Population and consumption: both major players

Growing footprint Consider this a working paper of sorts. It adds to the last post here which discussed the relationship between population and consumption. But it’s only a snapshot of an initial bit of online and library research. I hope to flesh out the topic more fully in the future.

At the end of that post I mentioned two issues I had barely touched on, which deserved more attention. They were (a) the question of whether, even hypothetically, we could ignore population growth and count solely on advances in clean energy technologies to escape ecological catastrophe, and (b) the implications of the observation that over the last century global energy consumption has increased more than population numbers. In my view, the former question is the simpler one, and I’ll get to in the near future. In this post I’ll provide some of what I’ve found concerning the latter issue.

The consumption argument

It’s a common observation that, over the last half century or more, resource consumption rates have increased at a faster pace than population size. I’ve seen this observation used to support the view that population growth isn’t as serious an environmental problem as our growing rates of consumption. Sometimes a proponent of this argument presents data showing that the magnitude of growth of total world energy consumption, or of total consumption of a specific resource, is considerably larger than that of population.

As an example, I found a page on the United Nations Earthwatch website where the writer points out that “materials use has grown far faster than population: in the US, total consumption of virgin raw materials was 17 times greater in 1989 than it was in 1900, compared with a threefold increase in population.” The implication is that the rate of consumption is the more important factor to consider. Is the writer’s argument justified? A closer look reveals it’s not that simple.

Let’s dissect this a little

Recall the equation, first published by John Holdren in 1991, which I discussed in the previous post:

E = P x e

That is, total energy use equals population size times energy use per capita. Likewise, the total use of a particular resource or resource sector (such as “materials use”) would equal population size times the per capita use of that resource. Comparing population growth to growth in total energy or resource use is, therefore, to compare one factor in the equation with the product. Naturally, we would expect the product generally to be larger!

For example, imagine a population of 2. Assume the per capita rate of use of some resource is 1. (i.e., one unit of some kind, applicable to that resource) This population’s total use of that resource use will be 2 x 1 = 2. Now assume the population grows 100% to 4, and the per capita resource use also grows 100% to 2. Now total resource use becomes 4 x 2 = 8. Total energy use has thus grown from 2 to 8, or 300%. This, while population only grew 100%. Can we say then, that resource use is the more important problem in this scenario? Definitely not. Notice that per capita resource use and population each grew by exactly the same amount. To determine which variable is the greater problem, we can’t compare one factor in the equation to the product; we must compare the two factors. The product, after all, is the problem. [1]

The more valid comparison

Let’s turn then to the more valid comparison of population growth to energy use per capita. Not surprisingly, here the data do not always show consumption growth to outpace population growth. For instance, per capita oil consumption was roughly stable from 1982 to 2005 (pdf), while population grew by about 40%. From 1950 to 2000, per capita CO2 emissions (a reflection of fossil fuel consumption) did not quite double. (And they’ve been roughly level since the late 1970s.) During the same period world population grew about 2.4-fold.

On the other hand, if we look from 1850 to 1990, per capita energy use of industrial forms of energy grew almost 22-fold, while world population grew about 4.7-fold. But per capita energy use of traditional forms of energy decreased by 42%. (Holdren, 1991. p. 245)

Holdren (1991) provides the math to reveal how much of the growth in total world energy use can be attributed to population growth versus growth in energy use per capita. (The basic equation is: population share of growth = annual average population growth rate / annual average energy growth rate. I refer you to the article for the details.) He concludes that with regard to industrial energy consumption from 1890 to 1990, population is responsible for 40% of the growth. For total energy consumption population accounts for 49% of the growth. The contribution of population growth to total energy consumption in the United States is even greater. Other authors’ analyses have suggested still larger contributions from population growth.

To be fair, these conclusions have been the subject of some debate in the Scientific literature. Prominent participants were John Holdren and Paul Ehrlich emphasizing the joint contributions of population, affluence, and technology (affluence being analogous to per capita energy use in the equation above), and Barry Commoner arguing for the primacy of the technology factor. Robert Kates provides a summary of this debate and his view of its current status.

