1. Carbon dioxide is naturally produced by various sources. such as volcanic eruptions. decomposition of organic matter. and respiration in plants and animals. 2. However. the primary source of carbon dioxide is human activities. The burning of fossil fuels. including coal. oil. and natural gas for energy production and transportation. accounts for the largest portion. Additionally. deforestation. industrial processes. and certain agricultural practices also contribute to CO2 emissions. 3. Both humans and animals release carbon dioxide through breathing. 4. The exchange between the ocean and atmosphere also plays a role in the distribution of CO2. The oceans both release and absorb carbon dioxide in a dynamic equilibrium. 5. Decomposition is another process that releases carbon dioxide into the atmosphere when bacteria break down the bodies of plants and animals. 6. Burning wood also releases stored carbon in the form of carbon dioxide.