Most developed countries are in this state now where their population would be declining but for immigration.
When today's fast-growing countries reach the same point in their demographic transitions, the whole world's population will enter decline.
This could happen even earlier than around 2100 when the UN estimates; other demographers are forecasting a date more like 2065. 
What will the economics be of a world in population decline? How will culture and policies change to eventually stabilise the decline? Lots of questions...
 Lutz et al 2018 : https://ec.europa.eu/jrc/sites/jrcsh/files/lutz_et_al_2018_d...
Great. Better to have it happen through declining birth rates than through natural disaster, pandemic, starvation, etc.
On the contrary, a shrinking population is much more likely not to be able to manage those issues.
When I was in college some of the profs offered extra credit if you wanted to go bag sand for major flooding about an hour away (a nice way to let people go home and help their family and friends).
Strong backs and enthusiasm are good for augmenting the experts in a disaster recovery situation.
Most of the projected population increase in Africa is based upon a small number of countries like Nigeria, where most of the people live on the countryside, and there never have been reliable census to accurately predict the future population.
The only thing we know is that Africans moving to cities stop having many children, and that the fertlity rate in the richer African areas is rapidly decreasing. In Northern and Southern Africa the fertlity rate is already below 2.5, approaching sub-replacement levels. 
Which means it is definitely possible that the entire world will be entering sub-replacement level in the coming decades.
Unfortunately the African coutries with a high-fertility projection haven an interest in lying about their numbers, because it means more NGO money and political influence. 
The country with the lowest fertility rate in the world is South Korea, which has a fertility rate of <1.  South-Korea is facing extinction. 
Additionally there are hints that China is lying about their population numbers as well. 
India, which is the most populated country in the world, has already fallen to sub-replacement levels in almost all counties, and stands at a fertility rate of 2.2, as of 2017. 
I'm not informed, as the quiz result suggests, I just spotted the pattern.
Religion is another factor that plays into birth rates. Muslims, for instance, have extremely high fertility rates and that stays true even once they migrate to developed nations. For instance the Muslim fertility rate in North America is about 2.7. It's also why the Muslim population is expected to increase 70% by 2060 whereas the number of unaffiliated is expected to increase by 3%, Buddhists decrease by 7%, and so on.  Those number increases are not affected by conversion which plays a roughly net zero role in Islam with about 25% of people leaving the religion, and 25% joining it.
So what you're looking at is more of a demographic switch than an economic one. People who are highly educated, secular, and high income will gradually die off, failing to replace themselves. At the same time individuals of lower income and those who place less value on education and more on religion will continue to increase in numbers well beyond replacement. Basically, so long as there is at least one group within a nation that consistently produces in excess of replacement, they will eventually replace any and every group that does not. And, in the longrun, that group will also guarantee that, over time, the population (local, nation, and world) will also continue to increase. So we'll see a population peak, a demographic swap paired with a population decline, and then a return to a growing population - likely with vastly different norms and values as a society than we have today.
Of course my analysis is also flawed because it assumes no revolutionary change in the norms of today. These range from the unpleasant to consider such as changes to welfare systems, to the highly pleasant to consider such as the possibility of expanding our populations outward with the colonization of new planets and space in general. But ultimately, I do not see longterm population decline as probable in any scenario.
Your article also affirms this hypothesis. For instance in their prediction graph they show that Sweden will now, even with 0 migration, see consistent population growth. Sweden is simply playing out this scenario in fast forward due to a very small population paired with high migration rates which did little than accelerate the rate of demographic replacement. E.g. in the 90s Sweden's population was less than 9 million and with negative fertility rates, they were starting to see population declines. Then enter the migrations and now their population is greater than 10 million and their population is now back to growing, even without any more migration.
 - https://www.statista.com/statistics/241530/birth-rate-by-fam...
 - https://www.pewresearch.org/fact-tank/2017/04/06/why-muslims...
