Understanding Methane's Global Warming Potential

The question asks us to compare the Global Warming Potential (GWP) of methane ($\text{CH}_4$) to that of carbon dioxide ($\text{CO}_2$). Global Warming Potential is a measure used to compare the warming effects of different greenhouse gases over a specific period, usually 100 years.

The GWP of carbon dioxide ($\text{CO}_2$) is used as the baseline and is defined as 1.

Methane ($\text{CH}_4$) is a potent greenhouse gas, significantly more effective at trapping heat than $\text{CO}_2$ over shorter time scales. The GWP value for methane depends on the time horizon considered:

• Over a 20-year period, the GWP of $\text{CH}_4$ is much higher.
• Over a 100-year period, which is commonly used for comparison, the GWP of $\text{CH}_4$ is estimated to be around 21 to 30, depending on the specific dataset and methodology used by organizations like the Intergovernmental Panel on Climate Change (IPCC).

Considering the options provided and the standard 100-year GWP estimates, the value of 21 is a widely accepted approximation for the GWP of methane ($\text{CH}_4$) relative to carbon dioxide ($\text{CO}_2$) taken as 1.

Therefore, the global warming potential of $\text{CH}_4$ is approximately 21 times that of $\text{CO}_2$ over a 100-year period.