No minor players

Given the evidence, it seems reasonable to conclude, much as Kates points out, that the consensus tends toward emphasizing the combined contributions of population and consumption. My impression, merely from perusing a lot of sources, is that with regard to energy related resources, per capita consumption may currently be the slightly more potent driver of total consumption. [2] But clearly, as I emphasized in the previous post here, we ignore either factor in the equation at our peril.

As I said at the opening of this post, this is just a preliminary look at this topic. I’ll return to it in the future, and will soon get to the remaining question from the previous post: Would population growth be a problem if we could develop and make widespread use of extremely clean energy technologies?
[1] In fact, the product, “E,” almost is the environmental impact in this scenario. To get the actual impact, we can plug “E” (or P x e) into a related equation in which it is multiplied by “i” which represents the environmental impact of the technologies used to provide each unit of consumption: I = P x e x i. This can be generalized to the better known I = PAT, in which “I” is environmental impact, “P” is population, “A” is affluence (analogous to “e”), and “T” is the environmental impact of the technologies used to provide each unit of consumption. That equation was published by Ehrlich and Holdren in 1971.

[2] I have not said much in this discussion about non-energy-related resources. I believe, in many of those cases, Population may be the greater driver of total consumption or environmental impact. I will of course devote some future space to investigating that question further.
Offline references:
Holdren, J. (1991). Population and the Energy Problem. Population and Environment, 12 (3), 231-255.

Ehrlich, P.R. & Holdren, J.P. (1971). Impact of Population Growth. Science, 171, 1212-1217.
Image source: The Sustainable Scale Project which encourages viewers to use its materials with attribution.

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23 responses to “Population and consumption: both major players

  1. Fortunately we’ve learnt to walk and chew gum at the same time. So too, we humans can deal with the problems of population growth and per capita consumption together. Neither can be left unattended to.

  2. I like the way Kates frames the problem. It’s all too easy for wealthy nations to point to the high population growth taking place in poorer countries and say “that’s the problem,” then for poor countries to point to the high consumption/pollution in weathy ones and say, “no, you fix your problems first.”

    As Verdurous points out, we can address both concerns, however, Kates says:

    …there is a profound asymmetry that must fuel the frustration of the developing countries’ politicians and scientists: namely, how much people know about population and how little they know about consumption.

    He notes “the quantitative analysis of consumption is just beginning” while the understanding of population is comparatively mature.

    So while we must address both, we need more focus on understanding consumption.

  3. Trinifar,

    Yep, I saw that comment in Kates’s article. I’m sure it’s true that we need to understand consumption better. At the same time, the population issue has become taboo, and that needs to be dealt with as well.

    Regarding the latter, I sometimes post comments under articles on Alternet. (under the name JohnF) These are articles on things like sustainability and global warming. The amazing thing is how they just about *never* mention population growth. The funny part is that I and others consistently mention that in the comments, but still the articles keep coming with no mention of population.

    OTOH, I’ve noticed that one online magazine that does sometimes address population is emagazine.com:


    Search for “population growth” and similar terms there and you’ll find quite a few articles.

    Anyway, yeah, it seems we need to develop a better understanding of the dynamics of consumption while we work to break down the ridiculous taboo that has arisen concerning population.

  4. Verdurous,

    I agree. At least I certainly hope we learn to attend to both. It’s amazing how often I see people take an either/or approach in discussion of these things when there’s no reason we can’t tackle both.

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  6. I think on both counts, continual growth is almost accepted as a given. At least that’s true in Australia. A shrinking population tends to be seen as a society in decline. Small towns in rural Australia for example. On growth in consumption, how can the punter in the street question a politician campaigning on “five successive years of economic growth” where the benefits don’t need to be explained they are just inferred. When the big retailers fail to sell more stuff than last year there are dire warnings that the “economy” will suffer. The “economy” is of course an abstraction and we should be more conscious of whether people are suffering.

  7. Verdurous hits the nail on the head in pointing out two issues that are close to my heart.

    1. In many places population growth being a problem is not tangible — Canada, the USA, and Australia being obvious ones.

    2. The “average person” thinks of the economy in terms of “how many units of the local currency do I get to spend each year” and “how secure is my job.” And nearly every message sent by governments and corporations re-enforces that thinking.