Btw, I've been wondering how population stabilization (it pretty much already stabilized in the US and EU) will influence real estate. Historically real estate have been a remarkably good investment. But historically population kept growing pretty fast. I'd love to hear some thoughts or recommended reading on that topic.
What happens to wages? Inflation? Energy? Companies? The share market? ...aged care?
Absolutely fascinating stuff.
Shares are too volatile to even predict in long term.
Aged care, not enough data for a conclusion.
edit: I've changed the link to a test that doesn't mark correct answers right away, previous link: http://factfulnessquiz.com/
Pretty serious given that there are only 13 questions and that's what the whole website is about. They didn't even leave any contact. I'll send an email to gapminder.
Nice catch, and a really bad job from whoever made the quiz website. Triple checking those answers should be a priority.
But in a time frame of 30-60 years... I'm not counting on getting the money back for my house.
(Interesting result : in many regions women have high rates of post secondary education than men.)
Going from $2/day to $8/day may not seem like much to you, but to someone at that level, their income has quadrupled. They might have access to a bicycle to get to a paying job now. Shoes. Clean water. School for their children, so the next generation has more opportunity. Go from $8 to $32 (using Rosling's quadruplings here), and you now have a car, potable hot and cold water from a tap, even the possibility of college for your kids. It's still "poverty" to us, but not all poverty is the same. Understanding this is a shift in perspective, and requires putting down our wealthy, western privilege for a moment.
Keep in mind, too, that a world of no health care, no clean water, no literacy, etc - the extreme poverty of the poorest nations - was the situation in much of Europe during the 19th century. It took Europe a long time to get to where it is today, and much of the progress happened in the post WWII, post colonial era. "Open exploitation" is not what you think it is, not anymore.
As I've pointed out elsewhere, much of the world has seen income increases from 20x-100x per capita in the past 50 years. That's the poor, "exploited" countries.
Economic change takes time. Generations. The fact that we wiped out two thirds of the world's extreme poverty isn't "boneheaded", it's incredible. But it will take several more generations to get the rest of the world up to the standards of our privilege.
I don't know what you're expecting. Someone snaps their fingers and everything is magically "fair"?
How do you define this standard?
> equitable wealth distribution would be much better.
Let me present you with two scenarios, all else being equal, and you tell me in which one people are better off:
1: Every one makes the equivalent of $5,000 a year.
2: 90% of the population makes $20,000 a year and the remaining 10% make $100,000.
> This is how the western world justifies open exploitation.
Can you quantify this exploitation?
With that in mind, is there any reason that the poor countries of Africa today can't be the Sweden of tomorrow? It's more irrational to say they'll stay poor and overpopulated than it is to say they'll become wealthy and modern with zero population growth.
Egypt doesn't have the resources or space to grow to a Swedish standard of living.
Don't give me that "They can't do it" nonsense.
Swedes have a huge country and increased from a very small population to a relatively small population.
The resource constraints are different; you can't have infinite growth in every country.
Typically the only useful info you can get out of such long term studies is the sign of the change and the order of magnitude.
The fertility rate is about 2 kids per woman now. But the generation of 20 year olds is much larger than the generation of 40 year olds. So even though the generation of 0 year olds is the same size as that of 20 year olds, in 20 years time we will have replaced a small 40 year old generation by a large 20 year old generation.
There are only two factors here: Fertility rate per woman, and death rate. This prediction is not terribly sensitive to either, and both are easy to measure accurately and on quite stable long term trajectories:
Sorry for the poor choice of words, no chaotic model was implied or intended.
> Fertility rate per woman, and death rate.
No, there is also technological development, wars and so on. So any prediction that looks 80 years out that only looks at fertility rate and death rate is going to be found wanting. It's a bit long for a long bet, but I'd be more than happy to take one for a 30% or more deviation from the prediction.
The degree to which people are willing to believe simplistic models without further qualification is astounding to me, given the past 80 years in development of medical technology, electronics and our ability to wage war any predictions about the next 80 years should come with huge error bars. And that's before we get into the consequences of Climate change.
