Question

Which of the following gases plays a critical role in the greenhouse effect despite its low percentage in the atmosphere?

• A. Oxygen
• B. Argon
• C. Carbon dioxide
• D. Nitrogen

Answer 1

Answer:

C. Carbon dioxide

• Correct Answer: Option C) Carbon dioxide

• Carbon dioxide (CO₂) plays a critical role in the greenhouse effect despite making up only about 0.03-0.04% of Earth's atmosphere. While this percentage seems small, CO₂ is extremely effective at trapping heat radiated from Earth's surface.

• The greenhouse effect works through the following mechanism:

• Solar radiation enters Earth's atmosphere and warms the surface

• Earth's surface radiates heat back toward space as infrared radiation

• Greenhouse gases like CO₂ absorb this infrared radiation and re-emit it in all directions

• This trapping of heat warms the lower atmosphere and Earth's surface

• Although nitrogen (78%) and oxygen (21%) make up the vast majority of our atmosphere, they are not greenhouse gases because they don't absorb infrared radiation effectively. Argon (0.93%) is also not a greenhouse gas.

• Carbon dioxide's molecular structure allows it to vibrate when it absorbs infrared radiation, making it highly effective at trapping heat. Even though water vapor is actually the most abundant greenhouse gas, CO₂ is considered the most important long-lived greenhouse gas due to human activities like burning fossil fuels, which have significantly increased atmospheric CO₂ concentrations since the Industrial Revolution.