Question

__________ is a greenhouse gas that contributes the most to global warming.

• A. Water vapour
• B. Methane
• C. Nitrogen
• D. Ozone

Answer 1

The correct option is A Water vapour

Water vapour accounts for the largest percentage of the greenhouse effect, as it is the most abundant greenhouse gas in the Earth's atmosphere. Between $36\%$ and $66\%$ for clear sky conditions and between $66\%$ and $85\%$ when including clouds, water vapour concentrations fluctuate regionally.

The other greenhouse gases with their percentage of contribution are as follows:

• Carbon dioxide $:9-26\%$
• Methane $:4-9\%$
• Ozone -$3-7\%$

Nitrogen is not a greenhouse gas.