What it is:

Global Warming is actually the Earth's temperature rising. It is caused by pollution. Pollution consists of smoke, carbon dioxide (air that we breathe out), and carbon monoxide. The more pollution is caused, the more global warming gets.Now this is the real problem. Plants convert carbon dioxide into oxygen. Now, because humans need more space to build houses, we cut down forests (which has plants), and we build buildings on it. That causes a huge difference because all the plants, which change all the smoke into fresh air, has been cut down. So more and more smoke is accumulating, and therefore, more and more pollution is caused.