When burned, which fuel source emits the highest amount of carbon dioxide?

The reason coal emits the highest amount of carbon dioxide when burned is primarily due to its carbon content and the efficiency of the combustion process. Coal is a carbon-intensive fossil fuel, meaning it contains a high percentage of carbon compared to other fuels. When burned, this carbon combines with oxygen to form carbon dioxide, a significant greenhouse gas contributing to climate change.

In comparison, while oil and natural gas also emit carbon dioxide, they generally have a lower carbon content per unit of energy produced. Natural gas, for instance, primarily consists of methane, which is a cleaner-burning fuel and produces less carbon dioxide than coal when combusted. Wood, while renewable, can also emit a substantial amount of carbon dioxide, especially if not managed sustainably, but its overall emissions are typically lower than those from coal.

This distinction highlights the environmental impact of different fuel sources and underscores the importance of energy choices in efforts to mitigate climate change. Thus, coal stands out as the fuel that, when burned, contributes the most to carbon dioxide emissions.