Extreme El Niño events, sometimes called “super El Niños”, are the strongest, most impactful members of the warm phase of the El Niño–Southern Oscillation (ENSO). They stand out from moderate El Niños due to their exceptional intensity, spatial characteristics, and nonlinear atmospheric responses.

Historical Examples

The clearest modern extreme events are:

1982–83: One of the strongest on record; caused massive flooding in Peru/Ecuador/California, droughts in Australia/Indonesia, and significant global temperature spikes.

1997–98: Often considered the benchmark “super” event; record SST anomalies, widespread fires in Southeast Asia and Amazon, coral bleaching, and strong North American impacts (e.g., heavy California rains, mild Northeast winters).

2015–16: Comparable in strength (especially as a mixed eastern/central Pacific type); contributed to record global temperatures and major regional extremes.

Earlier candidates include 1876–78 and 1972–73, with varying data quality.

These events typically peak in boreal winter (DJF) and last 9–18 months.

La Niña teleconnection patterns

La Niña teleconnection patterns refer to the atmospheric wave trains and remote climate impacts triggered by the cold phase of ENSO (cooler-than-average sea surface temperatures in the central-eastern equatorial Pacific). Unlike extreme El Niños, La Niña patterns are generally more symmetric with moderate El Niños but opposite in sign.

NOAA CPC, studies using reanalysis (ERA5), and CMIP models. Composites often use events exceeding -0.5°C (or stronger thresholds) in Niño-3.4.

La Niña patterns are generally more “reliable” in a linear sense than extreme El Niños but still modulated by internal variability, event strength, and location (e.g., central vs. eastern Pacific flavors).

North Atlantic oscillation impacts

North Atlantic Oscillation (NAO) is one of the most influential modes of atmospheric variability in the Northern Hemisphere, particularly during winter. It manifests as a seesaw in sea-level pressure (or 500 hPa geopotential height) between the Icelandic Low (near Iceland/Greenland) and the Azores High (subtropical North Atlantic).

The NAO index is typically measured as the normalized pressure difference between stations like Iceland and the Azores/Lisbon.

The NAO explains a large fraction of winter climate variability over the North Atlantic sector but interacts with other modes (e.g., AO/AAO, PNA, stratospheric influences). Predictability is seasonal at best, aided by ocean memory and teleconnections.

A new study in Geophysical Research Letters examining how extreme (“super”) El Niño events could behave differently under future climate warming.

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Reduced Distinctiveness of Extreme El Niño Teleconnections in Warmer Climates

“Reduced Distinctiveness of Extreme El Niño Teleconnections in Warmer Climates” is a 2026 research letter by Margot Beniche and colleagues (Jérôme Vialard, Andréa S. Taschetto, Matthieu Lengaigne) published in Geophysical Research Letters (DOI: 10.1029/2025GL121189). It is open access.

In the current climate, extreme El Niño events (e.g., 1982–83, 1997–98) — defined by strong eastward-shifted sea surface temperature (SST) anomalies and intense eastern Pacific rainfall (>5 mm/day) — produce distinctive atmospheric teleconnections.

These differ from moderate El Niños and La Niñas by triggering nonlinear tropical convection, leading to an eastward-shifted pattern resembling the Tropical/Northern Hemisphere (TNH) pattern rather than the classic Pacific-North American (PNA) pattern.

This paper builds directly on the authors’ prior work (e.g., Beniche et al. 2024 in Scientific Reports) establishing that extreme El Niños are not just stronger versions of moderate ones. They trigger unique nonlinear atmospheric responses due to intense eastern Pacific rainfall (>5 mm/day), shifting tropical convection eastward and producing a TNH-like (Tropical/Northern Hemisphere) teleconnection pattern rather than the standard PNA (Pacific-North American) pattern.

Why “Distinctiveness” Matters in the Present Climate

Moderate El Niños and La Niñas → Produce symmetric, classic PNA responses: warming/drying in the Northwest, some West Coast effects, but limited penetration to the eastern US.

Extreme El Niños (1982–83, 1997–98, arguably 2015–16) → Larger eastward-shifted SST anomalies drive basin-wide reorganization of tropical heat sources via nonlinear convection (convection threshold crossed in the normally dry east Pacific).

This yields:

• Stronger, eastward-shifted upper-level wave train.
• Enhanced California/Florida precipitation (high likelihood of >0.5 std wet anomalies).
• Pronounced warming over northeastern North America.
• Greater reproducibility across events/ensembles due to stronger signal-to-noise ratio.

