The Greenhouse Effect Subtitle

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?

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.

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.

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.

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.

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.

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.

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.

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.