World population in 1900 was one billion. Today it is more than eight billion. The UN population report that says India will soon become the most populous country in the world ignores this frightening growth. Some reactions have been silly, others predictable.

Silly because the Chinese foreign office spokesperson was gratuitously rude saying it isn’t the quantity but the quality of the population that’s important. Likewise, the Western media has been worrying about how India will cope with so many people. It forgets that these questions were asked in the 1960s too and India has managed better than what was feared back then. And so on. Thus the focus has been India whereas it should be on the world. Indeed, China and the West both need to worry about their own problems which are the opposite of the Indian one: they won’t have enough workers and their dependency ratio will be very hard to support. Of course, this will be true of India also where not only will a lot of old people have to be supported by the much smaller working population but also a lot of unemployed young people will need to be supported.

And that’s where the real problem lies for the world: the supply of labour has become unlimited. The world has gone from excess supply — which markets and policies can correct — to unlimited supply which, by definition, can’t be corrected. The counterpart on the capital side is that it, too, is in unlimited supply because there is no longer a gold or silver anchor to currency. Countries are free to print as much as they want subject only to inflation. And that’s now much easier to handle because even though too many people with too much money are chasing too few goods, thanks to global trade the product markets adjust far more easily now.

That said, the world now needs to worry about not only sustainability and climate change, which are actually a zero sum game between the developed and developing world, but also the returns to the factors of production like labour and capital, including land. These are bound to stay very low, or even turn negative, for the rest of this century. It is finally only around 2100 that the world population will start to decline. By then it would have reached nearly 11 billion. So despite all that talk about declining fertility and net zero, sustainability is going to be impossible. It just can’t be done except at a huge human cost. This is not just the Malthusian nightmare which was about food but goes well beyond that because the numbers are so staggering.

The resulting competition for resources, whether at the village or the global level, eventually always turns violent. As societies seek even low level stability, they will come up against the insurmountable walls of both excess labour and excess capital that’s also now embodied in new technologies. This is the real takeaway of the UN population report.