Answer:
A greenhouse gas (sometimes abbreviated GHG) is a gas that absorbs and emits radiant energy within the thermal infrared range. Greenhouse gases cause the greenhouse effect[1] on planets. Without greenhouse gases, the average temperature of Earth's surface would be about −18 °C (0 °F),[2] rather than the present average of 15 °C (59 °F).[3][4][5] The atmospheres of Venus, Mars and Titan also contain greenhouse gases.
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