1. Anything that causes pollution is called a pollutant. Examples:
Section 1 Environmental Problems
Pollution
An unwanted change in the environment caused by substances, such as wastes, or forms of energy, such as radiation, is called pollution.
Anything that causes pollution is called a pollutant.
Examples:
Garbage
Chemicals
Radioactive waste
Greenhouse gases: Carbon dioxide, CO2
Noise

2. Section 1 Environmental Problems
Resource Depletion
A renewable resource is one that can be replaced at the same rate at which the resource is used.
Examples
Water
Wind
Trees
Solar
A nonrenewable resource is one that cannot be replaced or that can be replaced only over thousands or millions of years.
Fossil fuels
Oil
Natural gas
Coal

3. Section 1 Environmental Problems
Exotic Species
People may carry plant seeds, animals eggs, or adult organisms with them as they move from one part of the world to another.
An organism that makes a home for itself in a new place outside its native home is an exotic species. Exotic species often thrive in new places, and can become pests and compete with native species.

4. Human Population Growth
Section 1 Environmental Problems
Human Population Growth
Overpopulation happens when the number of individuals becomes so large that the individuals can’t get the resources they need to survive. Some people argue that there may eventually be too many people on Earth.

5. Section 1 Environmental Problems
Habitat Destruction
When land is cleared for construction, crops, mines, or lumber, organisms that were living in the areas may be left without food and shelter. These organisms may die.
An organism’s habitat is where it lives. Every habitat has a number and variety of organisms, or biodiversity. If a habitat is damaged or destroyed, biodiversity is lost.

6. Section 1 Environmental Problems
Forest Habitats Trees provide humans with oxygen, lumber, food, rubber, and paper. For some of these products, trees must be cut down. Deforestation is the clearing of forest lands.
Marine Habitats Many people think of oil spills when they think of pollution in marine habitats. Spilled oil pollutes both open waters and coastal habitats. In addition to oil, chemicals and plastics are sometimes dumped into marine habitats.

7. Section 2 Environmental Solutions
Conservation
Conservation is the preservation and wise use of natural resources.
Conservation helps reduce waste and pollution. Conservation can help prevent habitat destruction.
The three Rs describe three ways to conserve resources: Reduce, Reuse, and Recycle.

8. Section 2 Environmental Solutions
Reduce
Reducing Waste and Pollution As much as one-third of the waste produced by some countries is packaging material. Products can be wrapped in less paper and plastic to reduce waste.
Reducing the Use of Nonrenewable Resources Some scientists are looking for sources of energy that can replace fossil fuels. In some parts of the world, solar energy can be used to power homes.

9. Section 2 Environmental Solutions
Maintaining Biodiversity
Protecting Species One way to maintain biodiversity is to protect individual species. In the United States, a law called the Endangered Species Act was designed to do just that.
Protecting Habitats Each organism is part of a huge, interconnected web of organisms. The entire web should be protected to protect these organisms.

10. Reduce and pesticide use. Protect habitats. Learn about local issues.
Section 2 Environmental Solutions
Environmental Strategies
Reduce pollution.
Reduce and pesticide use.
Protect habitats.
Learn about local issues.
Develop alternative energy sources.