World's future population: stabilized, older
Experts predict that in the next half century, Earth’s population overall will become more stable and older.
But first, world population is expected to grow from 6.5 billion people on Earth today to about 9.1 billion by 2050. That’s according to Joel Cohen, Professor of Populations at the Rockefeller University and Columbia University in New York City. Cohen told Earth & Sky that, over the last 45 years, fertility rates have been dropping worldwide.
On average, women in developing countries now bear about three children in a lifetime. That’s twice the number of children as in the developed countries.
Fertility rates are dropping as women gain access to education. Combined with a near–doubling of average life expectancy, these trends indicate that the population of tomorrow will be, in general, older.
Joel Cohen: And if that happens, we’ll sort of have an approaching stationary population size, possibly during the 21st century. So I think that we have finally outgrown our childhood and adolescence as a species. And we’re learning to be a mature adult, with an older population, not rapidly growing, as a species. And I think that’s a wonderful achievement.
Read Earth & Sky’s interview with Joel Cohen.
Our thanks to:
Joel E. Cohen
Laboratory of Populations
Rockefeller University & Columbia University
New York, NY
Ken Kostel
Senior Science Writer
The Earth Institute at Columbia University
New York, NY
Thanks, always, to one of the most prominent demographers on the planet, Dr. Joel Cohen.
Given the potentially profound implications of 9 billion human beings on the planet soon, the idea of a stabilizing human population on this marvelous planet God has blessed us to inhabit is truly appealing; however, the evolution of science regarding the dynamics of absolute global human population numbers appears no longer to adequately support this deeply attractive idea.
From my humble and inexpert vantage point, the data that indicate the occurrence of human population stabilization on Earth in the 21st century are preternatural.
According to scientific data from Russell Hopfenberg, Ph.D., and David Pimentel, Ph.D., on human population dynamics, the relationship between the world’s supply of food and global absolute human population numbers is a rapidly cycling positive feedback loop. This could mean that the spectacular success of humankind to massively produce food at will and without regard for limits as well as to store food in gigantic quantities and treat it a commodity, has unexpectedly resulted in a food-population spiral, one in which food availability drives up human population numbers and human population growth gives rise to a widely shared and consensually validated misperception that food production must be continuously and maximally increased. Not only Dr. Hopfenberg and Dr. Pimentel, but also other scientists have observed that the seemingly endless production of food to feed a growing human population leads to an even greater number of the human species on Earth.
Thanks for your consideration of not yet widely examined scientific data from Dr. Hopfenberg and Dr. Pimentel regarding the population dynamics of the human species.
Regardless of how long the predominant culture of the human species prizes seemingly endless growth of its gigantic economy on Earth, surely it is not too late to accept human limits and Earth’s limitations by altering human behavior in conformance to the “rules of the house” in which God has blessed us to live. Unanticipated scientific evidence appears to indicate that the widely shared and consensually validated belief that human beings can “live without regard to limits to growth” and defy biophysical reality is unfortunately based upon wishful, magical and preternatural thought; contrived logic; faulty reasoning; selective data; and an abundance of hubris. Assiduous denial by the leaders of the political economy and the mass media establishment leads to the tabooing of emerging good science related to human population dynamics and the human overpopulation of Earth.
Not since the building of another “high-rise,” the ancient Tower of Babel, has so impressive an ‘edifice’ been constructed as the world’s man-made economy. Many too many people in my generation, led by the masters of the universe, appear to be malignantly preoccupied with maintaining the spectacular, patently unsustainable success of the human economy at any cost, and regardless of what that success might mean for the integrity of the Earth, the preservation of biodiversity, the degradation of the environment and even the endangerment of our children and coming generations.
As in the days of the ancients, a gargantuan structure, that in our time takes on the shape of a huge pyramid and functions as a global pyramid scheme, is dominating every horizon. Whereas the rampantly growing modern world economy is protected and defended everywhere by seemingly everyone with wealth and power….without saying a word about what is happening; there is precious little more than benign neglect accorded to the “house” God has given us to inhabit.
It is only a hope; but at some point in the future I trust that our colleagues, the ones who are more dedicated to God’s “house,” humanity and science than to the endless growth of the human economy, will examine evidence related to the unbridled growth of per-capita consumption, big business activities and absolute global human population numbers.
