Population and the future.

2020 seems to be the year when the environment has moved up the agenda, and not before time. Even Trump has given a slight nod towards it by mentioning the 7 billion trees campaign. Then we have had Chris Packham with an hour long program on the TV, at the same time we have Greta also in Davos and later in the year we have another climate summit this time in Glasgow.

My original OHP

However I am not sure that the bullet is really being bitten. Back in the 1980’s and 1990’s I was running the East Anglian Field Study Centre and on the first night I would give the students an introductory lecture, during which I would speak  about population and the future. Back then the estimated human population was 4.4 billion and last night Chris Packham had little graphs showing the change and it is now 7 billion and he predicted 10 billion in another  30 years. He presented several graphs during his program and it reminded me of my lectures 30 years ago. I also had graphs and they were presented using an overhead projector.

This is the essence of what I said.

My first graph was the change in human population up to the present and then it continued upwards for the foreseeable future.

Then I suggested that it compares closely to the population graph for a microorganism inoculated into a culture medium. For example if you have a large flask, (this represents the world) and in the flask there is a solution containing sugars and nutrients and oxygen ( this represents the earths resources) and then you introduce into that flask a some yeast cells, and you monitor the population, initially they start to reproduce slowly as they get used to their conditions and this is known as the ‘lag phase’. For humans it lasted a long time right through to the 19th century but then the same as happens with yeast they enter what is known as the exponential phase which is where the population rapidly increases and doubles  every period of time, maybe every 30 minutes for yeast and a bit longer for us, but the same principle.

Human Population Graph

Now what happens next? and this is where we might follow the same path as the yeast. The next phase for our yeast in the flask is that problems will occur, these are known as limiting factors. For the yeast alcohol levels may be getting too high and this will cause them to die off. For alcohol read levels of pollution for humans. Another possibility for the yeast is that sugar and other nutrients might run out, for humans that is food supply and other resources.  So the growth curve stabilises with vast numbers of yeast being produced and vast numbers dying off . This is known as the stationary phase and if or when it happens to humans then the world would not be a good place to be living in.  It gets worse as this is followed by the rapid decline of the yeast population called the decline phase. If you are a home brewer then this is the stage when all the yeast drop to the bottom of your flask or Demijohn and the brew clears and is ready to bottle.  This can be followed by what a brewer would call a secondary fermentation when a few yeast have survived and we get a small population increase again followed by a subsequent decline. It will be the result of maybe some yeast becoming tolerant of the alcohol levels and using up the last of the sugar. Of course humans have more going on than yeast in a flask but the principles are the same. It is complicated with humans because there is the possibility of  control on population and there are factors like recycling or planting 7 billion trees or renewable energy.

Microorganism Population Graph

My lecture then went back to looking at the future options for human population and this is of course conjecture but I would say that there are three possibilities.

Option one is that we immediately hold the population at its present level of 4.4 billion, as it was back then, 7 billion today. However experts, not me, back then suggested that the world would not be able to sustain that population for ever and a day. Not given the rate that resources were being used up and the increases in temperature and the levels of pollution and the form of agriculture. Also they suggested that even with new initiatives and new inventions it would still be very unlikely that 4.4 billion could be sustained for ever.

Option 2 is that we level out our population and then lower it to a level of something like 3 billion which the world might be able to sustain indefinitely. This would cause all sorts of problems as for many years we would have to have a population containing more old people than young and it is the young who produce and the old who consume.

Both option one and option two whilst theoretically possible are never going to happen.

So we have Option 3 which is that the human population continues to rise but the birth control and early mortality reduces the exponential growth and there is a long period of slow but steady increase and during this time there will be some improvements in the way we treat the earth but not enough and gradually resources get used up and temperature increases and land mass declines and farmable areas erode and reduce, and the decline phase where the population rapidly  reduces will still kick in.

Future options for Human Population

My final throw of the dice in this gloom and doom lecture was to say that after the decline phase there might be some humans left and rather like the yeast entering a secondary fermentation we might embark on a secondary population  and a second ‘civilisation’ in which stability in all things most especially in population was taken on board having learnt from the apocalyptic catastrophe of the first civilisation. However the population that the earth would then be able to sustain in this future time would depend on the state it was left in after the present massive population increase and decline. And this would depend on the shape of the graph. If the earth has a high population  for a long period of time then the amount of permanent damage would also be high. If we follow a similar growth pattern to the yeast with a massive increase followed quickly by a massive decrease then the actual damage will be less. Basically the level of damage to the earth is equivalent to the area under the graph.

Graphs to show effects of Population on earths resources

I am afraid it is quite gloomy but I do  think that there is a very vague chance that population will stabilise and that technology will come up with new possibilities and we could then slowly reduce the population but I fear that will not happen. It seems to me that all people are talking about is ways to sustain the ever increasing population and not how to level it out and even reduce it. Chris Packham had a bit to say about that in his program….. that 2.1 children per couple would level the population however he also said that it might be off set by the population living longer and longer.

Anyway there it is… my lecture from 30 years ago. I wonder if there are any 50 year old’s who attended the Field Centre saying ‘the bloke at the centre I went to for my Field course used to bang on about population and that was when it was only 4.4 billion’.

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