The Southern Ocean Carbon Cycle 1985–2018: Mean, Seasonal Cycle, Trends, and Storage ...

• Main Authors: Hauck, Judith, Gregor, Luke, Nissen, Cara, Patara, Lavinia, Hague, Mark, Mongwe, Precious, Bushinsky, Seth, Doney, Scott C., Gruber, Nicolas, Le Quéré, Corinne, Manizza, Manfredi, Mazloff, Matthew, Monteiro, Pedro M. S., Terhaar, Jens
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: American Geophysical Union 2023
• Subjects: 530 Physics; 550 Earth sciences & geology; Southern Ocean
• Online Access: https://dx.doi.org/10.48350/193971; https://boris.unibe.ch/193971/

We assess the Southern Ocean CO2 uptake (1985–2018) using data sets gathered in the REgional Carbon Cycle Assessment and Processes Project Phase 2. The Southern Ocean acted as a sink for CO2 with close agreement between simulation results from global ocean biogeochemistry models (GOBMs, 0.75 ± 0.28 PgC yr−1) and pCO2-observation-based products (0.73 ± 0.07 PgC yr−1). This sink is only half that reported by RECCAP1 for the same region and timeframe. The present-day net uptake is to first order a response to rising atmospheric CO2, driving large amounts of anthropogenic CO2 (Cant) into the ocean, thereby overcompensating the loss of natural CO2 to the atmosphere. An apparent knowledge gap is the increase of the sink since 2000, with pCO2-products suggesting a growth that is more than twice as strong and uncertain as that of GOBMs (0.26 ± 0.06 and 0.11 ± 0.03 Pg C yr−1 decade−1, respectively). This is despite nearly identical pCO2 trends in GOBMs and pCO2-products when both products are compared only at the ...