The quote of Joel Cohen should read: “And we’re learning to be a mature adult, with an older population, not rapidly growing, CITY DWELLERS. As a species. And I think that’s a wonderful achievement.” City dwelling was left off.
Don’t get why city dwelling is an achievement…
Hey Eric! Thanks for the catch. We’ll fix it.
I don’t think he’s saying that city dwelling is an achievement. I think he’s saying that it’s wonderful that the human species is at the point of “outgrowing its adolescence.” In other words, the human species has always grown, much as a child grows. But now the human species has reached its full size. It’s likely that human population globally will grow to 9 billion by the middle of this century. But then, according to experts like Joel Cohen, it will start leveling off and even decline. It’s like when a person reaches their full size. They keep changing. But, for the most part, assuming they “stay healthy,” they stop growing in physical size.
Why will human population stop growing? Well … education. Birth control. More opportunities for women. Increased literacy. Increased access to information. This process we’re engaging in right at this moment … the process of communication. Above all things, we humans are geared for survival. And it’s pretty clear we can’t survive with a population that grows indefinitely.
Can you imagine a world that isn’t increasing in global population? Say … 100 years from now? There’s never been such a world on Earth in human history. It’s a world that’s gotten over its “growing pains” of youth … that still makes mistakes, sure … but that has the beginnings of true wisdom.
It appears the conclusion that human population will stabilize is rooted in assumptions about existing trends continuing to improve over a half-century or more. I know that these days this is conventional wisdom among population experts, but I’d be interested in hearing more details about why demographers are comfortable about making that assumption. It is a hopeful thought!
Urbanization need not follow the existing model and pattern. We definitely have the resources and imagination to make cities beautifully integrated with other forms of nature—we can set zoning laws to densify areas while opening up space and daylighting streams in other parts of the city. It would be beautiful to help the rapidly forming cities in developing worlds move beyond the examples in the developed world. The GTI Paper Series has a good paper on Sustainable Cities
Dear Eric Otto,
Your view is a good one.
Even if absolute global human population numbers are increasing at a DECREASING rate of growth, could someone please explain how Earth sustains the determinable 9+/- billion people who expected to belong to the human family in 2050?
If it is all right to do so, perhaps there are two other related questions worth asking:
What do population experts expect to happen later in Century XXI when the population numbers of the human species supposedly level off? Inasmuch as human population numbers are expected to continue skyrocketing from 6.5 to the 9 billion mark in the next 44 years, please explain how the widely accepted and consensually validated Demographic Transition Theory ‘predicts’ the end of human population growth?
Hello all. Notice that we’re commenting here on a short radio presentation with Joel Cohen. Earth & Sky also has a longer, very excellent interview with Joel Cohen that answers many of these questions. You’ll find the longer interview with Joel Cohen here.
As he says, the answer as to why human population is expected to level off is complicated … but there is an answer!
Human understanding of human population dynamics used to be just as complicated as Dr. Joel Cohen suggested in his excellent 2006 State of the Planet presentation in March. What has not yet been acknowledged by Joel, Paul Ehrlich and many other experts is this: research of Hopfenberg (2003) and Hopfenberg and Pimentel (2001) appear to indicate that the dynamics of human population numbers are no longer hopelessly complicated by a dizzying array of variables, so many variables that some scientists have concluded that human population dynamics are not suitable for scientific investigation, or even unknowable as Joel Cohen has reported elsewhere.
According to Hopfenberg and Pimentel, human population dynamics are knowable and these dynamics are essentially similar to, not different from, the population dynamics of other species. The population dynamics of the human species are similar to the population dynamics of other species, both in terms of complexity and simplicity of the governing elements.
Although it is vital to recognize and acknowledge the complications inherent in population dynamics, it is equally necessary not to allow these complications to blind us to the elegance and simplicity of emerging scientific evidence.
Russell Hopfenberg and David Pimentel have provided evidence that accounts for the salient factors governing the dynamics of the population numbers of the human species. From my humble vantage point, it appears that not one top rank scientist with expertise in population dynamics has refuted their emerging research.
Perhaps this wonderful venue provided by Earth & Sky enables our colleagues to discuss the unexpected data to which I am hopeful of drawing attention and comments. Please know that the apparently unforeseen research of Hopfenberg and Pimentel appear to have profound implications for the future of life as we know it on Earth.
