The Most Overpopulated Nation

Article author: 
Paul R.Ehrlich and Anne H. Ehrlich
Article publisher: 
Negative Population Growth
Article date: 
16 January 2019
Article category: 
Our American Future
Article Body: 

CAIRCO note: America's population is 328 million as of January, 2019, and world population is 7.5 billion.. Although American women voluntarily achieved replacement level fertility (2.1 children per woman) in 1972, mass immigration is now driving U.S. population to double. Economists, politicians, and cornucopianists would like you to believe that U.S. population can grow forever within the constraints of a finite country with finite resources. 

Yet the environmental reality is that infinite population growth is not possible. 

The following article was written in 1991, when America's population was 285 million and world population was 5.4 billion. The article frames population growth in an environmental perspective, and explains the fundamental ecological equation: I = P A T. Excerpts follow:


... Yes, poor nations have serious population problems, but in many respects rich nations have worse ones. Nothing recently has made the degree of overpopulation in the United States more obvious than George Bush’s confrontation with Iraq. If the United States had stabilized its population in 1943, when it was in the process of winning the largest land war in history, today it would just have 135 million people. Assume that per-capita energy consumption nevertheless had grown to today’s level – that is, our smaller population was still using sloppy technologies: gas guzzling automobiles, inefficient light bulbs and pumps, poorly insulated buildings, and so on. Even if its citizens were just as profligate users of energy as we are, the 135 million United States citizens could satisfy their energy appetite without burning one drop of imported oil or one ounce of coal....

I = P A T

The impact of a population on the environment can be roughly viewed as the product of three factors: the size of the population (P), the level of per-capita consumption or affluence (A), and the measure of the impact of the technology (T) used to supply each unit of consumption. This provides the short-hand equation I=PxAxT which, although oversimplified (because the three factors P, A, and T are not independent), provides a basis for comparing the responsibility of different nations or groups for environmental deterioration.
Using the I = P A T equation, one can see that the population problem in the United States is the most serious in the world. First of all, the P factor is huge – with 250 million people, the United States is the fourth largest nation in the world. And compared with other large nations, the A and T factors (which when multiplied together yield per capita environmental impact) is also huge – on the order of twice that of Britain, Sweden, France, or Australia, fourteen times that of China, forty times that of India, and almost 300 times that of a Laotian or Ugandan. In per-capita energy use, only a few oil producing nations in the Middle East such as Qatar and Bahrain, plus Luxembourg and Canada, are in our league, and those nations have comparatively tiny populations. When the population multiplier is considered, the total impact of the United States becomes gigantic, several hundred times that of Bangladesh.
Those multipliers are based on per-capita commercial energy consumption, which is the best surrogate for A x T that is readily found in government statistics. The contributions of very poor countries to environmental deterioration are underestimated by these statistics, since they don’t include the impacts of use of “traditional” energy sources (fuelwood, dung, crop wastes) that comprise 12 percent of energy use globally, but a much larger component in poor countries. Considering them would not change the U.S. position as the planet’s primary environmental destroyer, though....
Furthermore, each additional American adds disproportionately to the nation’s environmental impact. The metals used to support his or her life must be smelted from poorer ores at higher energy cost, or transported from further away. The petroleum and water he or she consumes, on average, must come from more distant sources or from wells driven deeper. The wastes he or she produces must be carried further away, and so on. Activities that created little or no environmental burden when the United States had a small population – such as putting CO2 into the atmosphere by burning fossil fuels – increase that burden with every additional individual when the population is large.

Consuming Our Capital

Basically, like most of the rest of the world, the United States has been consuming environmental capital – especially its deep, fertile soils, ice-age ground water, and biodiversity– and calling it “growth.” Furthermore, directly and by example, it has been helping other nations to do the same. It would not be remotely possible for Earth to support today’s 5.4 billion people on humanity’s “income” (which consists largely of solar energy) with present technologies and lifestyles – even though for billions their life-style is living in misery, lacking adequate diets, shelter, health care, education, and so on....

The key to civilization’s survival is reduction of the scale of the human enterprise and thus of the impact of human society on our vital life support systems. This can be achieved most rapidly by reducing all of the P, A, and T factors....

The American Role

The first step, of course, is for the United States to adopt a population policy designed to halt population growth and begin a gradual population decline. Such steps can be taken without immediately targeting an eventual optimum population size, since that optimum is far below 250 million....

Immigration and Population

Americans would also, of course, have to recognize that for every immigrant that arrives in the United States who is not balanced by an emigrant, a birth must be forgone. We can never have a sane immigration policy until we have a sane population policy. ...  even though immigration to the U.S. does not produce a net increment to the global population, it does produce a net increment in total environmental impact....

Optimum Population

With all of these caveats, let us give some personal opinions on optimum population for the United States. No sensible reason has ever been given for having more than 135 million people. The putative reason for choosing that number is that America fought and won (with lots of help from others) the greatest war in history with that number of people. ...

It suffices today to say that for our huge, overpopulated, superconsuming, technologically sloppy nation, the optimum was passed long ago....