How can deforestation contribute to global warming?
Deforestation is the removal of trees; thus, more carbon dioxide builds up in the atmosphere since it is not being removed by what process?
You know it--a process that uses carbon during carbon fixation, therefore reducing carbon dioxide. This process also happens to increase the oxygen concentration in that same atmosphere. Carbon will be fixed by these plants (trees) in order to do what?
To make, ultimately, food in the form of sugars. Sugars are really 'stored' chemical energy, or a different form of energy from sunlight.