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Let’s reduce consumption

February 4, 2009

Population, efficiency, consumption—they all relate so intimately.  Many authors better than myself have already pointed this out, so why bother?   I don’t know—just trying to put it out there publicly, I guess.

Discussing the size and growth of the human population is largely taboo, and the Global Population Speak Out seeks to change that.1 Many would disagree and would call the proponents (of discussion) whiners and point out that population is indeed brought up all the time, but they’re only part right.  I have seen population as an environmental issue brought up in a number of places, one of the more well known being in the Planet Earth series.2 The problem isn’t necessarily that it’s not brought up, but that serious discussion on the issue rarely follows the mention.  It’s a mere few sentences usually, a complete gloss-over.  Just as one can’t closely examine something on the ground from an airplane, we can’t look at the issue of population seriously if we refuse to give it more than a few sentence here and there.

One objection to discussing how to reduce the number of people on Earth revolves around the subject of one of my last posts; commonly the proponents are asked How do you suggest we reduce the population?  Since there isn’t a comprehensive plan-of-action, many refuse the issue right there because they think the proponents lack foresight.  This is a problem.  There is no comprehensive plan exactly because population isn’t talked about.  So we have people refusing to talk about population because there is no plan, and there is no plan because it’s not talked about.  It’s a big catch-22, and it’s one that could easily be avoided.  I illustrate the failure of this rejection because I think it shows how important it is to break the taboo.

A far sillier objection revolves around people not seeing humans fitting into the natural scheme of things.  A caller to a radio show that interviewed John Feeney and Jeffrey McKee on Feb. 2 had this to say:

… It sounds very moral up front—yes, we need to do this for the long-term—but the problem with this conversation is a world-view that devalues human life to the species of animals.  Humans beings are not animals; human beings are above animals. The problem with this philosophy is when you start saying to people “The governments of the world are going to tell you how many children you can have,” that is very disturbing to me.3

Fortunately he and one other were the only people saying such things; the majority of the callers were responsive to the message.  First things first: humans aren’t animals?  In what world?  Humans are above animals?  In what way?!  Are we on a totem pole?  I’m reminded of a bit from comedian Joe Rogan:

And the real problem is, most of us are dumb. We don’t want to admit it, but really, how many of us are really smart? Look, I know I’m stupid. I know. I know I’m stupid, but yet I’m smarter than almost everybody I meet.


The real problem is most of us are idiots; we just like to think we’re not idiots because we use a bunch of shit that smart people have figured out. But how many of us understand any of that shit? Think about the technological level that this world operates on. How many of us really understand that? What if everybody out there died and we had to take over the world? How well you think we’d do? [Sarcastic voice] Yeah, terrific! We would do awesome!

Yeah. Does anyone know how any of this shit works? [Smacks mic] Why’s that loud? Any idea? I’ve been a comedian for 16 fuckin’ years—I have no idea what’s in there! I dunno, some loud shit? I dunno. [Points to light] What makes that bright? Bright shit? I dunno.

Think about all the stuff you need to run your life: computers and palm pilots, cellphones—how many of you know how to make any of that shit?! I mean, if I left you alone in the woods with a hatchet, how long before you could send me an email?

We are not smart; we buy shit from smart people!

I like being a human, really, I do.  And is there something that, in a way, separates us from other animals?  Yes, I think so.  Human beings have an enormous capacity for complex thought, we’re highly adaptable.  Physically we kind of got the evolutionary shaft, though; our bodies are really best adapted for one thing and one thing only: walking.  In a race with a cheetah, or most other large mammals, we’ll lose every time.  In a hand-to-hand fight with a bear we’ll get our heads knocked off.  That doesn’t make animals better than us in general, but they’re certainly better than us in many ways, just as we are better than them in many ways.  Even mentally most of us, while perhaps at a higher thought-level than other animals, are far below the most advanced possible.  There is really no way to objectively compare us, nor should there be.  It’s irrelevant.  We’re members of the animal kingdom just like cheetahs and bears, and denying this is completely delusional.

But in my estimation, the biggest objection to discussing the numbers by far is the argument that the issue is not population, but consumption.  Again, a number of authors better than myself have pointed this out in the past,4 so why bother exploring the topic myself? And, again, I don’t know. I’ll attempt to make a few additions that, personally, have helped solidify this idea in my head.  This is where the Serious Business begins.

