Human civilization developed under natural levels of greenhouse warming. Extra carbon in the atmosphere is leading to global warming over and above natural levels.

 

Each of the Earth's spheres contains carbon.

 

• Carbon is found in the atmosphere mostly as carbon dioxide, an important greenhouse gas.

 

• Carbon is found in the lithosphere stored in carbonate rocks. It is also found in fossil fuels, such as oil, coal, and natural gas.

 

• Carbon is found in the biosphere stored in plants and trees. It is a basic building block of life.

 

• Carbon is found in the hydrosphere dissolved in ocean water and lakes.

 

The flux of carbon from one area to another is the basis for the carbon cycle. As carbon moves between the spheres, it affects or is affected by climate change.