What is the main gas responsible for the greenhouse effect on Earth?

The main gas responsible for the greenhouse effect on Earth is carbon dioxide (CO2). This gas plays a significant role in trapping heat in the atmosphere, allowing the planet to maintain a temperature conducive to life. Carbon dioxide is produced through various natural processes, such as respiration and volcanic eruptions, as well as human activities, like burning fossil fuels and deforestation.

While other gases, such as methane, also contribute to the greenhouse effect, carbon dioxide is the primary long-lived greenhouse gas in Earth's atmosphere, making it a critical focus in discussions about climate change. Methane, although much more effective at trapping heat over a shorter term, is present in smaller quantities compared to CO2, thus making carbon dioxide the more significant factor in the overall greenhouse effect.

Oxygen and nitrogen, while abundant in Earth’s atmosphere, do not significantly contribute to the greenhouse effect, as they do not have the same heat-trapping properties as carbon dioxide and methane.