Global warming is the one of the obvious effects of the deforestation. Trees make food by photosynthesis which can absorb the carbon dioxide and release the oxygen. Trees are cutting down and there are less trees to produce the oxygen. Just think about the Christmas in New York City, it supposes to snow, but it doesn't and the Yew Year' s too. Actually some trees are blooming.
Some people call rainforest the air condition of the planet earth.
The other effect of the deforestation of rainforest is destruction of habitat and cause many species disappeared from the earth. That is a incalculable medical value for human being. The animal species also decreased rapidly because of the destruction of rainforest. Now, we know that farming, ranching, and logging are three major cause of the destruction of the rainforest, then we have to learn something from these causes. After we knew the causes, we can do some efforts to reduce the causes.