1. CHAPTER 13 – ATMOSPHERE AND CLIMATE CHANGE Section 3a – Climate Change

2. The Greenhouse Effect Some of the gases in the atmosphere act like a greenhouse. Some gases will trap heat from the Sun and cause it to continually radiate through the Earth.

3. Greenhouse Gases Major Greenhouse Gases Water Vapor CO 2 Methane CFCs Nitrous Oxide Ozone Water Vapor and CO 2 account for most of heat absorption and reflection.

4. Measuring CO 2 Levels fall in the spring and summer. (Photosynthesis) Levels increase in the fall and winter. Records show a 20% increase in CO 2 in the last 50 years.

5. Rising CO 2 Levels Rise is mainly due to burning of fossil fuels. Levels today are higher than they have been for the last 420,000 years. Past levels can be estimated from ice core drilling samples.

6. Increased Greenhouse Effect Increased CO 2 production has lead to a greater greenhouse effect and warmer temperatures.

7. Global Climate Change Global Warming The gradual increase in the average surface temperature of the Earth. Temperatures are trending upwards. Short term oscillations occur but overall trend is up.