Malthusian Nightmare

Harry Harrison’s classic dystopia Make Room! Make Room!, written from the vantage point of a world of 3.4 billion in 1966, predicted a world of seven billion people by 1999. He was only a billion over, or twelve years too early, depending which way you look at it. (He overestimated the rate of US growth, though. The book ended with a Times Square billboard on new year’s eve announcing that the US had reached 344 million citizens. The chances are it’ll reach that figure this year.)

A recent thread at Metafilter on some bleak climate prospects saw one user note that “a sustainable planetary population of H. sap is going to be more like two billion than eight”. Maybe so, but we’re going to get to two billion plus eight soon enough. I crunched some of the numbers and considered their implications…

The population of the world was two billion in 1927. It had doubled by the time I was seven in 1975, 48 years later. By the time I was 55 last year—another 48 years later—it had doubled again.

It’s unlikely to double again by 2071. The rate of growth has slowed. Between 1951 and 1993 world population growth was never below 1.5% a year, and often closer to 2%. Between 1994 and 2012 it was never below 1.25%, but never above 1.5%. Since 2020 it hasn’t been above 1%. That’s better than past rates of growth, but it still suggests we’ll hit 10 billion around the middle of the century.

What’s especially striking is looking at the absolute growth figures. Every year since 1951, the world population has grown by between 43 million and 93 million people. Last year it grew by 70 million people. We’ve been adding a large country’s worth of people every single year for seven decades.

We aren’t going to get back down to two billion in any kind of timely way voluntarily. To get there by mid-century would require the global population to fall by 5% a year for the next 25–30 years: 400 million this year, a bit less next year, and so on down to a mere 100 million drop in the final year.

Birth control won’t make much difference by itself, either. In 2023, the crude death rate for the world was 0.755%, and the crude birth rate was 1.669%, giving net growth of 0.914%. Even if no children were born ever again, at a 0.755% decrease per year the world’s population would fall by only 25%, to around six billion, by 2062, after which the rate of decrease would rise as women aged out of childbearing. In the meantime, we’d be living in Children of Men, all of us looking forward to half a century of hopelessness in our old age.

If we halved the current global birthrate, like we have since the late 1980s, world population would plateau, which on its own wouldn’t relieve our current level of environmental damage. But we’d still have thirty-odd years of population growth in the meantime, unless we picked up the pace. Will we plateau at nine billion? Ten?

Our usual human methods of eradicating each other won’t get us there. The estimated deaths in World War II were 70–85 million, 3–4% of the global population of the time, and that was over six years. Total nuclear war might, but wouldn’t be very compatible with environmental repair.

As for involuntary means, Covid won’t get us there. Estimated global deaths in the pandemic have been somewhere in the region of 15–30 million (7 million confirmed to date), a fraction of a percentage point.

It would take something almost but not quite as bad as the Black Death: 50% of Europe’s population dying in the space of seven years was a loss of around 10% a year. At a loss of 5% a year it would take 13 or 14 years to halve a population. So we need two plagues in succession, each of them half as bad as the Black Death—or a series of equivalent events as awful and as devastating as that.

Much more needs to change than population, and much, much faster. The only plausible ways of getting us to where we need to be by mid-century, in terms of total human impact on the planet, are drastic changes in everyone’s lifestyle, horrifying plagues or natural disasters, and wars beyond all human experience. I’m guessing we’ll see a bit of each, alongside attempts to carry on with business as usual for as long as possible—which won’t be long.

Whichever way you look at it, it’s depressing.

4 March 2024 · Environment