In the first of three articles examining its origins and implications, we look at food. Even optimists doubt whether we can stretch production to feed the extra billions, reports Debora MacKenzie
Biology has few sweeping, universal laws. But here’s one: there are limits to growth. Put bacteria or sea urchins or reindeer in a suitable habitat, and they will multiply until they run out of a vital resource – food, or space. Then their numbers will plummet, or at least stop growing. Habitats can only support so many of a species. They are all bound by their ‘carrying capacities’.
What is the Earth’s carrying capacity for humans? Where are our limits to growth? And how far can we stretch them with technology? These are not academic questions. The number of humans on Earth has risen to unprecedented levels, and will increase for at least another fifty years. Countries with rapid population growth are already finding it hard to improve, or even maintain, the health of their people and their economies.
So governments will gather in Cairo next week to discuss one way of addressing the problem: slowing population growth, in part by making contraception available to the millions who want but cannot get it. Most of the debate in Cairo will revolve around how to provide it.
But demographers in Cairo will have another message. No matter how fast we expand access to contraception, the dynamics of population growth mean that a vast increase in numbers is inevitable ...