C4CC(6): The accumulating crises of our time (2)

That is the theory, but it is not simply a theoretical problem. In 1944, 29 reindeer were introduced to St Matthew's Island in Alaska. There was an abundant food supply for these reindeer and so the population grew rapidly. By the summer of 1957 there were 1,350 reindeer and by the summer of 1963 there were more than 6,000. Sadly, in the summer of 1964 there were fewer than 50 reindeer left alive. What had happened? Well, just as with the water-lilies choking off the wider life of the pond, the reindeer had grown exponentially and eaten all the food available. They had bumped into a resource limit, a 'limit to growth'. As the population had grown to an unsustainable level, the population had to drop until there was a balance between the number of reindeer and the amount of food that could be sustainably provided to the reindeer.

Ecologists call this phenomenon 'overshoot'. In a situation of temporary abundance (the food supply for the reindeer), there is a short period of exponential growth leading to a population explosion (lots more reindeer); once the temporary abundance has been exhausted there is then a crash while the system returns to an equilibrium (only 1% of the reindeer survived).

In horticulture there is a rule called 'Liebig's Law', sometimes called the Law of the Minimum. This states that for any organism or plant, the growth of that organism or plant is constrained by the essential resource that is least abundantly available. Consider a carrot being grown in the garden. That carrot requires water and sunshine and a wide variety of nutrients found in the soil. If the nutrients are lacking then it does not matter how much sunshine and water are available, the growth of the carrot will be limited. The growth of the carrot is restricted by the availability of the scarcest resource; it is the scarcest resource that establishes the capacity of a particular environment to sustain the growth of any organism or plant. In the case of St Matthew's Island, the scarce resource was food, but it could have been shelter or the presence of predators.

We now have in place the main conceptual planks for understanding the nature of the predicament in which our culture finds itself. Exponential growth leads to the continued doubling of a quantity over time, which leads to phenomenally large numbers. In any finite system there are resource limits, which represent boundaries beyond which no further growth can occur. The most important limit is the scarcest resource, and that can be any of a wide variety of factors.

So where do we stand as a species? The human population of the earth has been growing exponentially, and the numbers have exploded through the second half of the twentieth century and into the twenty-first. This spectacular growth was triggered by the rise of industrialisation, which allowed access to many further resources, especially the energy resources represented by fossil fuels. There are many other aspects of our human culture which show the same exponential growth, such as water use, food production or steel production. Our economy has been growing exponentially for a very long time. This has led to great abundance in the rich countries, and a much higher quality of life for those who live in industrialised economies. However, just as with the reindeer, exponential growth cannot go on forever and it will come to an end. The meaning of the word 'unsustainable' is, after all, that it will not be sustained and that it will come to an end. The exponential growth of our economies will come to an end in the first half of the twenty-first century.

This is not a new insight. It was first popularised through work sponsored by the Club of Rome in the early 1970s and published as The Limits to Growth. This was a work that was more misunderstood and maligned than read and considered. However, time has shown the essential insights of that report to be correct. The conclusion of the report was that, if nothing was done to amend the path that our culture had embarked upon then, in the early decades of the twenty-first century, our economy would start to hit the ecological resource limits and further growth would be prevented. There were no specific predictions about which resource limit would matter most; instead there were a range of scenarios outlining different possibilities. For instance, in one scenario it would be the peaking of energy supplies that would prevent further growth. In another it was excessive pollution. In another, it was the inability to feed ourselves. However, the specific limit that causes our system to breakdown does not need to be discerned for the overall point to be accepted. In a finite system, exponential growth cannot carry on forever and it will come to an end. Just as with the carrots in our garden, where the limit might be an absence of water, sunlight or nutrients, so too with our economy, in which the limit might be energy, pollution, food, social conflict or something else.

The crucial question is this: what is in fact the sustainable human population on earth? (How many reindeer can live on St Matthew's Island in the long run?) Again, there is guesswork involved as there are so many assumptions that go into working out an answer but three billion doesn’t seem unreasonable. We are using more resources than we are generating, we are borrowing from our future and either we change our way of life and abandon growth (and the expectation of growth) in material terms or we carry on blindly, we hit the wall and the human population collapses. Either way God is bringing our present way of life to a close.