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Southern Ocean upwelling, Earth’s obliquity, and glacial-interglacial atmospheric CO 2 change

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Author Ai Xuyuan E., Studer Anja S., Sigman Daniel M., Martínez-García Alfredo, Fripiat François, Thöle Lena M., Michel Elisabeth, Gottschalk Julia, Arnold Laura, Moretti Simone, Schmitt Mareike, Oleynik Sergey, Jaccard Samuel L., Haug Gerald H.,
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) 370(6522)
Page(s) 1348 - 1352
Title of proceedings Science
DOI 10.1126/science.abd2115


Previous studies have suggested that during the late Pleistocene ice ages, surface-deep exchange was somehow weakened in the Southern Ocean’s Antarctic Zone, which reduced the leakage of deeply sequestered carbon dioxide and thus contributed to the lower atmospheric carbon dioxide levels of the ice ages. Here, high-resolution diatom-bound nitrogen isotope measurements from the Indian sector of the Antarctic Zone reveal three modes of change in Southern Westerly Wind–driven upwelling, each affecting atmospheric carbon dioxide. Two modes, related to global climate and the bipolar seesaw, have been proposed previously. The third mode—which arises from the meridional temperature gradient as affected by Earth’s obliquity (axial tilt)—can explain the lag of atmospheric carbon dioxide behind climate during glacial inception and deglaciation. This obliquity-induced lag, in turn, makes carbon dioxide a delayed climate amplifier in the late Pleistocene glacial cycles.