Question

Without greenhouse effect, the average temperature of earth’s surface would have been
A) $ - 18^\circ {\text{C}}$
B) $33^\circ {\text{C}}$
C) $0^\circ {\text{C}}$
D) $15^\circ {\text{C}}$

Answer 1

Hint:
A greenhouse effect is created by carbon dioxide released in the atmosphere trapping the heat radiated from the earth. The earth would have been too cold to live in without this greenhouse gas.

Complete answer:
Without the greenhouse effect, the average temperature of the earth’s surface would have been $ - 18^\circ {\text{C}}$ which would have been too cold for life on earth. About $75\% $ of the solar energy reaching the earth is absorbed by the earth’s surface, which increases its temperature and keeps it warm thus making life perfect on earth. The rest of the heat is radiated back to the atmosphere. Some of the heat is trapped by gases such as carbon dioxide, methane, ozone, chlorofluorocarbon compounds (CFCs), and water vapour in the atmosphere.
Solar radiations pass through the transparent glass and heat up the soil and the plants in a greenhouse. Infrared radiations are then emitted by the warm soil and plants. Since glass is opaque to infrared radiations, it partly absorbs and partly reflects these radiations. This mechanism keeps the energy and warmth of the sun trapped inside the greenhouse. A similar situation is observed on earth also.

Thus, option (A) is correct.

Note:
When the level of carbon dioxide in the atmosphere increases due to factory smoke or car fumes, the heat retained increases the temperature of the earth. This is called global warming. This rise in temperature causes the snow and glaciers in the coldest parts of the world to melt. The sea level rises, as a result, causing floods in coastal areas. There may be drastic changes in the climate of a place leading to the extinction of some plants and animals in the long run.