Question

Which of the following gases give the lowest percentage contribution to total global warming?

• A. N2O
• B. NO2
• C. CFCs
• D. CH4

Answer 1

The Correct Option is B

The gas that gives the lowest percentage contribution to total global warming is NO₂ (Nitrogen Dioxide).

Additional Context:

• Global Warming Contributions:
  • CO₂: ~76% of total (not listed in options)
  • CH₄ (Methane): ~16% (high warming potential but shorter lifespan)
  • N₂O (Nitrous Oxide): ~6% (long atmospheric lifetime)
  • CFCs: ~1-2% (declining due to Montreal Protocol)
  • NO₂: <1% (short-lived, indirect effects)
• Key Properties:
  • NO₂:
    • Atmospheric lifetime: Hours to days
    • Indirectly affects warming via ozone formation
    • Primarily an air pollutant, not major GHG
  • Other gases:
    • N₂O: 114-year lifetime, 298x CO₂ potency
    • CFCs: 50-500 year lifetime, 1000s x CO₂ potency
    • CH₄: 12-year lifetime, 28x CO₂ potency
• Measurement Sources:
  • IPCC AR6 (2021) assessments
  • NOAA's Annual Greenhouse Gas Index
• Climate Impact Pathways:
  • NO₂ contributes more to:
    • Photochemical smog
    • Acid rain formation
    • Tropospheric ozone production

Correct Answer: (2) NO₂.