The not-so-elusive population-environment link

Strip miningThe most basic assumption driving this site is that population growth and corporate economic growth team with per capita resource consumption as the primary drivers of today’s ecological decline. Perhaps, then, it’s best to devote this early entry to a bit of support for that assertion. There are people, after all, who question it.

Let’s start with population growth. Especially prominent among those who dismiss the idea that population growth is a problem have been a few economists—most notably the late Julian Simon—who cheerlead population growth, arguing that it is always to our benefit. Natural scientists, for the most part, do not much question it as a major cause of environmental degradation. That in itself speaks volumes. Nevertheless, is it possible to use simple logic to demonstrate a link between population growth and environmental damage? I believe so.

More people, more warming

Consider climate change. There is now an overwhelming scientific consensus that human activity is contributing significantly to global warming. The implicated human activity is anything we do which causes greenhouse gas emissions. One of those things is driving cars which burn fossil fuels. Clearly then, everything else being equal, more cars means more anthropogenic greenhouse gas emissions — the primary gas of concern being CO2.

World population has doubled since the early 1960s. As a result of that doubling there are now far more cars operating than there were 40 years ago. There are, therefore, more auto-related emissions. Those increased auto emissions mean more CO2 emissions and more forcing of climate change. [1] [2] It is therefore indisputable that population growth has contributed significantly to climate change. [3]

There, that was easy enough. And we could construct similar analyses of the relationship between population growth and other human sources of greenhouse gases. We could just as easily demonstrate the links between population growth and other aspects of environmental degradation. For a fuller discussion of the population-climate change link, see the relevant page on the Union of Concerned Scientists site. For more on the general topic of population and the environment try Al Bartlett’s excellent article, Reflections on Sustainability, Population Growth, and the Environment – Revisited. In future entries I’ll try to provide equally simple arguments to support other aspects of this site’s basic assumptions.

[1] Note that CO2, the most significant greenhouse gas produced by human activity, has not historically been regulated by auto emissions standards.

[2] For voluminous information on the relationships between greenhouse gases and climate change see the various documents at the IPCC website. Of particular relevance to this post, see the top graph here, illustrating the increase over time of atmospheric CO2 and the associated estimated radiative forcing.

[3] Just to add some perspective, the U.S. Department of Energy reports, in fact, that, “In 2003, the transportation sector accounted for about 27 percent of total U.S. GHG emissions, up from 24.8 percent in 1990.” (Thanks to Wacki, who maintains the climate change blog, for that reference.)
Image source: Stephen Codrington, posted on Wikimedia Commons under a Creative Commons Attribution 2.5 license

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17 responses to “The not-so-elusive population-environment link

  1. John,

    Any thoughts on humane and potentially effective methods to bring about a stabilisation or gradual decline in the human population to sustainable levels?

  2. Verdurous — Yes, most of th experts focus on things like addressing poverty in developing countries, educational opportunities for women (in developing countries as well as in other countries – like the US – where you have a lot of unwanted children in lower income segments of society), and increased availability of family planning/birth control info. There’s a quick rundown of such items toward the end of this editorial by Jeffrey Sachs.

    Often it’s that very question, I think, which makes the whole population issue taboo to some people. They jump to the conclusion that stabilizing or gradually reducing population size means draconian measures of forced sterilization and such. But that’s just not the case. It is true that some important writers, such as Garrett Hardin who wrote The Tragedy of the Commons, have concluded that forced measures would be necessary, but I’m not sure the evidence supports that as we do seem to see trends of reduced fertility rates in most developed countries. Also, we just have so far to go in implementing the more humane measures that their potential is really untapped at this point.

    Of course it’s also key that cleaner technologies be developed. As a country’s standard of living goes up, so does it’s per capita resource consumption tend to rise. So we humans have a big project on our hands. It’ something I expect to devote a lot of posts to here.


  3. Thanks John,

    After reading your post I added a link on my site to “Sustainable Population Australia”.

    I guess I would add economic measures to your suggestions for humane means of influencing growth. This could be taxation but could conversely be incentive payments for people who have less kids. In Australia we have something called the “baby bonus” which is a grant of several thousand dollars for people when they have children. It was initiated by the federal government primarily to boost fertility rates.

