HUMAN POPULATION GROWTH

What is exponential growth?

It is growth that increases rapidly by doubling at a constant rate.

What is the Rule of 70 used for?

It estimates doubling time using the formula: 70 ÷ annual growth rate (%).

Why did human population start growing rapidly after the 1800s?

Because death rates dropped due to medical and technological advances.

What does TFR stand for?

Total Fertility Rate - the average number of children a woman has in her lifetime.

What is the replacement-level TFR?

About 2.1 (to replace both parents and account for non-reproducing individuals).

What is CBR?

Crude Birth Rate - births per 1,000 people per year.

What is CDR?

Crude Death Rate - deaths per 1,000 people per year.

How do you calculate AGR (Annual Growth Rate %)?

AGR = (CBR - CDR) ÷ 10

What is population momentum?

Continued population growth after fertility rates drop, due to a large number of young people reaching reproductive age.

What is carrying capacity?

The maximum number of people Earth can sustainably support.

What factors increase carrying capacity?

Better agriculture, technology, and resource efficiency.

What factors decrease carrying capacity?

Pollution, climate change, and environmental damage.

Why does the U.S. have a high CDR compared to other large countries?

Because it has an older population.

Why are countries like Niger and DR Congo still growing rapidly?

They have high fertility rates and a large percentage of young people.

What was the world population around 1800?

About 1 billion.

What is the current world population growth rate?

About 1.05% per year.

Why is the global population growth rate slowing down?

Because fertility rates are declining and populations are aging.

How long did it take Mexico City to grow from 3 million to over 21 million?

About 70 years.

How many doublings occurred in Mexico City's population from 1950 to 2020?

Almost 3 doublings.

What is the "chessboard" example used to show?

How exponential growth starts slowly but ends with huge numbers.

What happens in the bacteria-in-a-jar experiment at 10:59?

The jar is half full - one minute before it becomes completely full.

If the growth rate is 2%, what is the doubling time?

35 years (70 ÷ 2).

What does a negative AGR mean?

The population is declining.

What is one major reason populations grow even with low TFRs?

Population momentum.

What does a high percentage of people under age 15 in a country indicate?

Likely future population growth.