By Bill King for RealClearWire
I regularly talk to well-informed people who have no idea that the world’s population growth is rapidly decelerating. Currently, the UN estimates that world population will peak at around 10 billion in 2080 and then begin a long, slow decline. Other modelers project it will peak at 9 billion in 2060 and then decline more rapidly. Some scenarios predict that there will be fewer people on the planet at the end of the century than there are now.
The United Nations’ predictions for the U.S. are the same, with our population growing to about 380 million by the end of the century. This is consistent with Congressional Budget Office projections that predict the US annual population growth rate will decline from 0.5% to 0.2% over the next 20 years. Without immigration, the US population would begin to decline around 2035.
Many of us grew up reading Paul Ehrlich’s runaway best-seller, “The Population Bomb.”, It foretold a worldwide apocalypse. A book written in 1968 clearly predicted that “the battle for feeding all humanity is over.” In the 1970s, hundreds of millions of people starved to death. Of course, that didn’t happen and since around 2000, researchers have found that there are more obese people in the world than there are undernourished.
In part, this did not happen because of the explosion of agricultural technology known as the Green Revolution in the 1950s and 1960s. But Ehrlich’s prediction never materialized because he missed that at the time of his book, women were already starting to have fewer children.
A critical metric for population growth is the average number of children women have at any given time, known as the fertility rate. Other factors such as childhood survival and longevity affect population growth, but fertility rates are the biggest driver. It takes a fertility rate of 2.1 children per woman to maintain a stable population, known as the “replacement rate”. Above it and the population grows and falls below it.
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When “The Population Bomb” was published, the fertility rate was staggeringly high at 5. That astronomical rate would cause the world population to double after just 40 years. But what the authors didn’t see at the time was that the fertility rate was 5.3 nearly five years earlier. It began a steady slide to 2.3 today, slightly above replacement rate.
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However, the decline in fertility rates is not immediately apparent. It takes some time for the low rate to work through the generation cycle, which is referred to as “population momentum”. That’s why you still see a whopping 25% increase in world population in projections before the peak in 2080.
Many countries around the world are already beginning to feel the effects of slow population growth. Both Japan and Russia are facing population decline. China announced this year that its population had fallen for the first time. Some countries have adopted policies to encourage young couples to have more children.
Of course, there is no doubt that the decline in population growth is welcome news. Without deceleration we face the apocalypse that Ehrlich predicted as we place ever-increasing demands on Earth’s finite resources.
But our civilization has been based on steady population growth and astronomical population since the mid-20th century. Programs like Social Security and Medicare cannot function in a world where the population is flat or declining, without at least some substantial modification. Because low fertility rates correlate with educational attainment, the most uneducated, poor parts of the world are growing rapidly. Africa and Central Asia are the only places in the world that currently have above-replacement fertility rates. This duality leads to greater wealth inequality and conflicts.
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The new demographic model creates many headaches that our children and grandchildren will have to wrestle with. Some obvious and some perhaps unexpected. It would be great if the world started thinking through those issues and preparing now. However, human behavior over the centuries has shown that long-term planning is not one of our strong suits.
Syndicated with permission from RealClearWire.
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