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 rateRed=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.”