Sack Lunch Seminar (SLS)

A Simple Theory for Ocean Carbon Chemistry






In view of the ongoing anthropogenic emissions of carbon, it is of crucial importance
to understand which portion of future emissions will stay in the atmosphere
and how large a portion will be taken up by the oceans. To get a deeper insight
into this issue, we formulate an analytical theory for the ocean-atmosphere partitioning
of carbon based on simple carbonate chemistry; a newly defined ‘buffer
factor’ (O), analogous to the well-known Revelle buffer factor, turns out to be
crucial for the theory development. We apply this framework to derive the dependence
of the carbon partitioning on the average ocean temperature and alkalinity
and we predict how the partitioning changes with increasing emissions. The most
important effect impacting the carbon partitioning turns out to be neutralisation
of carbonate ions at the ocean surface which decreases the carbon uptake capacity
of the oceans. The predictions are found to be consistent with recent modeling
studies and it is thus illustrated that the theory can provide a mechanistic explanation
for oceanic carbon cycle simulation results. When applied to the next
centuries, the theory and simulations suggest that the neutralisation of carbonate
at the ocean surface will lead to a strong decrease of the portion of carbon
emissions that are taken up by the ocean.