How extreme El Niño teleconnections change in warmer climates

Recent studies have highlighted that extreme El Niño have distinct atmospheric winter teleconnections from those associated with other ENSO phases. While moderate El Niño and CP El Niño events display Pacific-North American (PNA)-like patterns opposite to La Niña teleconnections, only extreme El Niño events show a unique Tropical-Northern Hemisphere (TNH) pattern, driving warm anomalies over North America and increased rainfall in regions like California and Florida. However, despite projections of their increased frequency in warmer climates, future teleconnection changes for extreme El Niño remain under-explored. Using an extensive CMIP6 dataset spanning multiple Shared Socio-economic Pathways (SSPs) scenarios, models, and ensemble members, we perform a warming-level analysis of future changes in extreme El Niño winter teleconnections. Above +3°C warming, their specific TNH-like pattern weaken, and a signature similar to a negative North Atlantic Oscillation (NAO) pattern emerges. Wet anomalies over California and Florida weaken, dry anomalies over Northeast Brazil diminish, while dry anomalies over the Maritime Continent intensify during extreme El Niño. These changes appear to stem both from the eastward shift of tropical precipitation sources and changes in extratropical background circulation. Finally, we explore how changes in frequency of extreme El Niño and their associated teleconnection patterns drive changes in the broader ENSO teleconnection pattern.