When listing the most troubling global trends of our time, one has to consider the following: accelerating industrialization, widespread malnutrition, depletion of non-renewable resources and a deteriorating environment. At the root of all these converging crises is the issue of human overpopulation. Each person we add to the planet requires more energy, space and resources to survive. If the human population was maintained at sustainable levels, it might be possible to balance environmental issues with renewable resources and regeneration. Unfortunately our population is rapidly rising beyond the Earth’s ability to regenerate and sustain us with a reasonable quality of life. We are exceeding the carrying capacity of our planet.

One only has to look at the situation we find ourselves in with respect to water, soil and food depletion, biodiversity loss and the degradation of our oceans to know that the human situation is not sustainable. So, one has to ask, what level of human population is sustainable?

What is a Sustainable Population?

A sustainable population is one that can survive over the long-term (tens of thousands of years) without running out of resources or damaging its environment in the process. This means that a population must not generate more waste than natural processes can deal with, that those wastes do not generate harmful outcomes for the ecosystem and that the resources used are either renewable through natural processes or are able to be entirely recycled. A sustainable population must not grow past the point where those natural limits are breached. Clearly, the current human population is not sustainable.

Carrying Capacity

Carrying capacity is defined as “the population size of the species that the environment can sustain indefinitely, given the food, habitat, water and other necessities available in the environment.” Wiki If the numbers of a species are below the carrying capacity of its environment, its birth rate will increase. If the population exceeds the carrying capacity, the death rate will increase until the population numbers are stable.

The relationship of humans to their environment is obviously more complex than the relationship of other species to theirs. The human carrying capacity can be increased by the discovery and exploitation of new resources (such as metals, oil or fertile uninhabited land) and it can be decreased by resource exhaustion and waste buildup, for example declining soil fertility and water pollution.

If we look at a graph of world population from 1 AD to now, it’s perfectly obvious that something has massively increased the world’s carrying capacity in the last 150 years. For tens of thousands of years the human population rose very gradually as humanity spread across the globe. This began to change around 1800 and by 1900 the human population was rising dramatically. The population reached 6.1 billion in 2000. The United Nation projects that if continue along our current trajectory, world population for the year 2050 could range between 7.9 billion to 10.9 billion!

The Role of Oil in Population Growth

Oil first entered general use around 1900 when the global population was about 1.6 billion. Since then the population has quadrupled. When we look at oil production overlaid on the population growth curve we can see a very suggestive correlation.

Oil allowed humans to send fishing ships far out to sea, to drill deep water wells to irrigate crops and to grow, harvest, refrigerate and distribute vast quantities of food. It enables us to feed 6.8 billion people.

The “Green Revolution”

Another cause of the huge population growth during the 20th century was the enormous world-wide increase in food production created by the growth of industrial agribusiness. Popularly known as the “Green Revolution”, it’s clear that it has caused a massive increase in both yields and the absolute quantities of food being grown worldwide. I often think calling this particular revolution ‘green’ is a complete misnomer, given that it was actually based on cheap and easy access to large quantities of oil. First came mechanization, then the invention of pesticides and fertilizers. Both of these new technologies are completely reliant on petroleum products derived from oil. Without large quantities of cheap oil, this revolution could not have occurred.

In 2000, a University of Michigan study stated that for every calorie of food energy consumed in the United States, over seven calories of non-food energy (fossil fuels) were used to produce it. Other studies have placed the ratio at 10:1. The United States uses over 12% of its total oil consumption for the production and distribution of food. As the oil supply begins its inevitable decline, food production will be affected. Over the next decades the ability to maintain our burgeoning population will come under increasing pressure.

Source: Clay Bennett

Population Growth in light of Peak Oil

Over the last couple of centuries, Human carrying capacity has been added to the Earth in direct proportion to the use of oil.

As I outlined in a previous post, oil is a finite, non-renewable resource. As our oil supply declines, the disturbing implication is that the carrying capacity of the world will automatically fall with it. Our population today is many times as much as it was before oil came into our lives, and it is still growing. If this resource were to be exhausted, our population would have no option but to decline to the level supportable by the world’s lowered carrying capacity. Understanding the role of oil in expanding the earth’s carrying capacity brings a new urgency to the topic of Peak Oil. I’ll leave further discussion on that topic until another day.

Population Growth and other Environmental issues

As the world population continues to grow, much pressure is being placed on arable land, water, energy, and biological resources to provide an adequate supply of food while maintaining the integrity of our ecosystem. Each of these issues deserves a dedicated post, so in the coming months I intend to discuss the impact our growing population has on a variety of these environmental issues.

Read more from me:

Economy#1: How Money is Created

Energy#1: What is Peak Oil?