I want to thank you for this time to comment, as it says in the program, from a global perspective.
There are, of course, trends in one part of the world that are linked to developments in other parts of the world. This is especially true for migration, which is a big demographic factor for the
I would like to pick up on two statements, one made by John about international competitiveness with a view to the strong population aging the main competitors of the
I would like to add to this second point that the educational attainment in the rest of the world, as I mentioned earlier this morning, is changing significantly. The most important player—partly because of its sheer size but also because of its strong recent investment in education—is
The second point I want to make is that the people who come to
I would like to turn my attention to what we heard in the morning about the environment. Although the topic of this meeting is population and the environment, we have not really explicitly discussed how population growth affects on the environment. I want to give you a few examples.
Population and environment relationships are very controversial. You may remember that, during the world population conference in
Here is another statement by a group of women mainly from developing countries, who call themselves DAWN: “Population control in the South is a new form of Northern imperialism. White men fear the fertility of our wombs and do violence to us, but the real environmental problem is Northern over consumption.”
There is also some truth in this statement. You heard during last week’s climate conference in
But these two statements are slightly contradictory. The question is how to resolve these issues. Is there anything a scientist can say to make this ideological controversy more rational?
I’ll use the trends in the country of
Figure 1. Trends in population, CO2 emissions, and GNP per capita in
Several people have attempted to decompose the increase in emissions into its components. Can we say what proportion of increase in CO2 emissions is due to population growth and what proportion is due to growth in affluence or income? There is a third factor to be considered: technology. Technology can be dirty or clean, and by switching from one to the other, CO2 emissions may be reduced without a decline in affluence.
The model or paradigm most frequently used to study this is called the I=PAT equation. It was originally proposed by Paul Ehrlich and John Holdren. I, which is the impact on the environment—this can be CO2 emissions or deforestation or any activity that is detrimental to the environment—can be decomposed into three factors: P for population, A for affluence (assuming that the richer you are, the more you pollute) and T for technology (depending on whether you are using an environmental friendly or not so friendly technology). This can be calculated in terms of numbers:
We can see total CO2 emissions as being equal to the population times the GNP (the national income) divided by the population (the per capita income) times the CO2 emissions per units of national income, which is the technological efficiency of producing a certain unit of income or of a certain output.
This identity can be shortened into CO2 = CO2. The main purpose of this identity is to show that it is not any single factor that is contributing to the environmental problems but that it can be split into a combination of different factors.
It is a useful first approach, but it is not a good tool for actually assigning blame. Let me explain why this simple formula is not sufficient for explaining what is going on. All efforts to decompose this numerically have been problematic and cannot readily be used, so what is wrong with the I=PAT equation?
The three factors that are included in the identity are rather arbitrary. One could easily include other factors or more factors. For example, one could choose households instead of individuals as the emitting unit. An average household has a kitchen or an oven; it does not matter how many people live in the house. The number of households are the emitting units.
Let’s do a simple decomposition analysis. The total growth rate in energy consumption for the period from 1970 to 1990 has been increasing by 6.7 percent. Of this, 2.2 percent is due to population growth, 3 percent to income growth per person, and 1.5 percent to changes in technology. Because this is a developing country, we used the decomposition formula shown in Figure 2. We can say that about one-third is due to population and about two-thirds is the combined effect of income, growth, and technology.
Figure 2. Decomposition of annual growth rate of energy consumption, 1970–1990, in industrialized countries. (Source: POPNET 27 (Fall 1995): 1).
In the industrialized countries (see Figure 2) we had only a 2.1 percent increase, and there only one-third, 0.7 percent, was due to an increase in population size. It is interesting to note that the income per person increased by 2 percent but that technology had a negative impact. There has been a reduction in emissions due to more efficient technology. If we take 0.7 of this 1.4 percent, we still have one-third to population and two-thirds to this combined effort. If we take households rather than population as emitting units—the number of households times affluence times technology—the picture looks quite different than in the developing countries.
Suddenly in the industrialized countries, we have three-quarters due to the demographic variable number of households. While the population increased slowly in industrialized countries, the number of households increased rapidly for various reasons: People like to live alone, causing a change in lifestyle, they marry late, and they have higher divorce rates. Probably the most significant reason is population aging. The number of households has seen a very rapid growth in all industrialized countries because most elderly people have their own households. It has been even more rapid than the household growth in developing countries.
What proportion of the emissions is due to households and what is due to the number of people? We made some empirical analyses, where about half of the CO2 emissions are household specific and the other half are due to the number of individuals.
In the real world, the interactions between population and the environment are very complex with all kinds of feedbacks and interdependencies. To address this appropriately, one must choose a “complex systems perspective.” This approach assumes a nonlinear complex interaction between the ecological systems and the human systems. How can we study this?
At the International Institute for Applied Systems Analysis in
Between the population and the environment, there is a sphere of manmade environment that may be called development. It includes production, consumption, development, trade, policies, social infrastructure, and political institutions. They mediate between a change in the number of the people and, for example, the air—the question of biodiversity, other species and forests, water availability, land, soil composition, topography, and energy.
We have developed some interactive computer models to describe these complex interactions for specific sites. We can study some of these interactions or several jointly. We can see how the population affects air, emissions, or water, and we can look at the mediating economic factors. Through such a rather complex and differentiated approach, we can gain a better understanding of the complex population-environment interdependencies.
In short, there is a clear relationship. Population affects the environment at many different levels. Rapid population growth certainly has a negative, stressful effect on the environment. But it remains to be determined in rather specific cases: What are the specific impacts? What are the best coping strategies for populations to deal with changing environments? Unfortunately, there is no universal formula that can explain it; it requires some in-depth scientific analysis.