Question

Which of the following is the most important greenhouse gas in the earth's atmosphere?
1. Nitrogen dioxide
2. Carbon dioxide
3. Water vapor
4. Sulphur dioxide

Answer 1

Correct Answer - Option 2 : Carbon dioxide

The correct answer is Carbon dioxide.

• CO2 is the main greenhouse gas globally.
• Methane is the main greenhouse gas for tropical regions.
• Water vapor is the most important natural greenhouse gas for the tropical region. 

• GREENHOUSE EFFECT:

  • The rays coming from the sun get reflected after striking the earth's surface. Certain gases do not allow the reflected (infrared) rays to escape the earth's atmosphere and thus the heat gets trapped. This phenomenon is known as the greenhouse effect and the gases involved are termed greenhouses gases.
  • The heat trapped increases the temperature of the earth and this phenomenon is known as global warming.
  • Causes of Greenhouse Effect:
    • Burning of Fossil Fuels
    • Deforestation
    • Farming
    • Industrial Waste and Landfills
  • Effects of Greenhouse Effect:
    • Global Warming
    • Depletion of Ozone Layer
    • Smog and Air Pollution
    • Acidification of Water Bodies
  • The prominent greenhouse gases are - Water Vapour, Carbon dioxide, Methane, Nitrous oxide, Ozone, Chlorofluorocarbons, and Hydrofluorocarbons.
• The table given below shows the contribution of various greenhouse gases:

Greenhouse gases	Contribution
Water vapor (H2O)	36-72%
Carbon dioxide (CO2)	9-26%
Methane (CH4)	4-9%
Ozone (O3)	3-7%

• WATER VAPOUR (H₂O):
  • As evident from the above table, it is the most abundant greenhouse gas present in the atmosphere.
  • Warmer air has the capacity of holding more water vapor, which traps more heat. Due to this, a positive feedback loop gets created.
• CARBON DIOXIDE (CO₂):
  • Events like volcanic eruptions, forest fires, burning of fossil fuels lead to an increase in the carbon dioxide concentration in the atmosphere.
• METHANE (CH₄):
  • Though its concentration in the atmosphere is very low, its contribution is approximately 9% in greenhouse gases.
  • It has more heating capacity as compared to water vapor and carbon dioxide.