How does diffusion play a role in the carbon cycle?

Carbon cycle pertains to how the element carbon, and inorganic and organic carbon containing compounds are cycled in the environment. This involves the carbon dioxide that are breathed out of humans that are subsequently used by plants in carbon dioxide cycle; decaying organisms in the soil as organic carbon to fossil fuels; industrial emissions of carbon; and ocean circulation. In the ocean circulation, carbon rich water in deeper parts of the ocean are cycled towards the ocean surface. Since there is a higher concentration of carbon in the water than in the air, the propensity of the carbon is to diffuse to the atmosphere as carbon dioxide. 

Predator instincts is what causes it