El Niño & Extreme Heat: Drivers, Mechanics, and Global Impacts
El Niño—the warm phase of the El Niño-Southern Oscillation (ENSO)—is a large-scale climate pattern characterized by abnormal ocean surface warming in the central and eastern tropical Pacific Ocean. Beyond localized oceanic changes, El Niño fundamentally alters global atmospheric circulation. It serves as one of the primary drivers of extreme heatwaves, prolonged droughts, and record-setting global surface temperatures.
Ocean Warming
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Thermal Displacement: Under normal conditions, warm surface waters are pushed toward the western Pacific (near Indonesia and Australia). During El Niño, this vast warm water pool sloshes back eastward toward South America, raising sea surface temperatures by several degrees Celsius above average.
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Suppression of Cold Upwelling: The deep layer of warm water prevents the natural upwelling of nutrient-rich, cold ocean water off the South American coast, trapping heat at the surface.
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Massive Thermal Release: The expanded surface area of warm equatorial water acts as a massive thermal radiator, releasing enormous amounts of latent heat and water vapor directly into the global atmosphere.
