Deglacial Carbon Escape From the Northern Rim of the Southern Ocean

• Published in: Geophysical Research Letters
• Main Authors: N. E. Umling, E. Sikes, P. Rafter, N. F. Goodkin, J. R. Southon
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2024
• Subjects: Antarctic intermediate water; radiocarbon; ventilation; glacial; foraminifera; Geophysics. Cosmic physics; QC801-809; Antarc*; Antarctic; Southern Ocean
• Online Access: https://doi.org/10.1029/2023GL106413; https://doaj.org/article/69d96e5042954ed6b5ca7ceb1bdd7c95

Abstract The Southern Ocean regulates atmospheric CO2 and Earth's climate as a critical region for air‐sea gas exchange, delicately poised between being a CO2 source and sink. Here, we estimate how long a water mass has remained isolated from the atmosphere and utilize 14C/12C ratios (Δ14C) to trace the pathway and escape route of carbon sequestered in the deep ocean through the mixed layer to the atmosphere. The position of our core at the northern margin of the Southern Indian Ocean, tracks latitudinal shifts of the Southern Ocean frontal zones across the deglaciation. Our results suggest an expanded glacial Antarctic region trapped CO2, whereas deglacial expansion of the subantarctic permitted ventilation of the trapped CO2, contributing to a rapid atmospheric CO2 rise. We identify frontal positions as a key factor balancing CO2 outgassing versus sequestration in a region currently responsible for nearly half of global ocean CO2 uptake.