4.1. The historical debate on the population growth and the natural resources. From Malthus to the Rio Summit.

4.2. The current state of the debate.

4.2.1. . The zero growth: a desirable utopia?

4.2.2. The limits to growth. The carrying capacity.

4.2.3. The carrying capacity.

4.2.4. The quantification of the human activities impact: the ‘ecological footprint’.

4.2.5. Some final considerations: some past omissions and future investigation lines.

4.3. The final goal: the sustainable development.


The relationship between the population and the environment, and the human impact on the nature has been permanently studied along the history. The continuous population growth, which has become especially intense from the Industrial Revolution on, has been the main stimulus for the scholars to theorise about the effects of the population on the environment, generally, and on the resources, particularly, but always starting with different conceptual undergrounds.

Therefore, before continuing with the exposition, it is necessary to firstly give a general view on how both concepts we are working with, i.e. population and environment, have been defined.

Although there have been some exceptions, in most of the studies the concept of population has been limited to the demographic growth, the increase of the total population volume, without taking into account other significant demographic variables, such as age/sex structure, migration patterns, space distribution of the population, mobility patterns or the connection of the individuals with the activity. Few authors are being conscious of this lack and moreover, the attempts at changing this situation, such as the virtual forum arranged by the Population and Environment Research Network on their website, have failed and have also triggered the debate on the population being a simple amount of people, again.

Another constant omission is not taking into account other characteristic features of the societies, a part from the strictly demographic ones. Following this idea, several authors have stated that, given the connection of the population with the environment, it is necessary to consider the social and the cultural aspects of the society. Thus, in order to decrease the pressure on the resources, it is not enough to set up birth control policies (as China does currently, for instance), but it is also necessary to work on other factors, as the cultural, the social and the economic ones, and to emphasise some other elements too, as the poverty, the trade laws, or the government policies. So, in contrast with the direct relationship between the other species and the environment, this point of view accentuates the social and the cultural human organisation; accordingly, the environmental change is seen as a natural, but also a social process.

However, the most studies’ central idea, which is simple, but its simplicity doesn’t diminish its validity, is that the population growth puts an increasing pressure on the environment, due to the also increasing need of raw material for the community’s survival. Therefore, the population growth generates a bigger pressure on the soil because of the higher demand of cultivable land, the current competence between different economic activities and the exhaustion of certain mineral and fossil resources for the energy needs.

On the contrary, the environment has been defined in many different ways, including climate zones, urban or rural locations, or, above all, specific natural resources (air, water, forests and soils, mainly). Clarke (1995) has given three possible definitions of environment:

  • Physical/natural. The environment is seen as a landscape whose features (the climate, the soil, the geology, etc) have not been changed by the human impact.
  • Geographical. It takes into account the man-made changes, usually distinguishing between the inhabited and the uninhabited landscape, the urban and the rural one, etc. Nowadays, one of the most prominent investigations lines, as it can be seen further, is the relative importance quantification of the human and the natural factors in the environmental change.
  • Ecological. The environment is seen as the external or environmental conditions where animals and plants live.

However, in most of the cases, the description of the environment is reduced to the natural resource concept. Although there have been provided a lot of definitions, the most accepted one among the authors, perhaps because it is wide, is the United Nation’s one:  ‘all those nature products which are useful for the humanity’.

Although this definition is possibly an excessively general one, it contains three essential ideas which can be found in any definition: a) the fact that these products belong or are made from a natural system, b) they fulfil needs and c) they emphasise the passiveness of the natural resources availability; and it also ignores the active process of appropriation and transformation of the resources through the scientific-technical knowledge. Thus, their consideration as here presented may change through the time and along the space.

Therefore, the resources cannot be considered as a stock, since their value depends much more on the needs and the technological situation of a certain moment, than on the resources themselves. Actually, there is a regular resources flow, controlled by the dynamics of the natural phenomena, the social system and its ability of ‘creating’ new resources in order to replace the obsolete ones. Concurrently, the author underlines the difference between the concepts of resource and reserve. ‘Reserve’ merely refers to the known deposits, which can be exploited by using the technology available at normal prices. On the contrary, ‘resource’ is, as mentioned above, a quite wider concept. On the other hand, the demarcation between the renewable and the non-renewable is often used, even though it is rather ambiguous, since both categories are not totally mutually-exclusive.

To conclude, the variables used for calculating the environmental degradation include both, quantitative (the pollution, the soil deprivation) and qualitative (the population perception) dimensions.

UAnother important aspect in the studies of population and environment is the bidirectionality of the relationships between these two concepts. Thus, the first perspective studies the population as an agent that receives the environmental changes, such as environmental degradation, natural disasters, etc. That is to say that the population is affected by these changes, even though it may previously have been the direct or indirect responsible of them. Whereas this first perspective has been mainly developed in the studies focusing the Third World countries, another perspective has been given in the studies referring to the Western countries. In contrast, this second one considers that the population (its economic activities, the exploitation, the natural resources consumption, etc) is the main cause of the environmental degradation.

Finally, before showing the historical investigation lines on the relationship between the population and the environment, we should point out the data availability. The first difficulty we have to face is the frequent incomparability of both the demographic and the environmental data, since they are not related to the same area or period of time. One of the reasons of this fact is the separately-made collection of both data types, which have not been specifically taken for analysing the relationship between population and environment, but, on the contrary, have been taken for other purposes.

Generally speaking, the empirical base for estimating the distribution, the growth and the volume of the population is better than the one intended for the environment, since it contains information collected from the population census, the register of births, marriages and deaths, and surveys. Regarding the environment, there are great differences among the countries about the following topics: a) the primary data availability, b) the quality, the comparability and the frequency of the data collection and c) the quality of the resulting information systems.