    The notion of “Growth is Madness” (which should win some kind of award as best blog title) is all about pushing back on these bits of “common knowledge.” When I worked in Silicon Valley you couldn’t swing a dead cat and not hit some marketing or sales person salivating at the prospect of getting their products into China; they saw nothing but goodness in the idea of an economy growing at 10% per year — especially in a country with such a vast population. I suspect that remains the prevailing idea.

    This is part of what I had in mind with respect to better understanding of consumption. It’s too hard a sell to just say “use less.” We need to frame it (at least) as “improve your life” and get some help from some of those god-like figures of economic success. When we see a Bill Gates or Warren Buffet begin to talk about new and different economic models for a sustainable world, well, that will be a watershed moment.

  8. Trinifar and Verdurous,

    I first came into this in looking at small town growth issues and urban growth issues in general. You’re so right that government from the local level to the national as well as the corporate world just put out a constant message that the “benefits” of growth are simply a given. In the small town where we were living I was seen by the “establishment” as some kind of nut. They perpetuated illogical myths to the effect that the local economy needed residential growth to survive, though yes, they would eventually run out of room to grow. (I guess they expected the town to die at that point. :-/)

    And you read things in the paper that just assume growth to be good and desirable without stopping to even consider questioning it. Yep, we have to push back a little against such accepted thinking, even though we sound like nuts to some.

    Only one small point I’ll quibble with slightly, Trinifar. I grew up in the Phoenix area and now live in Boulder, where I went to college back in 19-cough-cough. 🙂 In both places the effects of population growth are almost shocking to anyone who remembers them way back when. In Boulder the effect isn’t seen right here as such. Boulder has in place some of the most progressive growth control measures in the nation. So Boulder itself is really a lot like it was back in the day. But the stretch between Denver and Boulder is another story. What used to be a half hour drive of open space and plains, is now almost totally built up with condos and malls.

    The Phoenix area is just a monster of growth that’s taken place over my lifetime. What used to be pristine, beautiful desert, *way* outside town, is now Porsche dealerships, housing developments and of course malls of all shapes and sizes.

    But yeah, I suppose population growth in many developing countries has much more troubling, tangible consequences. I just wanted to complain a little. 😦

  9. I was talking to a fellow anthropologist back in June 2006. I said: “If ever I had the chance to do some reasearch again (which unfortunately I don’t), I’d focus on the population explosion, as a key logical factor to understanding climate change and many other forms of environmental disaster.”

    Response: “Would that really be necessary?”

    I explained myself, and the man frowned at me. This topic of social science really was off limit.

  10. Oh, I have that same perception, John. Having grown up in a small rust-belt town that hasn’t changed much (yet is now getting clobbered with a Wal-Mart and several other big-box retailers), seeing the amazing growth in the SF Bay Area was shocking. It was almost as if you could see it happening before your eyes. As soon as I could I left — which is a shame because it is one of the most culturally vibrant areas in the country (and the weather is damn near perfect).

    I was there during the tech boom. One of the more ironic happenings: as more and more of GM’s EVs appeared on the highways the number of SUVs and Hummers exploded. I also got to experience California’s rolling blackouts, a result of power deregulation and Enron’s manipulation of the market.

    It was hard to meet anyone in the Bay Area who actually grew up there — because so many people moved in. The area between SF and San Jose used to be filled with small towns and orchards. Even 20 years ago it was fairly bucolic. Now it’s one solid mass of housing and businesses, and the sprawl on the other side of the bay seems completely out of control as well. Everywhere a BART station opens up a spurt of rapid growth begins. And on that side of the bay most of the growth was displacing some of the best topsoil to be found anywhere in the world.

    I used to sit with a Buddhist meditation group there. One night in response to a question there was a show of hands. Of the 100 or so people in the room, more than 80 worked in hi-tech. Most of us turned to meditation at least in part to cope with the hectic nature of our lives. We’d drive through the dense rushhour traffic after a long workday at the middle of a 60+ hour workweek in order to spend 90 minutes in a calm, quite environment — irony abounds. Certainly gave meaning to the Buddhist notion of refuge.

    Back to the topic…

    So, yes, there are many places where we can see rapid growth right here in the USA. And some of us are horrified by our view of what economists call the opportunity cost. Where I see the Porche dealership on the strip outside of Denver as an exemplar of insane consumerism displacing a section of cherished openspace, a hundred others see it as an indicator of a healthy wealthy community and, if confronted about growth, merely point to vast sparsely populate area that is western Colorado.

