Greenhouse gases other than carbon dioxide Which of the following substances are recognised greenhouse gases besides CO2?

Introduction / Context:
Greenhouse gases absorb and re-emit terrestrial infrared radiation, altering Earth’s energy balance. While carbon dioxide is the most widely discussed, other gases can possess higher global warming potentials and play outsized roles over specific time horizons.

Given Data / Assumptions:

• Methane (CH4), nitrous oxide (N2O), and chlorofluorocarbons (CFCs) are evaluated as atmospheric constituents.
• Focus is on radiative forcing contributions, not only abundance.

Concept / Approach:
CH4, N2O, and CFCs are all potent greenhouse gases. CH4 arises from agriculture, energy, and waste sectors. N2O originates from soils, fertilizers, and combustion. CFCs (and related halocarbons) are strong infrared absorbers; although controlled under international agreements due to ozone depletion, their greenhouse effect remains significant for molecules already emitted.

Step-by-Step Solution:

Verification / Alternative check:
Climate assessments rank CH4, N2O, and CFCs among key non-CO2 greenhouse gases, confirming the selection.

Why Other Options Are Wrong:

Common Pitfalls:
Conflating ozone-depleting potential with greenhouse potency; the two properties are related to different atmospheric processes.

Final Answer:
All (a), (b) and (c)