Fig 1 Acknowledgments to Optimum Population Trust and UNEP
The question of what to do about the ever-increasing world population of humans is edging ever closer to the surface of political debate. It is the most emotionally charged topic of all time, because it involves an encounter between the irresistible force of mathematical exponential series, and the immovable object of individual human liberty.
The Green Party mentioned it once in a Conference debate, and we did not get away with it. We were damned to hell by the tabloids, and banished to the wilderness.
Things have changed now. Journalists are beginning to ask why no politician ever mentions population. (Answer: see above). Commenters are saying "Never mind the CO2, it is the population increase that we need to worry about". It is quite possible that this is an elephant trap that they are setting, because they will go all libertarian on anyone who dares to pick up their gauntlet.
The man would be an idiot to take up this challenge.
So here I go.
First, an axiom (self-evident truth):
It is impossible to expand forever into a finite space.
(I met someone who was unwilling to accept this axiom, because it implied illiberal thinking. You see?)
Second, the mathematics of exponential growth.
That is a doubling series, and in 15 steps we have gone from 1 to 16,384 and rising. That is what happens if we keep on doubling a number. It is called exponential growth.
The doubling time for world population
between 1881 and 1960 was 79 years,
and for the years
between 1960 and 1999 was 39 years.
In exponential series, doubling times tend to fall by half in each round of doubling.
Since we live on a finite planet, we cannot go on with doubling population. Leaving aside the question of ecological footprint, there would come a time when we would be standing shoulder to shoulder on every piece of land on the planet, not just on the Isle of Wight.
Mathematically and ecologically, doubling population growth forever is a physical impossibility. It cannot happen. It is a dumb idea. It is nonsense. All growth must stop at some point.
And yet, to say that population growth must be stopped is intensely controversial.
Here is a simple biological model. Here is a Petri Dish.
The spots are bacteria.
(I got the photo from Richard Wiseman. Thanks Richard. I don't know where he got it from).
They grow and grow until one of, or a combination of, three things happens:
- They run out of nutrients
- They are poisoned by their own excretions
- They come up against the side of the Petri dish.
His message is:
"The greatest shortcoming of the Human Race is the Inability to understand the Exponential function".
I feel tired already. I'm going to stop now and have a little lie down, to see if anyone starts calling me a fascist who is reducing humanity to mere numbers, in the comment slot. There may not be any comments, because I have turned off the Anonymous comment facility.
The argument will be continued tomorrow: "Should we curb population, consumption, or both? "
*My local pedant points our that this should read " It is impossible to expand forever at a constant rate into a finite space" because it is possible to expand the series 1+1/2+1/4+1/8+&c forever into a finite space. Or is it?