Saturday, March 17, 2018

The Population Bomb Has Been Defused

In 1968, Paul Ehrlich wrote “The Population Bomb,” warning that unchecked population growth would lead to mass starvation in the 1970s. He was wrong. Global population did rise, but food production managed to keep up.

The prophets of overpopulation have been defeated by technological progress but it alone can never deliver a final victory in the battle to feed the world. It is the women who are having fewer children that is proving the solution. Family sizes are reducing. Unlike other animals, humans can voluntarily limit their reproduction.

The total fertility rate is based on the number of children women have been having. When the rate is lower than about 2.1, it means total population will eventually stabilize and decline. It’s worth noting that World Bank estimates of total fertility rates tend to err on the high side. In most countries, total fertility falls from a high level of about six or seven children to two or below, and stays there. Once smaller families become the norm in a country or region, they very rarely go back up. The shift from agriculture to urban life means less incentive for families to have kids to work on farms. Urban life also increases the cost of raising a kid. Higher education levels for women, freeing them from traditional gender norms, are probably a big factor as well. Importantly, none of these factors are temporary.

 Overall,  world fertility has fallen and the Cassandras of overpopulation have shifted their concerns from global to regional. If some regions continue to have big families forever, they will eventually outgrow the regions with limited population growth, causing the overall world fertility rate to go back up. People who worry about overpopulation are now concerned that some cultures will simply always have more offspring.

A decade ago, many believed that Muslim culture, with its emphasis on traditional gender roles, would defy the fertility transition. But then fertility rates in majority-Muslim countries plunged. Iran, Saudi Arabia, Bangladesh and Indonesia have mostly completed their fertility transitions, while Egypt’s and Pakistan’s are underway.

 Now the worry has shifted to sub-Saharan Africa. With a fertility rate of about five births per woman, it’s the only region of the globe that has not yet made the jump to small families. But even here, there are signs of change in a small but growing number of countries. Countries such as Nigeria, Ethiopia, Tanzania and the Democratic Republic of the Congo still have very high fertility rates. But if these last holdouts fall, the global triumph of small families will be complete.

There are suggestions that Africa will not buck the trend and overpopulate the world. First, there’s a strong association between fertility and income levels -- once a country passes about $5,000 in per capita annual gross domestic product, it almost never has a high fertility rate. Rapid growth in a number of African countries means that this level will be in reach within a few decades. Also, the transition appears to be happening much faster than in the past -- it took the U.K. 95 years to drop from a fertility rate of six children per woman to three, but it took Botswana only 24, Bangladesh 20 and Iran only 10.

Lower fertility won't immediately defuse the population bomb. The number of people in a country continues to rise for years after young people stop having lots of kids -- a phenomenon known as population momentum. Thus, the United Nations continues to project that global population will rise from about 7.6 billion today to more than 11 billion by the end of the century.

Much of sub-Saharan Africa will possess a surplus of people for decades to come, and many of those people will want to migrate to wealthy, aging countries in search of better opportunities, or to escape strife and conflict. 

Adapted from here


Trevor Goodger-Hill said...

The population bomb may have been "defused", but homo sapiens have outbred all the other species and our demands for a technologically-enhanced life encroaches upon the living space of all other species -- sentient and vegetal. Our glorious ignorance of the living-space requirements of other species has changed the composition of the oceans (acidity, temperature and mircro plastics), the planet's climate at a speed so swift other species cannot adapt and (already)the melting of the tundra, releasing millions of tons of carbon monoxide over a short geological period and, presently, we have arrived at the loss of 90% of the insect world's biomass -- the pollinators of all things living, to put it poetically.

Some 60 years after I started collecting our mankind-made disasters, I have now at the age of 86 begun "collecting" scientifically-based reports of final extinctions.

ajohnstone said...

"socialism or barbarism"

Or as it is now cited ..."socialism or barbarism, if we are lucky"