Human Population Growth

Human Population Growth

Middle School

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Learning Objectives

• Describe how the human population has grown throughout history.

• Analyze how population growth and resource use affect our planet.

• Use evidence to argue how human activities affect the environment.

• Explain how technology can change the impact of human population growth.

• Define carrying capacity and its link to available natural resources.

Key Vocabulary

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Population

All the members of a single species that are living in a specific area.

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Natural Resource

These are materials from the environment that organisms use for their survival and benefit.

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Carrying Capacity

The maximum number of individuals of a species that an area can sustainably support.

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Per-Capita Consumption

The average amount of a resource that is used by each person in a population.

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Human Impacts

The various effects that human activities have on the planet's environment and ecosystems.

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Earth's Systems

The planet's interacting physical systems: the atmosphere, hydrosphere, lithosphere, and biosphere (life).

Key Vocabulary

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Engineered Solution

An engineered solution is a type of technology that has been designed to solve a practical problem.

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Age Structure

Age structure refers to the number of males and females within different age groups in a population.

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Immigration

Immigration is when people move into a new country or region with the intention of staying there.

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Emigration

Emigration is the act of leaving one's country or main region of residence to live elsewhere.

A History of Human Population Growth

• For most of history, the human population was very low.

• The population began to grow rapidly in the last few centuries.

• Today, over 7 billion people live on Earth due to technology.

Multiple Choice

Which statement accurately describes the human population throughout most of history?

• It was very low for most of history.

• It has always been over 7 billion.

• It grew rapidly for most of history.

• It has stayed exactly the same.

Multiple Choice

What key change in human population growth occurred in the last few centuries?

• The population began to grow rapidly.

• The population started to decrease.

• The population returned to its historically low levels.

• The population stopped changing.

Multiple Choice

Based on the trends described, what is the best explanation for how the human population has reached over 7 billion people?

• The population has grown because it was always large.

• The population has grown despite a lack of resources.

• Technology has enabled a rapid increase in population.

• The population has decreased because of technology.

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How Populations Change

• A population grows from births and immigration (people moving in).

• ​A population shrinks from deaths and emigration (people moving out).

• Age structure shows age groups: pre-reproductive, reproductive, and post-reproductive.

• A wide-based diagram means rapid growth; a rectangular one means slow growth.

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Multiple Choice

What are the two factors that cause a population to grow?

• Births and immigration

• Deaths and emigration

• Births and deaths

• Immigration and emigration

Multiple Choice

What must be true for a population's size to shrink?

• The number of births and immigrants is greater than the number of deaths and emigrants.

• The number of deaths and emigrants is greater than the number of births and immigrants.

• The number of births is exactly the same as the number of deaths.

• The number of people moving in is the same as the number moving out.

Multiple Choice

An age structure diagram for a country shows a very wide base, indicating a large number of people in the pre-reproductive age group. What can you predict about this country's population?

• The population will likely experience rapid growth.

• The population will likely experience slow growth.

• The population is mostly in the post-reproductive age group.

• The population has an equal number of people in each age group.

Earth's Limits: Resources and Capacity

• Natural resources from the environment are essential for human survival.

• Earth's carrying capacity is the maximum population its resources can support.

• As populations grow, resources become scarcer, limiting further population growth.

Multiple Choice

What is the definition of Earth's carrying capacity?

• The total number of resources available on Earth.

• The maximum population that Earth's resources can support.

• The speed at which a population can grow.

• The amount of space available for people to live.

Multiple Choice

What is the relationship between population growth and the availability of natural resources?

• As a population grows, its resources become more abundant.

• As a population grows, its resources become more scarce.

• A population's size has no effect on its resources.

• Resources are only important for small populations.

Multiple Choice

If a population grows beyond its environment's carrying capacity, what is the most likely long-term outcome?

• The environment will create more resources to support the extra people.

• The population will continue to grow at an even faster rate.

• The population will eventually decrease due to a shortage of resources.

• The carrying capacity of the environment will automatically increase.

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Human Impact on Resources and the Environment

• Per-capita consumption is the amount of resources each person uses.

• People in developed nations use far more resources per person.

