Is overpopulation a problem? An honest answer is it may well be. This is a situation that we need to address but many parts of the Church has failed to do so. Indeed, some members of the Church actively deny there is a problem.

First, some basic facts. Currently, world population is just short of 7 billion; demographers tell us that the 7th billion person will be born some time in 2011. At the dawn of the 20th century, world population was about 1.5 billion, and for most of the 20th century it showed exponential growth: 2 billion in 1927, 3 billion in 1960, 4 billion in 1974. Population growth began to slow, but it still grew rapidly: 5 billion in 1987, 6 billion in 1999. It seems paradoxical, but even though population growth rates have slowed tremendously in the past 20 years, total population will continue to grow. (For the mathematically inclined, this can be seen by examining the behavior of the logistic equation after it passes the point of maximum growth rate.) Current predictions are that world population will continue to grow for the next 40-50 years, peaking at some where between 8.5 billion and 10 billion people in 2050-2060. At that point, barring further changes, population should stabilize or decrease, as reproduction rates stabilize at or below replacement rate (i.e., approximately 2.1 children per couple, the birth rate just sufficient to replace the existing population as it dies off). Many parts of the world, including western Europe and China, are already below replacement rate, and the prediction is that higher growth rates elsewhere will decline to this level in the next few decades.

Where do the problems lie? To understand them we cannot look just at population: we have to look on three axes: population, consumption and technology. To understand the first two, contrast the U.S. with sub-Saharan Africa. In the U.S. population is growing slowly, about 0.9% a year. However, each of these people consumes world resources (food, fossil fuel, water, etc.) at an extremely high rate, so they have a much bigger impact per capita. In Africa, the growth rate is more than double (around 2% depending on the country), however, each of these individuals will consume just a fraction of what each new American consumes, so their marginal impact is much less. Technology plays a role, because it has only been through technology, in particular advances in medicine and the cheap energy provided by fossil fuels, that have allowed populations to expand.

Is the world over-populated now? No, in the sense that there is enough food and water to feed everyone, and enough energy to sustain the status quo. However, it is uncertain (perhaps even doubtful)–given the threats of climate change, soil erosion, and depletion of water supplies and fossil fuels—whether the status quo can be maintained. Technology is the wildcard, since every previous boom in population has been aided by advances in technology. However, with the depletion of cheap energy from fossil fuels and the need, driven by climate change, to cut back on fossil fuels before they run out, it is not obvious that human ingenuity will, deus ex machina, produce solutions to these problems. It is certainly something I would work towards, but would not want to count on uncritically.

Will a world of 9 billion people be over-populated? Again, the concerns above about scarce resources will only be exacerbated by an increase in population. Further, looking along the axes of population and consumption, we have to ask how these 9 billion people will be supported. It is estimated that the world could feed 9 billion people; doing so equitably would require the first world (and prosperous developing nations like China) to scale back their consumption of meat considerably. The same applies to other forms of consumption: for the first world to maintain its current levels of consumption while the population expands by another 2 billion people means that the vast majority of people in the world will continue to get by on very little, while the select few (say 1-1.5 billion people in North America, Europe and Japan and a few other enclaves) consume the vast majority of the world’s resources. (Images of the rich man and Lazarus naturally present themselves.)

I think that this outline establishes that over-population is at least potentially a very serious problem, one which impacts upon all people and upon the Earth itself. But the Catholic Church seems to be in denial, arguing, sometimes vociferously, that it is not a problem. Two documents, both from Pro-Life Secretariat of the USCCB, make this point clear. The first is called The Myth of Over-Population. The second is called Ten Great Reasons to Have Another Child. While the latter could be interpreted as only arguing against the trend of childless or single child families, but the arguments about the impending “population crash” suggest otherwise. Also, anecdotally, the broader context suggests that world population is not an issue for some Catholics. The daughter of friends of mine (quite conservative Catholics) was interested in going to the University of Steubenville, and she and her mother went for a visit. The mother told me that during the parent events many of the moms were bragging about the size of their families (8 to 10 kids) and she felt a real sense of scorn when she announced she had two children.

Turning to the first article, the bulk of it is not devoted to over-population per se, but rather to criticizing the coercive means (abortion and forced sterilizations) adopted in some places (such as China and India) to combat it. It does not logically follow from the fact that the solution is flawed that the problem does not exist. Neither, in a related vein, does the fact that some people who raise concerns about over-population supported eugenics or other racist ideas. By way of analogy: that Hitler was a vegetarian says nothing about the ethical nature of vegetarianism.

The remainder of the article lays out a series of facile arguments that really do not work. The first is technological optimism: up until now we have always been able to use technology to expand our resource supply, so we always will be able to do so. As I noted above, there are credible reasons for thinking otherwise. The second is a mis-analysis of demographic trends. It points out, correctly, that many countries, such as France, lowered their population growth rate “naturally” and this will happen everywhere without intervention or concern. However, it is worth noting that France in the 19th century accomplished this by widespread use of contraception (either barrier methods or the withdrawal method). Noonan discusses the Church’s response to this in great detail in his book on contraception. The third in the peroration, is what I call the “there is plenty of room” argument:

Next time you are in an airplane flying virtually anywhere in the world, even in the very populous United States, look down from on high and what you will see is a remarkably empty planet straining to be made a garden by more of us.

This is a variant of the technological optimism argument, but it is so prevalent that it needs to be addressed separately. Variations are legion: the world population could comfortably live in Texas, Montana, the LA basin, with “acceptable” population densities. The calculations supporting these arguments all ignore infrastructure needs (roads, schools, stores) and the question of resources: we can put everyone in Texas, but there isn’t enough water in Texas for them all. We can redistribute population over the entire planet with a population density less than France, but if we simply cannot produce enough food for them, then population density is moot.

How to move forward? I am sure that I am going to be criticized vociferously about this post. Thoughtful responses are welcome: slams and nasty attacks will go in the trash without comment. As a first step, I would propose looking more closely at one sentence written by Benedict XVI in Caritas in Veritate:

Due attention must obviously be given to responsible procreation, which among other things has a positive contribution to make to integral human development.

How, in light of the real issues outlined above, should we understand “responsible procreation”?