The carbon cycle is a well known phenomenon. Plants take in CO2 when they respire and give out oxygen. When the plant dies and decays organic carbon enters the soil and CO2 is given off, when animals eat plants they store that carbon, except for the amount breathed out as CO2, until they themselves die. Carbon can be taken out of the cycle, at least temporarily, by preventing the organism from decaying in which case it becomes a fossil fuel. Also rock can absorb and store CO2 and the ocean also acts as a massive absorber although too much would increase ocean acidity.
Due to climate change and a fall in crop yield the amount of carbon entering the soil decreases. This is is a fey cycle as less carbon in the soil means less plants can be grown and so less carbon dioxide can be removed from the air and put in the soil. This could severely affect the productivity of various areas of farmland, or at least make it more expensive as more and different forms of fertiliser will need to be used. In order to see how detrimental this might be to agriculture over 50 samples were collected representing the important soil varieties found across Europe. Predictions for Bavaria have been made up until the year 2095, with expected rise of about 3°C over this time. It was predicted that carbon in the soil might fall by 15% in cropland and slightly less in grassland. This is important as previous predictions actually stated that the carbon content of the soil was going to rise over the coming century. This might be a very optimistic idea.