Question

Considering the global warming potential of CO₂ as one, the global warming potential of CH₄ has been estimated to be approximately :
1. 12
2. 15
3. 21
4. 35

Answer 1

Correct Answer - Option 3 : 21

The correct answer is 21.

• The Global Warming Potential (GWP) was developed to allow comparisons of the global warming impacts of different gases.
• Specifically, it is a measure of how much energy the emissions of 1 ton of a gas will absorb over a given period of time, relative to the emissions of 1 ton of carbon dioxide (CO₂).
• The larger the GWP, the more that a given gas warms the Earth compared to CO2 over that time period.
  • The time period usually used for GWPs is 100 years.
• CO₂ has a GWP of 1 of the time period used because it is the gas being used as the reference.

• Methane (CH₄) is estimated to have a GWP of 21 over 100 years.
  • The CH₄ GWP also accounts for some indirect effects, such as the fact that CH₄ is a precursor to ozone, and ozone is itself a GHG.
• Nitrous Oxide (N₂O) has a GWP 265–298 times that of CO₂ for a 100-year timescale.
• Chlorofluorocarbons (CFCs), hydrofluorocarbons (HFCs), hydrochlorofluorocarbons (HCFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF₆) are sometimes called high-GWP gases because, for a given amount of mass, they trap substantially more heat than CO₂.