The Parable of the Yeast Population
Visualize a large vat filled with grape juice. Add yeast. The yeast, being a living organism, feeds on the sugar contained in the grape juice. It’s party time. There is plenty of food (the sugar) and the environment is clean. The yeast population expands rapidly.
But eventually the supply of sugar is consumed and the liquid now contains substantial amounts of alcohol ― a toxic waste. The yeast population dies off, both because it runs out of food (sugar), and from alcohol poisoning.
Eventually a layer of dead yeast settles on the bottom of the carboy, and the living yeast population dwindles to a small fraction of what it was at its peak. All that is left is a vat full of clear wine. The party’s over.
Let us interpret this parable.
The large vat represents the world around us.
The grape juice represents the fossil fuels (coal, oil and natural gas) that we started to exploit 300 years ago.
We are the yeast. Our population has exploded from less than 1 billion in Biblical times to over 8 billion now.
The alcohol (the toxic byproduct) represents our pollution, particularly the greenhouse gases that we have dumped into the atmosphere.
Like the yeast, we are running into physical limits. In the words of Herb Stein,
If something cannot go on forever it will stop.
There is, however, one important difference between ourselves and they yeast. We understand what is happening and are able to change trajectory ― should be choose to do so.