File:Impact of elevated CO2 on soil carbon reserves.gif

English: Figure 1  Predicted effects of elevated carbon dioxide (eCO2) on soil carbon reserves. In the short term, plant growth is stimulated by eCO2, resulting in increased rhizodeposition, priming microbes to mineralize soil organic carbon (SOC) and adding CO2 to the atmosphere through respiration. But the net impact on greenhouse gas emissions will be reduced by the increased uptake of CO2 from the atmosphere by increased plant growth. However, over the long term, soil reserves of easily decomposed carbon will be depleted by the increase in microbial activity, resulting in increased catabolism of SOC reservoirs, thus increasing atmospheric CO2 concentrations beyond what is taken up by plants. This is predicted to be a particular problem in thawing permafrost that contains large reserves of SOC that are becoming increasingly susceptible to microbial degradation as the permafrost thaws (195, 196).