    One of the problems at present is that our concept of success is predicated on a growing economy and one crude way to achieve that is to grow the number of consumers. This must change.

    How about an “emmissions trading scheme” for fertility. People who have less than two children could sell their right to children to those who want more than two. Hey, I’ll claim the copyright on that idea if no-one else has !

  4. Verdurous,

    Yes, I absolutely agree with everything you say about economic incentives. And that’s a great idea… applying the “emissions trading” model to this. 🙂


  5. Verdurous,

    I found this article:

    …which provides a pretty thorough rundown of various countries’ experiences in trying to lower fertility rates. Though it’s vintage 1990, it does touch on a lot of different ideas, including monetary incentives and disincentives.

    This page:

    …, like the site it’s a part of, contains a huge volume of information on the subject pulled from all sorts of news articles and sources. Worth a look.

    It’s surprising to me that some lists (such as Sachs’s) of things we can do don’t include the monetary angle. Not sure what’s going on there. It would be interesting to see an update of the info in the 1990 article.


  6. Devil's Advocate

    We worked hard. We passed on the yearly vacations, we sent our kids to public school, we drove a small car instead of that big SUV. Finally it paid off! We now could afford a nice place in the country. Sure, a few trees needed to be cut down. Not to worry, there were lots of trees. Some wildlife had to
    be displaced. I told you we work
    ed hard for it, right? Perhaps you aren’t getting it. What are a few chipmunks? We’ll build a nature sanctuary to make up for it. We’ll give to charity. The disruption was minimal. We paid our taxes. We are good people. Life is good!
    But soon other’s wanted their place in the country too. Developers listened. They began clearing trees, buiding roads, making noise. Didn’t they know that would displace wildlife. Didn’t they understand it could cause precious washaway of nutrient rich soil? Why don’t they just stay where they are? Highrises aren’t that bad? Make do.
    We worked for it. Yes, we were fortunate enough to live in a prosperous nation. Ok, so maybe we created a little pollution. We had to do it. Else, we couldn’t build the greatest industrial machine, the great war machine, we couldn’t police the world. If it wasn’t for us, the developing countries wouldn’t stand a chance! Ever heard of Hitler?
    But they won’t listen!! They keep cutting their forests down. Polluting. They even want nuclear technology. Don’t they understand they aren’t ready for it? They could have a nuclear accident!

    I like my place in the country. I deserve it.


  7. Devil,

    I have to say you make some very good points — for me, but… 😉

    Actually, you touch on urban growth, which is an area I hope to examine in some future posts. Population growth, economic growth, urban growth, consumption growth… they’re all closely related, and there are people with financial stakes in making sure they all continue ad infinitum, or, well, at lease until we’ve committed ecoside.


  8. Here’s a piece of experimental maths.

  9. Magne,

    Thanks for the link. That’s an interesting site with a great deal of discussion going on. I was happy to see someone linked to GIM. 🙂

    The math of population growth can really be eye opening. Here’s a link to a little calculator which allows you to plug in the numbers, assuming a fixed growth rate, showing a graph of the resulting population:

    An interesting tidbit is that apparently even a declining growth rate (as we’ve seen in recent years) can, within certain limits, still be “exponential” in nature:

    I’ve researched it well beyond that link. The math goes beyond my own training, but several experts seem to agree on it. At any rate, the terminology isn’t as important as the fact that world population is still growing at a strong pace with no truly predictable end in site.

  10. Magne Karlsen


    Unfortunately, your link to the little calculator failed to open. What a shame. I’d love to see how it works.

    Anyway: the little calculator would certainly not amaze me too much, as I have been cursed with a clear understanding of the terms “exponential growth” and “population explosion” ever since I was 12 years old, when I figured out the maths of it on my own.

    Curiosity killed the cat. – – 😉

    Now, I’m seeing that you are trying to come up with ideas as to how to bringing the population explosion to an end. And yes: I know, very well, that it is not going to be easy. This is not just a question of how many children every woman gives birth to, but also a question of how old we are becoming, on average, before we finally call it a day, and die from natural causes.

