Rain forests are important not only for the plants and animals that live in them but for the medicines that come from them. They also have major effects on the earth's atmosphere and climate. According to some scientists, global warming is causing dangerous changes to the earth's climate. Rain forests can help us to fight global warming. Some scientists believe that rain forests cool the atmosphere by absorbing the sun's heat. To absorb means "to soak up." Also, plants and trees use carbon dioxide. The cause of global warming is an increase of gases like carbon dioxide in our atmosphere. So rain forests can clean some of the excess (extra) carbon dioxide out of the air.