A greenhouse gas is a gas in an atmosphere that absorbs and emits radiant energy within the thermal infrared range. This process is the fundamental cause of the greenhouse effect. The primary greenhouse gases in Earth’s atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone. Without greenhouse gases, the average temperature of Earth’s surface would be about −18 °C (0 °F), rather than the present average of 15 °C (59 °F). In the Solar System, the atmospheres of Venus, Mars and Titan also contain gases that cause a greenhouse effect.
- any gas, such as carbon dioxide or CFCs that contribute to the greenhouse effect when released into the atmosphere
- A component of the atmosphere that influences the greenhouse effect, namely carbon dioxide, methane, nitrous oxides, ozone, CFCs and water vapour.