Which process is responsible for the increase of carbon dioxide in the atmosphere?

The increase of carbon dioxide in the atmosphere is primarily linked to respiration. During respiration, organisms—both plants and animals—break down glucose and other organic molecules to release energy. This process involves the consumption of oxygen and the production of carbon dioxide as a byproduct.

Since most living organisms, including humans, carry out respiration, this process contributes significantly to the levels of carbon dioxide in the atmosphere. Even though plants also release carbon dioxide during respiration (especially at night when photosynthesis cannot occur), they generally absorb more carbon dioxide than they release during the day through photosynthesis. However, overall, respiration accounts for a continuous release of carbon dioxide by organisms, which plays a significant role in the carbon cycle and the atmospheric concentration of carbon dioxide.

In contrast, photosynthesis removes carbon dioxide from the atmosphere, nitrogen fixation pertains to the conversion of nitrogen gas into ammonia and does not directly affect carbon dioxide levels, and transpiration is the process of water vapor loss from plants, which also does not influence atmospheric carbon dioxide directly.