Pretty much everyone agrees that the Earth's carrying capacity is stretched by the current birth rates and that measures should be undertaken to slow down and eventually reverse the growth of world population. At the same time, developed countries are having significant concerns over the low birth rates in their countries and are constantly trying to improve the situation through increased incentives for parents or increased immigration.

Aren't the two problem statements in conflict with each other? Shouldn't Japan or Germany be lauded for finally making progress in increasing the sustainability of the world's population?

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    Arguably, these two are considered problems by two different (or at least not-completely-overlapping) sets of people
    – user4012
    Dec 26, 2018 at 22:25
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    "Pretty much everyone agrees that the Earth's carrying capacity is stretched by the current birth rates …" Can you cite references for this? The UN says the earth's carrying capacity is somewhere between 4 - 16 billion people, with a median of 10 billion (source). Current population is about 7.7 billion (source). So current birthrates are going to take us past 16 billion? Sounds a bit extreme. Dec 27, 2018 at 3:29
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    @Michael_B: The UN is hardly an unbiased source. Other estimates put sustainable carrying capacity at around 500 million - and simple observation should demonstrate that the current population (& lifestyle) is unsustainable. And what does poverty have to do with overpopulation? You can have horribly overcrowded places where people are quite prosperous - Manhattan, Silicon Valley, Singapore, Hong Kong, &c - but they survive only because their wealth allows them to import the necessities of life.
    – jamesqf
    Dec 27, 2018 at 5:43
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    But I do agree with you that the UN is not an unbiased source. Their bias, however, is normally in support of alarmism and left-leaning ideology. So I was surprised to discover this relatively mild population data coming from them. Because of their normal bias in the opposite direction, I felt this was a credible source. Dec 27, 2018 at 14:11
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    @jamesqf 500 million? The population of North America given the entire planet instead of just the one continent? That seems comically low. Last time the world population was that low was in the 1600's, well before the industrial revolution. Should most of us return to an Enlightment-era standard of living and population density? Dec 27, 2018 at 18:58

2 Answers 2


The original question makes the assumptions that overpopulation and low birth rates are problems. This is to answer those assumptions.

They are two completely different problems.

Overpopulation is a global issue. Global overpopulation is a problem dealing with 1 location and 1 study group. Planet Earth and humanity. The study of overpopulation looks at global capacities for food production and clean water.

There is clearly a problem with current trends. Some more information here.

Basically, the problem states that the current projections don't look good for keeping people fed and healthy over the long term. (side note: usually disparity in natural resources like food lead to wars, so have fun with that)

While some studies, facts, and opinions may have some valid claim to contradict that this is even a problem, there are many who perceive the problem to still exist. And the concept of that problem is that population growth will outpace food output and lead to wide-spread hunger using a global scale.

Low birth rates are a local issue. Developed nations having low birth rates are a local problem. Typically, low birth rates are referenced along with economic or cultural problems.

For example, a contributing factor to the current migrant tension in the EU has to do with low local birth rates with high numbers of immigrants. This has an effect of rapid shifts in demographics. This is not inherently bad. Looking at Dubai, 30 years ago it was basically empty.

This is a dramatic oversimplification for illustrative purposes. Another issue with low birth rates is the economic impact. In some senses, entitlement programs can be viewed as a pyramid scheme. Everyone pays in, first people get what they paid in out and then some. Subsequent people do the same. If the taxpayer base shrinks too much, the money to pay for entitlements (retirement) can run out.

Many of the social programs, like nice roads, free healthcare, free school, free police, free fire rescue, and others all cost tax money. Low birth rates that don't adequately resupply the workforce to pay the taxes needed leads to problems of how to pay for these social services.

These are not all of the issues, but describes how they are different and still a problem and the same time.

Edits to add clarity about the answer being specific to answering the question and refuting assumptions made in the question.

