ENSO Diversity in a Changing Climate

Abstract:

ENSO events display large inter-event differences in amplitude, spatial pattern, and temporal evolution. These differences, which have important consequences for ENSO teleconnections and societal impacts, have become known as “ENSO diversity”. In this presentation, we review our current state-of-knowledge on ENSO diversity, including its surface and subsurface characteristics, underlying dynamics, predictability, low-frequency variations and long-term evolution, as well as the representation of ENSO diversity in climate models. The various classification schemes introduced to characterize different event types, and the insights they provide on ENSO diversity are reviewed. The last two decades have seen a greater number of El Niño events with largest sea surface temperature anomalies in the central Pacific. The ongoing discussion on whether such changes in ENSO characteristics were the result of anthropogenic greenhouse gas forcing or just a manifestation of natural variability is also presented.