Iron fertilization of the subantarctic ocean during the last ice age

Alfredo Martínez-García, Daniel Mikhail Sigman, Haojia Ren, Robert F. Anderson, Marietta Straub, David A. Hodell, Samuel L. Jaccard, Timothy I. Eglinton, Gerald H. Haug

Research output: Contribution to journalArticlepeer-review

336 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)1347-1350
Number of pages4
Issue number6177
StatePublished - 2014

All Science Journal Classification (ASJC) codes

  • General


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