GLOBAL WARMING

What is global warming?
Global warming is when the earth heats up (the temperature rises).  It happens when greenhouse gases (carbon dioxide, water vapor, nitrous oxide, and methane) trap heat and light from the sun in the earth’s atmosphere.

What is the greenhouse effect?
The greenhouse effect is when the temperature rises because the sun’s heat and light is trapped in the earth’s atmosphere.

If you whant to enter to some pages with information in global warming enter to:
http://library.thinkquest.org/CR0215471/global_warming.htm
http://environment.nationalgeographic.com/environment/global-warming/gw-overview/