Chapter 20.1: People and Their Environments


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Grade 8 Integrated Science Chapter 20 Lesson 1 on people and their impact on the environment. This lesson is a short introduction of the positive and negative impact of human. Students should consider the net impact of the 7 billion people on earth and the effect that individuals can make.

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Chapter 20.1: People and Their Environments

  1. 1. Chapter 20 Lesson 1 P718-722 PEOPLE AND THEIR ENVIRONMENTS
  2. 2. Population and Carrying Capacity  For scientist, a population is all the members of a species living in a given area.  You are a population of humans! (hurray)  There are also birds and trees that make up separate populations in your area.
  3. 3. The Human Population  Earth was once home to relatively few humans  Today, about 6.7 billion people live on Earth. The greatest increase in human population occurred during the last few centuries
  4. 4. Population Trends  A sudden rise in human population that has happened in recent history is called a population explosion.  Look at the chart
  5. 5. What caused this sharp increase? • Improved health care • Clean water • Technological advancements * In 1 hour about 15000 babies will be born
  6. 6. Population Limits  All living things have certain needs.  What do humans need? Food, clothing, clean water, shelter  Where do all the materials we use for products come from? Nature!  Does Earth have enough resources to support an unlimited number of humans?
  7. 7. Population Limits  Earth has limited resources  It cannot support a population of any species in a given environment beyond its carrying capacity  Carrying capacity is the largest number of individuals of a given species that earth’s resources can support and maintain for a long time.  If the human population continues to grow beyond Earth’s carrying capacity, eventually Earth’s resources will run out.
  8. 8. Impact of Daily Actions  As of 2012, the human population is 7.046 billion Everyone is using resources Think, everyday people should be drinking 2-3 liters of liquids a day That’s 14,000,000,000L of liquid consumed in a day used just for drinking (if everyone got the necessary amount)
  9. 9. Consuming Resources  Like most people, I hope you are taking a shower everyday. What resources are needed to make that happen? The metals in the pipes are obtained through mining, which causes pollution and destroys habitats Gasoline is needed to transport those metals, which releases pollution into the atmosphere You probably use a cotton towel. Fertilizers often used to grow crops run off into water and affect overall water quality  Think about all the activities you do in a week and the resources needed to make them possible. Then, multiply that by 7 billion. This why using resources wisely, even at a personal level, can help Earth
  10. 10. Positive and Negative Impacts  Not all human activities have a negative impact on the environment.  What are some positive and negative impacts of humans?
  11. 11. Check Out GapMinder  Food Supply (Y-axis) Population (x) GDP (size)