Which have an effect on fertility and death rate. There is literally nothing that matters to population dynamics other than fertility and death rate.
We have extensive experience on that now: Technological and social development drives fertility to at or below replacement levels rapidly. This is the main factor. Importantly though, _this is not a prediction_. This reduction has already happened. So the bulk of the prediction is just playing out the consequences of developments we've already seen.
Of course major events like climate change have the potential to invalidate this prediction. But that doesn't mean this prediction is useless. And this is would not be due to "sensitivity to initial inputs".
Yes, but given that they are unknowns you can't just extrapolate from the presently available data and call it a day.
> But that doesn't mean this prediction is useless.
It's an open door that the world population will stabilize at some point, it is also an open door that the speed with which the world population is increasing itself is reducing. It has to, simply because more affluent people will have fewer children because they are not looking at their children as their source of income when they are themselves unable to generate any. Children as a pension scheme is a very common thing still, but that is fortunately changing.
> And this is would not be due to "sensitivity to initial inputs".
To a degree it is: any error in the predictions for the next couple of years will result in a much larger error in the future, simply because of the fact that population increase is a non-linear affair to begin with, and that any med-tech development that causes people to live longer will also cause a large increase in the number of people alive at any one moment.
Compounded those two could have an enormous effect.
For reference, the world, 80 years ago, so just before WWII had only 2.2 billion people.
It is still the case, just on a larger scale.
Moreover, the major causes of birth rate decrease, like vaccination and refrigeration (which strongly impacts food supply), aren't going away. Look at a country with a high birth rate today, and you'll still find people walking for miles with buckets full of the day's water for their household. And anywhere that indoor plumbing and clean tap water is universal, the birth rate is down to replacement level. There are fundamental causes for birth rate decrease, and they're not going away.
Frankly, I think you're clinging emotionally to the Malthusian model, not rationally.
You cannot predict the direction that culture will change. Any predictions I make about this are extremely speculative, but it is easily imaginable that 20 years from now the zeitgeist reacts against the corpus of current culture to be more family-oriented. Think about how much you hear people complain against "the machine." Whether it's on r/latestagecapitalism, or r/the_donald, everyone hates the piss out of broad society, and may find solace in tight-knit families.
Atheist women choose not to have children, christian women choose not to, muslim women choose not to.
Give people the option not to have children, remove the stigma and maybe they have 1-2 children, but no more.
Given how many single people there are, how tight the fertility window is for women who have careers, how tight schedules are in big cities, how expensive it is to have children today, there's nothing we can reasonably do to increase birth rates.
I'm not even sure what you are trying to say.
The implication being that the cultures of (some) people are unchanging and fixed. I think you'd agree with a statement like: Cultures and family values do change all the time, due to a variety of factors like better medical care, and economic empowerment, in reasonably predictable ways.
So it's not unchanging cultural differences between Africa and Europe that drive the different fertility rates, but rather different socio-economic factors that drive a different family culture. Changing the socio-economic factors will change the culture surrounding families, just as much in Africa as it did in Europe, the Middle East, Asia, etc... at various times in the last century and a half.
I'm sure an alien species or a computer simulation having a few of the same basic drives as humans do (sex is very pleasurable, contraception exists, raising educated children is extremely expensive and hard, state provides pensions in old age, people are free to have or not to have children, child mortality is low, work provides money, money satisfies needs, quality work is abundant only in high density cities and a coupe of others) will arrive at same fertility problem we have arriven at.
My second point was that there is nothing we can reasonably do without a major overhaul of human traits or shutting down the technological advanced world we live in.
One extreme unknown is global life expectancy. New diseases, or new cures for existing diseases can make a huge difference. Add in wars, economic growth, and a host of other factors making long term estimates are hard. Just consider how accurate past population estimates have been.
> Just consider how accurate past population estimates have been.
Uh, fairly accurate as far as I know? There were always bad extrapolations and naive papers and articles, but the state of the art predictions didn't do badly, especially after data quality improved.
