What Ehlich failed to take into account, and what those today inclined to raise Armageddon kinds of alarms of our imminent demise may as well, is that we are an extremely innovative and adaptive species.

Changes in how farming has been conducted, the so-called "Green Revolution," have permitted multiples of the pre-1960s crop yields to be harvested each year. Bioengineering has also increased productivity and decreased losses of edible plants to diseases, irregular weather patterns, or predation. The transformation of air (nitrogen) into inexpensive fertilizer has been an enormous boon, at least in the short-term. Cheap petrochemical fuels have facilitated our getting edible staples to both local farmers' markets and global supermarkets. The use of deep well technology has lowered water tables but, meanwhile, allows for the irrigation of enormous acreages in otherwise arid and semi-arid regions. All these developments might themselves have problematic long-term effects. However, till doomsday actually arrives, if may be premature to announce its inevitability.

With our population now close to double what it was when Ehlich wrote and lectured about how the sky appeared to be falling, and more than triple its level when my mother was little, what now? Shall the numbers, like our tempers and temperatures, simply keep rising? The answer seems to be: "Not so much."

First, consider that we really can deal with much higher density than is typically experienced by the average global citizen. Folks are not too uncomfortable in New York City to enjoy life or carry on profitable enterprise. The remaining almost 7 billion people are so spread out that they occupy an entire planet. If a huge compacter were to take all those people and squeeze them together as tightly as in the Big Apple, it would require quite a bit more space than in NYC, of course, about as much as the State of Texas. Folks in the Lone Star State like to say they are the biggest and the best, but compared with the entire surface of Earth, they occupy a quite small fraction of the space available for population expansion. Put another way, if we accept that the NYC level of compactness is a viable, if not always preferable, option, there is room for a total global population many multiples greater than our current census. Pick your number. Using just this criterion, then, a 100 billion eventual planet maximum population is entirely feasible. In fact, just considering the land surface of the globe (disregarding space available if we were to build out over the oceans), enough NYC level, Texas-sized densities could fit onto planet Earth to enable 174 billion of us to exist at once. Would there be other big troubles? You bet! However, population as such may not be the one to stay up nights worrying over. Naturally, the number of inhabitants must sooner or later decline. It puts too much stress on the planet's systems and resources, but it is going to go down anyway.

Waco, 2111

Next, let us consider some implications of too little population. Our economies, like the proverbial Ponzi schemes, are based for their success on ever more people joining in. What looks better for small towns: growing, staying the same size, or shrinking? I think most rural mayors would opt for their communities getting bigger and bigger and, within a few limits, would do almost anything to keep them growing. Otherwise, their revenues, services, and voters' satisfaction all go south in a hurry. Now think national and regional economies. In which would you rather invest, the U.S., India, and Brazil, whose populations are growing, or western Europe, Russia, China (where, despite today having the largest population in the world, the strict one-child policies have been effective enough that there may soon be too few among the younger generations to support aging ancestors), and Japan, places where births, on average, are not keeping up with the death rates? Among other major adjustments which must be made by areas with declining populations are substantially reduced or eliminated retirement benefits. To insist that population should on the whole no longer increase is to condemn the vast majority of the world's citizens to working till they drop.

It is simple arithmetic. To the degree that populations go down, consumer demand decreases. Our financial systems depend for their growth and vitality on consumer demand more than on any other factor. Think deflation, Great Recession, and/or depression.

For better or worse, though, population growth is in fact decreasing. As potential parents have better health care, education, and relative income, they tend to have fewer babies. Were it not for immigration from higher birth rate areas with more poverty, less education, and worse overall medical benefits, our own population would be plummeting. As it is, however, we can expect it to rise to around 400 million or more, contributing to a reasonably vibrant economy. Everything else being equal, to the extent we are successful in limiting politically sensitive influxes from abroad, our national business model becomes less sanguine, our huge debts must be repaid sooner, our currency strength declines, our country's credit ratings drop, interest rates rise, and average business growth decreases to zero, then turns negative, and our products get less costly as people wait and wait to buy, knowing that, in awhile the asking price must keep going down. Think recent real estate prices in Detroit: multiple empty residences going for $6000 or less.

Frustrations over insufficiencies in peoples' circumstances also lead to unrest, which too often results in conflict and major jeopardy to business activity.

So the problem is no longer one of excess population. The challenges are instead with lack of education, too much poverty, poor health care, political discontent and instability, and then with how we adapt to the inevitable decreases in population and concomitant increases in economic and societal disruptions. Those difficulties would still need to be resolved even if our population had already stabilized or begun to decrease.

From my point of view, the need is no longer so much to take action assuring lower population but rather, here in the United States and elsewhere, how best to decrease the number living in slums, those with unsatisfactory medical care, the people inadequately trained for needed jobs, and those with fear- and anger-based destructive and extremist reactions to the inevitable "un-growing pains" of a gradually stabilizing and then declining population.

Primary Source:
Population 7 Billion - Special Series. Robert Kunzig in National Geographic, Volume 219, Number 1, pages 32-69; January, 2011.