The Trouble with Exponential Growth

There is actually a lot of trouble with exponential growth, but I think the major, major one is that we humans seem particularly unable to grasp it either mentally or emotionally. The best way, I think, to convey what exponential growth looks like is visually.

This YouTube video shows very clearly how difficult it is for us to grasp the simple idea of doubling.

I think, often, when we think of doubling we accidentally think of adding. It’s hard for us to really grasp, mentally, how quickly something can grow when it is simply doubled, particularly with large numbers. Think of the difference between doubling a teaspoon of salt versus doubling a pot of soup. Once you start doubling bigger and bigger volumes that thing grows real fast!

That’s exactly what has happened with population growth on the planet. We’ve just kept reproducing and when humans reproduce they typically double themselves and it’s hard to slow that sucker down.

If you have four kids, you’ve doubled yourself and your partner. If those four kids doubled themselves, you might slip and think “8 kids” but actually, it’s 4 x 4, that’s 16. Then if those 16 grandkids double themselves – most of you will not even be able to do that quick sum in your head. You might think “32” off the top of your head, but that’s just double 16. We’re talking about 16 people having four kids each here – doubling themselves and their partners. That’s actually 64. Before you know it, you’ve grown a city in just several generations.

I’d like to compare here how a two or three child person family stacks up against a four person family, assuming each replicates the procreation pattern.

Four Children

Three Children

Two children













Great Grandkids




Great – Great Grandkids




GGG Grandkids

1 024



GGGG Grandkids

4 096



GGGGG Grandkids

16 384

2 187


GGGGGG Grandkids

65 536

6 561


GGGGGGG Grandkids

262 144

19 683


Isn’t this difference astounding?

This is why, when Abraham only had two children God was never worried about him ‘populating the earth’, see God knew about exponential growth. I’m not sure Abraham did.

It’s this little trick that compounding growth has that has left the world with a population like this:

By El T [Public domain], via Wikimedia Commons

Now, that’s a little scary, for sure. But as I said to my mum, is it better to ignore it? Pretend that this reality does not exist? Should we desist from having children out of fear? (Well, people often have children out of fear – fear of being alone in old age among other reasons) I’m going to leave that one up to you. What we each choose to do about something like this is up to each of us individuals. Whether we choose to remember and act as though our procreation efforts affect the world at large, is currently (particularly in a world with so few natural population controls) solely up to us.

But there are a few things I’d like to ask you to do:

  1. Can you continue to draw that graph? We’re up to over 7 billion now, draw this graph into the next couple of hundred years, go for 280 years, that’s 10 generations away. How is this graph going to look into the future? Think about it.
  2. Think about the world’s capacity to support such a massive jump in population. We’ve only hit 7 billion in recent times. Can the world support this volume of people indefinitely? – Compare it to how it has only supported way less that just one billion throughout all time. Think about plastic accumulation, species extinction, acquifer depletion, CO2 emissions – what are their rates of acceleration? Match that up with population increases. What could happen? We don’t really know that so ask: what is likely to happen?
  3. The last thing to think about is: Do we really want more growth? We hear it a lot, particularly when it comes to the economy, and in this case it’s the activity (and therefore the numbers) of people which supposedly fuels the economy (because people make things to sell, earn money and consume things). But is this real ‘growth’ (e.g. What’s growing? Trees? Drinkable water? Land? “Wealth”? Define wealth, please. Does “growth” or “wealth” (i.e.: money) actually create a better quality of life? OR would it be better to stop consuming, stop earning so much and maybe invest in some real growth – I’m thinking plants, trees, flowers and so on, while degrowing other areas (population and economy jump to mind).

Come on. This is the stuff we really have to think about – before we think about funding a mortgage or finding a job or buying another beer or holidaying in Europe or any number of those non-essential, life undermining activities that we nowadays accept as par for the course. Maybe if everyone stopped hanging out on aeroplanes and pubs and swanky restaurants on the internet or just at work we could all just plant some seeds and watch them grow – that’s some exponential growth I would like to see.

N.B. I stumbled upon this article on this very topic and I think it’s worth emphasising a few things therein. We can’t change what’s done, but we can work toward the future and toward informing our own choices, which is just as important as anything else. In this respect learning to live within self imposed limits is a really important factor in extending the planet’s capacity to deal with our current population. Things like: avoiding flying (that’s not flying less, it’s avoiding it), driving less (or avoiding it) and eating less meat all help to bring a person’s activity within more ecological bounds.