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The Rapid Slowdown of Population Growth

Wolfgang Fengler's picture

We are living in a paradoxical time of population growth. In the media, there have been alarming reports asking how the world will be able to deal with a much larger population in years to come. The challenges are real, especially in Sub-Saharan Africa, whose population is expected to double by 2050 and possibly quadruple by 2100. At the same time, we have been experiencing the most rapid decline in global population growth ever.

But how can we reconcile those two facts: a rapid expansion of total population numbers with a fast slowdown of population growth? Here is an analogy from the world of cars: imagine you are driving on a German motorway, where speed limits are notoriously non-existent. You are cruising at 160km/h (100m/h) but soon you cross the border into France, where 130 km/h is the limit. You are still driving very fast, though substantially slower than before. Now you switch to a regional road, driving at 80km/h, and now you slow down further to 50 km/h as you enter into a town. Meanwhile, someone else is still driving at 160 km/h on that Autobahn.

Global population growth is following a similar path. Even though we are still growing at a high rate the slowdown has already started and we will never revert to the high speed we had in the past. We have already passed two historical peaks of global demography a few decades ago:

  • In 1968, we reached the relative peak in global population growth rate. Then, the world grew at a record 2.09 percent – adding 73.2 million to a world population of 3.54 billion. This historical peak was part of a seven-year high-growth period – from 1966 to 1972 – and the only time in recorded history when the world’s population grew above two percent. I was also born at that time.
  • In 1988, just before the fall of the Berlin wall, we reached the absolute peak in global population growth (i.e. in the number of people added). The world gained almost 93 million people and since then world population growth has been declining also in absolute terms.
Today, the world is adding 81 million people a year, which is still significant and similar to the size of Egypt or Germany. But the relative growth of the world population is almost in free fall. It is expected to decline to 1 percent in 2020 (adding 76 million to 7.6 billion people), the lowest rate since the 1950s. Moreover, this trend is set to continue: by 2050, the global population growth rate will be below 0.5 percent (see figure), bringing us back to 17th and 18th century figures. The absolute number will decline in equal measure. By 2050, we will be adding only 46 million people a year (see Figures 1 and 2). 
 
Source: Created by Emi Suzuki, based on United Nations, The World at Six Billion;
projections based on United Nations Population Division, World Population Prospects 2012 Revision.
                 
These averages, though, mask enormous regional differences. Africa is still growing at a rate close to the world's highest ever recorded level: higher than two percent per year. Europe by contrast is hardly growing at all, while Asia is expending in line with the global average of around one percent.

But if population growth is declining, what justifies the alarmist statements and doomsday scenarios that the press is echoing? Could we have expected an even more rapid slowdown?

The neo-Malthusian assumption is that bigger populations will translate into greater disempowerment and deeper poverty. But that’s partly a "reverse causality fallacy," because most humans have been disempowered and poor all along. In most of the world’s history, high rates of fertility coincided with widespread misery, but the causality probably ran the other way. People had many children because they were so poor. Moreover, the world population didn’t grow much until the early 20th century because mortality remained high. Only once people became better off, when improvements in health, sanitation and nutrition were made available to a larger part of society, did world's population start to rise rapidly. This was the beginning of our journey from 1 billion to 10 billion people, a threshold we are expected to reach by 2060.

We are fortunate to live in a unique time. The period between 1950 and 2050 will go down in history as the time of the global demographic transformation that may remain unmatched forever. Learning from the successes of the last decades, we will need to enter the last frontier of poverty reduction, of child and maternal mortality, of illiteracy and disempowerment, so that everyone will be able to live longer, happier lives.

Comments

Submitted by Balu on

Interesting analysis.. Thanks for sharing.
What should be of concern though is the number of people living in the planet Earth. Therefore, it would be interesting to see this ‘birth’ data along with ‘death data’ . Would the planet earth maintain a healthy ratio of children, youngsters and older generation.. that is the key question to answer…

Submitted by Wolfgang on

Dear Balu,
you are right that the environmental risks would be dramatic if we extrapolate our current lifestyles to a world of 10 billion. However, remember that the current environmental destruction is caused by a relatively small number of people, mainly those in advanced economies and some in emerging economies.
In terms of the birth and death data you just gave me an idea for a future blog. In short: Since 1990, annual births have been broadly in the 130-140 million range while death rates continue to come down. There has been a slight bump around 2010 which you can see in the second chart which is due some of the cyclicality of demographics. You see this more clearly in rich countries where birth rates increased in the 1990s not due to higher fertility but because baby boomers were building families and baby boomers outnumbered their predecessors by a significant margin.
Best
Wolfgang

Submitted by John F. May on

Dear Wolfgang:

Thank you for sharing these views on long-term population growth, both in percentages and in absolute numbers.

