Why are changes in the global carbon cycle important?

Carbon is exchanged, or "cycled" among Earth's oceans, atmosphere, ecosystem, and geosphere. All living organisms are built of carbon compounds. It is the fundamental building block of life and an important component of many chemical processes.

Human generated climate change can be thought of as an enormous perturbation in the global carbon cycle. ... Once mobilized into the atmosphere in forms such as carbon dioxide and methane, greenhouse gasses can change the thermal conductance of the atmosphere, the chemistry of seawater, and the movement of our oceans.