Steve, it just doesn’t make sense to me that human population dynamics would be essentially similar to, not different from, the population dynamics of other species.
How can that be? Humans are fundamentally different from other species. We are conscious of others of our species all around the globe. We know our history … see the mistakes of our ancestors. We have science … projections into the future. We have birth control!
It just doesn’t seem logical to me that the same population dynamics would apply.
Hi Deborah,
Thanks for this remarkable opportunity to comment.
The unexpected data appear to indicate that as we increase the world’s food supply through our improving production and distribution capabilities, the number of people worldwide goes up, too. Consider that the relationship between population numbers of the human species is one in which food availability results in human population increase and the increasing number of people give rise to a widely shared but mistaken impression or else misperception that the production of food needs to increase even more, evermore. The data indicate that more food equals more people; less food equals less people; and, in any and all cases, no food equals no people.
Given their current scale and rate of growth worldwide, please note that business-as-usual big business productivity, per human consumption and the rapidly increase of human population numbers occur synergistically, in what has been described elsewhere as a positive feedback loop.
The governing dynamics of human population numbers present humanity with a biological problem that is independent of social, religious and cultural considerations.
Perhaps a point in human history is approaching when it will be patently unsustainable to pursue the predominant culture’s most prized course of action: the endless growth of its unbridled production, unchecked consumption and and unrestrained reproduction activities in our planetary home.
The data from Dr. Hopfenberg and Dr. Pimentel appear to indicate that consideration could be given to the humane regulation of currently unregulated human overgrowth activities that, even in these early years of Century XXI, can be seen blanketing the surface of Earth, extirpating biodiversity, degrading the environment, dissipating limited natural resources and endangering the Earth as a fit place for habitation by coming generations.
Human beings may choose to think of ourselves as masters of the universe, as a species that can live without having to accept limits to growth of our production, consumption and propagation activities. The wishes of humankind may be insatiable and infinite. We may choose to believe literally anything. Even so, if the Earth exists in space-time and possesses finite resources; if the Laws of Themodynamics apply to the human species as we know them to apply to other species, then the spectacularly successful growth of the human species and certain of its attendant activities, described repetitiously above, could present humanity with a leviathan-like, non-recursive biological problem.
Steve, you said The unexpected data appear to indicate that as we increase the world’s food supply through our improving production and distribution capabilities, the number of people worldwide goes up, too.
I see. This view of things reminds me of the book Ismael by Daniel Quinn. I read that some years ago … maybe a decade ago … and I have to say I didn’t believe a word.
Yes, perhaps at earlier times in human history, global population increased as food supply increased … much as for other animal species. That makes sense. But that was then. Before global communications. Before birth control. Before education and greater opportunities for women. Before the internet let people like you and me in widely different parts of the world communicate and share ideas.
There’s never been a time in history like now, when humans dominated the globe. You can view that as a problem … or you can view it as an opportunity.
I personally prefer to view it as an opportunity.
I believe humanity is in its “teen” years … and as one Earth & Sky community member said can you imagine the amazing possibilities?
Dear Deborah,
Thanks so much for this discussion. YOU are a wonder.
I agree with what you say about the opportunities and possibilities. They are amazing and they are real. But there are risks, too.
I find it difficult to imagine how human beings seize the opportunities before us without accepting the risks associated with biophysical reality: that we are members of an evolving species in a changing world with “rules” (e.g., Laws of Thermodynamics) to which humankind is subject. Otherwise, we could inadvertently be “dominating” our planetary home in ways that are perhaps harmful to biodiversity, environmental health, and the wellbeing of our children and coming generations.
Daniel Quinn is a story teller, one I like and respect; however, I am not asking us to look at a storybook but at unrefuted scientific evidence of a formidable challenge that could soon be posed to humanity by a too rapidly growing human population.
After hundreds of thousands of years of evolution of the species, Homo sapiens, it simply does not make sense to me that in 2006 we are in our teenage years, as you suggest, and then magically evolve by 2050 into the 9 billion “mature adults” that Joel Cohen imagines.
I can readily envision such rapid growth in the expansion of the world economy, if sustainable; but it does not appear that the general evolutionary process of biology accomodates such astoundingly fast maturation of human beings as is suggested by either you or Joel.