Also, again, the major driver for the predicted dynamics is the collapse in fertility rate that has already happened, and no longer needs to be predicted. This is a vastly simpler question now than it was in the 70s.
Look at this graph:
Of course in 1970 it's almost impossible to predict how quickly Asia will experience the cultural, economic and technological changes that reduced the fertility in Europe dramatically over the previous century. Today the transition towards small family sizes has happened. We still have drift (as we see in Europe too) but the important major driver of going from roughly 6 children per woman to 2 children per woman has happened. So the biggest uncertainty factor in old forecasts is gone.
They have gotten fairly close with long term estimates a few times, but a poor track record for predicting deviations from existing trends.
I spend a bit of time looking for the publications underlying this model right now, but couldn't find any.
But accepting the error bars doesn't change the story. Which is that this isn't that much of a prediction. The main driver behind the population dynamics of the next century is the decline in fertility that has already happened.
It's not a highly uncertain prediction that can turn out to be vastly different based on minor changes in the initial conditions.
But if we underestimate the decline of fertility in Africa (where it is changing the most at the moment ) over the next decade or two it could easily end up being off by 10% or more.
It's all fairly predictable.
 For example the 95th percentile prediction sees a sudden bump in Asia, taking it up to fertility levels not seen since the early 2000s by the mid 2020s, despite a perfectly smooth decline since:
Long term estimates need to consider such black swans as a real possibility. Relative amounts of war and disease in Africa over the next 20 years will have a real impact.
As those countries get more powerful and develop nuclear, the consequences of conflict get nastier. Things like restricting water supply bring back old style 20th century slaughter.
I guess its some combination of women's lib (women more likely to say no to sex, relationships and children, wanting careers), people working more (side hustles are now a thing), and there now being more things to do (you can now socialise on the internet without actually meeting anyone).
But I wonder how the model would be affected by, say, the mass availability of a significant longevity increase, brought about by some sort of medical breakthrough?
They mostly are actually. Barring the occasional exception there is a definite 20-40 or so age band where most females that have children will have them. This is in part because of society and custom and in part for very valid medical reasons, the chances of children having birth defects go up quite fast past the age of 35.
Medical breakthroughs tend to affect the latter rather than the former more, though the fact that people live longer has an effect on the age at which they start with having children. In my grandparents generation it wasn't rare for 19 year olds to be married and to have their first child on the way, my parents generation had their children when approaching 30 (on average), and the present day generation has their first child later still. There is some correlation here with education levels and of course from country to country there are still huge differences but overall those seem to be the trends.
So a significant longevity increase brought about by a medical breakthrough will likely cause people to have their children at an even later age (with all the associated risks, possibly resulting in much more screening), somewhat offsetting the effect of those people themselves being alive for longer.
Social security would be a real problem, especially if the time that people could work productively would not increase at the same rate as the longevity.
- If it's "stay old longer" then yeah, that's a problem (most of our present advances are this since they don't address ageing, just save people from its consequences).
- If it's "stay young longer (or indefinitely)" that will change a lot of assumptions. But it might also make people put off children until really late, like, "if you're less than 100 why are you even considering being a parent?"
Google: the SENS research foundation.
Actual therapies would go in and undo the damage, not stop it accumulating, but clean the existing damage down to a level where ageing symptoms would be reset back by decades. And could be repeated, leading to indefinite lifespans.
The downvotes to my comment above amused me, there are apparently people in denial here. :)
The people who aren't reproducing will die out. The people who are reproducing will do so, and their kids will keep reproducing too. These are separate sub-groups of the population.
As a very simple example, the Amish population doubles roughly every 20 years because of their high and early birth rates. It's not hard to calculate that there will be billions of them within a few centuries because of the power of exponential growth.
Any analysis which doesn't separate sub-groups by fertility, or handle the heritability of fertility, is meaningless.
All we're in now is a temporary state caused by rapid introduction of birth control and porn and other such technologies which suppress fertility. No different from hitting a bacterial colony with a drug that stops 90% of them from reproducing. It reverses growth for a few generations, but the logic of evolution and exponential growth always wins in the end and the population hits its carrying capacity once again. Which for humanity with modern tech, is going to be a very, very ugly situation.
