1. The Greenhouse Effect The sun emits solar radiation which the Earth absorbs (UV rays). The Earth emits its own energy (heat waves called infrared rays) back into space. Some gases in our atmosphere such as water vapor H 2 O, carbon dioxide CO 2, methane CH 4 and nitrous oxide N 2 O form a “blanket” around our planet and trap some of the outgoing infrared rays from reaching space. Because this energy is trapped in the atmosphere, it acts as a blanket and warms up the Earth.

2. The Earth Needs Greenhouse Gases! If there were no greenhouse gases warming up the Earth by intercepting heat waves from going to space, the Earth would be overall 33 ̊ C colder. The Earth would freeze, oceans would turn to ice and life would not be possible.

3. The Intensification of the Greenhouse Effect Over the last century, there has been a significant increase in greenhouse gases in our atmosphere (largely due to the combustion of fossil fuels which produce CO 2 and NO 2 ). More greenhouse gases means more heat being trapped in our atmosphere.

4. Clearing land for farming (burning forests) releases enormous amounts of CO2.

5. Methane CH 4 is a more dangerous greenhouse gas than CO 2 (it has the ability to trap more heat). Methane is released into the atmosphere when sheep and cattle digest, when manure is spread on fields, when household waste decomposes, in rice fields, etc.

7. Climate Change Because of the increase in greenhouse gases in the atmosphere, less heat waves emitted by the Earth are able to make their way to space. As a result, overall temperatures on Earth are increasing. Climate Change: Abnormal climatic conditions on Earth caused by human activity

8. Try This! 1. Which of the following gases do not contribute to the greenhouse effect? A. CO2 B. CH4 C. NO2 D. SO2 2. Explain how human activity has affected the accumulation of greenhouse gases in our environment. Describe some of these environmental impacts.