Deep-sea coral evidence for lower Southern Ocean surface nitrate concentrations during the last ice age

• Published in: Proceedings of the National Academy of Sciences
• Main Authors: Wang, Xingchen Tony, Sigman, Daniel M., Prokopenko, Maria G., Adkins, Jess F., Robinson, Laura F., Hines, Sophia K., Chai, Junyi, Studer, Anja S., Martínez-García, Alfredo, Chen, Tianyu, Haug, Gerald H.
• Format: Text
• Language: English
• Published: National Academy of Sciences 2017
• Subjects: Physical Sciences; Southern Ocean
• Online Access: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5380069/; http://www.ncbi.nlm.nih.gov/pubmed/28298529; https://doi.org/10.1073/pnas.1615718114

The concentration of atmospheric carbon dioxide (pCO2) varies by 80–100 ppm on glacial–interglacial timescales, with lower pCO2 during the ice ages. In the modern Southern Ocean, the surface nutrients are not fully consumed by phytoplankton, resulting in leakage of deeply sequestered CO2 to the atmosphere. It has been suggested that more complete nutrient consumption in the Southern Ocean would have caused the lower pCO2 during the ice ages. Here, we provide the most spatially comprehensive evidence to date in support of the proposal that the entire Southern Ocean was nutrient-depleted during the last ice age relative to modern conditions. These data are consistent with the hypothesis that Southern Ocean changes contributed to the lower atmospheric pCO2 of the ice ages.