What is the primary greenhouse gas of concern?

• A. Methane
• B. Ozone
• C. Carbon Dioxide
• D. Nitrous oxide

Answer: (C)

The main idea here is that the overall warming impact of a greenhouse gas depends on how much of it is in the atmosphere and how long it stays there. Carbon dioxide is present in the atmosphere in the largest amounts and remains for centuries, so human-made CO2 emissions accumulate and drive the majority of long-term climate warming. Methane, while more effective at trapping heat per molecule, lasts only about a decade or so, so its total contribution over many decades is smaller than CO2’s, despite its stronger heat-trapping per molecule. Nitrous oxide is potent and long-lived but far less abundant than CO2, and ozone acts as a greenhouse gas but is more variable and less of a long-term driver. So, carbon dioxide stands out as the primary greenhouse gas of concern due to its large, long-lasting presence and the dominant share of human-caused warming it represents.