Global population is eight billion and counting

LONDON, U.K.—I must have missed the memo, because there was no newborn baby picked out at random on Nov. 8 to be the designated eight billionth human being. Perhaps they finally realized how tacky that journalistic device was, or maybe they just got tired of nagging us. Anyway, happy Eight Billionth, whoever you are. After a long, bad patch, the population news is getting a bit better. For the past 60 years, the world’s population growth has been accelerating: it took 14 years to go from three billion to four billion people (1960-74), only 13 more years to get to five billion (1987), and a mere 12 years to six billion (1999). It also took 12 years to reach seven billion (2011), but here we are at eight billion, and that has only taken 11 years. Nevertheless, it really is going to slow down now: it will be a full 24 years before we reach nine billion (2046), and another 25 years before we hit 10 billion (2071). Ten billion. That’s insane: a fivefold increase in the number of human beings in little more than one century. But it was probably inevitable. Simple public health measures (more babies surviving) and better medicine and diet (longer lifespans) were bound to lead to a couple of generations of high-speed population growth. Then women’s education, birth control technologies, and urbanization slowed it down again. In fact, the United Nations Population Division’s latest forecast is that the world’s population will stabilize at 10.4 billion people in 2086. It probably won’t start going down significantly until the end of the 21st century or later, but at least the direction of travel is changing. Two-thirds of the global population lives in countries where 'lifetime fertility' is already below 2.1 births per woman, the level at which there is zero growth of population. It takes a decade or so for this to show up in the gross population figures, but 61 countries will have declining populations by 2050. India’s population, now 1.4 billion, will peak around 1.8 billion in 2063, and will be back down to 1.5 billion by the end of the century. China’s population, now also 1.4 billion, officially starts falling next year—some say it has been falling for years already—and it will be down by at least half by 2100. However, the global figures conceal an alarming discrepancy between the African continent and almost everywhere else. The ‘stabilization’ in 2086 is just the point at which the falling populations in most other parts of the world cancel out the still-rising populations in most of Africa. A few countries, like Morocco and South Africa, will only add 10 or 20 million people between now and the end of the century, but most African countries will at least double their population and many will grow threefold or fourfold. The African continent now contains about 18 per cent of the human population. By 2100 it will host 40 per cent of the world’s people: about 4.2 billion human beings. If that prediction comes true, then a great many of them will still be poor, and some will also be very hungry. They will still be poor because, although most of their economies are growing, their populations are growing almost as fast (or, in a few cases, even faster). And many will be hungry because, while Africa could probably feed twice its present population with the right investment (and no climate change), it couldn’t feed three times as many. Moreover, the investments are not being made and droughts, floods, and cyclones are already devastating much of the continent. Predictions about the scale and speed of climate change are estimates of probability, not precise forecasts. Similarly, predictions about both demography and economies grow increasingly unreliable as the time span lengthens. Nevertheless, the UN Population Division’s forecasts make grim reading, especially if you read between the lines. We are probably way past the long-term sustainable carrying capacity of our planet in terms of both population numbers and per capita energy use, and yet they will still be going up for most of this century. So the recent article about falling sperm counts in the journal Human Reproduction Update offers hope (of a sort) from an unexpected source. The rate of decline has been speeding up since 1973, and is now more than 2.6 per cent per year. The average sperm concentration, for men all over the world, is now less than half what it was in 1973. It’s clearly an environmental issue. Is the planet trying to tell us something? Gwynne Dyer’s new book is ‘The Shortest History of War’.