Review:Population Bomb

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Paul R. Ehrlich wrote the revised edition of The Population Bomb which was published in 1971. The importance of the book is that it seems to be the voice of the Zero Population Growth crowd, and their arguments do not seem to have changed much in 45 years. In 1971 the argument was that starvation was imminent and even immediate population control would not have been enough to completely prevent famine in several places within two decades. The argument has been revised to the extent that it is claimed that overpopulation will cause starvation but the date was not well expressed. There is some danger of famine such as happened in Europe in 1848 because of crop failure, but the ZPG crowd fail to take into account the expertise of agricultural producers. Farmers tend to know their market and not invest in extra production that they will not be able to sell. We have not had much shortage of food except where war prevented agriculture and prevented aid to the hungry. There is some shortage of money to buy food but if there were more money in the hands of the hungry, more food could be produced. Salt tolerant crops could be grown on desert land by the ocean if it were irrigated with sea water. Mushrooms could be developed to grow on much wood that currently lies dead in the forest until it provides fuel for a forest fire. New techniques of producing more food only need money to be realized.

The big problem with the book is that on page 5 Ehrlich refers to the problem of transporting billions of passengers from the Earth's surface to orbit as beyond possible solution. The Eddy Current Brake to Orbit article describes how these problems could be solved. There is more than one launch technology that could be used, such as Wheel Launch to Orbit. Ehrlich developed his defeatist position further writing that it would take only about 50 years to populate Venus, Mercury, Mars, the moon and the moons of Jupiter and Saturn to the same population density as the Earth. Here he was using the assumption of a continuing rate of doubling once per 35 years. A person can find a way to fail at anything if they try hard. The proper way to colonize the solar system is not covering the surface of Venus, Mercury, Mars, the moon and the moons of Jupiter and Saturn with people but rather mining these bodies down to the core and converting them into space habitats.

In the case of Venus this could be done by building a shade at the Venus/Sun L1 point to cause the atmosphere to freeze out and leave the entire planet available to be mined. The shade could be a cone shaped structure with the 50 degree apex angle pointing at the sun and the base turned toward Venus. The cone would be supported by ring structures in planes parallel to the base with the rings containing masses that move similarly to a halo orbit but somewhat faster and constrained to follow a circular path. Each ring would have two sets of masses circling in opposite directions with speed and spacing computer controlled. The rings would be connected in order from smallest to largest fixing their relative positions with perhaps three miles space between each ring and the next. That would require about 3000 rings with the largest being about the diameter of Venus. Attached to the rings on stalks would be about seven million three mile diameter spinning disks of shiny foil to act as umbrellas, shading the ring structure and shading Venus. The disks would spin alternately clockwise and counter clockwise to have no net gyroscopic effect. Control of the orientation of these umbrellas would provide station-keeping thrust by the direction that sunlight is reflected and so maintain the cone at the L1 point. The atmosphere of Venus would condense out in a year or so of torrential rains and eventually freeze solid. The structure of the rings and the structures between them would be active truss structures to allow gravitational perturbations from Jupiter to slightly alter the shape of the shade without breaking it.

By mining a certain set of planets and moons[1] to the core people would get enough material for 3.8 E 14 fusion powered space habitats (380 million million) for more than 1.0 E 19 people (10 billion billion) at about 500,000 metric tons of habitat per person. This is 167 times more people than Ehrlich suggested could be alive in 900 years at a constant growth rate. If people fail to develop fusion power, orders of magnitude fewer solar powered space habitats would use up as much of the light from the sun as is practical. From his position of ignorance of the technology of colonization of the solar system, Ehrlich did not hesitate to call the problems involved insurmountable. Some of the Zero Population Growth crowd have continued to call space colonization fantasy and in discouraging it have moved from warning of starvation from lack of economic resources to causing it. If mankind fails to colonize extraterrestrial space, it will be our worst failure since our ancestors came down out of the trees to live on the ground. The ability to produce space habitats will not be proven until it is accomplished, but assuming that it is impossible does not make it impossible.

Some people might think that this review demonstrates that colonizing the solar system is a fantasy by suggesting that Venus be shaded with an umbrella as large as Venus. The shade could be on the order of 80 billion tons of mainly Calcium-Aluminum-Magnesium alloy but the alloy is just a guess. It may be better to separate the metals that are available and use them as binary alloys. None of this will be done until the industry in cis-lunar space has gone through a large quantity of materials, building space based solar power, space telescopes, habitats and other things.

The Zero Population Growth crowd should understand compound interest. Ehrlich made frequent references to it in his work. It governs not only population growth but also the growth of industrial abilities when the output is in some degree redirected to investment in capacity beyond the replacement level. If the level of industrialization of the moon is reached at which it is only barely possible to build one space based solar power station per year, the industrial capacity should steadily increase as more things are built until the shade for cooling Venus is a reasonable possibility. As Ehrlich wrote that his suggested scenarios were just possibilities for the future, not predictions. Habitats for 1.0 E19 people is just a suggested possibility.

Ehrlich wrote that we must have population control in the U.S. If it can't be done voluntarily, then by compulsion.[2] He wrote that abortion is a good means of population control.[3] It seems as though he is thinking of members of the Zero Population Growth crowd being in charge, telling people how many children they can have, and aborting the rest. He wrote that population control is the only solution to such problems.[4] Apparently he did not have much respect for the sizable portion of the population in convents and monasteries in Europe in the fifteenth century.

When Ehrlich suggested that conscious regulation of population must reduce the rate of increase to zero and we must at the same time greatly increase the supply of food,[5] it was a good thing his advice was not followed. There would have been excess food rotting in storage. People should have some faith in supply and demand influencing each other through market forces. A powerful totalitarian government is able to mismanage things to the extent of having great exesses of some things and almost none of other things that people are desperately lacking.

There is at least one alternative to Ehrlich's only one Earth. People have the technical possibility of expanding into the Solar System if they can meet the political and economic challenges. We do not need to have a high rate of population growth to do it.

One strategy seems doomed to certain failure. That is the strategy of killing one's neighbors now to make room for one's grandchildren. In that direction lies failure of the technological economy, barbarism covering the Earth, and the end of the human species without ever extending the human economy throughout the solar system.


  1. Planets and moons included are Earth's moon, Mars, Venus, Ceres, Vesta, Titan, Europa, Ganymede, Enceladus, and Callisto
  2. THE POPULATION BOMB by Dr. Paul Ehrlich (c) 1968 & 1971. BALLANTINE BOOKS pages xi-xii
  3. ibid page 44
  4. ibid page138
  5. ibid page 93