This distinctiveness underpins much of ENSO’s asymmetry and provides a key predictability source for seasonal forecasts.

Projected Changes: Multi-Model, Multi-Ensemble, Multi-Scenario Robustness

The study selects 13 CMIP6 models that realistically simulate extreme El Niños (those with strong eastern Pacific rainfall) and their present-day teleconnections. They use large ensembles across scenarios and bin events by global warming levels (GWLs) relative to pre-industrial for clean isolation of warming effects.

Key quantified changes (strongest at +3.5°C GWL):

500 hPa geopotential height (Z500) anomalies: Extreme El Niño pattern shifts ~20° farther east and weakens by ~33% over North America. A negative NAO-like response strengthens.

Surface impacts: Northeastern US winter warming diminishes sharply. California and Florida wet anomalies weaken (30% at +2°C; >50% at +3.5°C). Northern Amazon drying also reduces.

By +3.5°C, extreme events’ North American fingerprints converge toward those of moderate El Niños — the “distinctiveness” largely vanishes.

Extreme El Niños still show larger amplitude changes than moderate events or La Niñas, but these changes make them less unique.

Mechanisms (Deeper Physical Insight)

Teleconnections depend on:

1. Tropical forcing (location/intensity of convective heating).
2. Mid-latitude waveguide (jet structure guiding Rossby waves).

In warmer climates:

• Mean state shifts toward a more El Niño-like Pacific (weakened zonal SST gradient, eastward-expanded convection).
• Mid-latitude jets strengthen and shift, increasing Rossby wave wavelength → eastward steering of wave trains.
• For extremes specifically: Their already-eastward convection shifts further or interacts differently with the altered background, reducing the relative nonlinearity/distinctiveness.
• Background warming and circulation changes dominate over the simple increase in extreme frequency.

This aligns with broader literature on ENSO teleconnection shifts (e.g., eastward PNA migration, stronger NAO links) but highlights amplified effects for extremes.

Decomposition and Broader Implications

The authors decompose overall ENSO teleconnection changes (via regressions) and find that while extremes change most dramatically, their increased frequency + pattern evolution contributes only modestly to total projected shifts. The changing climate background is the bigger driver.

Implications:

• Forecasting & Adaptation: Historical “super El Niño” analogs (California deluges, Northeast mild winters) become less reliable. Seasonal models may need recalibration; water managers and energy planners should not bank on past extremes delivering the same punch.
• Regional Nuances: Stronger North Atlantic/European signals possible (negative NAO → wetter SW Europe?).
• Limitations & Caveats: Model-dependent (only well-performing models selected); focuses on boreal winter DJF; mechanisms warrant further process studies (e.g., single-model pacemaker experiments like Trascasa-Castro et al. 2025 support the shifts). Internal variability remains large.
• Frequency vs. Intensity Trade-off: More frequent extremes, but each packs less distinctive remote “punch” over key populated areas.

This work underscores a subtle but important nuance in climate change: it’s not just about more extremes, but about evolving patterns of impacts. Familiar archetypes from the 20th century may not hold, complicating risk assessment even as overall ENSO variability potentially increases.

Published: Geophysical Research Letters (2026)

DOI: 10.1029/2025gl121189

Journal information: Geophysical Research Letters

Authors: Margot Beniche, Jérôme Vialard, Andréa S. Taschetto, Matthieu Lengaigne

Abstract

In today’s climate, extreme El Niño events (e.g., 1982–1983, 1997–1998) generate stronger and eastward-shifted teleconnections relative to moderate El Niño and La Niña events, leading to distinct North American impacts such as enhanced rainfall over California and warming over northeastern North America.

A multi-model, multi-member, multi-scenario CMIP6 analysis shows that as warming exceeds +2°C, extreme El Niño teleconnections shift even farther eastward (by 20°), weaken (by 33% at +3.5°C over North America) and develop a negative North Atlantic Oscillation–like response, echoing the changes seen in moderate El Niño–Southern Oscillation (ENSO) phases.

Extreme El Niño North American impacts become progressively closer to those of moderate events, with little distinctiveness left beyond +3.5°C.

Although future teleconnection changes are much stronger for extreme El Niños, their increased frequency and altered future patterns contribute only modestly to the overall change in ENSO teleconnections.