Greenhouse gases (GHG) are the gases present in the atmosphere that have the property to absorb and re-emit the infrared radiation waves emitted by the Earth’s surface (both land and ocean). The absorption & re-emitting inhibits the radiation from exiting the atmosphere, thus generating a greenhouse effect which increases the temperature on the planet, also known as global warming. Amongst the different GHGs, the most abundant one is carbon dioxide (CO₂).

Source: Intergovernmental Panel on Climate Change