I’ve come across two equations that relate population and consumption; there are probably more but these are the two I’m familiar with.  The first was first brought about by John Holdren and Paul Ehrlich in the ’70s and is known as the IPAT equation,5 and the second is something of a revision put forth in 1991 by Holdren. IPAT looks like this:

I = P A T


Impact = Population × Affluence × Technology

While the revision looks like this:

E = P e


Total Energy Use = Population × energy use per capita

If that little taste of math scared you, stop reading now.  This is, after all, essentially an issue that revolves around numbers, and the rest of this post will be filled with them.

These are similar equations, and for my  own understanding and preference I’ve modified the two of them slightly.  The second equation has essentially combined affluence and technology into per capita energy use, and I think this is kind of the right thing to do; however, keeping them seperate has its uses as well.  My version of the equation would look like this:

I = c P A E


Impact = constant × Population × Affluence × Efficiency

… where I = 1 represents the planet’s carrying capacity for humans and c is simply a constant used to make I = 1.  The constant will be determined later.  Impact, in my version, is much the same: total global impact of human societies.  Population, also, remains the same.  Affluence, as I understand it, represents the total use of technology, the total spread of high-standard-of-living lifestyles, etc.  Efficiency is how efficiently our technology is used and how efficiently we consume natural resources.  I < 1 represents all that is livable while I > 1 represents overshoot.  Growing A means growing worldwide wealth, consumption, etc. while shrinking A means the opposite.  E will be a decimal percentage; technologies becoming more efficient will be represented by a shrinking number.  I think these are reasonable definitions.

(A little extra on efficiency: let’s say we call a certain technology 60% efficient.  What I would take that to mean is that 60% of the energy that goes into a device, machine, whatever will be converted into a useful task.  For comparison, a bad technology that is 0% efficient would put 0% of the incoming energy to a task, while a good technology that’s 100% efficient would put all of its energy into the task.  From what I remember from chemistry and physics classes I’ve taken, the law of the conservation of energy6 makes it so the energy within a system remains constant, and cannot be created or destroyed.  Therefore no technology could be more than 100% efficient—that is, it cannot create more energy than used—and in practice it is highly unlikely that some energy will not be lost as heat energy, etc., making 100% only theoretical.  I’m unsure on whether or not negative efficiencies are possible, though in the way I would calculate the equation it seems applicable.  Using a benchmark of 60% I would calculate E thusly: 1 – .60 = .40.  This makes higher efficiencies lower decimals, thus lowering I.  90%: 1 – .90 = .10.  An example of a negative 10%: 1 – -.10 = 1.10.  A negative-efficient use of technology would thus raise I.)

I don’t hope for this equation to reach the public really, I’m not sure on the true scientific merits of it either, but to me it makes sense, so I’ll use it to illustrate why reducing comsumption alone is not a solution.

(Note: Numbers will be far from exact, but that doesn’t matter.  Estimates will illustrate my point just fine; exact figures would only make it more accurate.)  Population we’ll use in billions.  So, today, P = 6.7; in 2050 it’s estimated to be anywhere from 9 to 12.  I considered using HDI for A, but it appears the global average (which I cannot find) might actually be lowering; meanwhile, global consumption of resources is still growing.  For this reason I’ll use world real GDP figures (in thousands) instead.7 (I don’t think either measure exactly what I want particularly well; if someone knows a better way, please let me know.)  Using the figures I’ve come across it appears we’re at roughly A = 7.9(?).  Using the 33-year average growth rate of 3.46%, that will put us at 33.8 in 2050 (or roughly 33,800).  As far as technological efficiency goes: I have absolutely no idea how to measure this, or how to estimate where we’ll be in 2050.  So I’m just going to go with wildly inaccurate guesses.  For today I’m going to say we’re at 25% efficiency, or E = .75.  Let’s say by 2050 we’ve bumped that by 10% to 35%, or E = .65.  We’ll fiddle with this number later.

