Suppressed Atlantic Niño/Niña variability under greenhouse warming

The Atlantic Niño/Niña is a dominant mode of interannual variability peaking in boreal summer with substantial climate impacts. How the Atlantic Niño/Niña sea surface temperature (SST) variability may change under greenhouse warming remains unclear. Here we find a robust suppression in future Atlantic Niño/Niña variability in models that simulate a reasonable mean climatology of the equatorial Atlantic. Under greenhouse warming, the equatorial Atlantic atmosphere becomes more stable, reducing sensitivity of the equatorial zonal winds to the zonal SST gradient; further, weakened trade winds lead to a deepened thermocline in the east, reducing SST sensitivity to thermocline anomalies. These changes feed into Bjerknes feedback to cause suppression in Atlantic Niño/Niña SST variability. These findings are in stark contrast to the Pacific and the Indian Ocean where El Niño/La Niña SST variability and strong Indian Ocean Dipole variability are projected to increase.