“[T]he difference in mean AQ [‘amishness’] between young Amish men and their non-Amish neighbors is about 2.8 standard deviations. In the IQ world this would correspond to a group different of 42 points. In the stature world this would correspond to a height difference of about 8 inches.”
Also, who said anything about genes? Sub-groups can be separated by culture, religion, genetics, or any combination of the above. Amish are separated by all 3.
Religiosity is also linked to genetics; this is scientifically established (though not totally proven yet).
As the Amish community grows, they will face the same challenges faced by all growing, successful "challenger" cultures: envy and resentment, followed by active undermining of their culture and attempts at assimilation through popular media, fashion, and a hostile legislative environment. (This presents itself as a sort of "embrace, extend, extinguish" effect, with the end product being ethnic restaurants and kitsch once the culture has been fully digested.)
The Amish may be able to adapt to face this challenge, but what often happens is that the process of adaptation ruins the good and unique things about the culture, and the assimilation happens anyway. Cultures that resist this effect stay small by necessity.
An example of a culture recently reaching this "breakout" point where pushback is encountered is the Hasidic community in New York. A good example of a culture that is left alone due to its small size is the Sikh-American community. An example of a fully digested culture is the Italian-American community, which no longer exists as a separate identity.
I agree the pathway would definitely change. You'd see pushback. It's not like the Amish will be 300 million in their exact current format.
So let's say that does happen and the Amish start getting targeted for "embrace, extend, extinguish", or some variation of semi-forced immigration and assimilation.
Amish aren't homogenous. Some of them would be taken by this, assimilate, and drop birth rates. Some would not. Whatever characteristics made that last part not assimilate would then get replicated into a larger and larger population share. And the process continues.
We may see several phases of this, but at the conclusion of the process, the evolutionary logic leads to a certain result: A population who are absolutely, totally immune to any influence that would assimilate them into a negative-birthrate culture. And that population will rapidly expand until it hits physical limits.
The reason I think this is inevitable is because evolution is relentlessly adaptable, while the countermeasures are fairly static. It's like a new antibiotic. Even if it works really well, the bacteria's evolutionary process will just keep trying and trying until it finds a new replication pathway. The replicators can adapt forever while the force that is stopping them cannot.
Robin Hanson has described this a fair amount as well. Some cultures have a "price of admission" that can't be easily faked (I forget his term for this) in order to protect their group resources against disloyal outsiders who may take advantage of the group. This explains a lot of the bizarre, contradictory, and otherwise illogical practices that you see in these insular cultures.
But a country of Amish? They'd be conquered in a day.
What is the reason for low fertility prediction?
Well it's a simplification. Better education also correlates with lower fertility.
And yes, I'm not showing causation. But anti-conception does require some basic money and education.
Worldwide experience has been that increasingly developed nations have lower average fecundity. There are various likely reasons but the correlation seems to be quite robust. In most countries it seems that the causal link was from development to fertility. It is arguable that China reversed the causation, politically limiting fecundity.
This is a uniquely human dynamic. Pretty much every other species in the world drives its population to its Malthusian limit.
If you are in the US you may not appreciate how heavy the tax burden is in Europe. It varies by country but its normally something like: 30% payroll tax paid by employer. 30% income tax paid by you. 20% sales tax paid by you. Then, very expensive housing due to the high population densities and limited room to expand.
Additionally in Europe, many parents want their children to be educated in English, however the language of instruction is usually the local language. This is partly why the migrant stream into the Anglosphere is so high. The alternative are private international schools, which are hideously expensive.
Housing in a second-tier Polish city is more expensive than Chicago!
All forecasts predict another 60% (!!) increase in global population before it stabilises.
Forget about banning plastic straws or flying less (which are feel-good measures more than anything else) with such numbers... We need to take dramatic and effective steps.
