El Niño–Southern Oscillation (ENSO) is a coupled ocean–atmosphere phenomenon in the tropical Pacific characterized by quasi-periodic fluctuations between warm (El Niño), cold (La Niña), and neutral phases. It arises from interactions among equatorial Pacific sea-surface temperatures, trade winds, and the Walker circulation, producing large-scale anomalies in convection, thermocline depth, and surface pressure, notably the Southern Oscillation index. ENSO modulates global atmospheric circulation, altering precipitation, temperature, and storm tracks on interannual timescales, and serves as a key source of seasonal-to-interannual climate variability and predictability in climate diagnostics and modeling.
El Niño is a recurring climate event with impacts across the globe. It has three phases: one cold (known as La Niña), one neutral, and one warm (El Niño).
Earth Sciences
Jun 3, 2026
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A portion of one of the most ambitious ocean monitoring networks ever built will go dark this month when scientists board a research vessel and motor off the Oregon coast to pull a research buoy from deep out of the Pacific.
Environment
Jun 3, 2026
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There is an 80% chance of the warming El Niño phenomenon developing between June and August, increasing the risk of extreme weather events, the World Meteorological Organization said Tuesday.
Environment
Jun 2, 2026
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Waves of higher, warmer water move eastward across the Pacific Ocean a few months before an El Niño emerges. Several have shown up in 2026 satellite data.
Earth Sciences
May 27, 2026
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Increasingly, the world's oceans are telling us our climate system may be changing faster and more dramatically than expected.
Environment
May 25, 2026
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The arrival of a potentially powerful El Niño weather system this year could devastate coral reefs around the world already weakened by back-to-back rounds of bleaching, scientists warn.
Ecology
May 22, 2026
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Forecasters say a potentially "super" El Niño is rapidly taking shape in the Pacific—but whether it evolves into a history-making event could hinge on fickle winds and other volatile atmospheric shifts.
Earth Sciences
May 22, 2026
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Extreme heat and drought could damage harvests and worsen global food insecurity this summer.
Environment
May 19, 2026
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A potentially powerful El Niño could take shape later this year. While its effects are often felt dramatically across parts of the United States and around the globe, experts say the picture for Southern Appalachia is more ...
Environment
May 18, 2026
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Multi-year La Niña events—so-called "double-dip" or even "triple-dip" La Niñas—are becoming more common. But why do these events persist for multiple years in the first place?
Earth Sciences
May 15, 2026
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