Recall water vapour, carbon dioxide, nitrous oxide, methane and CFCs (chlorofluorocarbon) are green house gases
As shown in the diagram when infra red rays come from the sun come rays could be reflected back into space (50%), turned from UV into Infra Red rays on the surface (available as heat) or trapped in our atmosphere by green house gases. What greenhouse gases does is when infra red rays get reflected back out the space the infra red rays could hit greenhouse gases, it will absorb the energy and re-emitt the infra red but also re-distributes the energy back into the surface which increases the surface temperature. Enhanced greenhouse effects refers to the thickening of the greenhouse gas layer through pollutants such as carbon dioxide, methane which will absorb more infra red which will raise the temperature and can lead to climate change.CFCs deplete the ozone layer (O3) into O2, O3 is good at absorbing UV light and depleting it means more UV light will get to the surface. [CCl2F=sunlight>CCLF+CL-] Sources of CFCs are aerosols, air conditioner, refrigeration etc.