    I don’t know the correct English term for this, but in Norwegian we are talking about “the wave of elders”. –

    In terms of “planning for the future”, I have always believed that the maths of population growth should be taught to children. I believe that if the problem itself has its place in the minds of children and youth even before they are making their sexual debut, much of it will be solved.

    But who’s going to do the teaching? You know: this won’t be done, ever; not in catholic schools nor in muslim schools.

    Another problem is CULTURE. – I am a social anthropologist myself. There are plenty of regions around the world, where the extended family system comes almost as a law of nature: “If it wasn’t for the seven, nine, eleven children you got, who’d take care of you when your working days are through?”

    The problem is: I would not be amazed if the world’s population pushed past the 10 billion mark very soon; and much, much sooner than US and UN-employed demographers would like to have us think. – And now: in this world of over-industrialization … like you: I wonder … what will be the outcome ..?

  11. Hi Magne,

    Right now the calculator is opening for me. Maybe it was just down temporarily when you tried it. Another way to try to get to it is through this link:

    In the left collumn, under “Modeling,” click “exponential growth model.”

    I agree with everything you say. I’ll just comment on a couple of items:

    You’re right that increasing life spans play a role in population growth as well. Of course that’s not something anyone wants to impede. But gives one pause to imagine what the outcome might be of some major breakthrough in life extension. Could be a lurking issue of real significance, I suppose.

    I agree that teaching the math of population growth to younger children could potentially be a very valuable intervention. But, as you say, it’s not going to happen in some schools and some areas. Perhaps some of those who recognize the problem of population growth need to engage in some sort of diplomacy with those who don’t. (something like what Edward O. Wilson has done with his book, The Creation: An Appeal to Save Life on Earth.)

  12. Magne Karlsen

    Some sort of diplomacy will be needed, of course. But how?

    I mean: if diplomacy was a deck of cards game, a lot of people would quickly throw either one of a multitude of “God-cards” at anyone who started to question the tradition of giving birth to a minimum of five children per woman; which is the customary practice all over Africa, in India, Malaysia, Indonesia, the Philippines, and Latin America.

    Did you ever hear Michael Palin singing: “Every sperm is sacred in this neighbourhood.” ..? – – 😉

  13. Magne Karlsen


    I realize that you’re an American. In case you didn’t know: Michael Palin in a member of the famous British comedy ensemble known as Monty Python.

    The movie in question here is: “The Meaning of Life”

  14. Magne,

    Yes, I know of Michael Palin. 🙂 As for diplomacy, well, it will take very clever diplomacy. I could only wildly speculate beyond that. Basic education might have some impact too, but that God card could be an obstacle, yes. But there are areas (Mexico is an example), where fertility rates have come down from around 7 to the 3-4 range, seemingly in part as a result of various programs. Karen Gaia Pitts posted a comment under the “Population Solutions” post here describing how a program aimed at women’s reproductive health (see comment for details) had helped lower the fertility rate in Bangladesh from ~ 7 to under 3.

    So “diplomacy” and education, yes, but also just improving opportunities for women is another kind of thing that will have an impact. Educated, working women tend to have fewer children.

  15. Magne Karlsen

    John wrote: “You’re right that increasing life spans play a role in population growth as well. Of course that’s not something anyone wants to impede. But gives one pause to imagine what the outcome might be of some major breakthrough in life extension. Could be a lurking issue of real significance, I suppose.”

    – —

    You know: in the western world (and, in time, also the rest of the world), the ageing population dilemma is among the demographic factors that really has “come to annoy us” … 😉

    What is going to happen to society, as the birth rates start to go down (“good news”), at the same time as the medical science makes it possible (even likely) for people to become more than 100 years old, on average (“good news”)?

    The population pyramids are about to become quite skewed. Who is going to do all the extra amount of nursing this rapidly growing amount of senior citizens?

    I think we’re going to discover that “good news” plus “good news” equals “not-so-good news” …!?

  16. Magne Karlsen

    Statistical handbook of Japan.

    – —

    See Figure 2.3 ~ “Changes in the Population Pyramid”

  17. Magne, I love your phrase ‘“good news” plus “good news” equals “not-so-good news”’! How true.