The effects of buffer and temperature feedback on the oceanic uptake of CO2

Abstract

The feedback between climate and carbon cycle systems is critical tothe prediciton of future CO2 concentration inthe atmosphere and the capacity of the oceans to take up CO2 from the atmosphere.We calculated the magnitudes of the potential feedback between the increase of atmospheric CO2 concentration, the carbonate chemistry of the oceans (via a buffer factor), and the global temperature. We find that the magnitude of the buffer feedback depends strongly on the level of the dissolved inorganic carbon(DIC) in the oceans and increases rapidly with the increase of the atmospheric CO2 concentration. The buffer feedback would result in an increase of 95 ppm in the atmospheric CO2 concentration and a decrease of 236 GtC absorbed by the oceans from the atmosphere between year 2000 and 2100 under the Intergovernmental Panel on Climate Change (IPCC) scenario IS92e. By coupling our buffer feedback model with a global energy balance model, we find that global mean temperature increased 0.65°C from 1860 to 1990, which agreed well with the recorded value of 0.61°C. However, the ocean carbonate chemistry is quite insensitive to global temperature.