If there was no CO2 in the earth’s atmosphere, the temperature of earth’s surface would be
Less than the present level
When sunlight is absorbed by the surface of the Earth, the surface heats up and emits a different kind of radiation, known as infrared radiation. Carbon dioxide is a special compound which is transparent to solar radiation and yet it absorbs infrared radiation. Thus, the presence of carbon dioxide in our atmosphere allows sunlight to penetrate to the surface but inhibits the emission of infrared radiation to space.