And ageing is the new way of the world. You wouldn't guess it from the public debate so far about the seven billion landmark, but the average woman in the world today has half as many children as her mother or grandmother did 40 years ago: 2.5 children, compared to five. And the number keeps on going down. Dozens of countries are already below two, including Iran, Burma, Vietnam, China of course – and much of southern India, too.
In the long run, that's not enough to keep up numbers. Many expect world peak population by mid-century, and decline thereafter. Whether it happens then or later, mass global ageing is now a certainty.
I suspect that the global economic binge of the 20th century was a product of a booming, youthful population. It will die as we age. Japan's lost decade, and its likely repetition now across the western world, is perhaps the first sign. About time too. We all know that we cannot go on as we have. The planet cannot stand it. The party is over.
The population crash will kill our economy – good news for the planet