As far as global communication, universal education, empowerment of women, birth control, and sharing of resources are concerned, let me be crystal clear. I am for all of it, and in much greater measures than we find them in the world today. I believe we need for the masters of the universe who are overseeing the world’s political economy to give at least an equal amount of time, energy and resources to global communication of the best available science, to an education for every child, to affirmative action programs leading to many more opportunities for women of the world, to free and voluntary birth control options planet-wide for males and females, and to more equitable distribution of the Earth’s resources.
Thanks for the interesting exchange.
If the average person from 1957 was instantly placed in todays world, might it not seem pretty “magical” to them?
I am young, but it is quite amazing to me how rapidly things can change. Each and every day there are individuals who make monumental changes in there lives through force of will – smoker to nonsmoker, omnivore to herbivore. Further, there are natural changes in our lives that occur relatively rapidly – puberty, menopause. If one considers facts such as these in light of Dr. Cohen’s anaolgy of individual human growth with our growth as a species, is it unreasonable to think that we might exhibit completely deferent behavior as a species in 50 years?
It is apparent that David is young… and a man. :) I am a 53 year old woman and I can tell you that menopause does not occur “relatively rapidly!” In my case the transition has taken ten plus years and counting of symptoms. To quantify that, that’s 19% of my life! When I was young I thought it would be a non-event too, I was wrong! This was off the subject but I couldn’t resist! :) I enjoyed reading the discussion.
David and Marlene, welcome to this discussion! We welcome all voices here.
Steve raised a very compelling issue when he said after hundreds of thousands of years of evolution of the species, Homo sapiens, it simply does not make sense to me that in 2006 we are in our teenage years, as you suggest, and then magically evolve by 2050 into the 9 billion “mature adults” that Joel Cohen imagines.
Absolutely! How can this happen? As it so happens, a parallel discussion of this same subject began today on a mailing list of scholars interested in these issues …
That mailing list is associated with from the Great Transition Initiative. A few years ago, this group provided an interesting perspective on the subject in their wonderful essay essay called (pdf) Great Transition: The Promise and Lure of the Times Ahead
Here’s a long quote from that essay:
The historic record may be organized in different ways, with alternative demarcations between important periods. Yet, a long view of the broad contours of the human experience reveals two sweeping macro-transformations — from Stone Age culture to Early Civilization roughly 10,000 years ago, and from Early Civilization to the Modern Era over the last millennium (Fromkin, 1998). We are now in the midst of a third significant transition, we argue, toward what
we shall refer to as the Planetary Phase of civilization.
Historical transitions are complex junctures, in which the entire cultural matrix and the relationship of humanity to nature are transformed. At critical thresholds, gradual processes of change working across multiple dimensions — technology, consciousness and institutions —reinforce and amplify. The structure of the socioecological system stabilizes in a revised state where new dynamics drive the continuing process of change …
In other words … yes! A new dynamic must emerge to drive a new socioecological system …
HOW will it emerge? Through chaos and need? Or in a more orderly way? That’s unknown at this time.
But emerge it will, I believe. Emerge it must!
What is happening here and now could be vital. We owe a great debt to one another as participants in discussion and to the whole wondrous community of Earth & Sky. Thank you, thank you, thank you all :)
We would want to be reality-oriented, I suppose, in our assessments of the remarkable matrix formed by nature, the human species and its predominant culture. Whether the imagined transformations are chaotic or orderly could well depend upon our communal understanding of the way the world in which we live actually works and our acknowledgement of the human species as one of many species to be blessed by God to thrive in this miraculous planetary home.
Always,
Steve
As I mentioned above, the same topic we’re discussing here – how the transition to a new sort of world might be possible – is also being discussed today by scholars and futurists associated with the Great Transition Initiative. I was able to get permission to post the initial post in their discussion on Earth & Sky’s blog. So I’m going to close this post now … and I direct you all to:
Another world is possible … but how? Guest post from James Goldstein of the Tellus Institute and the Great Transition Initiative. Does the world need a “great transition” to a future of enriched lives, human solidarity and a healthy planet? If so, will a global crisis be necessary to motivate the transition?
Thank you all for your great comments!
All voices welcome.
All viewpoints respected.
– Deborah