Terrestrial feedback in atmospheric oxygen regulation by fire and phosphorus

The regulation of atmospheric oxygen levels (pO₂) occurs on million-year timescales and is effected by modulation of sedimentary organic carbon burial and weathering rates^1,2. Until recently it was believed that these processes were dominated by material produced by marine organisms; now it appears that terrestrial plants contribute a significant amount of organic detritus to marine sediments. Here I explore the possibility of a coupling between the rates of terrigenous and marine sedimentary organic carbon burial (B_OC) that might stabilize PO₂ at or near the present atmospheric level. The coupling involves fire as a means to transfer phosphorus, the nutrient that limits global B_OC^3,4 and thus global oxygen production rates, from terrestrial to marine environments.