1. Unit 4 Lesson 2 Reducing Human Impacts on the Environment

2. Keeping It Clean What are conservation and stewardship?
Unit 4 Lesson 4 Protecting Earth’s Water, Land, and Air
Keeping It Clean
What are conservation and stewardship?
Humans greatly affect the land, water, and air.
If we wish to keep using our resources in the future, we need to conserve and care for them.
Conservation is the wise use of natural resources. By practicing conservation, we can help make sure that resources will be around for future generations.

3. What are conservation and stewardship?
Unit 4 Lesson 4 Protecting Earth’s Water, Land, and Air
What are conservation and stewardship?
Stewardship is the careful and responsible management of a resource.
Stewardship of Earth’s natural resources will ensure that the environment stays clean enough to help keep people and other living things healthy.
Any action that helps maintain or improve the environment is an act of stewardship.

4. What are sources of energy?
Unit 4 Lesson 4 Protecting Earth’s Water, Land, and Air
What are sources of energy?
A renewable resource is an energy source that can be easily reproduced or replaced by nature.
Renewable resources are replaced at a rate equal to or greater than the rate at which they are used.
Some examples of renewable resources are sunlight, wind, trees, and crops.

5. What are sources of energy?
Unit 4 Lesson 4 Protecting Earth’s Water, Land, and Air
What are sources of energy?
A nonrenewable resource is an energy source that cannot be produced, grown, or restored as fast as it is used.
For example, minerals such as uranium are nonrenewable because they can no longer be formed.
Other examples of nonrenewable resources are coal, petroleum, and natural gas. They formed over millions of years below Earth’s surface, and can take millions of years to form again.

6. Water Wise! How can we preserve water resources?
Unit 4 Lesson 4 Protecting Earth’s Water, Land, and Air
Water Wise!
How can we preserve water resources?
Earth’s freshwater supply is limited, so it is important to use this resource very carefully.
There are many ways to reduce water usage.
People should also be careful to avoid polluting water, because the quality of water is important to the health of both humans and ecosystems.

7. How can we preserve water resources?
Unit 4 Lesson 4 Protecting Earth’s Water, Land, and Air
How can we preserve water resources?
The main way to protect drinking water is by keeping pollution from entering streams, lakes, and other water sources.
Certain laws indicate how clean drinking water must be and limit the types of chemicals that can be released into water.
Individuals can help by disposing of toxic chemicals safely and by reducing the amount of fertilizer used on gardens.

8. This Land Is Your Land How can we preserve land resources?
Unit 4 Lesson 4 Protecting Earth’s Water, Land, and Air
This Land Is Your Land
How can we preserve land resources?
We must protect land resources from overuse and pollution and repair damage that has already been done.
Preservation, or protecting land from being damaged or changed, is very important.
Local, state, and national parks protect many natural areas and help ensure the survival of many species.

9. How can we preserve land resources?
Unit 4 Lesson 4 Protecting Earth’s Water, Land, and Air
How can we preserve land resources?
Reforestation, which is the process of planting trees to re-establish forestland, is important.
Some old forests need to stay intact for the animals that need them to survive.

10. How can we preserve land resources?
Unit 4 Lesson 4 Protecting Earth’s Water, Land, and Air
How can we preserve land resources?
Land can be damaged by mining, development, and agriculture.
Reclamation is the process by which a damaged land area is returned to nearly the condition it was in before people used it.
Many national and state laws guide land reclamation.

11. How can we preserve land resources?
Unit 4 Lesson 4 Protecting Earth’s Water, Land, and Air
How can we preserve land resources?
Urban sprawl is the outward spread of suburban areas around cities.
Urban sprawl leaves less land for native plants and animals.
Reducing urban sprawl helps protect land resources. This can be done by constructing taller buildings and placing businesses and houses close to one another.

12. How can we preserve land resources?
Unit 4 Lesson 4 Protecting Earth’s Water, Land, and Air
How can we preserve land resources?
One of the most important things we can do to preserve land resources is recycling.
Recycling is the process of recovering valuable materials from waste or scrap.
Everyone can help protect land resources by recycling.

13. How can we preserve land resources?
Unit 4 Lesson 4 Protecting Earth’s Water, Land, and Air
How can we preserve land resources?
Soil conservation protects soil from erosion or degradation by overuse or pollution.
For example, farmers can change the way they plow to conserve soil.
Soil conservation can be done through contour plowing, strip cropping, terracing, crop rotation, or no-till farming.

14. Into Thin Air How can we reduce air pollution?
Unit 4 Lesson 4 Protecting Earth’s Water, Land, and Air
Into Thin Air
How can we reduce air pollution?
Everybody can help reduce air pollution in many different ways.
Energy conservation is one of the most important ways to reduce air pollution.

15. How can we reduce air pollution?
Unit 4 Lesson 4 Protecting Earth’s Water, Land, and Air
How can we reduce air pollution?
Fossil fuels are energy resources made from carbon-rich plant and animal remains (coal, petroleum, natural gas).
Fossil fuels are the most commonly used energy resource. When burned, they release carbon dioxide, harmful acids and other forms of pollution into the air.

16. What are some fossil fuels?
Unit 4 Lesson 4 Protecting Earth’s Water, Land, and Air
What are some fossil fuels?
Coal is a sedimentary rock formed from the remains of dead plants at the bottom of ancient swamps.
Coal mining can involve removing soil and rocks or creating deep mines.
These processes can destroy landscapes and pollute water supplies.

18. What are some fossil fuels?
Unit 4 Lesson 4 Protecting Earth’s Water, Land, and Air
What are some fossil fuels?
Some fossil fuels are gases that became trapped in rock formations.
Methane is the main component of natural gas.
Natural gas burns more cleanly than other fossil fuels. However, it does produce carbon dioxide upon burning, and leaks can be dangerous.

20. What are some fossil fuels?
Unit 4 Lesson 4 Protecting Earth’s Water, Land, and Air
What are some fossil fuels?
Petroleum means “rock oil.” It formed from the remains of single-celled aquatic organisms that lived long ago.
After petroleum is mined, it is separated into fuels such as gasoline, diesel, and jet fuel.
Transporting oil can result in spills that pollute the environment and harm wildlife. Burning petroleum produces pollutants.

22. How can we reduce air pollution?
Unit 4 Lesson 4 Protecting Earth’s Water, Land, and Air
How can we reduce air pollution?
There are many ways to conserve energy, such as by using energy-efficient appliances, decreasing our use of air conditioners and heaters, and using public transportation.
There are also many ways to generate energy without creating much air pollution.
By developing technology for alternative energy resources, we reduce the amount of pollution created by burning fossil fuels.
For example, electricity can be generated by wind turbines, solar panels, moving water, and geothermal energy.

24. How can we reduce air pollution?
Unit 4 Lesson 4 Protecting Earth’s Water, Land, and Air
How can we reduce air pollution?
Governments in many countries work independently and together to reduce air pollution.
Because air isn’t contained by borders, some solutions must be international.
The Kyoto Protocol is a worldwide effort to limit the release of greenhouse gases—pollution that can warm the atmosphere.