    Most people struggle when faced with a problem with many variables: water, soil, global warming, energy, pollution, living space, taxes, consumption, landfills, …. That’s why I was so taken with the E = p * e equation — just two variables. It’s a great tool, a bit like putting training wheels on a bicycle, a way to get to started so you can begin to aquire a more nuanced view.

  11. Magne,

    “This topic of social science really was off limit.”

    Interesting story. It’s a troubling sign. Science really should be able to explore freely any legitimate topic. But then I guess there are some which carry so much political or emotional baggage that even scientists (who should ideally exercise some sort of scientific neutrality) shy away from them. And when one wants to deal with such a topic, others try to discourage it. That’s the troubling part.

  12. Trinifar,

    Heh, I could talk about our years in San Diego too. I got there around ’83, which I think was sort of the tail end of its having been more or less a laid back surf town. From there it just sprawled tremendously. It’s still a nice city, I think, but without the character from what it once had.

    Yeah, that equation is a great help in clarifying things. The better known equation is I=PAT (which I touched on in a footnote to the article). But the one I focused on has to be understood anyway to understand I=PAT.

    BTW, just a few days ago I received a journal article which appears to be *the* most current one to make use of I=PAT. I need to look at it more closely, but I think their conclusions are in line with what I described in the post. I may write a post about it or add it as an update to the one above.

  13. “I explained myself, and the man frowned at me. This topic of social science really was off limit.”

    – —

    On a different note: here’s what Dalai Lama had to say – back in 1989 – about the challenges our generation is faced with.


    “We all know the immensity of the challenges facing our generation; the problem of overpopulation, the threat to our environment and the dangers of military confrontation. (…) Freedom is the real source of human happiness and creativity. Only when it is allowed to flourish can a genuinely stable international climate exist.”

    Unfortunately, it seems to me like the political, economical, and even scientific milieus of this world have grown ever more sensitive toward any version of “the truth” that might include bad implications for the future of mankind.


    If Albert Einstein was alive today, I bet you he would hardly be allowed to make this simple statement in public: “We shall require a substantially new manner of thinking if mankind is to survive.” (1949)

    As if today, this statement has somehow become politically and economically incorrect. Those who make such statements today will always be tagged as “doom-and-gloom” enviro-fanatics of the meaner mould.

    It’s sad, really. Realistically, everybody ought to understand that there must be a limit to growth. And realize that we’re rapidly closing in on that wretched limit. – This is another truth that has, quite obviously, been banned.

  14. “Those who make such statements today will always be tagged as “doom-and-gloom” enviro-fanatics of the meaner mould.

    It’s sad, really. Realistically, everybody ought to understand that there must be a limit to growth. And realize that we’re rapidly closing in on that wretched limit. – This is another truth that has, quite obviously, been banned.”

    That captures it very well. If you make statements such as the one Einstein made, you’re called an “alarmist,” or a “doomsayer.” If you say much less, you’re simply ignored.

    And yes, it really should be so simple to see that there are limits, that the earth is finite. But denial is powerful.

    I was watching a little video which will (probably) appear in my next essay here (coming up very soon) which included comments from a couple of “eco-psychologists.” This was a new term to me despite my past training as a psychologist. As I understand it, they deal with our psychological relationship to the environment and our emotional responses to. ecological issues. I wonder if they’d see the near “banning” of certain topics, as you mentioned, as an aspect of a larger collective denial. I think it may be.

  15. I’m already looking forward to your next essay, John. 🙂

    “Eco-psychologist” – that’s an interesting term. I have been spending a lot of time on the forums of http://www.theenvironmentsite.org, trying to get people to discuss theses emotional and socio-psychological responses to ecological issues. I have found that it is difficult for most people to discuss the issue. – Some people do, though. It takes courage, I guess. In some cases it takes a few character flaws, as well. 😉

    Here’s Ehrlich again:


    Quote: “President of the Stanford Center for Conservation Biology, Ehrlich recently proposed the creation of a global Millennium Assessment of Human Behavior (MAHB), a follow-up to the United Nations Millennium Ecosystem Assessment and similar climate-change efforts but with a specific focus on human behavior.

