Tuesday, January 19, 2010

World Population: the Biggest Question of All

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.
1-2-4-8-16-32-64-128-256-512-1024-2048-4096-8192-16384- &c.
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:

  1. They run out of nutrients
  2. They are poisoned by their own excretions
  3. They come up against the side of the Petri dish.
Here is a video by a maths professor just to show that I am not making this up:

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?


Siân said...

At that point I start garbling about going into space, which I suspect doesn't help much, but I can't support any curtailment of repro freedoms. Tough stuff.

DocRichard said...

Blimey Sian, that was quick.
No, space travel does not help, because the carbon footprint of a rocket with a couple on board is worse, much worse, than taking a 4x4 on a shopping trip. and 6000,000,000 - 2 is 5999,999,998, which doesn't help a lot.

You are not alone in opposing curtailment of reproductive freedom.

More on this later.

Kaihsu Tai said...

The Greens’ understanding of ‘freedom’ is not the same as the classical libertarian/neoliberal ‘absence of all restraints (for those who can afford it)’, but the provision of a planet where all can flourish. Considerations of reproductive freedom in a Green context would take this as the point of departure as well. Education, access to proper healthcare, and social constraints (e.g. do not expect us to congratulate the birth of your thirteenth child) may play important roles. In so far, the Green Party is not a liberal party.

DocRichard said...

You have run ahead of me. I am going to do this in easy bite sized chunks.

Phil said...
This comment has been removed by the author.
Phil said...

It was nice to hear Al Bartlett on Radio 4's "More or Less" the other week:


Listen to it here: http://www.bbc.co.uk/programmes/b00plzyj


DocRichard said...

Hi Phil
Many thanks for providing this link. I had Prof Bartlett in mind when I wrote the piece, but had lost contact with his piece.
His message is:
"The greatest shortcoming of the Human Race is the Inability to understand the Exponential function".
I have put his video on the original blog now.
Thanks again.

Kaihsu Tai said...
This comment has been removed by the author.
DocRichard said...

And also, before anyone says the Petrie dish example above means that I equate humanity with bacteria, I say this: I do not. It is an illustration of the constraints upon population expansion of any and every biological organism. Science. If you do not agree with science please go away. Thanks.