A classic science fiction movie from 1973 is Soylent Green, set in overpopulated and resource-depleted New York City in the year 2022. The movie is based on Harry Harrison’s 1966 novel Make Room! Make Room! What brings the film to mind is a recent report from the UN that earth’s population in 2011 is 7 billion. The population of the world in the novel is – you guessed it – 7 billion. The US population in Make Room! Make Room! is announced on a Times Square screen as 344 million. The actual 2011 US population is 312 million; at the current rate of increase, 344 million is just about right for 2022. The UN projects world population will reach 9 billion by 2050, though that estimate assumes a decline in the birth rate in non-Western countries; it may be conservative by a billion or more.
Ironically, the low fertility rates in advanced Western countries have been much in the news lately, and, it is true, in parts of the West, the birth rate actually has dropped below replacement level. Policymakers worry about a dearth of new taxpayers to pay for all the entitlements we have voted ourselves. A smaller tax base may indeed require adjustments in expectations by older generations, but perhaps our own public benefits should not be our only concern. In any event, the West is not the world, and in Europe and (especially) North America immigration in fact keeps all but a few populations rising.
Alarm ran high in the 1960s that global environmental and economic resources in coming decades would be insufficient to support the projected populations at any more than subsistence levels. One of the most popular doomsday books of the time was1968’s The Population Bomb by Paul Ehrlich, who warned of rapidly approaching famine and impoverishment. The goal of Zero Population Growth (ZPG) was promulgated by many (including Ehrlich) in the 1960s environmental movement.
The scale of population growth in recent times truly is staggering. For thousands of years, the number of humans rose and fell according to the spread of disease and the fate of empires. The last big die-back was the Black Death in the 14th century. Afterward, population rose slowly worldwide, reaching 1 billion for the first time probably in the early 19th century. Thanks to the industrial revolution and improved living conditions, growth accelerated. By 1911 there were 1.75 billion of us. What happened next is just astonishing: the population quadrupled in a single century. Centenarians are few, but there are many people alive today who have seen the world population triple in their own lifetimes. The rate of increase in the 21st century is at last slowing, but in absolute numbers we still will add substantially more people in the next 30 years than were alive on earth in 1911.
The rapid economic gains of the past two decades in the world’s developing nations, most notably China and India, seem to mock the 1960s gurus. For this reason, we don’t hear much about ZPG these days; the whole notion seems rather quaint. The doomsayers clearly underestimated future economic productivity, especially the Green Revolution which vastly increased food production. That they were premature in dating the onset of crisis, however, doesn’t mean they were fundamentally wrong in the longer term. Are there limits to wealth? Is a Western lifestyle really possible for 9 billion people? Is it for 7 billion? It is hard to imagine 9 billion people cruising freeways and living the high life, however much the prospect pleases OPEC.
Every single one of the environmental issues which dog us today is, at bottom, a population issue: greenhouse gasses, habitat loss, water pollution, sea stock depletion, and so on. Just as one example, any expected improvement in auto mileage in the next decade will be utterly overwhelmed by the increased numbers of drivers and cars in the same period: oil consumption therefore will rise. Every single environmental issue would be addressed far better by population decline than by any possible conservation measure. Also, despite the aforementioned tax concerns, fewer people for the same resources would mean greater wealth per person.
In truth, ZPG is no longer radical enough. There already are too many of us. We need Negative Population Growth. Whenever I make this point, someone inevitably asks, “So, are you volunteering to go, then?” No. I don’t have to volunteer. Neither do you. The sad fact is, we’re going, like it or not, as we all do, and all too soon. The question is whether we all should be replaced, and I’m arguing we shouldn’t be. The global birth rate is declining, which is at least a trend in the right direction, but far too slowly. Current estimates are that world population will peak at 14 billion before stabilizing – that’s a doubling of the 2011 number. It’s another whole earth. The trouble is, we don’t have another earth.