Previous Year Question
The increasing amount of carbon dioxide in the air is slowly raising the temperature of the atmosphere, because it absorbs
Correct Answer: D
Detailed Solution
Carbon dioxide is a greenhouse gas. It operates through the following process:
Most incoming short-wave solar radiation passes through the atmosphere and reaches the Earth’s surface.
The Earth’s surface absorbs this energy and becomes warm.
The heated surface emits energy back as long-wave infrared or terrestrial radiation.
Carbon dioxide absorbs part of this outgoing infrared radiation and re-emits it in different directions.
This slows the loss of heat to space and raises the temperature of the lower atmosphere and the Earth’s surface.
Other options:
Option (a) is incorrect: Carbon dioxide does not retain heat by absorbing atmospheric water vapour. Water vapour is itself a greenhouse gas.
Option (b) is incorrect: Stratospheric ozone performs the major role in absorbing ultraviolet radiation.
Option (c) is incorrect: Carbon dioxide does not absorb all forms of solar radiation.
Scientific clarification: Option (d) refers to “solar radiation,” but greenhouse warming is primarily caused by CO₂ absorbing the long-wave terrestrial infrared radiation emitted by the Earth. Nevertheless, infrared radiation is the intended concept, making option (d) the correct answer.