Study Suggests Global Warming Is Making El Niño Stronger and Less Stable

Ancient coral records are exposing an unusual shift in Pacific climate behavior, with consequences that could reach far beyond the ocean.

Planetary warming may be altering the climate cycle associated with El Niño, making it less stable and intensifying its warm phases. This is the conclusion reached by the authors of a study published in the journal “Science.”

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The analysis showed that over the past 40 years, El Niño events have been, on average, 36% more powerful than during the pre-industrial era. Compared with events recorded in the 20th century, their strength has increased by approximately 16%. The current super El Niño in the tropical Pacific could prove to be the strongest since at least 1950.

Corals helped reconstruct the climate of the past

To investigate these changes, scientists analyzed corals from the Galápagos Islands. This region in the eastern tropical Pacific plays an important role in the formation and intensification of El Niño.

Chemical compounds preserved in coral skeletons make it possible to determine what the temperature and other ocean conditions were like while the corals were growing. This allowed the researchers to reconstruct a history of temperature fluctuations over the past thousand years.

Corals are like the sea’s time capsules. They preserve, in the chemical composition of their skeletons, a record of the conditions in which they grew, and we can reconstruct that history by analyzing chemical indicators.

– Julia Cole, lead author of the study

The data obtained were compared with the results of 12 modern climate models. The comparison showed that the pattern of changes observed in recent decades extends well beyond the range of natural variability characteristic of the previous millennium.

Something highly unusual is happening now, and it is most likely connected to human-caused climate change.

– Jonathan Overpeck, co-author of the study

At the same time, the scientists do not claim that the causal link between global warming and the intensification of El Niño has been conclusively proven. However, human-induced climate change remains the most likely explanation for the trend observed over the past several decades.

How a stronger El Niño affects the weather

El Niño occurs when the surface waters of the equatorial Pacific become unusually warm. This alters atmospheric circulation and can affect temperatures, precipitation, and weather conditions far beyond the Pacific Ocean.

Powerful warm phases can raise the average global temperature and increase the likelihood of extreme events, including intense heat, heavy precipitation, and droughts.

The researchers also recorded changes in the alternation between El Niño and the cooler phase of this cycle, La Niña. According to their findings, the climate cycle is shifting increasingly toward stronger warm episodes.

A threat to coral reefs

Prolonged ocean warming creates an additional risk for coral ecosystems. When water temperatures become too high, corals lose the organisms that provide them with their color and some of their nutrients. This causes bleaching, and if overheating persists, the corals may die.

Mass bleaching events have already occurred during strong El Niño episodes, including in 2015–2016. Scientists fear that a large-scale event could happen again in 2026, so they are working to collect as many samples of healthy corals as possible while they still survive.

The growing body of evidence that burning fossil fuels is intensifying El Niño forces us to consider a future with even stronger weather and climate extremes against a backdrop of overall worsening climate conditions. This will have far-reaching consequences for communities and ecosystems around the world.

– Kim Cobb, coral researcher

If this trend continues, strong El Niño events could become a defining feature of a warmer climate. This would mean greater risks of extreme heat, precipitation, and drought, as well as further destruction of coral reefs and other vulnerable ecosystems.