    “[MAHB] was named to emphasize that it is human behavior toward one another and toward the planetary systems that sustain us that requires assessment and modification,” Ehrlich said.”

  16. http://news-service.stanford.edu/news/2004/august4/esa-84.html

    This is a very interesting read. Now, I don’t know what came of it (the proposal was made in August 2004), but I think it’s fair to say that the issues raised back then is being discussed more freely today, in 2007, than it used to be no more than two or three years ago; … although, mainly by independendent actors, bloggers and the like. Well, it’s a start.

  17. Magne,

    It would be nice to see some progress on getting social scientists, ecologists, and other natural and biological scientists to begin to help reframe the way people treat one and other and the environment.

    It all seems to go in bursts, then blowbacks. Maybe that is the only way any progress happens. In the meantime the doomsday clocks keep ticking.

  18. Japan’s population is already shrinking, just like Russia and half of Eastern Europe. 505 of the world’s population lives in a country with below replacement level fertility and the other 50% lives in a country where fertility is in decline. The United Nations predicts world population will peak within 30 years – and they have always guessed high and long! Total population will almost certainly never top 8 billion and might not reach 7 billion, then begin sharp reduction.

    And this isn’t good news! Declining markets and deflationary economics will mean a lack of funds for clean energy initiatives. A declining population will lower interest in conservation and clean energy.

  19. Hi Deep Thought,

    You write: “The United Nations predicts world population will peak within 30 years…”

    Actually, no, it doesn’t. See this post for the details, but the UN report is widely misunderstood.

    However, even if world population were to progress exactly in line with the UN projections (which the authors make clear are very different from predictions) that would mean around a 40% increase above a population that has already overshot the earths carrying capacity by many expert accounts. With world population already too large for the earth, there is not much comfort to be had from the specter of a 40% increase.

    “Total population will almost certainly never top 8 billion and might not reach 7 billion, then begin sharp reduction.”

    You may be right on that. There is good reason to be concerned, as Lester Brown points out in the current post here, that our overshoot of the earth’s carrying capacity will impose limits on population growth before it reaches the levels described in the UN’s projections. The risk is that population growth will be stopped by disease, starvation, etc. Before many millions of people die by such means, we need concerted efforts to reduce fertility rates in order to stabilize population growth sooner and minimize the damage.

    “Japan’s population is already shrinking, just like Russia and half of Eastern Europe. 505 of the world’s population lives in a country with below replacement level fertility and the other 50% lives in a country where fertility is in decline.”

    (You meant 50%, not 505, I’m sure.) If you’re going to pose such an argument to challenge what I said, It would be considerate if you’d site your sources. Not only will it strengthen your argument (if the sources are legitimate), but it will allow me to assess it more easily. In any event, I’m aware of the general idea you outline: A few countries’ populations are beginning to shrink slightly, and a few (e.g., in Europe) now have sub-replacement fertility rates. And the rate of world population growth has been slower in recent years. (We can’t actually say it is “in decline,” as we can only examine it in the rear view mirror, so to speak.) Still, world population continues to grow, currently at about 1.14% per year. Though it sounds small, that’s pretty vigorous growth, as you know if you’ve looked at the math of population growth.

    That is all good news! But it’s not enough. The earth is finite. It cannot sustain infinite population growth, and many serious estimates of carrying capacity put it somewhere not far from current population levels, often lower. See Joel Cohen, for the most comprehensive survey. He has studied carrying capacity more than probably anyone, and concurs that we are probably beyond the earth’s carrying capacity for any sort of decent standard of living. So while it’s good the population growth rate is slower now, it’s still vigorous, and needs to come to a halt ASAP. Read what scientists have been telling us, and I think you’ll come to the same conclusion.

    Your concerns about deflationary economies is misplaced. (I’m guessing you’ve picked up those concerns in right wing, perhaps libertarian, writings.) Adjusting to that will be trivial compared to adjusting to a hard collision with the earth’s carrying capacity. I’ve written here before about the steady state economy and other aspects of ecological economics. We need a whole new economic model, one which recognizes the limits of the ecosystem. Implementing that will be a challenge, but nothing like the challenge of famine, war, disease, etc.

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