Sources of Atmospheric Carbon

Atmospheric carbon represented a steady state system, where influx equaled outflow, before the Industrial Revolution. Currently, it is no longer a steady state system because the influx exceeds the outflow. Therefore, we are experiencing an increase in atmospheric carbon, mainly in the form of carbon dioxide. Where does the carbon dioxide come from?

Oceans: 90 Gt/yr. [(Gt) 1 gigatonne = 1x1012 kilograms]. This carbon comes mainly from respiration and decomposition of organic material in the ocean.

Land: 107 Gt/yr. Of this, 100 Gt comes from land and soil-based respiration and decomposition. The other 7 Gt comes from the burning of fossil fuels (5 Gt) and deforestation (2 Gt).

So a total of 197 Gt of carbon are added to our atmosphere annually. What will happen to all of this atmospheric carbon? It must be recycled back for reuse by living organisms. However, the amounts recycled are different from the amounts received from the land and the oceans. Compare the figures from the paragraphs above with the ones below.

Back to What is the Carbon Cycle?