• This growing population and resource use negatively impacts the Earth.

• This pattern helps predict problems like pollution and deforestation.

Multiple Choice

What does the term 'per-capita consumption' mean?

• The total number of people living on Earth.

• The amount of resources each person uses.

• The speed at which a population grows.

• The size of a country's economy.

Multiple Choice

What is the relationship between a growing population and higher per-capita consumption?

• They combine to cause more harm to the environment.

• They cancel each other out, leading to no environmental change.

• A growing population leads to lower overall consumption.

• Higher consumption helps the environment support a larger population.

Multiple Choice

Based on the patterns described, what is a likely consequence if a developed country's population continues to grow?

• A decrease in overall pollution.

• An increase in deforestation.

• A reduction in the resources used by each person.

• An improvement in environmental health.

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Impacts on Earth's Systems

• More people and consumption change the appearance and composition of the environment.

• For instance, burning fossil fuels for energy can cause harmful air pollution.

• Needing more farmland can lead to deforestation, changing the land’s surface.

• More people consuming resources leads to changes in Earth’s air, water, and land.

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Multiple Choice

What is the primary reason for changes to the appearance and composition of Earth's environment?

• An increase in the number of people and the resources they use.

• The natural changing of the seasons from winter to summer.

• The migration patterns of birds and other animals.

• The frequency of earthquakes and volcanic eruptions.

Multiple Choice

What is the relationship between human activities like burning fossil fuels and needing more farmland, and Earth's systems?

• They can lead to air pollution and deforestation.

• They only have an impact on Earth's water systems.

• They generally result in cleaner air and more forests.

• They have no significant effect on the environment.

Multiple Choice

If a city expands by clearing a large forest for new houses and building a new power plant that burns fossil fuels, what is the most likely outcome for the local environment?

• There would likely be an increase in air pollution and changes to the land's surface.

• The air quality would improve, and the land would remain unchanged.

• There would be no change in air quality but a significant loss of water resources.

• The amount of farmland would increase, and air quality would improve.

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The Role of Science and Engineering

Science

• Science helps us understand the effects of our actions, like how population growth impacts the environment.

• It provides evidence and data about the world and the consequences of different choices.

• However, science itself does not make decisions for society about what actions to take.

Engineering

• Engineering uses scientific knowledge to create solutions that manage our impact on the environment.

• Engineers develop renewable energy sources like solar panels and wind turbines to reduce air pollution.

• These solutions alter our resource use but can also have their own long-term consequences.

Multiple Choice

What is the main role of science?

• To provide evidence and data about how the world works.

• To create solutions that manage our impact on the environment.

• To decide what actions society should take to solve problems.

• To develop new energy sources like solar panels and wind turbines.

Multiple Choice

What is the relationship between science and engineering?

• Engineering provides the data that scientists need to study.

• Science creates the environmental problems that engineering must fix.

• Engineering uses scientific knowledge to create solutions to problems.

• Science and engineering are separate fields that do not affect each other.

Multiple Choice

If scientific data shows that a factory is polluting a river, what is a likely next step based on the roles of science and engineering?

• Scientists will force the town to pass a law against using the river.

• Engineers will decide that the pollution is not a problem for the fish.

• Engineers might design a new type of water filter, but it could be expensive or produce waste.

• The town will have to find a solution without using scientific data.

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Common Misconceptions

Misconception	Correction
Population growth is the same in all countries.	Growth rates are different everywhere. Some countries grow fast, others don't.
Earth has unlimited resources.	Earth's resources are limited. There is a limit to how many people it can support.
Impact only depends on population size.	The amount of resources each person uses also matters a lot.
Science tells us what actions to take.	Science explains the results of our actions. People decide what to do based on this.

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Summary

• Human population grew slowly for most of history but has increased rapidly recently.

• A population’s age structure, birth rates, and death rates help predict its growth.

• Earth has a carrying capacity, which limits the population it can support.

• Population growth and resource consumption negatively impact Earth’s systems.

Poll

On a scale of 1-4, how confident are you about the concepts covered in today's review?

• 1

• 2

• 3

• 4