Weakened Submesoscale Eddies in the Equatorial Pacific Under Greenhouse Warming

Submesoscale eddies in the equatorial Pacific induce a pronounced upward heat flux from the subsurface to the surface ocean. Yet their response to greenhouse warming and feedback on the mean-state change remain unknown. Using a long-term high-resolution climate simulation under a high carbon emission scenario, we show that submesoscale eddies in the central and eastern equatorial Pacific weaken, leading to an ∼50% reduction in their upward heat flux at the end of the 21st century, compared to its mid-20th century level. This reduction is caused by an intensified stratification and a weakened cold tongue thermal front associated with a projected El Niño-like warming pattern. The reduced vertical submesoscale eddy heat flux plays an important role in the anomalous heat budget of the surface layer over the central and eastern equatorial Pacific under greenhouse warming, acting as negative feedback on the El Niño-like warming pattern.