Global Warming Chapter 13 Section 3

Learning Targets Students will understand the importance of the greenhouse effect. Students will understand why the carbon dioxide content of the atmosphere is increasing. Students will understand the consequences of a warmer Earth.

The Greenhouse Effect One minute quick write: Why might the Earth be similar to a green house? The Earth’s atmosphere acts like glass in a greenhouse. Some heat escapes to space. The rest of the heat is absorbed by Earth’s gases, called GREENHOUSE GASES. KEEPS US ALIVE!!

Types of Greenhouse Gases Water Vapor Carbon Dioxide Chlorofluorocarbons Methane Nitrous Oxide Water vapor and carbon dioxide account for most of the absorption of heat

Carbon Dioxide Levels World carbon levels measured in Mauna Loa Hawaii. CO 2 levels have increased by 20% in less than 50 years. This increase is due to the CO 2 released by burning fossil fuels. CO 2 levels are the highest they have been in 420,000 years.

One minute quick write: How do scientists associate increase in average global temperature to an increase in greenhouse gases?

Global Warming Global Warming- an increase in the average temperature at Earth’s surface over the 20 th century to today The temperature is rising at a similar rate to the increase in greenhouse gases. One minute quick write: What part of history do you think may have contributed the most to increases in greenhouse gases.

Consequences of a Warmer Earth Melting Ice and Rising Sea Levels Ice melts as global temp. rises One-Minute: Does ice already in water cause sea levels to rise? Why? Sea levels rise from ice on land melting. Millions of coastal residents will be affected. watch?v=JMQ21p93JZc&fe ature=related Global Weather Patterns If Earth warms up, oceans will absorb more heat. Hurricanes thrive on warm water. Hurricanes may become more common. Might cause a change in ocean patterns affecting weather.

Consequences of a Warmer Earth Agriculture Extreme weather events may happen such as droughts will be more frequent Higher temps may result in decreased crop yields Demand for irrigation may increase Effects on Plants and Animals Temperature changes may cause forests to move further to the poles Can change migration patterns of animals and where animals live Can ruin the food chain in the ocean May destroy coral reefs

To finish up… Recent Findings Scientists have found that avg. global temps have risen 0.6˚C. Snow and ice cover have decreased Avg. global sea levels have risen Reducing the Risk Kyoto Protocol 1997 Required nations to reduce carbon emissions by 5% below 1990 levels US did not ratify the protocol Some countries have engaged in reforestation projects