THE INFLUENCE OF GLACIAL-INTERGLACIAL VARIABILITY IN DUST DEPOSITION TO THE SOUTHERN OCEAN ON ATMOSPHERIC CO2

A recent in situ iron fertilization experiment in the Southern Ocean has demonstrated the critical role that iron availability plays in controlling biological carbon uptake. Increased iron supply derived from atmospheric dust during the Last Glacial Maximum in this climatically important region has previous been suggested as a causal mechanism for the concurrent low concentration of CO₂ observed in ice cores. Here we present results from a fully dynamic ocean-atmosphere carbon cycle model driven over the last four glacial/interglacial cycles by a variable dust flux to the Southern Ocean. We show that by using reasonable assumptions concerning present-day deposition rates in this region and taking the amplitude and phase of our dust signal from the Vostok ice core record, the model is able to account for much of the observed variability of atmospheric CO₂ during glacial times. In addition, the timing and much of the magnitude of the atmospheric CO₂ rise and synchronous d¹³CO₂ fall during the initial stages of glacial terminations is well reproduced.