The rainforest's use up almost all of the oxygen that they put out. As far as carbon dioxide they are pretty net zero in the end. It is the Algie blooms that

The rainforest's use up almost all of the oxygen that they put out. As far as carbon dioxide they are pretty net zero in the end. It is the Algie blooms that produce the oxygen surplus. While fun to say, rainforest's are not the earth's lungs. But don't take my word for it, checkout either the very good video (or search the transcript for "lungs") http://www.pbs.org/wgbh/nova/space/earth-from-space.html http://www.pbs.org/wgbh/nova/space/earth-from-space.html