The world population size is
1. 6.9 billion
2. 6.2 billion
3. 8.1 billion
4. 7.6 billion
The current population size of the state of
Minnesota is
1. 3 million
2. .9 million
3. 6.5 million
4. 5.3 million
The current population size of the United States
is
1. 108 million
2. 1 billion
3. 310 million
4. 259 million
Human Population Growth
http://www.beltramiswcd.org/Aquatic%20Biology/Human%20Population%20Growth.jpg
What do we mean by
growth rate?
Pop Size this year-Pop Size last year
_______________________________
Pop Size last year
The current growth rate of ~1.3% per year is
smaller than the peak which occurred a few
decades ago (~2.1% per year)….
But since this rate acts on a much larger population
base, the absolute number of new people per year
(~90 million) is at an all time high=POPULATION
MOMENTUM
Runner analogy –
Even if runner slows down and goes fewer miles
per hour they are still accumulating miles…
We are still adding huge
numbers of people…..
http://www.worldometers.info/world-population/#growthrate
Total Fertility Rate - number of children born to an
average woman in a population during her life
Age Structure
http://www.census.gov/popclock/
How does MN compare?
Demographic Implications of
Living Longer
• A population growing rapidly due to natural
increase has more young people than does a
stationary population.
– Even if total fertility rates were to fall, the
population would continue growing as young
people enter reproductive age.
• Declining populations have more old people than
young people.
Blue=birth rate
Red=death rate
A Century of US Birth Rates
Some demographers think that a demographic
transition is taking place now in developing
nations.
Others take a more pessimistic view. Lester
Brown warns that poorer countries may be
caught in a demographic trap.
The population is growing so rapidly that there
are not enough resources to complete
modernization and enter stage IV.
What are some problems with our obsession with
absolute population size-what do we miss by
obsessing over numbers of people?
Environmental Effects of Population
Effects of population on the environment are not due
to numbers alone.
I = PAT
I = environmental impact
P = population size
A = affluence
T = technology
A single American living an affluent lifestyle produces
more pollution than an entire village of farmers in
Africa.
Two Demographic Worlds
• First is poor, young, and rapidly growing.
– Less-developed countries
• Found in Africa, Asia, Latin America
• Contain 80% of world population, and will
account for 90% of projected growth
• Second is wealthy, old, and mostly shrinking.
– In North America, Western Europe, Japan
• Average age is about 40
• Populations expected to stabilize or decline
Increasing urbanization.. Megacities
There are no easy answers to the questions: “How
many people can the earth support?”, and “At what
level of well-being?”. Cohen suggests we think in
terms of three possible (and non-exclusive) solutions:
1. Make a bigger pie: Increase human productive
capacities through technology and innovation
2. Put fewer forks on the table: Reduce numbers and
expectations of people through such means as family
planning and vegetarian diets
3. Teach better manners: Change the terms of
people’s interactions through improved planning and
government to enhance social justice.
Proceedings of the National Academy of Sciences
Bradshaw and Brook
Human population reduction is not a quick fix for
environmental problems
Nov 2014
Created a computer model that projects human population
growth from 2013 to 2100-had variables they could modify to
create different scenarios.
How sensitive human population growth is to different
changes…including a “business-as-usual” scenario in which
death and fertility rates stayed the same as they were in 2013.
The other scenarios projected the effects of longer life spans,
mothers having their first children at older ages, the imposition
of a global one-child policy, and catastrophic deaths due to
war or pandemics.
The business-as-usual model matched U.N. projections of 12
billion people by 2100, giving the researchers confidence in
their model.
Global catastrophic deaths of up to 5% of the population, the
same seen in World War I, World War II, and the Spanish
flu=population still boomed!
“It actually had very little effect on the trajectory of the human
population,” Bradshaw says.
What about burden of elderly dependents that leads to
economic collapse?
But the team’s model showed otherwise.
Two factors did have an impact on human population growth:
•Eliminating unwanted pregnancies, which make up about 16%
of all live births
•Adopting a global one-child policy
These resulted in population sizes in 2050 and 2100 of about 8
billion and 7 billion, respectively.
Fortunately by Remy Charlip.
“Fortunately, Ned was invited to a
surprise party.
Unfortunately, the party was a
thousand miles away.
Fortunately, a friend loaned Ned an
airplane.
Unfortunately, the motor exploded.
Fortunately, there was a parachute in
the airplane.
Unfortunately, there was a hole in the
parachute.”