Too many people may be the problem

There is widespread agreement that the world's population is increasing at an unsustainable rate

There is widespread agreement that the world's population is increasing at an unsustainable rate. We have a population crisis that must be controlled. A small minority does not agree, believing that technological advances will solve all problems. This would seem to be naively optimistic. One useful exercise for clarifying the mind in this area is to work out the human carrying capacity of the earth.

United Nation's projections have shown that if the human population continued to grow at 1990 rates in the major regions of the world, it would increase more than 130 fold in 160 years. That would bring world population from 5.3 billion in 1990 to 694 billion in 2150. On the other hand, if, starting in 1990 and continuing thereafter, couples produced exactly the number of children needed to replace themselves, world population would increase from 5.3 billion in 1990 to 7.7 billion in 2050, and would level off at about 8.4 billion by 2150.

Again, UN projections show that if from 1990 onwards the average couple gradually approached a fertility level of one-tenth of a child more than required to replace themselves, world population would increase from 5.3 billion in 1990 to 12.5 billion in 2050, and 20.8 billion in 2150.

Conventional agricultural methods could not produce enough food for the 694 billion people who would arise from unrestrained population growth. Considering the worldwide problems we currently have in supporting a world population just short of six billion, one can readily imagine the horrendous situation the world would face in coping with a population of 20.8 billion which would arise from a greatly slowed down rate of population increase. It seems clear, therefore, that we should not continue to allow people to have, on average, more children than are required to replace themselves. But what about the possibility that technological advances will allow the world to support far greater numbers than are currently conceivable?

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How many people can the earth support? There is no single answer because the question is too broad. In order to elicit a meaningful answer, the question must specify the conditions under which the people will live. For example, how many people can the earth support assuming that everyone has a standard of living equal to the top 10 per cent of the present population of France, and enjoy an environment as good as the average current environment in France?

Perhaps the first estimate of the maximum number of people the earth can support was made in Holland by Antoni van Leeuwenhoek, the inventor of the microscope, in 1679. He calculated that the earth could carry 13.4 billion people if all the habitable land in the world had the same population density as Holland - 120 people per square kilometre. Over the past 100 years, various reports have made calculations of the earth's human carrying capacity, ranging from a billion to 1,000 billion. Where does the truth lie?

Some people believe that developments in technology will enable the world to carry comfortably a much greater population than at present. Since we can know only relatively little for certain about the future, a more sensible way to evaluate the power of technology is to examine how well it has coped so far in helping the world to accommodate its rapidly increasing millions. The results are not impressive.

While it is true that the excessively straitened circumstances prevailing in large poor areas of the world with teeming populations are largely caused by poor social and political structures, it would be irresponsibly naive to assume, when visualising future scenarios, that these social and political problems will disappear. But even in the rich countries, our best technologies are failing to keep abreast of the problems created by large populations and unrestrained economic growth. Thus we have the enhanced greenhouse effect, the depleted ozone layer, acid rain, escalating violent crime, political terrorism, social disintegration, rampant drug abuse, etc.

Let us continue to examine the present condition of the world. Most of the population of the world live in overcrowded and physically poor conditions. The United States is a rich country. What would the practical consequences be of raising the living standards now of everyone on earth to the average living standards of the US?

In order to maintain its standard of living, the US alone accounts for 28 per cent of the annual world consumption of commercial energy (1986 figures). If the living standards of the rest of the world were to be raised to US levels, total annual world energy consumption would have to increase four fold. That would have disastrous environmental consequences. Even raising living standards to half the US level would call for a doubling of world energy consumption and would cause crippling environmental consequences.

This leads to the inescapable conclusion that the present world population exceeds the carrying capacity of the earth, once we add the rider that people must enjoy a reasonable standard of living. So, how many people could the earth carry at a reasonable standard of living in a wellprotected environment? Many ecologists have estimated that this figure is no greater than two to three billion - less than half the present world population. But let us be very optimistic and assume that technological, social and political changes could allow us to carry comfortably the current population of almost six billion. What changes will be necessary in order to make this realistic?

First, and obviously, world birth rates must be reduced to, at most, replacement levels. This means widespread and effective artificial birth control.

Second, the economic models based on continuous growth will have to be changed. It is not possible to continue producing more and more, faster and faster, without further and further degrading the environment. We no sooner have started to tackle one new environmental problem when two more unexpectedly arise.

The second condition necessarily calls for great attitude and lifestyle changes on the part of citizens of the richer countries. We will have to live more frugal lives. The good news is that this applies only to material things that don't really matter. There will be no ceiling on development of the important things - our cultural, spiritual and recreational lives.

Third, the richer countries must supply massive assistance to poorer countries to allow them to develop along the right lines. If this is not done, the environmental havoc created on a global scale by these countries as they attempt to develop along traditional lines will more than offset the good effects of all improvements made in the richer countries.

And fourth, we must ensure that we continue to have a world fit for habitation. The second World War was the last war in history that could be waged at full force. World war three cannot happen because it will destroy civilisation. It will therefore be necessary to form a world government to ensure that large-scale wars can never break out again.

(William Reville is a senior lecturer in Biochemistry at UCC.)