Falling Fertility

Thomas Malthus forecast in 1798 that population growth would outstrip the world's food supply. But with industrialization fertility fell sharply, first in France, then in Britain, then throughout Europe and America. When people got richer, families got smaller; and as families got smaller, people got richer.
Now fertility is falling in developing countries like Brazil, Indonesia, and parts of India. The fertility rate of half the world is now 2.1 or less - the magic number that is consistent with a stable population and is usually called replacement rate of fertility". Between 2020 and 2050 the world's fertility rate is expected to fall below the global replacement rate.
From this the author concludes that "Worries about a population explosion are themselves being exploded."
The transition from a rate of five to that of two, which took 130 years to happen in Britain - from 1800 to 1930 - took just 20 years - from 1965 to 1985 - in South Korea. Mothers in developing countries now have on average three children. Their mothers had six. In some countries the speed of decline in the fertility rate has been astonishing. In Iran, the fertility rate dropped from seven in 1984 to 1.9 in 2006 - and to just 1.5 in Tehran.
For subsistence farmers, who risk falling victim to drought, a family of eight may be the only insurance against disaster.
If you have a generation or two in which fertility is neither too high nor too low and in which there are few dependent children, few dependent grandparents - and a bulge of adults in the middle - you have the recipe for economic opportunity.
Malthus's heirs say there are too many people for the Earth's fragile ecosystems. It is time to stop - and ideally reverse - the population increase. To celebrate falling fertility is like congratulating the captain of the Titanic on heading towards the iceberg more slowly.
If the poor copy the pattern of wealth creation that made Europe and America rich, they will eat up as many resources as the Americans do, with grim consequences for the planet.
In principle, there are three ways of limiting human environmental impacts: through population policy, technology and governance. The first of those does not offer much scope. Population growth is already slowing almost as fast as it naturally could. Only Chinese-style coercion would bring it down much below that.
Mankind needs to develop more and cheaper technologies that can enable people to enjoy the fruits of economic growth without destroying the planet's natural capital.