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Iron Fertilization of the Subantarctic Ocean During the Last Ice Age

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Author Martinez-Garcia Alfredo, Sigman Daniel, Ren Haojia, Anderson Robert, Straub Marietta, Hodell David, Jaccard Samuel, Eglinton Timothy, Haug Gerald,
Project SeaO2 - Past changes in Southern Ocean overturning circulation - implications for the partitioning of carbon and oxygen between the ocean and the atmosphere
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Original article (peer-reviewed)

Journal Science
Volume (Issue) 343
Page(s) 1347 - 1350
Title of proceedings Science
DOI 10.1126/science.1246848


John H. Martin, who discovered widespread iron limitation of ocean productivity, proposed that dust-borne iron fertilization of Southern Ocean phytoplankton caused the ice age reduction in atmospheric carbon dioxide (CO2). In a sediment core from the Subantarctic Atlantic, we measured foraminifera-bound nitrogen isotopes to reconstruct ice age nitrate consumption, burial fluxes of iron, and proxies for productivity. Peak glacial times and millennial cold events are characterized by increases in dust flux, productivity, and the degree of nitrate consumption; this combination is uniquely consistent with Subantarctic iron fertilization. The associated strengthening of the Southern Ocean’s biological pump can explain the lowering of CO2 at the transition from mid-climate states to full ice age conditions as well as the millennial-scale CO2 oscillations.