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    But if no one wants to have low birth rates, how does anyone expect the world population to shrink? Dec 26, 2018 at 23:09
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    "There is clearly a problem with current trends... Basically, current projections don't look good for keeping people fed and healthy." Respectfully, this is just your opinion and that of others. Dec 27, 2018 at 3:44
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    Human population is projected to grow by 2-3 billion from today's 7.7 billion by 2050. No reason to think we can't handle that. We have the ingenuity and technology to make it happen. World poverty is already on a steady decrease for decades (and actually cut in half between 1990 and 2010, according to the World Bank). We're good on the population front in appears. Dec 27, 2018 at 3:44
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    @Michael_B I appreciate the comments, however, the original question asks how both of these concepts are perceived as problems simultaneously. The question doesn't speak to the veracity of each question. Refuting the accuracy of the assumption in the question isn't answering it. It isn't even my opinion. It is a direct answer to how the opinion can be perceived as a problem at the same time as a contradictory opinion.
    – David S
    Dec 27, 2018 at 15:11
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    @H20NaCl Faulty logic. The amount of an element needed for human existence is a function of human population and current use of element per person. The amount of mass of the element is a limit on how much we can use. Mass need not be destroyed in order for mass to be limited, in fact since matter is conserved it demands it be limited
    – spmoose
    Dec 27, 2018 at 18:14

There are the two sides of the same coin

Name of the coin is "kicking the can down the road"

Low birth rate: Capitalsim is a savage system based on dog-eats-dog. To achieve the modern levels of comfort, welfare and general wealth some western countries have (had?) and the rest aspire to, several socialist improvements from (both utopic and Marx's) communism were added to the system, such as paid holidays, limited hours timetables, sick days, unemployement benefits and pensions.

The key here is pensions. Since all of these things are paid through taxes, you can count on employed people to pay for the benefits of the unemployed, and you can count on healthy people to pay for the medical costs of the sick and injured. As long as there are more people working than unemployed or sick, the system works.

With pensions, the thing gets trickier. Unlike unemployement or illness, pension is a permanent condition - unemployement can be, but your benefits aren't, and so can be illness, but the cases are rare and the benefits small. There are two methods to paying pensions: you either save some money during your working life to spend it later (the savings method) or you pay for your elders pension when you are young and working, and you count on those who will come after you to fund yours (the redistributive method). With the first method, inflation will render all your life savings into small change unless you invest it, but there's no guarantees the investments are going to be profitable and if publicly managed is a temptation too great for politicians to milk off, and the second method is only sustainable if there are much more young people working than there are pensioners.

Most countries chose the redistribution method, but they did it at a time were people started working when they were 14yo, worked until 65yo, retired and died before hitting 70. So is they worked 50 years then benefited from pension less than 5. Nowadays these countries are finding that young people start to work (with pay and taxes) at twenty-something (in some countries, twenty-lates), retire or are retired early, before even they are 65 and then go on to live until 80 years old or more. And they need two and a half young workers to pay for every single pension. It is not sustainable anymore.

The thing is, the prospects are already dire and low birth rate make it impossible to solve. If you are 40 years old or less and live in a western country you are not going to have a pension. It's as hard as it sounds, but no politician dares to reform the pension system. Pensioners vote. Massively. And they are already way too many. The system is already broken.

Overpopulation: we are way too much people on Earth, as is evident given that all ecologic problems of the Earth are anthropogenic. There's only two solutions to this, either we reduce our numbers or we reduce our pollution footprint. The first solution can only be achieved by genocide or reducing birth rate below replacement ratio (so is, making worse the low birth rate problem we were talking about before). The second solution implies inventing not just cleaner technologies for (almost) everything we use today, but completeley biodegradable and ecologically neutral ones, which is doubtful they can even exist - the second law of thermodynamics is a hard mistress. Giving to choose, the first solution seems more acceptable, especially so if the genocide is not carried against you but by you.

We have already dodged at least one bullet - the nitrogen crisis, which was averted by Fritz Haber. It's not clear we are going to avoid the CO2 crisis (climate change) or survive the end of oil without major famines and wars.

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