Reduced El Niño variability in the mid-Pliocene according to the PlioMIP2 ensemble

Several proxy reconstructions for the midPliocene show highly reduced zonal sea surface temperature (SST) gradients in the tropical Pacific Ocean, indicating an El Nino-like mean state. However, past modelling studies do not show these highly reduced gradients.

Efforts to understand mid-Pliocene climate dynamics have led to the Pliocene Model Intercomparison Project (PlioMIP). Results from the first phase (PlioMIP1) showed clear El Nino variability (albeit significantly reduced) and did not show the greatly reduced time-mean zonal SST gradient suggested by some of the proxies.