The finding arrives as a strong El Niño strengthens in the tropical Pacific. The World Meteorological Organization said July 31 that the event was expected to intensify during August–October 2026, while the International Research Institute’s August outlook strongly favored El Niño continuing into early 2027.

What the coral record shows

The study, published in Science, reconstructs eastern-Pacific sea-surface temperatures over roughly 900 to 1,000 years. Researchers analyzed 29 modern and fossil coral samples from the Galápagos, including fossil material dating to about 1100.

Corals preserve indirect evidence of the water around them. Their growth bands resemble tree rings, while the proportions of elements such as calcium and strontium and different oxygen isotopes vary with seawater temperature. Uranium-thorium dating helped establish when fossil coral formed.

The record is not a continuous, year-by-year instrumental history. It is patchy, with gaps and sampled windows from different periods. But the researchers say the recent four decades show an unusual rise in ENSO variability, driven largely by stronger and more frequent El Niño events rather than simply a higher average ocean temperature.

Why the Galápagos matters

The islands sit in the eastern tropical Pacific, a region where El Niño’s warming signal is especially pronounced. During an El Niño, weakened trade winds allow warm water to move eastward. That changes where heat is released into the atmosphere and can alter weather patterns far beyond the Pacific.

Instrumental observations cover only about 75 years, which makes it difficult to separate a long-term climate trend from natural fluctuations. A longer paleoclimate record offers a broader comparison, although it also carries uncertainties tied to sampling and the way coral chemistry reflects temperature.

What the study does not prove

The study authors link the recent increase to human-caused warming, and some outside scientists view the coral evidence as important support for that interpretation. Kim Cobb, a coral and climate scientist at Brown University who was not involved in the research, told The Associated Press that the results add to paleoclimate evidence pointing toward stronger El Niño events under global warming.

Other scientists remain skeptical about how much the record demonstrates. Michael Mann of the University of Pennsylvania and John Bruno of the University of North Carolina told AP that the coral results conflict with some recent instrumental observations near the Galápagos. Mann said recent observations show a substantial decline in El Niño-related variations in that region, while Bruno said the chemistry could be reflecting background greenhouse-gas warming rather than a change in El Niño itself.

The study also cannot determine whether El Niño will continue strengthening in coming decades. Some climate models suggest warming could increase ocean stratification, leaving a warmer surface layer more responsive to wind changes. But researchers say the future direction remains uncertain, and the study is not a forecast for any particular country or city.

Why the timing matters

WMO said the developing 2026 El Niño could bring above-normal temperatures across much of the world and shift rainfall patterns, increasing drought risk in some areas and flood risk in others. Its outlook also identifies potential effects on wildfire conditions, agriculture, fisheries, water management and public health. The agency stresses that its maps show probabilities, not certainties, and that “super El Niño” is not part of its operational classification system.

IRI’s August outlook assigned a 100% probability to El Niño conditions from August–October 2026 through February–April 2027, followed by lower probabilities later in 2027. Those figures describe the model outlook for the ENSO state; they do not mean that particular weather impacts are certain. The forecast is also separate from the coral study: the paper reconstructs past climate variability, while the forecast monitors the current event.

For governments and communities, the practical message is preparation rather than prediction. Seasonal outlooks can guide decisions on water supplies, crop planning, fisheries, wildfire readiness, health services and humanitarian response. The new coral record strengthens the case for taking ENSO-related risks seriously, while the scientific debate remains open over exactly how much of the recent change reflects human-driven intensification.

Sources

• Science study: Global warming is intensifying eastern Pacific El Niño variability
• Associated Press: El Niños are getting stronger and study says it is because of climate change
• World Meteorological Organization: Strong El Niño expected to intensify
• International Research Institute: August 2026 ENSO Quick Look