What are the 4 steps of the carbon cycle?

Answer

The four basic steps of the carbon cycle are the earth (lithosphere), the air (atmosphere), the oceans (hydrosphere), and all living organisms (biosphere).

The simplest part of the carbon cycle runs the same course as the rock cycle. Carbon is expelled into the atmosphere by volcanic eruptions. This carbon is mostly in the form of carbon dioxide (CO2) and methane (CH4). Carbon dioxide is absorbed by some kinds of rocks as they weather. Weathered rock fragments eventually wash into the sea and settle to the sea floor. These sediments can eventually be compacted and cemented into new rock on the ocean floor. Tectonic movements sometimes lead ocean floors to be pushed deeply under continental plates. When they get pushed deep enough under the earth's surface, heat and pressure eventually cause the rocks to metamorphose and even melt. The cycle completes with another volcanic eruption.

This is the simple form of the carbon cycle mainly because it does not take account of life. But you can see carbon being exchanged between the earth (lithosphere), the air (atmosphere) and the sea (hydrosphere). This part of the carbon cycle existed before the evolution of life (biosphere).

Before adding the complication of "life", we should note that there is also a direct exchange of carbon dioxide between the air and the oceans that actually goes in two directions. Depending on the temperatures the oceans can either absorb and dissolve CO2 or they can release CO2 into the atmosphere. Think about soda pop or other carbonated drinks.

The biosphere (life) adds many more complications to the cycle. Plants (from algae to trees) absorb CO2 from the air (atmosphere) in photosynthesis. Many forms of marine life absorb CO2 from the oceans (hydrosphere) to make their shells. All plants and animals release CO2 into their surrounding environment during respiration. Plants and animals also release their carbon when they die and decay. On land the carbon is released into the air and the soil. On land, burning (combustion) of plant material will also release carbon into the air and the soil. In the sea the carbonate much of the shells of dead animals settle onto the ocean floor and become part of the carbon/rock cycle.

Under certain conditions the sediments formed from dead organisms (mostly plants) can form special metamorphosed materials that we use as fossil fuels. This adds another of life's complications: humans.

Humans are affecting the carbon cycle in many ways. Obviously the burning (combustion) of fossil fuels releases carbon (as CO2) into the atmosphere. CO2 is also released into the atmosphere when limestone is burned to create lime or cement. Humans also affect the carbon cycle through the clearing (deforestation) of land. When trees or burnt or allowed to rot they release CO2 into the atmosphere. Certain types of farming can release even more CO2 into the atmosphere. Rice paddies form artificial swamps that generate methane (CH4), and methane is also produced by concentrated numbers of livestock and poultry.

For more information on this subject, try wikipedia or university sites for a more detailed answer.

• When is Spring season in new york?
• What is the dhivehi name of 'slippery sea cucumber?
• What are the biggest waves in the world called?