Now we come to finding c.  To do this I’ll use a theoretical I = 1 situation.  To do this I’m going to plug in 2050’s numbers and assume that this will bring us to the planet’s carrying capacity.  Personally I think humans are already in overshoot,  but again, I’m illustrating a point.  So again, the equation:

I = c P A E

And we get…

1 = c × 9 × 33.8 × .65

Rearranged for c…

c = 1 / (9 × 33.8 × .65)

c = 0.00505740150711

We’ll round it to 0.0051.  With todays figures that would be:

I = 0.0051 × 6.7 × 7.9 × .75

I = 0.20245725

Whoa!  Way below carrying capacity.  Or, if you want to look at it another way: today’s impact is only 20%, or only one fifth, of what it will be in 2050.  If you think that we’re already over carrying capacity today, like I do, ask yourself this: Is that OK?

Let’s look at what it will look like in 2050 if population grows to 12 billion instead of 9:

I = 0.0051 × 12 × 33.8 × .65

I = 1.344564

Uh oh, we’re 34% over in this scenario!  So what can be reduced to bring us to carrying capacity?  We don’t want to reduce people’s standard of living, do we?  No… And we don’t want to take away stuff from people who already have it, so reducing A is out of the question.  So that leaves technological efficiency.  Surely we can make our technology more efficient, right?  Let’s take a look:

E = I / (c × P × A)

I = 1, so…

E = 1 / (0.0051 × 12 × 33.8)

E = 0.483428085238

Or 52% efficiency in energy and resource use.  Doable?  Maybe.  That means we have to have technology that’s twice as efficient as the technology we have today.  I’m not saying it’s impossible, but the 10% increase seems more realistic.

Now we’re going to backtrack a little.  According to the work done by the Global Footprint Network humans already use the equivalent of 1.3 planet Earths,8 and other studies have similar findings.  What this means in terms of the equation I’ve been using is that I = 1.3 today, not in 50 years.  This is a statistic which many accept, esspecially the environmentalists (and others) who claim there is a problem, but that it can be dealt with by addressing consumption, not  population.

Recalibrating c with this statistic:

c = 1.3 / (6.7 × 7.9 × .75)

c = 0.0327476541344 or 0.0327

Now we’ll use this new value of c to predict global impact in 2050.  Ready?  I’m not.

I = 0.0327 × 9 × 33.8 × .65

I = 6.465771

Do you find this number acceptable?  Even possible?

So how do we bring that down to 1?  Well, if the problem has nothing to do with population and everything to do with consumption, we need to either reduce global affluence or increase efficiency.  First A:

A = 1 / (0.0327 × 9 × .65)

A = 5.22752816331

As you’ve probably already noted, that’s a lower value than we have today.  (Remember, I used world real GDP per capita, which today is just below 8000.)  Try again for efficiency:

E = 1 / ( 0.0327 × 9 × 33.8)

E = 0.100529387756

We need to get to 90% efficiency.  Noting that my guesses for efficiency today are probably way off, it’s more accurate to look at how it compares.  A jump from 25% efficiency to 90% efficiency means an increase of 3.6 times.  Note again that if efficiency for today is above even 28% this increase is impossible; an increase by a factor of 3.6 would result in just over 100% efficiency which, as noted earlier, is an impossibility. What’s crossed out is bad math.  If starting efficiency is different that means we have to start all over and we’d get a different c-value.  Just out of curiosity I went with a starting efficiency of 50%, and with the new c-value this step would give us an even smaller E-value of 0.06695134378, which equates to 93.3% efficiency and an increase by a factor of 1.866.  75%: 0.03347567189 or about 96.7% efficiency.  So starting with a low efficiency and ending with a high efficiency means an improbable jump, but higher starting-points mean higher and higher ending points, placing us in the highly improbable range as far as the possibility of these technologies is concerned.

(For a look at how unlikely this huge efficiency jump is, let’s look at cars.  In 1980 the average fuel efficiency for a passenger car in the United States was 24.3 miles-per-gallon.  For 2008 model-year cars it was 31.2 mpg.9 That’s a factor of 1.28, or, not even close to doubling.  The difference from 1980 to 2008 for imports is even smaller.  In 28 years there has been progress, but in the next 40 years we’ll need to see progress like never before as far as increased efficiency is concerned.)

Let’s make a compromise: let’s say we do increase to 50% efficiency by 2050 like I said was improbable earlier, or, in more accurate terms, (see above) we double our efficiency, worldwide, in that time.  This way we can account for a more realistic efficiency gain and only reduce global affluence some.

A = 1 / (0.0327 × 9 × .50)

A = 6.7957866123

Again, a decrease in real GDP per capita.

