1. The Greenhouse Effect Subtitle

2. What you need today: Pencil Bellringer sheet Everything else on the counter. Bellringer # 3 What are greenhouse gases? How are they related to the greenhouse effect?

3. Today’s Objectives Students will be able to: Explain the greenhouse effect. Build and test a physical model of greenhouse effect. Describe how atmosphere insulates the planet.

4. The Greenhouse Effect  In a greenhouse, sunlight shines in and warms the plants and air inside, but the heat is trapped by the glass and can't escape.  Earth's atmosphere is similar to greenhouses because gases in the atmosphere do the same thing that the roof and walls of a greenhouse do.  These gases, such as carbon dioxide, are called greenhouse gases.  Greenhouse gases help keep temperatures on Earth warm enough for living things to survive, by absorbing Earth’s outgoing infrared radiation.

5. Earth’s Rising Temperature  But what happens if the greenhouse effect is too strong?  Higher levels of greenhouse gases, like CO2, create a greater greenhouse effect.  Average temperatures on Earth have been increasing for the past 100 years, in addition to the carbon dioxide concentration in the atmosphere.

6. Global Warming  The rise in Earth’s average temperature during the past 100 years is often referred to as global warming.  Natural sources of carbon dioxide include volcanic eruptions and forest fires.  Cellular respiration in organisms contributes additional carbon dioxide.

7. Global Warming  In 2007, the Intergovernmental Panel on Climate Change (IPCC) concluded that most of this temperature increase, or global warming, is due to human activities.  These activities include burning fossil fuels and the large-scale cutting and burning of forests, which release greenhouse gases into the atmosphere.

8. Deforestation  Humans use deforestation to obtain fuel or clear farm land.  Burning trees adds more carbon dioxide into the atmosphere.  How else does eliminating forests keep the carbon dioxide concentration high?  Deforestation affects global climate because there are fewer living trees to help remove carbon dioxide from the air.

9. Environmental Impact  Increasing temperatures can impact the environment in many ways.  Melting glaciers and polar ice sheets can cause sea levels to rise and coastal ecosystems to be disrupted.  Extreme weather events can become more common.  Permanently higher temperatures and other ecosystem changes can affect migration patterns of insects, birds, fish, and mammals.

10. What can we do? There are ways to reduce pollution and greenhouse gases:  developing alternative energy sources, such as solar and wind energy.  building energy-efficient buildings.  controlling greenhouse gases and pollution by conserving fuel and recycling.