BIOCHEMICAL FEEDBACKS IN THE OCEANIC CARBON-CYCLE

This paper presents the results of a coupled ocean circulation and bio chemical model to study carbon uptake of the oceans by chemical buffer ing and primary production. The circulation model is a 2-dimensional m odel (latitudinally averaged per ocean basin with a 20 degrees resolut ion, and 12 vertical layers). The biochemical model includes the eleme nts C (as inorganic, particulate and dissolved organic), N, O, Ca and C-14, and models the fluxes between the various species (atmospheric e xchange, physical transport, primary production, calcification, decomp osition and dissolution). Steady-state results show good agreement wit h measurements. The model is then used in a sensitivity analysis to st udy the effect of possible changes in biochemical processes by running it to the year 2070 (projected atmospheric CO2 doubling under ''busin ess as usual'' scenario). It turns out that most of the feedbacks are positive, i.e.: ocean uptake capacity decreases more rapidly than in t he simulation with constant process rates. As a result, atmospheric pC O(2) may rise considerably faster than is currently predicted using no -feedback ocean models.