What causes the Greenhouse effect :-

There are some natural greenhouse gases: water vapour, nitrous oxide, carbon dioxide, methane and ozone.

However, over the past fifty years, production of carbon dioxide, nitrous oxide and methane has risen sharply, and a new type of chemical - the chlorofluorocarbon, or CFC - has been introduced as a refrigerant, solvent and aerosol propellant, but it is also a very powerful greenhouse gas, because it can trap a lot of radiation - one molecule of CFC is 12,000 to 16,000 times as effective at absorbing infra-red radiation as a molecule of carbon dioxide.