Final answer:
Methane has a residence time of approximately 9 to 12 years and is 25 times more effective at trapping heat than CO2 on a 100-year time scale.
Step-by-step explanation:
The residence time of methane (CH4) in the atmosphere is approximately 9 to 12 years. Methane is a potent greenhouse gas which traps significantly more heat than CO2; it is about 25 times more effective at trapping heat on a 100-year time scale. Methane emissions come from a variety of sources, including natural processes and human activities such as agriculture, fossil fuel extraction, and landfills. Although methane is present in smaller quantities than CO2 in the atmosphere, its high heat-trapping ability makes it an important target for climate mitigation efforts, such as flaring at oil drilling sites.