Don Bogard, radio-geochemistry, nuclear geochemistry, planetary science: Carbon (C) exchange rates among C reservoirs tend to be at equilibrium unless and until a significant environmental change disturbs that. A significant increase in atmospheric (Atmos) CO2 concentration over the past century has been such a disturbance, and as a consequence a large fraction of that growth in Atmos CO2 has manifested as new plant growth and to increased ocean C levels. Increased temperature over the past century (which mostly has only modestly affected the ocean) and any tendency for warmer surface ocean to degas more CO2, has been over-powered by higher Atmos CO2 shifting the chemical equilibrium toward more dissolution of Atmos CO2 into the oceans. Higher decay rates of soil biotic material caused by the increased temperatures may be a source of part of the Atmos CO2 increase over the past century. However, it is most unlikely that organic decay has been other than a minor source, especially in the past few decades when Atmos CO2 was growing most rapidly.
