Is Earth’s Population Unsustainable?

Is it getting crowded around here? Over the last few hundred years, Earth’s population has skyrocketed. This rapid growth of the numbers of human beings has had a significant effect on all aspects of the biosphere, ranging from new diseases to resource depletion. Current projections of population growth suggest that this trend is not likely to ebb without significant effort on the part of humanity. Human population control, how do we do it? Controlling our population is likely to become more and more important in our lives as time goes on.

Is Earth's Population Unsustainable?


Photo Credit: Rob Pongsajapan

To understand the importance of human population control one should begin by looking at the history of human population on the Earth. From the beginnings of the human species, our population remained around 5 million. Our lifestyle as spread-out hunter-gatherers limited the possibility of large expansion in numbers. Things began to change dramatically at the onset of agriculture.

As agriculture took off around the world, human population quickly began to rise. Perhaps the most important factor in this rise was the simple increase in food production for a given area. Where before a population would need 2.6 km^2 to support each person, they could now supply each person with only .5-1 km^2 each, and this figure is before the advent of irrigation techniques. This led to a steady increase in human population which held from around 10,000 BC to the industrial revolution. During this long breadth of history, the population still remained significantly below one billion people.

All of that changed dramatically at the onset of the industrial revolution. In the last 300 years, the human population has ballooned up to nearly 7 billion. The constant increase in the productivity of agriculture as well as massive breakthroughs in medicine and technology have allowed humanity to multiply rapidly. It is worth noting that out of the rise to 7 billion, 5 billion of that growth came between 1800 and 1950.

Conclusions vary about this trend, with some sources finding that it is slowing down and perhaps stabilizing, while others argue that the trend will continue upward even in the face of catastrophic loss of life (on the order of half a billion people). In either case, the human population is expected to fall somewhere between 9-12 billion people by 2100.

So what? Why should you be concerned about human population control? What’s going to happen that will make it matter for you? To understand this we have to think about the Earth’s carrying capacity. Carrying capacity is the number of humans that the Earth can support, in terms of food, water, shelter, and other resources. Many estimates put the upper limit on this number around 10 billion people, though this calculation requires that we give up meat as a species and focus all our agricultural production towards a vegetarian diet. Food often plays a central role in these calculations (more on this below) but other resources are vital to consider.

Fresh water is of tremendous importance to human life, but not just for drinking. Agriculture takes up the vast majority of water used in the United states, a trend which is common around the rest of the world. This has placed a significant drain upon the water stored in aquifers around the country. As the human population grows and food production must be scaled up, the effects on water consumption will be felt more and more widely.

If humans continue to eat meat, disease could become a more significant factor in human population control. As the farming of animals is scaled up, the animals are grown in more and more cramped conditions, leading to higher rates of disease among the farm population. To combat this spread of disease among the livestock, many farmers have turned and will turn to antibiotics. Natural selection could lead to any number of antibiotic-resistant strains of disease coming about in these farms. Once that happens, it is only a matter of time until a new pandemic begins to spread around the world.

All of that is really depressing though, so let’s take a moment and look back to one of the first major proponents of human population control, Thomas Malthus. Malthus was a British economist at the turn of the 19th century. As he studied the growth of human populations around Europe in his own time, he came to a chilling conclusion: food production could not possibly keep up with the growing population.

Happily, Malthus was wrong. Not just a little wrong, but entirely wrong. Completely wrong. Recalling our discussion of human population at the beginning of the article, Malthus was writing at a time when the human population was just reaching single billion. Advances in farming technology have consistently led to higher and higher yields from farms, keeping pace far ahead from the growing population. So perhaps it is worth taking some of these predictions with a grain of salt.

But it still may be best to prepare for the worst, so what are some plans that could effect human population control. First, our current fears may simply be short-sighted. Using the United States as an example, after many of the technologies which allowed greater populations had been distributed, there was a gap in time before the birth rate began to decline.

Many of these technologies have now been distributed worldwide, eliminating the necessity for families to have a large number of children to ensure that they will have children survive to adulthood. As a result, it is possible that many of the countries which still have high birthrates will see those birthrates drop in the coming years. In addition to the cultural shift in response to these technologies, many societies have not yet adopted widespread practices of birth control, whether “One Family, One Child” policies like China’s or the simple usage of medication.

Perhaps though, the best and most exciting solution to human population control is expansion. The Earth is limited, but there remains an option which is not. Stephen Hawking has said it best, “Our only chance of long-term survival is not to remain inward looking on planet Earth but to spread out into space.” If humanity can spread to the stars, there is a practically infinite amount of resources and star systems to be colonized and developed over the growth of our species.

All these considerations in mind, human population control is still likely to be a significant factor in the survival of our species. Either Malthus will continue to be entirely wrong and humanity will continue to produce food and other resources at a rate greater than our population climbs, or we shall be forced to adopt measures to control our population, limiting ourselves to a number we can support.