Assessment of Global Ocean Biogeochemistry Models for Ocean Carbon Sink Estimates in RECCAP2 and Recommendations for Future Studies ...

• Main Authors: Terhaar, Jens, Goris, Nadine, Müller, Jens D., DeVries, Tim, Gruber, Nicolas, Hauck, Judith, Perez, Fiz F., Séférian, Roland
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: American Geophysical Union 2024
• Subjects: 530 Physics; 550 Earth sciences & geology; Southern Ocean
• Online Access: https://dx.doi.org/10.48350/194339; https://boris.unibe.ch/194339/

The ocean is a major carbon sink and takes up 25%–30% of the anthropogenically emitted CO2. A state-of-the-art method to quantify this sink are global ocean biogeochemistry models (GOBMs), but their simulated CO2 uptake differs between models and is systematically lower than estimates based on statistical methods using surface ocean pCO2 and interior ocean measurements. Here, we provide an in-depth evaluation of ocean carbon sink estimates from 1980 to 2018 from a GOBM ensemble. As sources of inter-model differences and ensemble-mean biases our study identifies (a) the model setup, such as the length of the spin-up, the starting date of the simulation, and carbon fluxes from rivers and into sediments, (b) the simulated ocean circulation, such as Atlantic Meridional Overturning Circulation and Southern Ocean mode and intermediate water formation, and (c) the simulated oceanic buffer capacity. Our analysis suggests that a late starting date and biases in the ocean circulation cause a too low anthropogenic CO2 ...