Sep 28 2009

The Overpopulation Hubbub

The question of human overpopulation of the earth is one of those empirical scientific questions that garners a strange amount of emotional opinion.  It is as if the sense of overcrowding and depleting resources triggers something primal in our monkey brains. On the other side, we resent being told to curb what is perhaps our strongest natural instinct – to make more versions of our genome.

Another feature of this debate that encourages or at least allows emotion to reign over data is that the core questions involve predicting the future. We are very bad at predicting the future. Predicting the future is really just an exercise in projecting our biases onto the future. The best we can do is extrapolate current trends forward, but there are often multiple overlapping trends that we can choose from, some trends are really cyclical, and the appropriate curve (linear, geometric, exponential) may not be obvious.

It is also important to identify in a controversy where there are value judgments that cannot be resolved objectively with facts. The abortion debate continues to rage because at its core is a personal choice of value – the mother’s biological freedom vs the life of a fetus. In the population debate there are value judgments regarding humanity’s rights and responsibilities toward the earth and all other life on it.

A recent issue of New Scientist explores various points of view regarding the population debate. For anyone interested in this topic this makes for good fodder. The basic facts are this – human population is now reaching 7 billion people. It is estimated that by 2050 we will exceed 9 billion. However it is also true that as our technology progresses we are able to sustain more people with fewer resources.

It often seems, therefore, that where one stands with regard to the population issue depends upon whether one is a pessimist or optimist. Although, even for the maximal optimist it must be acknowledged that there must be some upper limit to what population the earth can comfortably support, and that at some point (despite technological advances) increasing population becomes an increasing drag on the environment and other species – for reasons of physical space if nothing else (setting aside expanding the human population off planet and focusing just on the population of the earth).

Taking the pessimistic point of view is Paul and Anne Ehrlich, who write:

Somehow, cultural attitudes toward large families everywhere need to be changed. It should be considered immoral to have excessive numbers of children – an attitude that already exists in most industrialised nations with low birth rates. Nothing is more clearly a governmental responsibility than keeping a nation’s population size sustainable by benevolent measures.

As well as curbing population growth, we shouldn’t forget the pressing issue of excessive consumption by the rich.

Their argument amounts to a peak resources position – it will get more and more difficult to sustain an increasing population with fewer and fewer resources. Again, this is likely to be true at some point, but saying that we are essentially there now seems to ignore the role of technological advance.

Staking out the other end of the spectrum is Jesse Ausubel who points out that while the population has been increasing at a rate of about 1% per year, crop yields have been increasing at a rate of 2% per year, allowing us to grow more food on less land. In this interview he says:

Technology has liberated humans from the environment. Today we live about equally well in polar and tropical, arid and wet environments. The new question is whether humanity can use technology to liberate the environment itself. E-books, landless agriculture – farming that uses very little land because of high yields – and subterranean maglevs show the way.

It is important to note, however, that even a techno-optimist like Ausubel points out that we need to prioritize those technologies that do “free nature” by allowing us to do more with less. He is not saying that we should ignore the issues of population and resources – but that we can rely upon technological advances to give us solutions, if we choose to use them.


I admit I am more toward the Ausubel end of the spectrum than the Ehrlich end. Doom and gloom predictions over the last century about population increase and dwindling resources have not come true. Reading the Ehrlich’s warning about rising death rates sound a lot like the predictions of massive die offs that have been made and failed to manifest on a regular basis over the previous decades.

At this point I think we can conclude that it is not terribly useful to make predictions based upon current sustainability, because technology is constantly changing the equation. And technological advance has continued to surprise us. It seems likely that in 100 years the problems humanity will be facing are likely to be different than most of those causing current worry.

This does not mean, however, that we should just shrug and not worry. Thoughtfully contemplating the implications of our industry and population, and how to prioritize technological development and research is likely to have a huge impact on our future. I am optimistic that technology will give us potential solutions to the problems caused by a rising population within finite resources.

But we still need to develop and implement those solutions. Some of them will happen as a matter of course – people will use light bulbs that use less electricity and last longer simply because they will save money. But others may require more deliberate application, and we may need to bridge to “better” technologies through a cost-ineffective transition. For example, we may need to subsidize solar energy against the very cost effective fossil fuels before fossil fuel prices surge because of scarcity.

I say “may” because I personally don’t know – this is a specific technical question best left to appropriate experts. An approach I generally recommend over ideology.

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