Question

Without the presence of greenhouse gases in the atmosphere, the earth's average surface temperature would be ______ ${}^{\circ }\text{C}$.

• A. -18

Answer 1

The correct option is A -18
The naturally occurring greenhouse gases like carbon dioxide and water vapour, have a warming effect on the Earth. Without them, the entire energy radiated by the Earth and the objects on it, would escape into the space and the average surface temperature would fall to about $-{18}^{\circ }\text{C}$, instead of being at a normal ${15.5}^{\circ }\text{C}$.