep our current numbers alive. We have only vague theories as to how we might keep our numbers alive without consuming resources faster than they renew. Notice how this article and for example, the wikipedia article, don’t comprehend that concept.

    There is a further failure. Experts have no definition or concept for the limit that the population cannot exceed. We are in a finite sized environment, there is certainly some limit that cannot be exceeded. In addition, we know that this limit will be higher if we are more efficient with sustenance extraction. For example if we use only hunting/gathering technology, then the Earth cannot keep anywhere near 7 billion alive at one time. If we don’t use modern fertilizers that are created by burning fossil fuels, we do know know how to keep our current numbers alive. We must understand this hard, yet movable limit.

    It is hard, because it cannot be exceeded. It is moveable because we have discovered more efficient techniques for sustenance extraction. When a population is at the limit, some amount of child mortality is directly caused by averaging too many babies. For example, if the population limit is a steady value, then (x-2)/x children must die where x is the number of babies adults average. This tells us that how many babies we average, determines the death rate of children.

    Notice how this article, and generally every population related article never mentions whether the population is peaking for the wrong reasons or the good reasons. We are on a finite planet, when the population peaks is it peaking because we are unable to feed more? How would you know the difference? How do you know that our numbers are not at the limit right now, while we are increasing that limit?

    Think of the Earth as a bucket with holes in it. The water in the bucket is the population. Water that flows out is dead people. Water is poured into that bucket at a rate that is proportional to how much water is in the bucket. I am saying that the bucket is full and over flowing. The water pouring over the top is caused by pouring water into the bucket too fast, and is analogous to child mortality caused by averaging too many babies. The size of the bucket has been increased, but the increases have never been fast enough to stop the overflow. In addition, the size of the bucket is significantly larger than what can be sustained. We do not know how to keep the bucket size from dropping dramatically when those resources become scarce.

    Everyone, and this includes Malthus and Ehrlich and countless other population “experts” mindlessly assume the bucket is not full. They have been fooled by the fact that humans can control their fertility. They assume that we control it such that the bucket is not full and over flowing. This assumption is dead wrong. Nobody has ever found a mechanism that ensure we control it such that we prevent the overflow.

    The child mortality is painfully obvious. It occurs in economic clumps throughout the world. The horrid child mortality rates found in developing countries is exactly what one would predict if one did not make the mindless assumption that our numbers are not at the limit right now.

  • Evelyn L. Ford

    All people think about is having babies; there is no love anymore- people only breed for the money that is made off of the kids when they grow up and start shopping; it’s all about capitalism and money, and in the end we may all sadly pay for our selfishness with the end of the world; why do people spay and neuter animals, specifically pets? So more people can make and have human babies! Put 2 and 2 together, folks!

  • rodentx2

    Think what the impact of human overpopulation has on doomed domestic animals: 7 billion people devouring close to 60 BILLION “food” animals! Think of the magnitude of misery, suffering, and death to the animals as the global human overpopulation continues to demand more and more meat/flesh, dairy, and eggs, produced by any and all means available (including technology)!

  • rodentx2

    I think it’s time we realized that “reproductive freedom” for humans is a luxury the planet and ALL (domestic and free-living) animals can no longer accommodate! And it isn’t just species extinctions in the wild. It’s the insane production (not to mention the misery, suffering and violent deaths) of more and more “food” animals by ANY and ALL means available in an attempt to keep up with the demand for animal products (even when there’s plenty of plant-based foods that are healthier and more sustainable). I’m vegan, but it’s like a nano drop of water in a flooded, overflowing tank!

  • Jeremy

    I agree with most of what you’ve said here but in fact, child mortality rates have been consistently decreasing nearly everywhere since 1970 (Source: Unicef). But more people means more consumption and more overshoot.

  • JohnTaves

    I don’t see the relevance that the child mortality rates have been consistently dropping, unless you are suggesting that this should be extrapolated into the future and that we should draw conclusions from this trend. If that is what you are saying, then this is an excellent example of how population scientists are seriously confused and part of the problem. Population scientists are generally doing studies that are nothing more than correlations and extrapolations, and then making the mistake of drawing conclusions from these studies.

    Population scientists need to comprehend the fundamental concepts I described above and teach them. They need to stop wasting time and causing confusion by providing these trends and drawing conclusions from them.

    Is the falling child mortality a good thing? Yes.

    Does it make logical sense to extrapolate that trend into the future? No.

    Does the falling child mortality give us any reason to believe that there is some magic that regulates our fertility such that our numbers are not at the limit now, or such that our numbers will not be at the limit in the future? No!

  • Stephen Powell

    In less than 10 thousand years, the earth will be a sphere of human flesh expanding outward in all directions at the speed of light. Unless something happens.

  • Tada

    Reducing consumption and controlling population growth through birth control are both needed.

  • Kayla Rae Worden

    You had a lot of good thing to say. Too bad you did not liberate your language. “Killing so many birds with one stone.” Truly an unfortunate phrase which promotes murder. Think before using such archaic, offensive
    language please and thank you.

  • Kayla Rae Worden

    Going vegan is the answer.

  • Kayla Rae Worden

    Bring on the Zika virus!