Some months ago, I wrote a long post on population growth and the problems of over-population. I had intended to revisit this when the Earth’s population passed the 7 billion mark, but my colleague Brett, who also has written on population in the past, beat me to it. (No hard feelings!) I was too busy to comment on his post, but I have been thinking about the question and some of the issues he raised. And this seems an appropriate moment, since as I am writing this piece, world population is going to (at least nominally) hit 7 billion, 5 million people. More precisely: the same demographic model which showed world population reaching 7 billion on October 31 shows that the population has grown by another 5 million people in the 24 days since then.
It is worth contemplating that number. Here is one way to put it into perspective: if we gathered all 5 million newborns into a single location, they would create the 58th largest municipality in the world, and would be the second largest city in the United States, behind only to New York. (Note that these numbers depend on the precise definition of “city” and “municipality” used: they suffice for a qualitative comparison.) Further, this does not stop: every 24 days, the equivalent of another city of 5 million people will be added to the world’s population. Currently, world population is growing at at a rate of 1.1% annually, down from a peak of 2% annually in the 1960’s. It is predicted that this rate will continue to decline steadily to about 0.5% in 2050. These changes are significant. If the population continued to grow by 1.1% annually until 2050, the population would be approximately 10.8 billion people, as opposed to the predicted value of just over 9 billion. Were population to have continued to grow at 2% per year from 1960 onwards, it would reach over 17 billion by 2050.
How big a population is too much for the earth to support? Answers are quite varied, and I must agree with Brett when he says that it depends. I disagree with him in that I have a much more pessimistic than he is. The answer depends not only on the size of the population but on the rate of consumption and here we come to the crux of the matter. A typical member of the middle class (however defined) in the U.S. or Canada consumes considerably more than someone living in Western Europe or Japan, who in turn consume more than the average member of the middle class in the emerging industrial nations of Brazil, China and India. One way of quantifying both population and consumption is in terms of the global footprint or ecological footprint of the inhabitants of a country. This is a statistical measure which tries to determine the total renewable resources that the earth produces: fish, crops, lumber, etc. It converts these to a standard measure called a “global hectare.” (Intuitively, you can think of a global hectare as the number of hectares required to produce all the renewable resources consumed by one person. It does not include non-renewable resources such as fossil fuels, iron ore, etc.) The global footprint of the average person in each of the countries listed above is as follows:
- US 8.0
- Canada 7.01
- Spain 5.42
- Germany 5.08
- France 5.01
- Italy 4.99
- Japan 4.73
- Brazil 2.91
- China 2.21
- India 0.91
Averaging over the entire earth, the mean global footprint of an individual is 2.7 global hectares. However, the best estimate of the carrying capacity of the earth for a population of 7 billion people is 1.8 global hectares per person (given total resources equivalent to 12 billion gha). In other words, we are consuming the Earth’s resources faster than they can be replenished. Now consider again the 5 million people born in the last 24 days: they will require approximately 13.5 million gha to support themselves. (This number again is qualitative, since it assumes that each requires the global mean of 2.7 gha; in fact most of these people are born in developing countries where the global footprint is smaller. The average global footprint of Latin America is between 2 and 3 gha, but for Africa is between 1 and 2, with parts of central Africa being lower still.) And for years to come, every 24 days this number will increase by another 13.5 million gha.
We can debate the accuracy of the global footprint metric, but it is a fairly sophisticated attempt to measure, in one statistic, disparate phenomena we see around us: depleted aquifers, deforestation, the collapse of fishing stocks. It is more accurate as a global measure; it appears to be less useful for local or regional analysis, since it obscures what is being over-consumed in a given region. But I see no reason to believe it is not accurate at least as a first order approximation. Given this, then I think two intertwined conclusions follow from this analysis. First, world patterns of consumption are unsustainable in the long run. The developed world simply cannot continue to consume natural resources at the rate at which it does, and even large parts of the developed world have consumption patterns that are not sustainable. Second, increasing population makes matters worse. A population of 9 billion could be supported only with a per capita consumption of 1.33 gha. (Countries that currently have such an average ecological footprint include the Philippines, Indonesia and Vietnam.) Given current disparities, the reality could well be a world in which some small fraction maintains much higher levels of consumption, while the vast majority of people exist on far less.
