Southern Ocean anthropogenic carbon sink constrained by sea surface salinity ...

• Main Authors: Terhaar, Jens, Frölicher, Thomas, Joos, Fortunat
• Format: Article in Journal/Newspaper
• Language: English
• Published: University of Bern 2021
• Subjects: Southern Ocean
• Online Access: https://dx.doi.org/10.48350/156125; https://boris-portal.unibe.ch/handle/20.500.12422/42002

The ocean attenuates global warming by taking up about one quarter of global anthropogenic carbon emissions. Around 40% of this carbon sink is located in the Southern Ocean. However, Earth system models struggle to reproduce the Southern Ocean circulation and carbon fluxes. We identify a tight relationship across two multimodel ensembles between present-day sea surface salinity in the subtropical-polar frontal zone and the anthropogenic carbon sink in the Southern Ocean. Observations and model results constrain the cumulative Southern Ocean sink over 1850-2100 to 158 ± 6 petagrams of carbon under the low-emissions scenario Shared Socioeconomic Pathway 1-2.6 (SSP1-2.6) and to 279 ± 14 petagrams of carbon under the high-emissions scenario SSP5-8.5. The constrained anthropogenic carbon sink is 14 to 18% larger and 46 to 54% less uncertain than estimated by the unconstrained estimates. The identified constraint demonstrates the importance of the freshwater cycle for the Southern Ocean circulation and carbon ...