Population Where We Stand Now

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Paul Ehrlich (Bing Professor of Population Studies and Professor of Biological Sciences, Stanford University) and Anne Ehrlich (Senior Research Associate, Department of Biological Sciences, Stanford) are familiar names to ecologists and environmentalists everywhere. But while most folks are aware of the Ehrlichs'popular writing in the areas of ecology and overpopulation (most of us — for instance — have read Paul's book The Population Bomb) ... few people have any idea of how deeply the Ehrlichs are involved in ecological research (the type that tends to be published only in technical journals and college texts). That's why we're pleased to present this regular semitechnical column by these well-known authors/ecologists/educators.

by Paul and Anne Ehrlich

In the 15 years since The Population Bomb was written, well over a billion people have been added to the human total. Amazingly, that number is greater than the entire population of the Earth at the time of the American Revolution.

Indeed, a short half-century ago there were just 2 billion people in the world. Now, there are 4.6 billion. In less than one brief lifetime, then, the population of our planet has more than doubled.

Of course, such unprecedented growth might not be terribly serious were Earth not already overrun by people. In fact, today's human family is so large that it can survive only by behaving in a way no sane family would want to ... by destroying its capital. The vast number of people now on this planet, you see, can be supported only by consuming or dispersing a one-time bonanza: our store of inherited wealth, which cannot be replenished on a time scale of any interest to society.

That capital includes, of course, nonrenewable energy resources such as petroleum and coal. It also includes soils (see "A Resource Down the River", MOTHER NO. 64, page 136) . . . "fossil" fresh water (see "Poison From Below", MOTHER NO. 78, page 146) ... and the living species of our planet, which are intimately involved in supplying ecosystem services to society (see "Extinction: It Should Concern Us All!", MOTHER NO. 68, page 154). Furthermore, as those resources are depleted, the number of human beings that can be supported—Earth's "carrying capacity"—will be greatly diminished.

Therefore, one major concern of humanity must be to bring population growth to a halt as rapidly as is humanely possible, and then to start a gradual decline by keeping the birth rate (which is generally expressed as the number of people born annually per thousand people) slightly below the death rate. And that process must continue until a population is reached that can be supported indefinitely on renewable resources.