1. Chapter 7 : Climate Interactions
Lesson 6: Human Activity and Climate Change

2. Lesson 6: Human Activity and Climate Change
Objectives:
To keep in mind:
After this lesson, students will be able to:
Explain the importance of the ozone layer and how it had been damage.
Explain how the green house effect helps to insulate the planet by keeping the atmosphere at a relative even temperatures, and how human activities are affecting the temperature of the atmosphere.
How does the ozone layer protects Earth?
How does the atmosphere help to insulate Earth?

3. How big is your footprint?
Today people are measuring their effect on the environment by looking at their carbon footprint. Carbon is one of the greenhouse gases most responsible for warming Earth’s climate. Your carbon footprint measures the total amount of greenhouse gases you emit directly and indirectly. Cars, factories, and home heating all rely on fuels that release carbon into the atmosphere. The manufacturing of products you use, like food and clothing, does, too. When people know how big their carbon footprints are, they can make changes that improve their own lives and the environment.

4. How does the ozone layer protects Earth?
Ozone is a form of oxygen that has three oxygen atoms in each molecule instead of the usual two.
Ozone in the atmosphere absorbs some of the harmful radiation from the sun. The ozone layer is a layer of the upper atmosphere.
It is about 15 to 30 kilometers above Earth’s surface.
It protects people from the effects of too much ultraviolet radiation.

5. Ozone Cycle
Ozone in the atmosphere is constantly being created and destroyed.

6. How does the ozone layer protects Earth?
Ozone is constantly being made and destroyed as part of the ozone cycle.
The amount of ozone in the ozone layer is decreasing, creating an ozone hole.
Scientists determined that the major cause of the ozone hole is a group of gases called CFCs. CFCs, or chlorofluorocarbons, are human-made gases that contain chlorine and fluorine.
CFCs were used in many household products. Most uses of CFCs were banned in 2000.
Scientists predict that if the ban on ozone-depleting substances is maintained, the ozone layer will gradually recover.

7. Human Activities and Climate Change
Ozone Hole
The ozone hole (shown in blue) is over Antarctica. The hole has grown over time, but its size varies seasonally and from year to year. Mario José Molina and two other scientists won the Nobel Prize for Chemistry in 1995 for their theory that gases used in many household products help create the hole.

8. How does the atmosphere help to insulate Earth?
Greenhouse Effect
The sun warms Earth’s surface, and the heat is radiated back through Earth’s atmosphere to space as infrared waves.
The atmosphere keeps Earth’s surface warm through the greenhouse effect.
Greenhouse gases
Carbon dioxide, methane, and water vapor absorb the heat leaving Earth’s surface. They make up only 1 percent of the atmosphere.
Levels of Greenhouse Gases
Many human activities are increasing the level of greenhouse gases in the atmosphere.
This increase is causing global temperatures to rise.

9. Human Activities and Climate Change
Greenhouse Effect
Which word in the Word Bank completes each sentence?

10. How does the atmosphere help to insulate Earth?
Carbon Dioxide Levels
The most abundant greenhouse gas is carbon dioxide.
Most of the carbon dioxide in the atmosphere was released by human beings burning fossil fuels— energy-rich substances formed from the remains of organisms.
Over the last 120 years, the average temperature of the troposphere has increased 0.7°C.
This gradual increase in the temperature of Earth’s atmosphere is called global warming.
Models of climate change predict that global temperatures will rise several degrees over the next hundred years.

11. Human Activities and Climate Change
Carbon Dioxide Levels
The graph shows the levels of carbon dioxide in the atmosphere over time.

12. How does the atmosphere help to insulate Earth?
Effects of Global Warming
The effects of global warming include melting glaciers, rising sea levels, drought, desertification, changes to the biosphere, and regional changes in temperature.
Global temperature changes affect regions differently.
Rising global temperatures cause some regions to get very warm and dry.
Severe droughts cause some lands to become deserts, and this process leads to food shortages.
Rising temperatures cause sea levels to rise because of melting glaciers, and they upset the balance of organisms in some ecosystems as organisms are forced to move to new locations to find familiar climates.

13. Human Activities and Climate Change
Sea Level Rise
The satellite image shows how sea level rise could affect the eastern United States.