Which of the following gases is a potent greenhouse gas with a high global warming potential and is a key concern in natural gas systems due to leaks?

• A. Nitrous oxide
• B. Carbon monoxide
• C. Water vapor
• D. Methane

Answer: (D)

The main concept is that methane is a potent greenhouse gas with a high global warming potential, and leaks in natural gas systems make it a major climate concern. Methane molecules trap a lot more heat per unit mass than carbon dioxide, especially in the near term, so even small leak rates from production, processing, transmission, and distribution translate into a significant warming impact. Over roughly a century, methane’s global warming potential is about 28–36 times that of CO2, and over a shorter 20-year window it’s higher still, around 80–90 times CO2. Because natural gas is predominantly methane, any fugitive emissions directly increase atmospheric methane levels, making leak detection and reduction a priority. The other options don’t fit this context: nitrous oxide is also a powerful greenhouse gas but isn’t the typical leak-related concern in natural gas systems; water vapor is a large greenhouse gas but its levels are governed mainly by temperature and natural processes, not leaks from energy infrastructure; carbon monoxide is toxic and, while it affects air quality, it is not a long-lived greenhouse gas.