In fact, future demographic challenges will need to be tackled chiefly at the level of individual countries. What is making current and future demography so interesting is the fact that some countries' populations will expand very rapidly (in sub-Saharan Africa, as you say), whilst other countries will age and contract. To this, we must add the challenges of rapid urbanization and increasing international migration. The demography of the world has become not only more fragmented but also much more complex.

The main cause of the rapid population growth was the rapid (often exogenous) decline of mortality, whilst fertility declines have been slower, delayed, and sometimes have even stalled. To the decline of mortality and the lag in fertility declines, one needs also to add the phenomenon of the population momentum (positive or negative) to explain the increase or decrease of specific populations.

Finally, the issue of causality that you raise at the end of your Blog is perhaps the most contentious and complex issue in the area of demographic behavior. You mention that "the causality probably ran the other way". Might it not be safer to assert that it may run both ways and that the causality may change directions at different stages of the demographic transition?

Best,

John F. May
Population Reference Bureau

Submitted by Wolfgang on

Dear John
I am glad we are both continuing the passion for our subject, a fundamental one for world development as development is ultimately abut life and death. The main purpose of the blog was to highlight the quite dramatic and unprecedented dramatic decline in global population growth which started as early as 1968 (or 1988), depending on what metric we are using.
If you overlay population growth with life expectancy and economic development the causality is actually quite straightforward. Only once living conditions improved the world population started to increase dramatically. In the 20th century women did not give birth to more children than in the 19th, 18th, 17th or any earlier century, did they? As highlighted elsewhere, larger population densities can also contribute to economic development due to economies of scale (but this is not the inverse causality you referred to).
I don’t see much evidence of the opposite, i.e. that population growth contributes to social and economic malaise, except we use a subset of indicators (e.g. congestion). If we use life expectancy as an indicator, then there are not many cases where the population is expanding but life expectancy is declining, is there?

Best

Wolfgang

Submitted by John F. May on

Dear Wolfgang:

Thank you. This debate is most welcome as the Bank is currently trying to revamp its "P" efforts. The perspective is different whether we look at world/global aggregates or at the levels of specific regions/countries. Yes, the increase of life expectancy is correlated with population increases--simply because more people live longer thanks to the survival revolution. I also agree that population densification may foster economic growth under some circumstances. However, I still want to submit that rapid population growth may also lead, sometimes and in some places, to adverse outcomes (e.g., increases of poverty levels).

Best, John
Jmay@prb.org

Submitted by Wolfgang on

Thanks John,

your conclusion that "sometime in some places rapid population growth may lead to adverse outcomes" is a good way to find agreement among our different perspectives.
For me the bigger message and bottom line, however, remains: "High fertility is associated with poverty and often a result of it. Rapid population growth, to the contrary, was typically associated with better development indicators."

In my view, the key is to disconnect high fertility with population growth. High fertility was there is most of human history but the world population did not grow because too many children (and parents) died early.

Wolfgang

Submitted by John F. May on

Dear Wolfgang:

Thanks. Yes, the survival revolution has been the major engine of rapid population growth and it is very good to remind people about this (too often, people equate rapid population growth to high fertility). Nonetheless, high fertility levels and the lag in the fertility declines have also contributed to rapid population growth in specific stages of the fertility transition. The rate of natural population growth (or "r") is the arithmetic difference between the crude birth rate and the crude death rate. A third factor explaining the population growth is the (positive) population momentum brought about by the young age structure which itself is linked to past high fertility levels. Best, John.

Submitted by Peter Quest on

Dear Wolfgang,

Population growth in itself is not really a challenge, but the challenge come in when the concentration of the people are pushed to few places yet the rest of the Country remain undeveloped.

Best Regards,

Peter.

Submitted by Wolfgang on

Dear Peter,
Actually, people want to move to the cities because this is where the economic opportunities are. Research shows, that if you try to spread the wealth you will likely destroy opportunities for everyone. The key would be to keep cities strong and to use the resulting economic gains in a way that rural services also receive better services, especially education, health and infrastructure.
For, Kenya here is the link to a piece I wrote earlier, titled: “Why do Kenyans want to live in cities”?
Wolfgang

Submitted by Hanna C Norberg on

Really useful and well written! Thanks for posting .

