Which Gas is not a Greenhouse Gas

APPSC PGT 2018

Which of the following gases is not a greenhouse gas?

• (A) CO
• (B) O₃
• (C) CH₄
• (D) H₂O Vapour

Correct Answer: (A) CO

Explanation:

Carbon Monoxide (CO) is not a direct greenhouse gas because it doesn't significantly absorb infrared radiation. While it influences the lifetime of methane and ozone, it is categorized as a criteria pollutant rather than a primary GHG.

• (B) O₃ (Ozone): A greenhouse gas in the troposphere that traps outgoing longwave radiation.
• (C) CH₄ (Methane): A potent GHG, roughly 25 times more effective at trapping heat than CO₂ over a 100-year period.
• (D) H₂O Vapour (Water Vapour): The most abundant greenhouse gas, responsible for the largest portion of the natural greenhouse effect.