There are 80 years left until the end of the century. This increase is far from being inevitable! But, again, we prefer to ignore these key issues and focus on marginal, feel-good measures instead.
Why should rich people continue to fly around the world while you try implementing big restrictions on everyone? This makes no sense.
Perhaps you meant "In addition to bans on (...), we need dramatic measures"? Also, suggesting some steps would help understand how stronger your proposals are.
The important point is that this is a large increase when we already cannot manage now.
Correction: we don't want to manage now. The world has far more than enough wealth and resources to hold climate change to 2 degrees and to stop clear cutting rain forests.
Two thirds of the global extreme poverty (defined by the World Bank as about $1.80/day in current dollars) has been eradicated in just the past two decades.
We're doing awesome.
That’s quite a bit of uncertainty to make any real definitive statements beyond continuing growth expected.
I am mostly simply reacting to people trying to use specific estimates.
> We need to shift 100% of our foreign aid to education, contraception and abortion for women.
You're essentially advocating for colonialism. Not every culture is the same and some do not want abortion, for example. It's not the west's role to forcibly import our culture into other countries just to lower their birth rate to that of our's (which is too low, not even replacement level).
Saying growing populations disprove Malthus is like saying since smoking one cigarette didn't cause cancer, cancer from smoking is a myth.
No, because people who smoke do die from cancer. The earth has never hit a hard limit on how many people it can support. We are no where near the physical limit of how much food we can grow. Not even close (hence the actual population gain that only slows due to cultural changes and not resource limits).
Again, the population of third world countries keeps increasing rapidly. They have no problem with population growth. We in the first world have a population problem but that's because we're not reproducing at replacement rates.
EU parliament elections, EU local elections, USA presidentials, Brazil, and the list goes on.
Basically, most of the liberal parties have found this "hack" to win elections. Where they wouldn't be able to win elections normally, they simply keep importing more and more people, and these immigrants reliably vote for these parties. Eventually, these places end up becoming one party states. Consider the case of California as an example.
It's quite an indictment of the democratic processes.
The only thing I could think that would make it seem abnormal to you is the demographic of the immigrants.
It's their ideology and it is up to the democratic process to judge it (favorably or unfavorably). And - although personally I favor controlled immigration only - it is perfectly healthy for a democracy to have parties that defend and present other perspectives.
Like I just said, it's working extremely reliably. Look at California, the opposition is decimated there not by the merit of liberal parties work or argument but by the sheer number of immigrant votes. Granted there is a delay factor such that new immigrants can't vote but the mechanism of immigrants voting for liberal party is still at work.
This is just for state level, I predict something similar happening at Federal level elections in a 1-2 election cycle period. Trump election was an exception IMO.
We need people to (a) understand that the world's population is increasing but that the rate of increase will inexorably slow and that (b) this means that the population will plateau. We then need people to ask themselves can the Earth support that level of population of 11 billion. The answer is an incontrovertible "yes". Anybody who claims the Earth cannot support 11 billion people is factually incorrect. Is it going to cause environmental stress? Yes. Will it cause environmental collapse? No.
People also fail to understand this other simple fact. Even though there will be more mouths to feed, there will be more hands to make the food. And given economies of scale, it'll arguably be easier to feed 11 billion than 7 billion.
At our current population 40% of insects could be extinct in the coming decades, and over the last 50 years 60% of animal populations have been wiped out: https://www.cnn.com/2019/02/22/health/food-biodiversity-repo...
edit: To clarify, people say that we have exceeded the carrying capacity of the Earth or that we'll exceed it as the population mushrooms. This data proves the population won't mushroom, and I assert that 11 billion is well within the carrying capacity of the Earth. Do I have any proof? No. But neither do the doomsayers who claim otherwise. That's the specific narrative I'm trying to push back against.
What you meant to say is that we can't survive below some threshold of biodiversity. Nobody's talking about zero biodiversity. What do you think that threshold is? I think we can survive (and the environment will be okay with) less biodiversity. How much less that turns out to be I guess we're going to find out.