The two main sources of carbon in the atmosphere are carbon dioxide and which other compound?

The two main sources of carbon in the atmosphere are carbon dioxide and methane. Methane is a potent greenhouse gas that contributes significantly to the overall carbon content and is produced through both natural processes and human activities. Natural sources include decomposition of organic matter in wetland areas, while human activities contribute to its release through agricultural practices, landfills, and fossil fuel extraction. Methane is approximately 25 times more effective than carbon dioxide at trapping heat over a 100-year period, making it a crucial component of atmospheric carbon management and climate discussions.

The other options do not serve as significant sources of atmospheric carbon. Nitrogen is a major component of the atmosphere but does not contain carbon. Carbonation refers to the process of dissolving carbon dioxide in liquids, like carbonated beverages, rather than a source of atmospheric carbon. While living organisms do contribute to carbon cycles through respiration and decomposition, they are not a direct source of atmospheric carbon in the same way that carbon dioxide and methane are.