What can the world expect during the next century as its population increases and its resources diminish? Last week in Manhattan three Caltech experts, Geochemist Harrison Brown, Biologist James F. Bonner and Psychologist John R. Weir, who have been studying this problem as a team, were optimisticwith qualifications.
They agreed that the world's population, now 2.6 billion, will continue to increase, reaching about 6.5 billion in 100 years. Industrialism will spread to underdeveloped areas. Both these trends will put tremendous strain on supplies of mineral raw materials.
Mine the Rock. Fortunately, Dr. Brown says, ore deposits get bigger as they fall in grade. Clay, which is everywhere, is a low-grade aluminum ore, and sulphur can be extracted from plentiful calcium sulphate (gypsum). Even ordinary rocks can be processed for their minerals. One hundred tons of an average igneous rock, e.g., granite, contain eight tons of aluminum, five tons of iron, 1,200 lbs. of titanium, 180 lbs. of manganese, 70 lbs. of chromium, etc. Dr. Brown believes that the time may come when rock is refined into 20 or 30 products. Rock reserves will last indefinitely, and only energy will be needed to exploit them.
But what about energy? Some authorities believe that a world population of 3 billion living at the "American level" would exhaust accessible deposits of fossil fuel in 23 years. Atomic energy, however, is inexhaustible. After all rich uranium ores are gone, the same granite that is processed for metals will supply uranium and thorium for atomic energy. Each ton of average granite contains as much energy as 50 tons of coal.
Biologist Bonner took a hard, imaginative look at the world's future food supply. He points out that if all the carbon produced on earth by land plants (16 billion tons a year) were in edible form, it would feed 46 times the present human population; the carbon from cultivated lands alone is ten times as much as is needed. A large part of it is inedible stems, leaves, etc., and another large part is wasted by domestic animals or consumed by insects and other pests, but Dr. Bonner believes that with effort more of it could be made available.
The U.S. is not likely to have much food trouble. Allowing for a reasonable improvement in agricultural methods, U.S. land can feed 400 million. The people will still eat well, but will not get quite as much meat. Most of the rest of the world will not fare as well, but Dr. Bonner believes that if all potentially arable land is cultivated intensively but still conventionally, about 7.6 billion people can have a passable diet.
Water the Desert. Dr. Bonner does not think much of chemical synthesis of food or growing algae in nutrient solutions. Much more promising, he believes, is the irrigation of the world's deserts by freshened sea water. Such agriculture will be expensive, but it can be done if the need is great enough. Another potential resource is the ocean. Wild fish will never be a really large source of food, and the microscopic vegetation of the sea is too dilute for easy harvesting. But Dr. Bonner thinks that some algae-eating animal (a "sea-pig") may be domesticated or developed to graze on sea water as cattle graze on grass. His conclusion is that there is no practical limit to the amount of food that the world can produce.