Zero Population Growth was a fashionable cause in the 1970’s, continuing as an issue on the fringe of public life in the 2000’s, with one key ZPG Web site now devoted to haranguing Congress and the media about the necessity for worldwide abortion and contraception rights.

The economic case for ZPG, wholly independent of the “woman’s right to choose,” appears to have been lost somewhere. Thomas Malthus, where are you when we need you?

Conventionally, economists and, more particularly, stock analysts, celebrate economic growth from wherever it comes. Greater capital intensity is fine, it increases labor productivity (until the capital investment turns out to have been misguided, trillions are lost, labor productivity’s growth reverses, and total factor productivity takes a bath.)

Greater use of resources is fine, provided the resources are priced by the market. Technological advance is of course fine, even if it makes our economy increasingly vulnerable to natural or man-made disaster. And, above all, population growth is just dandy — it leads to economic growth, which drives up stock prices.

Here, however, there is a clear disconnect with reality.

On the global scale, increasing population increases the use of resources. As the Kyoto negotiations, however misguided, clearly demonstrated, the world is not capable of supporting its current population at anything approaching Western living standards without heating up like a meatball in a wok. Climate control is thus a zero sum game: either the poor have to be kept poor and consuming little of the world’s energy, or the rich have to be taxed out of existence to produce enough spare thermal capacity to allow the poor to get even a little bit richer.

At the micro level, population growth has a huge adverse impact on quality of life, which is not picked up in economic statistics but should be. As the U.S. has demonstrated, rapid population growth around large cities produces new and unattractive “Edge Cities,” as celebrated in Joel Garreau’s 1991 book of that name, each with more than 5 million square feet of office space together with residential and retail space.

Theoretically, such Edge Cities have the scale required for civilized amenities to appear. In practice, such amenities never appear and the cities rapidly decay. An unpleasant example of this is Washington itself, a conurbation of 6 million population that has seen more population growth than Singapore in the last 30 years. The Washington Metropolitan Statistical Area has sprouted a number of thoroughly unpleasant Edge Cities in the 1970’s and 1980’s, some of which are showing clear signs of senescence.

Merrifield, Va., for example, was in 1991 celebrated by Garreau as a new full-blown Edge City, containing Mobil’s headquarters, even though it is located less than three miles from its neighboring Edge City of Tysons Corner. Merrifield, which of course no longer boasts a “flagship” corporate headquarters, is now a thoroughly unattractive morass of aging ferro-concrete and automotive gridlock, and is likely to be a slum within a decade — or blown up, like the notorious Pruitt-Igoe housing project in St. Louis.

New York, a much bigger city than Washington, has avoided the Edge City excrescences, at least northwards, because its population has in recent decades grown more slowly, and hence there has never been a need for such unpleasant speculative building excesses. By avoiding the creation of Edge Cities, the New York area has preserved to a much greater extent than Washington its traditional environment, and the housing stock in many areas, both rich and modest, is more than 100 years old, surely a better and more efficient use of resources than continual quick-buck blast and rebuild.

Between the micro and the global level are the unpleasant national consequences of rapid population growth, which in the Third World leads almost inevitably to impoverishment and degradation. Kenya, a well run country in the 1960’s and 1970’s, is a good example of this. Of course, authoritarian countries such as China have taken steps to deal with the problem, to the extent that, with modern ultrasound and abortion techniques available, the Chinese sex ratio at birth is now 117 boys for every 100 girls. However draconian and unpleasant, this at least has the merit of presumably reducing the next generation by about 8 percent compared with its size if the sexes were equal.

A further problem with overpopulation is that, to put it bluntly, there is a continuous adverse selection involved. Both within countries and, to a still greater extent, between countries, there is a large inverse correlation between wealth and education, and the fertility level. Hence, whether 30 percent or 80 percent of intelligence is inherited (and I know of no serious study that does not fall somewhere between those levels), differential reproduction rates, unaccompanied, unlike in more primitive societies, by significant differences in infant and childhood death rates, must cause a substantial and continuing degradation in the quality of the human stock from generation to generation. Frankly, as we enter the 2000’s, one can put it in a slogan: “Back up the Trees, Before the 3’s.”

To paraphrase the National Rifle Association, cars don’t cause pollution, machinery doesn’t cause pollution, people cause pollution. A reduction by half in world population by 2100 would eliminate the entire global warming problem, given even moderate efficiency in energy usage, while at the same time providing proper western living standards for the Third World.

Conversely, while the Club of Rome in 1970 may have been alarmist, there can be no question that on a 100 year view we are reaching the limit of this planet to support population growth.

The solution need not be particularly draconian, and certainly need not involve mass promotion of abortion. A 1 percent per annum decline in population, after all, halves the population in 70 years, and such a decline can be produced (after a generation’s interval) by a fertility rate of 1.5 births per mother, above the level currently seen in Italy and several other parts of Western Europe.

The actuarial problem of a low birth rate producing an aging society is also not a real one. Provided the average length of retirement is less than the average length of childhood, there should be some benefit; thus, as medical knowledge improves, the problem is easily solved by mandating a later retirement age. The problem thus comes down to how rapidly we can bring Third World fertility down to Western European levels.

Having stated the problem in this way, the solution becomes relatively simple. A generous (in terms of local living standards) system of old age pensions should be provided, funded by the West, so that Third World oldsters no longer need to rely on a large family for support. Conversely, all “flat payment” pro-natal tax policies (such as the increase and extension of child tax credit in the Bush tax plan) should be ended, as such flat payments are worth relatively more to the less able in society, and encourage differential fertility — any pro-natal tax credits should be by means of a reduction in the tax rate, so that the richer and more able are encouraged to be more fertile.

By all means, provide free contraception, but not free abortions, which are too often used as a “fail-safe” method of contraception, and, being unpleasant and psychologically harmful, result in a significant “leakage” of unplanned childbirths.

As usual, economic incentives should be used to produce economically desirable results; there is no need to compromise basic human freedoms, or to engage in unpleasant forms of state control. The incentives must be substantial, however, to avoid the dystopia of an overpopulated, overheated, intellectually under-endowed 2100.

Thomas Malthus, your warnings were prescient, but your predictions too gloomy. With firm, courageous policy, ignoring populist squawking, economics does not have to be a Dismal Science.

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(The Bear’s Lair is a weekly column that is intended to appear each Monday, an appropriately gloomy day of the week. Its rationale is that the proportion of “sell” recommendations put out by Wall Street houses remains far below that of “buy” recommendations. Accordingly, investors have an excess of positive information and very little negative information. The column thus takes the ursine view of life and the market, in the hope that it may be usefully different from what investors see elsewhere.)

This article originally appeared on United Press International.