A climate change signal in the tropical Pacific emerges from decadal variability

Abstract Recent debates have centered around whether the La Niña-like sea surface temperature (SST) trend pattern in the tropical Pacific in the past several decades is a response to anthropogenic forcings or internal variability, particularly the Interdecadal Pacific Oscillation (IPO). This study identifies an emerging SST warming pattern in the tropical Pacific featuring a narrow equatorial cooling band, in stark contrast to the meridionally broad SST trend pattern shaped by the IPO. The emerging SST trend pattern is associated with changes in subsurface temperature structure and sea level height that are distinct from those related to the recurrent IPO. The differences are primarily driven by their different surface wind stress patterns. The emerging wind stress pattern also drives distinctive ocean dynamical processes, fostering the unique eastern Pacific cooling. Our findings set a path to distinguish the often-tangled tropical Pacific climate change signals from internal variability through the underlying dynamics of each.