Atmospheric Variability and Teleconnections in El Niño Phenomena
Summary
El Niño–Southern Oscillation (ENSO) represents a coupled ocean–atmosphere system in the tropical Pacific, oscillating between warm (El Niño) and cold (La Niña) phases. Variations in sea surface temperature (SST), thermocline depth and atmospheric circulation over the equatorial Pacific can trigger far-reaching teleconnections that modulate rainfall, drought and temperature patterns on a global scale. In warm phases, weakened trade winds and deeper thermocline in the eastern Pacific amplify SST anomalies, which in turn alter convection and jet stream positions, propagating effects into remote regions from the Americas to Africa, South Asia and beyond. Recent work has highlighted the emergence of multi-year El Niño events driven by changes in upper-ocean stratification, as well as the distinct dynamics of extreme coastal El Niño episodes where local feedbacks between downwelling Kelvin waves, coastal winds and deep convection produce intense marine heatwaves. Interactions with other modes—such as the Pacific Meridional Modes (PMMs) and the Indian Ocean Dipole—further complicate the ENSO footprint, with compound occurrences intensifying drought, flood and socio-economic impacts. Understanding these mechanisms enhances seasonal forecasting skill and informs adaptation strategies under a warming climate.
Research from Nature Portfolio
Recent studies have combined palaeoclimate reconstructions with multi-model simulations to reveal that over the past seven millennia the frequency of multi-year ENSO events has increased five-fold, linked to a shallower thermocline and enhanced upper-ocean stratification in the tropical eastern Pacific. This longer ENSO period underscores a sensitivity to orbital and anthropogenic forcing, signalling heightened risk of persistent global climate extremes. Complementary work on the 2017 coastal El Niño off Peru demonstrates a positive feedback between equatorial downwelling Kelvin waves, anomalous northerly coastal winds and local deep convection. This coupled process not only explains the rapid onset of extreme rainfall but also provides early predictability, with seasonal models successfully forecasting the event several weeks in advance. Climate projections suggest more frequent extreme coastal El Niño occurrences under continued warming.
Atmospheric Variability and Teleconnections in El Niño Phenomena publication trend
The graph below shows the total number of articles in atmospheric variability and teleconnections in el niño phenomena across all publications each year (not limited to Nature Index journals).
Technical terms
El Niño Southern Oscillation (ENSO): A coupled ocean–atmosphere phenomenon in the tropical Pacific characterised by alternating warm (El Niño) and cold (La Niña) phases.
Teleconnection: A climate anomaly in one region that is linked via atmospheric or oceanic pathways to anomalies in a distant region.
Thermocline: The transition layer in the ocean where temperature decreases rapidly with depth, influencing ocean heat storage and SST anomalies.
Pacific Meridional Mode (PMM): A subtropical mode of SST and wind variability in the Pacific that can trigger equatorial anomalies and influence ENSO development.
Multi-year ENSO event: An El Niño or La Niña episode that persists for two or more consecutive years, producing cumulative climatic impacts.
References
- Increased frequency of multi-year El Niño–Southern Oscillation events across the Holocene. Nature Geoscience (2025).
- Coupled ocean-atmosphere dynamics of the 2017 extreme coastal El Niño. Nature Communications (2019).
- Extreme coastal El Niño events are tightly linked to the development of the Pacific Meridional Modes. npj Climate and Atmospheric Science (2024).
- Effects of El Niño and the Positive Indian Ocean Dipole (+IOD) on Health, Food Security, Economics, and Conflict in Low‐ and Middle‐Income Countries in the Indo‐Pacific: A Systematic Review. Campbell Systematic Reviews (2025).
- Amplified risk of spatially compounding droughts during co-occurrences of modes of natural ocean variability. npj Climate and Atmospheric Science (2021).
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