Does the World Have Too Many People?
We live in new times
o sometime in October 2011 world population moved beyond 7 billion
o India will soon have more people than China
o on 23 May 2007 the global urban population, for the first time in human history, became
bigger than the global rural population
o Does the world have too many people?
World population dramatically took off after 1800…
…and even more noticeably after 1950, especially in developing countries
2100 Project: 10.1 billion
10,000 years ago, when settled agriculture began, the world’s population was perhaps 5 million
2000 years ago, during Roman times, the population reached 250 million
By 1427, world population reached perhaps 427 million
By 1800 population reached 1 billion
From 1900 to 1950 the world’s population grew from 1.6 to 2.5 billion people
Now, it is more than 7 billion
Thus, over a century, the population has grown by a factor of four, which is historically
Birth and Death Rates
Population growth is caused by birth rates (number of births per 1000 people in a given year)
exceeding death rates (number of deaths per 1000 people in a given year)
An intersection between those who die and those who live
Birth rates and death rates have been in decline, but:
o birth rates have been declining more rapidly than death rates in rich countries
births > deaths while both decline
o death rates have been declining more rapidly than birth rates in poor countries
deaths > births while both decline
The result: population growth in poor countries has greatly exceeded population growth in rich
countries These trends in births and deaths builds in more population growth, because many people in
poor countries have yet to reach their reproductive age—there is a population growth
momentum that will not slow until late in the century, at around 10 billion
This seven billionth baby won’t be counted until 15 years from now – babies born now create growth for
the 2020s and 2030s.
Population distribution - 1960 Population distribution – 2050
Africa is bigger, Europe is smaller
In 1950, 2 Europeans for every African
In 2050, 2 Africans for every European
Africa is the epicentre for poverty. It would imply that there is a potential for a massive
worsening of poverty. This is both a threat and an opportunity to end poverty
Why has the death rate declined?
• increased life spans—people everywhere live longer
• cuts in infant mortality (the number of deaths of children under 1 per 1000 live
births)—children everywhere are less likely to die due to simple improvements in
Both have contributed to declines in birth rates: if fewer deaths, there is less need for the
economic support of a larger family
We’re two parents with two children – one of the two is likely to die. The response of a parent in
a poor country where a child is insurance for the future (they will provide for you) is to have
another child – and if one is likely to die, you’re going to have two. Which means you’re really
having four. But if you know your second child is likely to live, you’re less likely to have those two
This is a very positive sign of development
Consider: promotion programs that educate people about the importance of handwashing
and/or providing free soap save lives and are cheap
So, for every US$1000 spent on sanitation and hygiene promotion programs people in a
community will live in total an average of 300 years longer (ie, disability-adjusted life years
[DALYS]), or just of US$3 per DALY
Simple, cheap hygiene fixes can have a crazy dramatic impact
Future population growth depends critically on the relationship between death rates and
fertility rates (the number of live births per 1000 women between 15 and 44)
The key indication of trends – it’s very simple to estimate the fertile rate at which the population
is stable – no increase, no decrease. Is the replacement level (the fertility level at which women are having only enough children to
replace their parents) exceeded, and to what degree?
A replacement level of 2.1 births per adult female holds a population stable
Women are having less babies, as a whole
Currently, there are many rich countries with replacement rates far below 2.1, indicating that
the population is at best stable or declining
Japan: 1.25; Spain: 1.3; Canada: 1.48; Ireland: 1.99; and others
However, in some poor countries the fertility rate exceeds 4, generating large increases in
In Ethiopia, for example, every mother has 5 children: the population increases by 2.5 million
Is the world overpopulated?
1. It is worth noting that the population density of Bangladesh, where 150 million people live,
is, at 1000 per square kilometre, the same as Fremont, California, south of San Francisco Bay
2. High fertility rates are now the exception, not the rule
o Asian fertility rates:
South Korea, 1.15
Hong Kong, 1.04
In the developing world as a whole, fertility rates fell from 6 to 3 between 1950 and 2000, and in
some places dropped far more dramatically
This decline in fertility is unprecedented – we’ve never seen declines in population like this before
North America, Asia and Europe are below replacement level; Latin America and Oceania (which
normal people call Australia) are at replacement; Africa is about double replacement
the average Ecuadorian woman had 5 children; in 2001, the number was less than 3
the average Thai woman had 3.5 children in 1980; in 2001, the number was less than 2.1
Even in Ethiopia: in 1950 she had 7 children; in 2009 it is 5
Much is driven by China, with an official fertility rate of 1.8 for more than 15 years – China's
population should drop by 450 million between 2025 and 2100! They have a “one child policy” and have for years – it only applies to people in cities; if your first
child is a girl, you can get an exemption. How nice.
