Introduction

Human perspectives

Every person in the world faces a series of pressures and problems that require his attention and action. These problems affect him at many different levels.

These very different levels of human concern can be represented on a graph like that in figure 1. The graph has two dimensions, space and time. Every human concern can be located at some point on the graph, depending on how much geographical space it includes and how far it extends in time.

Most people’s worries are concentrated in the lower left-hand corner of the graph. Life for these people is difficult, and they must devote nearly all of their efforts to providing for them selves and their families, day by day.

Other people think about and act on problems farther out on the space or time axes. The pressures they perceive involve not only themselves, but the community with which they identify. The actions they take extend not only days, but weeks or years into the future. A person’s time and space perspectives depend on his culture, his past experience, and the immediacy of the problems con fronting him on each level.

Most people must have successfully solved the problems in a smaller area before they move their concerns to a larger one.

In general the larger the space and the longer the time associated with a problem, the smaller the number of people who are actually concerned with its solution.

The problems faced in the report

U Thant (3rd Secretary-General of the United Nations) suggested that “there remains less than a decade to bring these trends under control”.

  • If they are not, what will the consequences be?
  • What methods are available to mankind to solve these global problems?
  • What will be the results and the costs of employing each of them?

The model

The world model, described in the report, was “built specifically to investigate five major trends of global concern : accelerating industrialization, rapid population growth, widespread malnutrition, depletion of nonrenewable resources, and a deteriorating environment.”

It is a formal, mathematical model, that includes important variables such as population, food production and pollution, and treats them dynamically as interacting elements, as they are in the real world.

With this model, the authors are seeking to understand the causes of these trends, their relationships to each other, and their implications in the future.

The conclusions

The conclusions that have emerged from this work are :

  1. If the present growth trends in world population, industrialization, pollution, food production, and resource depletion continue unchanged, the limits to growth on this planet will be reached sometime within the next one hundred years. The most probable result will be a rather sudden and uncontrollable decline in both population and industrial capacity.
  2. It is possible to alter these growth trends and to establish a condition of ecological and economic stability that is sustainable far into the future. The state of global equilibrium could be designed so that the basic material needs of each person on earth are satisfied and each person has an equal opportunity to realize his individual human potential.
  3. If the world’s people decide to strive for this second outcome rather than the first, the sooner they begin working to attain it, the greater will be their chances of success.

The era of great growth is over, and now should emerge the era of directing ourselves to a global equilibrium.

Exponential growth

Suppose you own a pond on which a water lily is growing. The lily plant doubles in size each day. If the lily were allowed to grow unchecked, it would completely cover the pond in 30 days, choking off the other forms of life in the water. For a long time the lily plant seems small, and so you decide not to worry about cutting it back until it covers half the pond. On what day will that be?

Answer [Click to reveal] On the 29th day, of course. The lily plant doubles in size each day, so on the 29th day it will be half the size of the pond, and on the 30th day it will double again and cover the pond completely. You have one day to save your pond.

This is one illustration of the fact that exponential growth can yield surprising results.

Exponential growth is a dynamic phenomenon, it is a common process in biological, physical, financial and many other systems of the world.

In simple systems, like the lily pond, the cause of exponential growth and its future course are relatively easy to understand. In more complex systems, when many different quantities are growing simultaneously, the interactions between them can lead to unexpected results. The analysis of the cause of growths and of the future behavior of the system becomes much more difficult.