What Level of Human Population Is Sustainable?

"In the last 200 years the population of our planet has grown exponentially, at a rate of 1.9% per year. If it continued at this rate, with the population doubling every 40 years, by 2600 we would all be standing literally shoulder to shoulder." says Professor Stephen Hawking as reported by Edward Morgan in Looking at the New Demography.

Suffice to say the rate of population growth will not continue, and Morgan makes the case we are already in stage 5 of The Demographic Transition Model

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Peak Oil Implications on Population Growth

Whereas Morgan presents a relatively benign view of things, even wondering if there are ways to reverse stage 5 decline, Paul Chefurka in Population: The Elephant in the Room sees things quite differently, primarily because of oil usage.

Each of the global problems we face today is the result of too many people using too much of our planet's finite, non-renewable resources and filling its waste repositories of land, water and air to overflowing. The true danger posed by our exploding population is not our absolute numbers but the inability of our environment to cope with so many of us doing what we do.

It is becoming clearer every day, as crises like global warming, water, soil and food depletion, biodiversity loss and the degradation of our oceans constantly worsen, that the human situation is not sustainable. Bringing about a sustainable balance between ourselves and the planet we depend on will require us, in very short order, to reduce our population, our level of activity, or both. One of the questions that comes up repeatedly in discussions of population is, "What level of human population is sustainable?"

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 correspondence:

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A closer look at the two curves from 1900 to the 2005 reinforces the impression of a close correlation:

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The first questions everyone one asks when they accept the concept of Peak Oil is, "When is it going to happen?" and "How fast is the decline going to be?"

The steepness of the post-peak decline is open to more debate than the timing of the peak itself. There seems to be general agreement that the decline will start off very slowly, and will increase gradually as more and more oil fields enter decline and fewer replacement fields are brought on line. The decline will eventually flatten out, due both to the difficulty of extracting the last oil from a field as well as the reduction in demand brought about by high prices and economic slowdown.

The post-peak decline rate could be flattened out if we discover new oil to replace the oil we're using. Unfortunately our consumption is outpacing our new discoveries by a rate of 5 to 1. to make matters worse, it appears that we have probably already discovered about 95% of all the conventional crude oil on the planet.

A full picture of the oil age is given in the graph below. This model incorporates actual production figures up to 2005 and my best estimate of a reasonable shape for the decline curve. It also incorporates my belief that the peak is happening as we speak.

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In ecology, overshoot is said to have occurred when a population's consumption exceeds the carrying capacity of its environment, as illustrated in this graphic:


Populations in serious overshoot always decline. This is seen in wine vats when the yeast cells die after consuming all the sugar from the grapes and bathing themselves in their own poisonous alcoholic wastes. It's seen in predator-prey relations in the animal world, where the depletion of the prey species results in a die-back of the predators. Actually, it's a bit worse than that. The population may actually fall to a lower level than was sustainable before the overshoot. The reason is that unsustainable consumption while in overshoot allowed the species to use more non-renewable resources and to further poison their environment with excessive wastes.

In the case of humanity, our use of oil has allowed us to perform prodigious feats of resource extraction and waste production that would simply have been inconceivable before the oil age. If our oil supply declined, the lower available energy might be insufficient to let us extract and use the lower grade resources that remain. A similar case can be made for a lessened ability to deal with wastes in our environment.

Excess Deaths

[Chefurka goes through a series of grim charts culminating with with this explanation of what is coming]

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The Cost

The human cost of such an involuntary population rebalancing is, of course, horrific. Based on this model we would experience an average excess death rate of 100 million per year every year for the next 75 years to achieve our target population of one billion by 2082. The peak excess death rate would happen in about 20 years, and would be about 200 million that year. To put this in perspective, WWII caused an excess death rate of only 10 million per year for only six years.

Given this, it's not hard to see why population control is the untouchable elephant in the room - the problem we're in is simply too big for humane or even rational solutions. It's also not hard to see why some people are beginning to grasp the inevitability of a human die-off.

UN Population Projections

Let's put aside the really grim projections and simply ponder the "low population track" in the following charts of population projections from the UN.

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I cannot find the article or source for that chart but the image is from a link on Seeking Alpha.

Demographic and Economic Questions

  1. Is that low UN track that unbelievable? If not, what if the starting point is now, not 2040?
  2. Who is going to pay the medical costs of all the retirees in the developed-world if people live longer and the population simply stagnates?
  3. Where are the energy resources going to come from if the population keeps growing instead?
  4. Where are the energy needs of China alone going to come from at the current rate of China's economic growth regardless of whether the Chinese population grows or not?

Those who think we are going to "grow" our way out the the current global economic mess better have good answers for the questions in points number one and three above.

Problem number two is a huge problem in Japan right now. Thee US will face the same problem not too far down the road.

Those who suggest immigration and population growth is the solution to problem number two better have an answer to question number three while also explaining how immigration and population growth is nothing more than a can-kicking exercise.

The China problem is right here, right now. Peak oil all but ensures China's growth rate is going to plunge in the not too distant future, there is going to be a huge global showdown over oil supplies with China the winner, or a cheap easy to produce means of renewable energy is found in the next five years?

Source: Global Economic Analysis

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