Why has fertility dropped?
Family planning technologies were used by 10 – 12% of developing country households in the
early 1960s; now it is over 60 %
The global rate of population growth is slowing down at an historically unprecedented rate, but
population momentum continues to drive up the number of people
The momentum is still driving the population, but the momentum has slowed. Good job world
Even in Africa, if its 1970s fertility rate had been maintained there would have been 8 % more
people by now
Overall, by 2050 only 51 countries will reach replacement rates!
This brings with it 3 less obvious problems
1. In 2010 7.6% of the world's population is over 65; by 2100, 22.3% will be – who will support
2. China and India will have major male – female discrepancies – tens of millions of men will
not be able to marry
You can choose which foetus to abort – every lady has a man if she wants one, but lots and
lots of men have to be gay. Seriously though, this can cause social disorder because China
and India are both view marriage as being very important to society.
3. Africa will grow from 1 bn to 3.6 bn – with important implications for global inequality
But is the world overpopulated?
But this does not answer the question: is the world overpopulated?
Carrying capacity: the idea that there are a finite number of people who can be supported
without degrading the natural environment and social, economic and cultural systems
It is an indirect measure of the maximum level of stress that the ecosystem can maintain
That stress is real: human beings have
o exploited 50% of the photosynthetic potential of the planet
o put ¼ of the carbon dioxide now in the atmosphere
o to use 60% of global accessible river run-off
o been responsible for 60% of the earth’s nitrogen fixation
o been responsible for 1/5 of all plant invasions
o made ¼ of all bird species extinct over 2 millennia
o have overexploited more than ½ of the world’s fisheries
Human activities dominate the world, and not always for good—but we are in charge!
Carrying capacity is particularly promoted by
o certain groups within the global environmental movement
o the ideas of Paul Ehrlich (The Population Bomb) and Garrett Hardin (The Tragedy of the
Some suggest a planetary carrying capacity figure of 12 billion; some 2!
Yet the concept is of limited use (Cohen 1995) o With what distribution of material well-being
o With what technology?
o With what domestic and international political institutions?
o With what domestic and international economic arrangements?
o With what domestic and international demographic arrangements?
o In what physical, chemical and biological environments?
o With what variability or stability?
o With what risk or robustness?
o For how long?
o With what values, tastes and fashions?
Thus, under certain conditions, the planet could support 15 billion, but under other conditions
only 1 billion—or less!
A particular problem of increased population is the view that an inability to sustain carrying
capacity generates ecological degradation
To reduce poverty we should reduce the number of people – too many people competing over
too few resources
Machakos: where, with rapid population growth, ecological conservation has deepened
A place in Eastern Kenya where the fertility rate was six
o more sustainable land use, in terms of tenure, crops, livestock and land management
(soil, water and tree management)
o changes in social institutions, farming and income systems to sustain the ecology
1937/1991: Machakos demonstrates that the link between population and degradation is not
There are many other examples that could be drawn upon
Moreover, ecological problems are globally not uniform Ecological Crisis
The ecological crisis is not the same for the rich and the poor; they face significantly different
The ecological crisis of the poor is a function of their poverty; the ecological crisis of the rich is
a function of their prosperity
So the causes of the ecological crisis cannot be evenly attributed to the rich and the poor: they
must be disproportionately borne by the rich, who are by far responsible for the bulk of the
environmental problems that the planet faces because of overconsumption
One should not be sanguine about the impact of population growth on the planet: but barring
the next 50 years in Africa, many parts of the world are more likely to face population pressures
in the form of an ageing population
Too many old people :D
We actually have enough food to feed 10 billion people, but we feed animals
As for Africa, the solutions are well known:
o reproductive health services
o female education
o increased incomes
Population growth nonetheless signals important changes in processes of international
o 1950: 86 cities with a population of more than 1 million
o 2006: 400 o 2015: 550
o 2/3 of global population increases are in urban areas
o 2006 urban population (3.17 billion) is greater than the global population in 1960
Even if people are predominantly rural right now, by 2030, the majority of people will live in cities
Cities are the products of trade: initially, food crops, and then the manufactures that they
Trade has expanded astronomically: and with it, cities
So, for example, Dongguan, in southern China, a town with tens of thousands in the late 1980s.
At the confluence of the Pearl River megalopolis, it now has a population of 7 million and
produces 30 % of all the magnetic recording heads used in hard drives in the world and 16 % of
all the world’s electronic keyboards
o factories cluster, to economize on skills and infrastructure
o workers migrate to places where their skills are in demand
o business services cluster around growth poles
Why? Cheap transport makes vertical specialization and higher productivity in global supply