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  • 1
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    Southern Ocean dust-climate coupling over the past four million years (2011)
    Nature Publishing Group (NPG)
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    Publication Date: 2011-08-05
    Description: Dust has the potential to modify global climate by influencing the radiative balance of the atmosphere and by supplying iron and other essential limiting micronutrients to the ocean. Indeed, dust supply to the Southern Ocean increases during ice ages, and 'iron fertilization' of the subantarctic zone may have contributed up to 40 parts per million by volume (p.p.m.v.) of the decrease (80-100 p.p.m.v.) in atmospheric carbon dioxide observed during late Pleistocene glacial cycles. So far, however, the magnitude of Southern Ocean dust deposition in earlier times and its role in the development and evolution of Pleistocene glacial cycles have remained unclear. Here we report a high-resolution record of dust and iron supply to the Southern Ocean over the past four million years, derived from the analysis of marine sediments from ODP Site 1090, located in the Atlantic sector of the subantarctic zone. The close correspondence of our dust and iron deposition records with Antarctic ice core reconstructions of dust flux covering the past 800,000 years (refs 8, 9) indicates that both of these archives record large-scale deposition changes that should apply to most of the Southern Ocean, validating previous interpretations of the ice core data. The extension of the record beyond the interval covered by the Antarctic ice cores reveals that, in contrast to the relatively gradual intensification of glacial cycles over the past three million years, Southern Ocean dust and iron flux rose sharply at the Mid-Pleistocene climatic transition around 1.25 million years ago. This finding complements previous observations over late Pleistocene glacial cycles, providing new evidence of a tight connection between high dust input to the Southern Ocean and the emergence of the deep glaciations that characterize the past one million years of Earth history.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Martinez-Garcia, Alfredo -- Rosell-Mele, Antoni -- Jaccard, Samuel L -- Geibert, Walter -- Sigman, Daniel M -- Haug, Gerald H -- England -- Nature. 2011 Aug 3;476(7360):312-5. doi: 10.1038/nature10310.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Geological Institute, ETH Zurich, Zurich 8092, Switzerland. alfredo.martinez-garcia@erdw.ethz.ch〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/21814203" target="_blank"〉PubMed〈/a〉
    Keywords: Alkanes/analysis ; Atlantic Ocean ; Atmosphere/chemistry ; Carbon Cycle ; Carbon Dioxide/analysis ; *Climate ; Diatoms/metabolism ; Dust/*analysis ; Ecosystem ; Geologic Sediments/chemistry ; History, Ancient ; Ice/analysis ; Iron/analysis ; Nitrates/analysis ; Oceans and Seas ; Reproducibility of Results ; Seawater/*chemistry ; Uncertainty ; Wind
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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  • 2
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    Iron fertilization of the Subantarctic ocean during the last ice age (2014)
    American Association for the Advancement of Science (AAAS)
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    Publication Date: 2014-03-22
    Description: 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.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Martinez-Garcia, Alfredo -- Sigman, Daniel M -- Ren, Haojia -- Anderson, Robert F -- Straub, Marietta -- Hodell, David A -- Jaccard, Samuel L -- Eglinton, Timothy I -- Haug, Gerald H -- New York, N.Y. -- Science. 2014 Mar 21;343(6177):1347-50. doi: 10.1126/science.1246848.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Geological Institute, ETH Zurich, 8092 Zurich, Switzerland.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24653031" target="_blank"〉PubMed〈/a〉
    Keywords: Antarctic Regions ; Atlantic Ocean ; Atmosphere ; Biomass ; *Carbon Dioxide/analysis ; *Climate ; Cold Temperature ; Foraminifera/chemistry/metabolism ; *Geologic Sediments/chemistry ; *Ice Cover ; *Iron/analysis ; Nitrates/analysis/metabolism ; Nitrogen Isotopes/analysis ; Phytoplankton/growth & development/metabolism ; Seawater/chemistry ; Time
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 3
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    A stagnation event in the deep South Atlantic during the last interglacial period (2014)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2014-12-20
    Description: During the last interglacial period, global temperatures were ~2 degrees C warmer than at present and sea level was 6 to 8 meters higher. Southern Ocean sediments reveal a spike in authigenic uranium 127,000 years ago, within the last interglacial, reflecting decreased oxygenation of deep water by Antarctic Bottom Water (AABW). Unlike ice age reductions in AABW, the interglacial stagnation event appears decoupled from open ocean conditions and may have resulted from coastal freshening due to mass loss from the Antarctic ice sheet. AABW reduction coincided with increased North Atlantic Deep Water (NADW) formation, and the subsequent reinvigoration in AABW coincided with reduced NADW formation. Thus, alternation of deep water formation between the Antarctic and the North Atlantic, believed to characterize ice ages, apparently also occurs in warm climates.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Hayes, Christopher T -- Martinez-Garcia, Alfredo -- Hasenfratz, Adam P -- Jaccard, Samuel L -- Hodell, David A -- Sigman, Daniel M -- Haug, Gerald H -- Anderson, Robert F -- New York, N.Y. -- Science. 2014 Dec 19;346(6216):1514-7. doi: 10.1126/science.1256620.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology (MIT), Cambridge, MA 02142, USA. Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY 10964, USA. cthayes@mit.edu. ; Geological Institute, ETH Zurich, 8092 Zurich, Switzerland. ; Institute of Geological Sciences and Oeschger Centre for Climate Change Research, University of Bern, 3012 Bern, Switzerland. ; Department of Earth Sciences, University of Cambridge, Cambridge CB2 3EQ, UK. ; Department of Geosciences, Princeton University, Princeton, NJ 08544, USA. ; Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY 10964, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25525246" target="_blank"〉PubMed〈/a〉
    Keywords: Atlantic Ocean ; Climate Change ; *Ice Cover ; Oxygen/analysis ; Salinity ; *Seawater
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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