Greenhouse effect is basically the process through which infrared radiations are emitted by the atmosphere which result in warming of a planet's surface. Aforestation has reduced the number of trees. The trees play a major part in producing oxygen as they inhale CO2 gas and exhale Oxygen. CO2 is the major part of greenhouse gases that create green house effect. So elimination of trees means less Oxygen and more CO2 which results in more greenhouse gases.