I’ve been wondering lately: are there any respected scientists, or anyone who regularly studies human population, who doesn’t believe population needs to be reduced—that we are not in overshoot?  I seriously wonder, but I haven’t been able to find any who are of this opinion.  A few months ago I even searched for days; most of the websites you’ll find refuting the population-decrease position are for religious organizations and present almost wholly moral arguments, and the rest all revert to “Everyone on the planet could fit inside the state of Texas.”

As far as this post is concerned: I’m not a mathematician or a scientist, but a concerned citizen of the planet.  If my math is wrong or I have made some leap in logic, please let me know (but respectfully, of course!).  Thanks.  Oh, and also: anyone who has ever said algebra doesn’t have real-world applications was wroooonnnngg!

Notes and Links

  1. Global Population Speak Out – Breaking down the barrier to public discussion of population
  2. Planet Earth (TV Series) at
  3. Link to just this caller (788kb, low-bitrate Ogg Vorbis) and link to the entire radio show at
  4. An unholy matrimony and Population and consumption: both major players at
  5. IPAT equation at
  6. Conservation of energy at
  7. Growth in World Per-Capita Real GDP to Continue at
    To calculate the 2050 value I used this equation: G(t) = G0 e^(0.0346 t) where G = GDP, G0 = current GDP, 0.0346 = % growth, and t = years. I used 2008 statistics so I figured t = 42. G(42) = 7.9 e^(0.0346 × 42) = 33.7865488233
  8. World Footprint at
  9. Average Fuel Efficiency of U.S. Passenger Cars and Light Trucks at
3 Comments leave one →
  1. josh bowers permalink
    February 4, 2009 6:01 am

    i believe that once we reach a plateau in efficiency, human population will continue to increase, but will eventually have to follow suit, and most likely in a series of catastrophic occurrences. technology will only take us so far. but it would be interesting to see where we decide to take ourselves in the future, if we have a long one ahead of us that is. can you imagine a world of 15 billion, 20 billion? what would life have to be like in order to sustain such a large population?

  2. Nick Smith permalink
    February 4, 2009 6:13 am

    Way to make me feel dumb, Tony. You and all your fancy maths…

    Seriously though, it seems to me that one of the main reasons that we don’t hear much in-depth discourse on the subject stems from the fact that it presses too many sensitive buttons. Aside from the fact that it forces people to question their own consumption and conmtribution to the problem, calling out the fact that the population is increasing at a rate that will spell doom flies directly in the face of the core beliefs held by most Jews, Christians, and Muslims. It forces people to either question God’s omnipotence and “perfect plan” or it forces them to rethink their basic interpretation of the Bible/Torah/Qur’an’s teachings. This is one of the main reasons why I don’t feel particularly compelled to be 100% tolerant of certain religions.

    Another root problem I see is the way in which over-population is looked at. Almost every article I’ve read addressing the issue (aside from a few neo-Malthusian pieces) speaks strictly in terms of food availability and hunger. While that is clearly a large part of issue, it seems to me that focusing solely on the availability of food is intellectually dishonest. Without considering and measuring water, mineral, soil, and other resource depletion, the issue is far too easy to dismiss.

    Of course I really don’t know that much on the issue…

  3. February 4, 2009 9:24 am

    Thanks to both of you for the feedback.

    @Nick: It’s certainly a hot-button issue, but I feel that’s reason enough in itself to bring it to the forefront. People definitely have their own reasons for wanting to avoid the issue. People who don’t want to believe we “came from monkeys” are definitely going to hate learning the fact that we’re a part of nature too. Yes, we’ll have to reexamine some of Western industrial society’s core beliefs, which will be hard, but we’re beginning to see that some of these beliefs were at odds with reality and require new directions. Perhaps the most important to reexamine is the grow-or-die mentality.

    And you’re also right about it being talked about solely in terms of food availability (and we can ignore for the moment that food availability is one of the main driving factors). Equally, or perhaps more, aggrevating for me is when people say things like “Oh, so people are just reduced to a carbon footprint now?” I hate when any environmental issue is reduced down to carbon emissions. Your groundwater being poisoned with dioxin has nothing to do with carbon dioxide! One of the things I really hope is accomplished throughout the month with GPSO is that people will see population as a very broad-ranging topic with many implications. It’s not simple, and that’s why it needs serious discussion.

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