While the ocean as a whole is losing oxygen due to warming, oxygen minimum zones (OMZs) are maintained by a delicate balance of biological and physical processes; it is unclear how each one of them is going to evolve in the future. Changes to OMZs could affect the global uptake of carbon, the generation of greenhouse gases, and interactions among marine life. Current generation coarse-resolution (~1°) climate models compromise the ability to simulate low-oxygen waters and their response to climate change in the future because they fail to reproduce a major ocean current, the Equatorial Undercurrent (EUC). These shortcomings lead to an overly tilted upper oxygen minimum zone (OMZ) (Figure 1), thus exaggerating sensitivity to circulation changes and overwhelming other key processes like diffusion and biology. The EUC also plays a vital role in feeding the eastern Pacific upwelling region, connecting it to global climate variability.
A recent high‐resolution climate model study in Geophysical Research Letters significantly improved the representation of both the EUC and OMZ, suggesting that the EUC is a key player in OMZ variability. This study emphasizes the importance of improving transport processes in global circulation models to better simulate oxygen distribution and predict future OMZ extent. The results of this study imply that the fundamental dynamics maintaining this key ocean current could be categorically misrepresented in the current generation of climate models, potentially influencing the ability to predict future climate variability and trends.
Julius J.M. Busecke (Princeton University)
Laure Resplandy (Princeton University)
John P. Dunne (NOAA/GFDL)