Ocean iron fertilization by South American dust: From present-day data to last glacial conjectures

COSENTINO, N. J.

Buenos Aires

Workshop; Iron Supply in the Patagonian Shelf-Break Front 2024; 2024

IFAECI

Mineral dust aerosols reduce atmospheric carbon dioxide (CO2atm) by fertilizing iron (Fe)-limited oceansand enhancing primary productivity. The resulting perturbation to Earth´s radiation budget is, however,highly uncertain, as the scientific understanding of this dust-climate interaction is very low. SouthernSouth America (SSA) is the main dust supplier to the Southern Hemisphere?s high-latitude oceans, themost susceptible to Fe fertilization. Iron limitation is first encountered <700 km offshore of SSA, wheresimplified models show that most dust-borne soluble Fe originates from super-coarse dust (with diametersbetween 10-62.5 micrometers). Thus, better constraining the role of super-coarse particles in SSA?s dustcycle is key to quantifying the indirect effect of dust on global climate. The greatest changes in globaldust activity occur at glacial-interglacial timescales, and it has been proposed that the weakening of thisfertilizing effect of dust is one main contributor to the rise in CO2atm during the last deglaciation. In thispresentation, I will review available evidence for present-day fertilization of the SW Atlantic Ocean bydust, discuss possible implications for the last glacial maximum, and suggest a research agenda for thefuture in terms of dust fertilization.