ALL III

THE GREENHOUSE EFFECT

The Good

The greenhouse effect, when functioning normaly, keeps our planet warm. Natural gases in the atmosphere form a blanket which allows sunlight to reach the earth's surface, but prevents heat from escaping, like the glass in a greenhouse. This gas blanket traps heat close to the surface, and warms the atmosphere.

The Bad

For the first time in history, human activities are altering the climate of our entire planet. In less than two centuries, humans have increased the total amount of carbon dioxide in the atmosphere by 25% from the burning of fossil fuels and the destruction of forests...Unless we reduce emissions of greenhouse gases, the stable, hospitable climate on which civilization is based could become a thing of the past.