The impact of the AMO on multidecadal ENSO variability

Multidecadal shifts in El Nino-Southern Oscillation (ENSO) variability have been observed, but it is unclear if this variability is just a random variation in the ENSO cycle or whether it is forced by other modes of climate variability. Here we show a strong influence of the Atlantic on the multidecadal variability of ENSO. The Atlantic Multidecadal Oscillation (AMO) is the dominant mode of multidecadal sea surface temperature (SST) variability in the Atlantic Ocean. Changes in AMO-related tropical Atlantic SSTs are known to force changes in the Walker circulation in the tropical Pacific Ocean. Using conceptual and coupled model experiments, we show that these changes to the Walker circulation modify ENSO stability on both annual and multidecadal time scales leading to a distinctive pattern of multidecadal ENSO variability that we find in observations and ocean reanalyses.