Animals affect the amount of carbon in Earth's atmosphere primarily through the process of cellular respiration. When animals eat plants, they consume carbon stored in plant tissues. Through cellular respiration, animals convert this carbon in glucose into energy, releasing carbon dioxide (CO2) and water as byproducts back into the atmosphere

. This CO2 contributes to the atmospheric carbon pool. More specifically, animals inhale oxygen and exhale carbon dioxide produced by metabolizing the carbon compounds in their food. This process increases the carbon dioxide concentration in the atmosphere

. Additionally, farm animals produce measurable amounts of CO2 through respiration and manure decomposition, which can vary depending on species and size

. Thus, animals play a role in the carbon cycle by returning carbon from plants back into the atmosphere as CO2, influencing atmospheric carbon levels and, consequently, Earth's climate system