Human Population Size — 014

In this video, Paul Andersen explains how the world population has undergone exponential growth since the industrial revolution. Predicting the future world population is difficult because each country will grow at different rates. Age-structure diagrams and the demographic transition model can allow countries to plan for future growth. Government policy can either increase or decrease population growth to avoid catastrophe. China’s one-child policy is an example of one such policy.


Transcript provided by YouTube:

Hi. It’s Mr. Andersen and this is environmental science video 14. It is on human population

size. One of the pioneers in this field was Thomas Malthus. He put forth this essay on
how changes in our population in the past and in the future will impact human happiness.
It is not really a happy story. It is called the Malthusian catastrophe. And so countries
can produce food but they can only increase food production in a linear fashion. And we
know that populations increase exponentially. So as long as you are in the green you are
okay. But once our population surpasses the amount of food that we can produce we have
a catastrophe. We have famine. People are going to die. Now this happened in the last
century. Countries like Mexico and India saw that the food production was not increasing
at a rate that could supply food for their growing population. So what did they do? They
brought in the biologist, Norman Borlaug came in. He brought new farming practices, new
varieties. We called this the green revolution and it solved the problem. It is a pretty
nice thing to put on your resume, saved a billion lives. Now that is just one solution.
We can increase through technology food production or we could simply stabilize that population.
And we know that human populations have been stable for a long time and have only increased
exponentially through industrialization. Once we have constant food, modern sanitation,
modern medicine, populations will simply take off. Now what is going to happen to the world
population into the future? It is a really hard question to answer. Because we are not
just one country. We are a world that is made up of a number of different continents and
different countries on that. And each of those are at different stages along what is called
the demographic transition. But we have powerful tools. We have age structure diagrams. I talked
about that in the last video that are a snapshot of the population but can give us some predictions
of what may happen in the future. And then we have history of this demographic transition.
We know what happens to countries as they are industrialized. In other words the population
will increase, stabilize and then we find that it actually starts to drop off. Now if
you are either side of this, as your population is taking off, it puts pressure on the environment
and on the economy. And so that is bad. And as it drops off, now we do not have people
in the work force who can supply economy for the people who have retired. And so where
do you want your population. You want it stable. Maybe not here, maybe here or maybe here,
we want our population to remain the same. And countries can see this happening. And
so what can they do? Well they could just let it occur. Or they can institute policy
that can make changes, both policy changes that affect overpopulation, so that increasing
population, or that population decline. The most famous example is China’s one child
policy. But we will talk about some other ones as well. And so if we look at where we
are today, 2015, there are 7.3 billion people on our planet. What does the UN predict our
population is going to do into the future? Well we have high, medium and low predictions.
So which of these is right? We do not know. We will have to see what is going to happen
into the future. And the reason it is difficult is that we have all of these different continents.
So Asia right now has 4 billion people, but it could increase to the point where there
are more people in Asia then there are people on the planet today. Or it may not. You can
see that Africa is definitely going to increase into the future and that some areas are actually
going to decrease. But we have these regions that are broken down into countries. Now in
AP Environmental you should know the top 10 as far as population goes, countries on the
planet. You probably could guess a few of those. It is going to be China, India, then
the US. And then we go to Indonesia, Brazil. We have Pakistan, Nigeria, this would be Bangladesh,
Russia and then Japan. And so if you look at the population of these countries, just
those countries account for about 60 percent of the population on our planet. Now is that
going to be the same percent into the future? Probably not. Because if we look at that same
map and look at the growth rate, you can see that in some areas, like the US, it is increasing.
In a lot of these areas the population is actually decreasing. And a lot of Subsaharan
Africa it is really increasing into the future. And so that top 10 is definitely going to
change as we look into the future. And what is going on is we have all these countries
going through the industrialization. And we talked about that in the last video. It is
this demographic transition. And so what happens is first of all the death rate drops then
the birth rate drops. And so if we are looking at what happens to the population over time,
during this transition it will radically increase, then it will stabilize, and then it is eventually
going to drop off. And so this is just a model. It does not always work exactly this way,
but it is a pretty good prediction on what is going to happen as countries start to industrialize.
Now is anybody in type I? Not really. So there are some countries, due to war and like the
