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 United States and a very big factor for Texas, as we have just heard.

            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 United States are experiencing. The other, mentioned by the previous speaker, is the prospect of a possible decline in the average educational attainment of the labor force in Texas.

            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 China. According to our projections, in about 15 years, China will have more people with secondary or tertiary education than Europe and North America combined. This is partly because it has such a large population but is also because it invested so heavily in primary and secondary education and, more recently, in college and advanced education.

            So far, China is not yet a serious competitor in the kind of high tech that North America, Europe, and Japan to some degree monopolize. I think this will change in the future as China becomes a key player with a very highly and well-educated population. But we should look not only at the number of people but also at their education and skills. Age structure certainly has a major impact. I do not want to play this down—we have heard a lot about it—but skills and educational attainment also make a difference.

            The second point I want to make is that the people who come to Texas or to the United States are not the average people of a developing country. They are the more educated, the more mobile, the more motivated people. Their departure may create a significant problem in their home countries that we used to call “the brain drain.” Take, for example, the Indian programmers who are coming by the thousands and tens of thousands to California, and most recently to Germany and other European countries. As we heard earlier, India has not invested in the general, broader education of its population—half of its population is still illiterate—but rather has invested in elitist education. Now these elites are leaving the country to work in other parts of the world. This is not very good for India unless these people stay in contact with India, unless they return—and some of them do—unless they send money to their families in India or transfer knowledge, which is probably the most important in the long run. This issue of the brain drain should not be forgotten when we talk about immigration as a solution to many issues. It needs to be taken into account although it is a complex issue.

            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 Cairo in 1994 or the environment conference in Rio in 1992, there was a lot written about this controversy in the newspapers. Let me give you two statements. Norman Myers of Oxford University wrote, “Population growth plays a prominent and probably predominant part in environmental problems. The most productive and readily available mode of adaptation to the global warming threat would be to reduce population growth,” implying developing country population growth. This statement seems to make sense because most of the population growth occurs in a developing country and, clearly, additional people are contributing to additional emissions.

            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 the Hague that the United States, with just 5 percent of the world’s population, releases more than a quarter of the total CO2 emissions in the world and is by far the largest contributor to global warming.

            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 Tunisia to illustrate part of this problem. Figure 1 shows the population of Tunisia increasing, almost doubling over the last 30 years. The per capita income increases; there are very steep CO2 emissions. You can see that a very sharp increase in CO2 emissions has been encompassing the fact of population increase and some increase in income.

Figure 1 

Figure 1. Trends in population, CO2 emissions, and GNP per capita in Tunisia.

            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 

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 Austria, we have completed in-depth studies on population-development-environment (PDE) interactions in different parts of the world: Mauritius, the Yucatan Peninsula, and most recently, Namibia, Botswana, and Mozambique. We examined the population by age, sex, and educational status, included other socioeconomic characteristics, and then related this to the natural environment. In doing so, it is important to understand that we are not independent of the environment. We are part of nature. We cannot exist, we cannot breathe, we cannot do anything without air, water, energy, land—without nature.

            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.

            Thank you.