The study was published in Science on August 27, 2026, as the 2026 El Niño continued to intensify. The International Research Institute at Columbia University said in an August 19 update that the event could become one of the strongest in the historical record, although its eventual peak remains uncertain.

For people in the United States, the research matters because El Niño can shift the odds of winter rain, snow, temperature extremes and related risks. It does not provide a city-by-city forecast or guarantee the same outcome for every state.

What the coral reconstruction found

Researchers led by University of Michigan paleoclimate scientist Julia Cole reconstructed past El Niño-Southern Oscillation, or ENSO, variability from coral fossils in the Galápagos Islands.

Coral skeletons preserve chemical signals related to the ocean conditions in which they formed. The team used measurements including calcium-to-strontium ratios and oxygen isotopes to estimate past sea-surface temperatures, while uranium-thorium dating helped establish when the corals grew.

The reconstruction included 29 coral fossils, according to The Associated Press: 14 from before the industrial era, 14 from the modern period and one from around the beginning of industrialization. The oldest sample dated to about the year 1100, producing a patchy record covering more than 900 years.

As reported by AP, the study found that El Niño events were more than 36% stronger than during the preindustrial period and about 16% stronger than twentieth-century events. The largest increase appeared during roughly the past 40 years.

Here, “stronger” refers to the magnitude of El Niño-related variability in the reconstruction. It does not mean that every individual El Niño will be stronger than the one before it or that every event will produce the same weather in the United States.

Cole told AP that the increase closely parallels the rise in global temperatures caused by human activities such as fossil-fuel burning. The study therefore argues that human-caused warming may be amplifying a natural climate pattern that already influences weather around the world.

Why the finding remains debated

The coral reconstruction is important evidence, but it is not the final word on how ENSO is changing. Coral records come from a particular part of the Pacific and must be interpreted as indicators of a larger, interconnected climate system.

AP reported that outside scientists disagreed about the study’s interpretation. Brown University climate scientist Kim Cobb described the coral evidence as valuable for extending a short instrumental record. University of Pennsylvania climate scientist Michael Mann and University of North Carolina marine scientist John Bruno said the coral result conflicts with some recent observations near the Galápagos. Bruno argued that the signal could reflect greenhouse-gas-driven warming rather than a change in El Niño itself.

That dispute is one reason the result should be described as evidence in an active scientific debate, not definitive proof that climate change will intensify every future El Niño.

Separate research published June 15, 2026, in Geophysical Research Letters also examined eastern Pacific coral records, but it addressed ENSO variability about 4,000 years ago rather than the modern industrial-era comparison in the new Science study. The work illustrates why location and time period matter when scientists compare coral records from different parts of the Pacific.

The 2026 El Niño is already strengthening

The timing of the new study is significant because the current El Niño is intensifying. The IRI’s August 19 update said the weekly Niño 3.4 index centered on August 12 had reached plus 2.7 degrees Celsius. Niño 3.4 measures sea-surface-temperature anomalies in a central equatorial Pacific region used to monitor ENSO.

IRI said 25 of 26 models placed October through December 2026 in the “very strong” category, defined by the institute as a Niño 3.4 anomaly of at least plus 2 degrees Celsius. Fifteen models projected anomalies of at least plus 3 degrees Celsius, beyond the top of that classification scale.

The institute said that, if current conditions continue, the 2026 event could become one of the strongest in the historical ENSO record. That is a forecast, not a confirmed ranking. El Niño events typically reach maximum strength between October and February, so additional observations and later outlooks will matter.

What El Niño could mean in the United States

NOAA says El Niño changes atmospheric circulation and modifies the mid-latitude jet streams. Its influence on U.S. temperature and precipitation is generally strongest during winter and can continue into early spring.

Typical El Niño patterns include wetter and cooler conditions across much of the southern tier, from California to the Carolinas, and warmer conditions in the Pacific Northwest and southern Alaska. The northern tier can also experience lower heating demand in some winters.

Those patterns are probabilities, not guarantees. NOAA emphasizes that each El Niño is different. Other ocean and atmospheric patterns, short-term weather variability and local geography can change the result, including whether a particular area is wetter, drier, warmer or colder than the broad seasonal tendency.

What readers and planners should watch

Residents should rely on later NOAA seasonal outlooks and local forecasts rather than treating the El Niño designation as a prediction for a specific community.

Farmers and water managers may need to track precipitation and drought outlooks. Utilities can watch temperature forecasts that affect heating and electricity demand. Transportation agencies and emergency managers may need to review flood, landslide, snow and severe-weather planning as regional forecasts become more specific. Health systems can also monitor later guidance if winter conditions raise risks from cold, storms, respiratory illness or disruptions to care.

The long-term coral evidence and the short-term 2026 forecast answer different questions. The study examines how ENSO variability may have changed over centuries. The IRI assessment estimates what the Pacific Ocean and atmosphere may do over the next several months. Both make clear why U.S. planning should account for changing climate risks while avoiding claims that one forecast determines the winter everywhere.

Key sources

• Associated Press report on the coral study and outside expert reaction
• Columbia University IRI August 2026 ENSO Quick Look
• NOAA Climate.gov El Niño and La Niña FAQ
• Geophysical Research Letters coral-record study