Different Methods in Assessing El Niño Flavors Lead to Opposite Results.

El Niño‐Southern Oscillation (ENSO) flavors have been defined to characterize ENSO events and their teleconnections. Studying El Niño flavor evolution during the Holocene period can provide valuable insights into changes over long time scales. We investigated ENSO flavor evolution using simulations spanning the last 6,000 years and present‐day observations. Two approaches to computing ENSO flavors, in agreement in the present, lead to opposite trends in the last 6,000 years. The methods also differ significantly in their representation of ENSO flavor patterns. However, incorporating the sensitivity of the methods to calibration periods and mean state changes yields similar interpretations of ENSO variability changes. Both methods suggest an increase in El Niño variability spreading to the west and east tropical Pacific over the past 6,000 years. Standardizing El Niño flavor definitions is necessary for meaningful comparisons between studies and robust climate variability analysis. Plain Language Summary: El Niño events are the dominant mode of interannual variability. Looking at El Niño events in the past, during the Holocene period, could shed light on the linkages between the characteristics of El Niño patterns and changes in the climate mean state. Different indicators are used to characterize El Niño pattern diversity depending on the available data. While equivalent under present‐day conditions, these indicators lead to opposite conclusions on the evolution of El Niño patterns over the last 6,000 years. An in‐depth analysis indicates that all the methods suggest that El Niño‐related variance has spread to the west and east tropical Pacific over time when accounting for sensitivity to calibration periods and changes in the mean state during the Holocene. Agreeing on a standard definition for El Niño flavors is essential for accurate comparison between studies and for avoiding misleading conclusions. Key Points: Two equivalent indicators of El Niño‐Southern Oscillation (ENSO) flavors in the present give opposite evolution during the HoloceneResults show that the conflict between methods comes from the representation of ENSO flavor patterns on short and long timescalesA proper assessment must account for the indicator's patterns and calibration, as well as the climate mean‐state change over time [ABSTRACT FROM AUTHOR]