Submitted by Sarah Tisch on

Fascinating analysis and thank you! I wonder if it is possible to disaggregate the data and estimates by sex?

Submitted by Wolfgang on

Thanks Sarah,
in most countries women have around 5 years longer life expectancy than men. At the same time, you probably know of the massive gender disparities in some developing countries, including due to the millions of "missing girls" which have been documented in the World Development Report on Gender (www.worldbank.org/wdr2012)

Wolfgang

Wolfgang,
A good piece but you know my stand. Africa must slow down its population growth rates. People must learn to have a number of children they can afford to raise period. You have stated that "Only once people became better off, when improvements in health, sanitation and nutrition were made available to a larger part of society, did world's population start to rise rapidly". We did not wait for people to become better for the population to raise. We are doing it with all challenges and this is why we must behave like the rest of the world.

Submitted by Wolfgang on

Dear Ndemo,

Thank you very much for your thoughts. I agree that rapid population growth in Africa (which coincides with a rapid slowdown globally) creates many new challenges for transition economies like Kenya (see also above discussion with John May). Let me add two thoughts to your comment:
a. Despite these challenges – new and old – there have also been great improvements in recent years in advancing the well-being of Africans (and many other people around the world). Take child mortality where we are witnessing a rapid decline in most of Africa. This is a key factor contributing to higher life expectancy and in turn high population growth. In 1960, life expectancy in Sub-Saharan Africa was 40 years; in 1990 is was already 50 years and today it is almost 60 years. This is a result of “development” and explains to a large extend why there are so many more people in Africa. Hans Rosling tends to make similar points when he makes fun of Westerners who are blinded by sensational news and don’t realize the big shifts underneath.
b. Future population growth in Africa is inevitable if this progress continues. As Africans will start to live even longer and approach the current world average of 72 years the continent’s population will continue to rise rapidly, even if fertility declines as projected. This is why will may all be witnessing an Africa of 2 billion and our grand-children eventually an Africa of 4 billion.

It would be good to start preparing for this big shift.

Wolfgang

Submitted by John F. May on

Dear Wolfgang (and Ndemo):

Nowadays, one of the most striking features of SSA demography is the disconnect between the rapid decline of mortality levels (esp. infant and child mortality) and the slow erosion of high fertility levels. Hopefully, mortality levels will continue to improve, which will foster population growth. However, one should also accelerate the fertility transition to mitigate the population growth. The latter is quite challenging since the mere supply of contraceptive services will only go so far. One will needs also to work on the demand side (e.g., education, legal reform, and economic opportunities). Best, John

Submitted by Lorne Benedict on

The world’s population growth rate is 1,2%. It doesn’t sound like much but just the sheer addition of people added every year offsets the reduced growth rate. In 1963, the world’s growth rate was 2.1% and the annual increase was 69 million people. In 2003, the world’s growth rate decreased to 1.26% but the annual increase was 79 million! The growth rate now is 1.17%, and the annual increase hasn’t changed. This is because the base population continues to climb and is a major factor in determining annual increase. The population of the world was 3.2 billion in 1963. Fourty years later (2003), the world’s population was almost double – to 6.3 billion. Despite a decrease in growth rate (by 0.79%), the annual increase in the world’s population from 1963 to 2003 was 10 million. By 2010, the growth rate dropped by 0.09% but the annual increase didn’t change. What did change was the total world’s population – the world’s population is now 6.931 billion!

Only 11 countries contributed to 63.5% of the world’s annual increase. Out of 79 million people, this would be 44.5 million. The eleven countries are (in order of population increase): India, China, Pakistan, United States, Nigeria, Indonesia, Ethiopia. Brazil, Congo (Dem. Rep. of), Bangladesh, and the Philippines. India’s population increase is double that of China’s. This is because India’s growth rate is much greater that China’s. India and China contributes more than 50% of the annual increase by these 11 countries. The United States’ annual increase is contributed mainly by immigration while the others are by the birth rate. All of these countries have large base populations (at least over 70 million people). As far as growth rates go, China has the lowest (0.66%) while two have growth rates over 3% (Ethiopia and Democratic Republic of the Congo)

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