Carbon isotopes characterize rapid changes in atmospheric carbon dioxide during the last deglaciation

• Main Authors: Bauska, Thomas K, Baggenstos, Daniel, Brook, Edward J, Mix, Alan C, Marcott, Shaun A, Petrenko, Vasilii V, Schaefer, Hinrich, Severinghaus, Jeffrey P, Lee, James E
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: eScholarship, University of California 2016
• Subjects: Earth Sciences; Physical Geography and Environmental Geoscience; Geology; Climate Action; Life Below Water; ice cores; paleoclimate; carbon cycle; atmospheric CO2; last deglaciation; Southern Ocean; Taylor Glacier; Antarc*; Antarctica
• Online Access: https://escholarship.org/uc/item/5hc8m4h7

An understanding of the mechanisms that control CO2 change during glacial-interglacial cycles remains elusive. Here we help to constrain changing sources with a high-precision, high-resolution deglacial record of the stable isotopic composition of carbon in CO2(δ(13)C-CO2) in air extracted from ice samples from Taylor Glacier, Antarctica. During the initial rise in atmospheric CO2 from 17.6 to 15.5 ka, these data demarcate a decrease in δ(13)C-CO2, likely due to a weakened oceanic biological pump. From 15.5 to 11.5 ka, the continued atmospheric CO2 rise of 40 ppm is associated with small changes in δ(13)C-CO2, consistent with a nearly equal contribution from a further weakening of the biological pump and rising ocean temperature. These two trends, related to marine sources, are punctuated at 16.3 and 12.9 ka with abrupt, century-scale perturbations in δ(13)C-CO2 that suggest rapid oxidation of organic land carbon or enhanced air-sea gas exchange in the Southern Ocean. Additional century-scale increases in atmospheric CO2 coincident with increases in atmospheric CH4 and Northern Hemisphere temperature at the onset of the Bølling (14.6-14.3 ka) and Holocene (11.6-11.4 ka) intervals are associated with small changes in δ(13)C-CO2, suggesting a combination of sources that included rising surface ocean temperature.