AIDS epidemic in Africa that are pushing them back into I. But in general they are either
in phase II, II or IV. So if we look at some ones that are in different phases, Nigeria,
so this is UN predictions. All of these lines are different predictions, but this would
be the average prediction. This is what we think will happen to Nigeria into the future.
So my 2100 we could have maybe 700 million people in Nigeria. So you can see that is
going to move it way up on the list. Where would we put that? It is somewhere in here,
in phase II. If we look at the US you can see into the future it is going to stabilize.
If we look at birth and death rates it should be stable but we have a lot of immigration
coming into the US. And then if we look at Japan you can see that into the future the
population in Japan is radically going to drop off. And so we would put Japan in this
phase IV right here. And so remember, a model that we have used throughout this whole course
is the idea of sustainability. That the earth or the country in this case, has to support
society which is driven by economy. And so as the size of society gets larger and larger
it puts more constraints on the environment. But sometimes when the population gets smaller
it puts more constraints on the society itself, when we do not have people working anymore.
And so how do we use government policy to avoid this problem of over population. Well
one of the most famous examples is China’s one child policy. What they did is made a
strict policy where you could only have one child. You could have more but there are going
to be economic constraints put on you. Not rewards. You will not get rewards. And so
if we look at how this played out in the age structure diagram, it rolled out in the 1980s.
And so those people would be 30 right now. So you can see that the population dropped
off radically in 30 year olds. And so what is going to happen over time, you know the
age structure diagrams will move up, and so these are predictions in 2015. Now we are
looking at 2020. And now 2025. And now 2030. And so you can see that that age structure
which was a clear pyramid, it was headed of exponential growth has really narrowed out.
Now why is this a problem? Well in China they call it the 4-2-1 problem. You have four grandparents,
two parents and one child. And that one child has to support all of that. And so as it gets
narrow in age structure it is going to be hard for them to support all those people
who are retiring as an economy. And then you can start to see a more subtle thing here
in the age structure diagram. I do not know if you can see this, but there are more males
than females. You can see it is shifting more to the left. And if we actually graph that,
this is a graph that would show 100 females, and this is what number of males that we are
getting. So the number of males are increasing. And the reason why is that they see males
as more valuable, especially in rural areas. Higher status and they can do more work, and
so sometimes they are even abandoning those females. Now the one child policy will probably
be modified a little bit in China, but it is incredibly popular there. If we look at
other countries and what they are doing, so if we look at Nigeria, what is the problem
they are going to have is going to be over population into the future. So they have a
panel in Nigeria that has been put forward to kind of tackle this problem. And here are
some of their recommendations. We need to number one educate every child. Promote family
planning. In other words allow birth control to be accessible to all people in their population.
Especially educate and employ women. Now these three things right here are super important.
Because if women are not educated, if they are not employed, what do they do when they
become adults? Well a lot of times they will get married and start having kids. And that
is just going to lead to an increase in the population over time. We have to get that
fertility rate down. And also Nigeria is realizing that our economy has to support all of this
growing population. And so we need to have a bigger economy and we also have to take
care of environment. So countries are doing things. If we look at Japan, for example,
they have the exact opposite problem. So this is their age structure in 1920. Here it is
in 1940, 1950. Same kind of thing as China, that it had this nice pyramid. But now look
what happens. They are having less kids and less kids. And so now it is really narrow
on the bottom. So what problem is Japan going to face? They are not going to have enough
workers to take care of all of these people up here that have retired. And that is going
to be a big deal. So what have they done? They want them to have more kids. And so the
have instituted free child care, maternity leave. Increased benefits if you have children.
And a lot of this is really not working in Japan. So now they are going to have to put
forward ideas of like raising the retirement age. And eventually they are going to have
to increase immigration because their workers are going to quickly fall back to the level
of where they were in the 1950s. And so did you learn the following. Could you pause the
video at this point and fill in all of the blanks? Well let me do that for you. So over
time populations will undergo exponential growth whenever we have industrialization.
What will happen in the future, remember it is difficult to tell because the continents
are broken down into different countries. Two powerful tools we can use are age structure
diagrams and the knowledge of the demographic transition. That goes here. What can countries
do? They can use policy. Policies that affect overpopulation and policies that affect a
decline in the population as well. And I hope that was helpful.


This post was previously published on YouTube.