I want to stress that these are intertwined: we cannot concentrate on one or the other. Consider China, India and the US. Multiplying their respective per capita global footprints by their population sizes, you see that the US requires 2.47 billion gha, while China requires 2.95 billion gha. India, with its much lower rate of consumption, still requires 1.06 billion gha. India, however, has both a growing economy (8% a year) and growing population (1.4% a year). Suppose for the moment that global footprint grows at the same rate as the economy; then if these values remain constant, in 10 years India will require 2.6 billion gha, more than double the resources it currently consumes.
What is the solution? That is unclear. I believe that technology will necessarily be part of the solution: technology allows us to use resources more efficiently. However, I do no believe that some magic bullet will be discovered that will eliminate all of the problems that come together under the heading of over-consumption. Estimates that the Earth can sustain a population of 100 billion in carefully designed cities strike me as both hopelessly simplistic and predicated on unproven technological advances.
But I think we must also confront population growth, and it would be in everyone’s best interest if the rate of population growth were slowed as much as possible. Family size is a personal matter, but it also has global consequences. Yes, at the far reaches of demographic projections (90-100 years from now) population begins to decline due to projected falling birth rates and the concomitant aging population. However, the problems caused by population will have to be confronted long before we reach this point,and indeed before we reach the projected maximums. Population growth can and should be moderated in a non-coercive fashion: nothing I am saying should be construed as endorsing the Chinese model. According to demographers, the best approach to reduce the rate of population growth is via economic development and the the empowerment of women. Brazil is a very good example of this phenomenon.
Ironically, economic development will result in fewer people, but each one consuming more than in the past. Therefore, future development must follow sustainable models; the developing world cannot simply mimic the history of development in the West. Furthermore, the necessity of change falls more heavily on the West than on developing countries, since it is the West that needs to reduce its consumption and reconfigure it into more sustainable forms. To put it simply, we will have to make the greatest changes in our lifestyle. Based on my own experience, this is far harder than it seems: recycling, using cloth shopping bags, planting a garden and driving a Prius are good steps, but they are not sufficient. My wife and I have made a considerable effort to live simply, and by American standards we do. But the key is that this is by American standards: measured against a per capita ecological footprint of 8.0 gha. As a rough guess, I would say that we are, approximately, at European consumption levels: lower than the US average, but still far beyond what appears to be sustainable.
The solution, such as it is, will require a radical application of solidarity. The developing world will need to slow population growth. This will require extensive economic development. The resources for this must come from the West, which in turn must consume less and consume in a sustainable fashion. To make this work, everyone’s life must change. From the West it will require not simply charity, but a very different understanding of ownership and consumption. Here, I think, the Catholic tradition has something to say. One of the Eastern fathers, St. Basil, accurately described the understanding that will be necessary to achieve a just, sustainable future:
Naked did you not drop from the womb? Shall you not return again naked to the earth? Where have the things you now possess come from? If you say they just spontaneously appeared, then you are an atheist, not acknowledging the Creator, nor showing any gratitude towards the one who gave them. But if you say that they are from God, declare to us the reason why you received them. Is God unjust, who divided to us the things of this life unequally? Why are you wealthy while that other man is poor? Is it, perhaps, in order that you may receive wages for kindheartedness and faithful stewardship, and in order that he may be honored with great prizes for his endurance? But, as for you, when you hoard all these things in the insatiable bosom of greed, do you suppose you do no wrong in cheating so many people? Who is a man of greed? Someone who does not rest content with what is sufficient. Who is a cheater? Someone who takes away what belongs to others. And are you not a man of greed? are you not a cheater? taking those things which you received for the sake of stewardship, and making them your very own? Now, someone who takes a man who is clothed and renders him naked would be termed a robber; but when someone fails to clothe the naked, while he is able to do this, is such a man deserving of any other appellation? The bread which you hold back belongs to the hungry; the coat, which you guard in your locked storage-chests, belongs to the naked; the footwear mouldering in your closet belongs to those without shoes. The silver that you keep hidden in a safe place belongs to the one in need. Thus, however many are those whom you could have provided for, so many are those whom you wrong.
In the end, here I find something far sadder than the problems facing the Earth. For there are solutions, and we, as a Church, hold a strong part of the solution in our hands. But to share it, we must first acknowledge that there is a problem.