Carbon dioxide, CO$_2$ allows the passage of short wave radiations such as ultraviolet and visible radiations but impedes the passage of infrared ( or heat) radiations. Consequently the temperature of earth's surface gets increased. This is known as green house effect. Hence, CO$_2$ is the major green house gas. Other green house gases are CH$_4$, N$_2O$ and H$_2O$ etc.