Global Population
Practical Limits

In the past, global population has never come close to pushing the limits imposed by the technology of the time, whether it was gathering, agriculture, or industry.  But, all other factors being equal, population tends to increase exponentially.  Even during major wars and famines, global population has steadily increased outside the areas immediately affected; only during the period of the Black Death during the middle ages did world population actually decrease, and even then it had fully recovered fifty years after the epidemic.

As the table below illustrates, for the first time in history the global population is rapidly approaching the physical limits of our technology and resources to provide for it.  Unless the current rate of population growth (around two percent per year) is somehow curbed, it is certain that world population will reach an absolute ceiling sometime during the middle or late twenty-first century.  When that happens, there will simply not be enough food, energy, and other essentials to go around, regardless of how hard we work to produce them or how efficiently we distribute them.  The consequences are obvious and unprecedentedly horrific—but avoidable, if we have the foresight to act wisely and decisively in time.

The good news:  It is possible that the maximum sustainable global population will increase somewhat due to applications of computer technology.  However, at this point it is difficult to gauge how great such an increase might be.  A very conservative estimate (which I have used here, due to lack of reliable forecast data) might be no increase at all over the current limit based on industrial technology.  On the other hand, a very optimistic projection might forecast a ten-fold increase, from 20 billion to 200 billion people worldwide.  This would yield an average population density of 1,333 persons per square kilometer of earth's land mass, including polar, desert, mountain, and other regions not generally considered habitable.

The bad news:  Future projections are based primarily upon the ability of earth's population to feed itself, as enabled by the dominant technology.  They do not take into account the depletion of various natural resources due to growing demand; nor do they take into account the possible reduction of fertile land as a result of coastal flooding due to global warming.  If, as is likely, critical non-renewable resources become drastically depleted, the maximum sustainable future population might actually turn out to be much less than even the current global population of six billion.

This implies, of course, that a tremendous drop in world population must occur sometime in the next several decades.  Precisely how that reduction is manifested—through protracted global war, mass starvation, pandemic disease, adverse climate change, uncontrolled pestilence, selective extermination ("ethnic cleansing"), compulsory sterilization . . . or through education and voluntary birth control—may well determine whether or not human civilization survives into the 22nd century.

Unfortunately, few in power today are likely to do anything to avert the crisis.  Even if they think about it at all (which is unlikely), the current middle-aged and elderly leaders of government, business, and religion do not expect to be around when the real crunch hits later in the 21st century or early in the 22nd, and hence lack any motivation to address the issue.  Indeed, because this is the first time that this situation has ever arisen in a global context, the horrendous implications are absolutely unfathomable to most, and business and politics go on as usual in a state of blissful ignorance and incomprehension.

I am ashamed to say that it is my own generation which is shirking its responsibility in dealing with this global time-bomb.  Even if someone happens to think of the issue occasionally, the usual reaction is one of resignation:  "What can we do?  Let our kids worry about it when the time comes!"  If we persist, we are accused of being alarmist kooks, and admonished to mind our own business.

In the past, mankind could afford to be cavalier in dealing with crises, because they affected only a nation or a region, or at most a continent or two; they did not threaten all of civilization.  But those days are past; like it or not, this situation is global, and it is not going to go away by itself.  If we do not figure out what to do about it and act in time, nature will inevitably make the necessary changes for us in ways not at all to our liking.  Because of the myopic irresponsibility of the current generation, the next will have some very grim and agonizing decisions to make.  For the sake of themselves and of their children—and yes, even of their civilization—they had better see to it that they are informed, equipped, and prepared to make those decisions wisely.

Good luck, kids!

=SAJ=

• World Population: Figures approximate; data prior to 1800 CE estimated.
• Population Density: Based on even distribution of human population over earth's total land surface of 150,000,000 km², including mountain, jungle, desert, Arctic and Antarctic regions.
• Estimated Maximum Population: Maximum population sustainable with technology of the period.
• % World Capacity: Proportion of maximum represented by population of the time.

Some historical population figures from Earth: Our Crowded Spaceship, 1974, Isaac Asimov.
Projected population figures based on approximate current growth rate of 2% per year.
Maximum sustainable population figures for a given technology are optimistic scientific estimates.