Atmospheric iron fluxes over the last deglaciation: Climatic implications

A decrease in the micronutrient iron supply to the Southern Ocean is widely believed to be involved in the atmospheric CO 2 increase during the last deglaciation. Here we report the first record of atmospheric iron fluxes as determined in 166 samples of the Dome C ice core and covering the last glacial‐interglacial transition (22–9 kyr B.P.). It reveals a decrease in fallout flux from 24 × 10 −2 mg Fe m −2 yr −1 during the Last Glacial Maximum to 0.7 × 10 −2 mg Fe m −2 yr −1 at the onset of the Holocene. The acid leachable fraction of iron determined in our samples was the 60% of the total iron mass in glacial samples, about twice the value found for Holocene samples. This emerging difference in iron solubility over different climatic stages provides a new insight for evaluating the iron hypothesis over glacial/interglacial periods.