Impact of iron fertilisation on atmospheric CO₂ during the last glaciation

Abstract. While several processes have been identified to explain the decrease in atmospheric CO2 during glaciations, a better quantification of contribution each these is needed. For example, enhanced aeolian iron input into ocean glacial times has suggested drive 5 28 ppm decrease. Here, we constrain this by performing set sensitivity experiments with different patterns and solubility factors under boundary conditions corresponding 70 000 years before present (70 ka), time period characterised first observed peak dust flux. We show that as function Southern Ocean follows an exponential decay relationship. This response arises due saturation biological pump efficiency levels out at ∼21 our simulations. changes are more sensitive than regional distribution fluxes. If surface water considered constant through time, find drawdown ∼4 ∼8 ppm. However, there evidence was higher times. A best estimate changing from 1 % interglacials 3 yields ∼9 11 ka, while plausible range between 4 16 obtained using wider but possible 10 %. would account for ∼12 %–50 reconstructed (∼32 ppm) 71 64 ka. further simulations concentration solely driven fluxes south Antarctic polar front, fertilisation elsewhere plays negligible role.