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.

One thing that I do think is that bringing children in this world is one of the most recklessly hopeful things anyone can do and hope is definitely something we could all do with around here!

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.


    1. 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? 

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.

Canberra City Planning – cycling

I get on my bike as often as I can. This can be tricky with three kids but my older two are competent cyclists and my youngest is very easy to put into either of my three options – front seat, back seat or trailer.

Having a bike trailer is a game changer for a mum – probably for anyone, but it makes a family so much more portable on bikes, increasing crucial lugging capacity, and, I have found, is well worth the investment!

So, we cycle around town as much as we can.

This is one benefit of living in the inner-north that I would not want to give up in order to settle out in one of Canberra’s sprawling suburbs. Being able to cycle to events, the pool, the library, the supermarket and friend’s houses enhances our lives is worth the sacrifice of extra space for a large garden. We are satisfied with our small one (which is jam-packed with veges) and more than satisfied with being able to walk and ride to close-at-hand amenities and luxuries, rather than guzzle up fossil fuel (and extra time) to get there.

So my cycling around town is an urban planning matter. It is closely linked to how we build our cities, how we are building Canberra.

Canberra is about as good as it gets for commuter cyclists in Australia. This is unfortunate because Canberra could be better. Fortunately, from what I can gather, ACT’s current government does seem to be pro cycling and active travel, pro medium to high density in parts  (personally I am more in favour of medium density over high density in this city) and, I am hoping, also in favour of creating human scale, hospitable, fun and friendly public spaces. These things are all key to creating equitable, friendly cities where people do not have to rely on a car to get around.

In my cycle from Dickson, through O’Connor, into Civic and on into the Parliamentary Triangle and back again I encountered a range of cycling conditions. From my house I have to cross a busy intersection. This can be a little frightening with a 7 year old dare devil who loves to scream down the hill, “check your brakes!” I often call to him, not that it makes any difference. Then it is a squishy ride down a narrow but fairly quiet path to the main riding throughfare which runs from Dickson College right into The Australian National University, and on to Lake Burley Griffin, where offshoots can take you into various southern suburbs along idyllic rides by the lake. This path took me just a few block from the city centre where, after navigating a couple of less than desirable paths (caused by tree roots, so I won’t complain, I’d rather have the trees) I easily parked and did some grocery shopping.

This leg, my friends, was a journey easier than a car trip in peak hour and having to find and pay for parking in some of the storied car parks attached to the shopping centre. It included the added bonus of feeling the wind in my hair and a particular feeling that I was truly alive! If there is any feeling closer to flying than actually flying do tell because riding on a hotmixed Canberra bike path on a bike feels as much like it as I’d care to know!

After this we went on to the triangle where I made sure to take the Eastern bike path along Commonwealth Avenue bridge so that I could slide off onto the bike path taking me (along with twenty-odd mums with prams and various joggers and people in business attire) right to the back end of the National Gallery where I parked my bike and took my bonny daughter in to their excellent play space.

Canberra-Cycling-Mum (1 of 1)


Truly, being a mum of a little one in Canberra does feel positively utopian at times!

The journey back home again was equally straightforward, except for finding a new, quieter, route home through Reid, which is yet another joy of cycling – adaptability and adventure.

There is certainly room for improvement in Canberra, living location is certainly one important factor to being able to make this choice. My point is that it is definitely, in my eyes, a choice worth choosing. I prefer this mode of travel above all else!

As Steve Jobs is attributed as saying: A bicycle is the most efficient form of transport. It is also, I argue, the most fun.