What is the main source of carbon dioxide in the atmosphere?

The main source of carbon dioxide in the atmosphere is the complete combustion of carbon-containing fuels. When fuels such as coal, oil, and natural gas are burned efficiently, they react with oxygen to produce carbon dioxide and water. This process occurs in power plants, vehicles, and industrial facilities where carbon-based fuels are used, leading to significant emissions of carbon dioxide.

While incomplete combustion does occur and also produces carbon dioxide, it primarily results in other by-products like carbon monoxide and particulate matter, which is a less efficient process. The decomposition of vegetation can release carbon dioxide, but it happens at a slower rate and is typically balanced by photosynthesis in plants. High temperatures in car engines can indicate inefficient combustion, but they do not directly represent a primary source of carbon dioxide compared to the efficient burning of fossil fuels.

Therefore, the complete combustion of carbon-containing fuels is identified as the primary contributor to the increasing levels of carbon dioxide in the atmosphere, highlighting its significant role in climate change and global warming.