Stronger Oceanic CO2 Sink in Eddy‐Resolving Simulations of Global Warming

Abstract Accurately representing the ocean carbon cycle in Earth System Models (ESMs) is essential to understanding the oceanic CO 2 sink evolution under CO 2 emissions and global warming. A key uncertainty arises from the ESM's inability to explicitly represent mesoscale eddies. To address this limitation, we conduct eddy‐resolving experiments of CO 2 uptake under global warming in an idealized mid‐latitude ocean model. In comparison with similar experiments at coarser resolution, we show that the CO 2 sink is 34% larger in the eddy‐resolving experiments. 80% of the increase stems from a more efficient anthropogenic CO 2 uptake due to a stronger Meridional Overturning circulation (MOC). The remainder results from a weaker reduction in CO 2 uptake associated to a weaker MOC decline under global warming. Although being only a fraction of the overall response to climate change, these results emphasize the importance of an accurate representation of small‐scale ocean processes to better constrain the CO 2 sink.