Scientists are watching the Pacific Ocean closely as what could be one of the most powerful climate events in recorded history rapidly builds beneath its surface.
According to the most recent forecasts from the National Oceanic and Atmospheric Administration (NOAA), the probability of an El Niño – a periodic warming of the tropical Pacific that reshapes weather patterns across the globe – emerging by July now sits at 61 per cent.
While these events happen every few years, this one may be supercharged. NOAA gives a one-in-four chance of the event reaching “very strong” intensity, which would qualify it as a so-called ‘super’ El Niño. Such a threshold has been crossed only a handful of times in recorded history, each moment triggering droughts, floods and record temperatures across multiple continents.
What’s more, scientists who study these phenomena closely say such an event coupled with the impacts of human-caused climate change could make it unlike anything seen before.
“I would suggest there is roughly a 50 per cent chance of the event becoming the strongest in the historical record right now,” Paul Roundy, a professor of atmospheric science at the University at Albany, in the US, told BBC Science Focus. “A few weeks ago, I was suggesting maybe 20 per cent.”
What is El Niño, and why is this one different?
El Niño is a recurring climate cycle driven by the warming of surface waters in the tropical Pacific.
Every few years, the trade winds that normally push warm water westward weaken or reverse, allowing accumulated heat to spread eastward along the equator.
A super El Niño is defined by sea surface temperatures in a key stretch of the central Pacific rising more than 2°C (3.6°F) above normal. Only three have happened in recorded history: in 1982/83, 1997/98 and 2015/16.
In 1876, before modern meteorological records, a super El Niño is thought to have contributed to a global famine that killed as many as 50 million people.
This year, Roundy explained, a series of extraordinarily powerful westerly wind bursts over the Pacific have pushed a vast reservoir of accumulated water eastward toward the equator.
The closest parallel is a wind event in early 1997, which preceded what was probably the strongest El Niño of the 20th century.
“The warm water to the east of this year’s westerly wind burst is about half a degree warmer than the warm water was at the same time in 1997,” Roundy said. “It has basically been hit with all the momentum that is needed to bring the event over the intensity of what was achieved then.”
Still, the outcome is anything but settled. Future wind shifts could still partially offset the developing event.
Roundy said: “Based on the distributions of historical surges in the trade winds and the distribution of westerly wind events, and how strong the recent event has been, it would take an event well beyond the 99th percentile in intense trade winds to render the developing El Niño event just strong and not extremely strong.”
In other words: a very strong El Niño is now close to certain. But whether it breaks all records remains an open question.
What does a super El Niño actually do?
The impacts of El Niño are felt the world over. From diminished fish stocks off the coast of Peru to suppression of monsoons and rainfall in India, China and much of Southeast Asia, barely a corner of the planet is left unchanged.
“Normally wet places become dry and suffer fires,” Roundy said. “Normally dry places become wet.”
In the US, impacts of the developing El Niño could begin to be felt this summer. Typically, more rain hits the Midwest and West during the summer months, while periods of drier weather are seen stretching from the Gulf Coast to the East Coast.
By winter, as El Niño becomes more established, it strengthens the southern storm track – bringing heavy rain across the South from California to the East Coast.
1982 and 1997 were, in Roundy’s words, “incredible flood years” in the US. Meanwhile, the northern tier of the US runs warmer than usual over the winter.
One possible benefit of a strong El Niño is a suppression of the Atlantic hurricane season as increased wind shear prevents storms from forming.
Into uncharted territory
None of this would be straightforward in any year. But 2026 is not any year. Global temperatures are already running over 1.4°C above pre-industrial levels, and a strong El Niño layered on top of that baseline takes the climate system somewhere it has not been in modern human history.
“We’ve never experienced a strong or very strong El Niño event amid pre-existing conditions that were this warm globally,” Dr Daniel Swain, climate scientist at the University of California Agriculture and Natural Resources (UCANR), said in a statement. “Therefore, it would not be surprising to see some unprecedented global impacts by later in 2026 into 2027 in terms of flood, drought, and wildfire-related extremes.
“Either 2026 or 2027 (or both) stand a good chance of setting a new global temperature record, yet again.”
At such high temperatures, wildfires become particularly concerning. A super El Niño “against the backdrop of elevated baseline temperatures could increase the risk of widespread or unusually intense fires in normally damp regions where such fires are not common,” Swain said, pointing specifically to the Amazon and parts of Oceania, where peatlands “can burn for months on end”.
A December 2025 study in Nature Communications adds a longer-term dimension to these concerns. Analysing all three super El Niños on record alongside climate model projections, researchers found that events of this intensity significantly increase the likelihood of “climate regime shifts” – abrupt, persistent transitions in temperature, sea surface conditions, and soil moisture that can endure for years or even decades after the El Niño itself has faded.
Under global warming scenarios, the study found, this effect would be “greatly amplified”, with the central North Pacific, the Gulf of Mexico, East Africa, the Amazon, central Australia, and the Maritime Continent around Indonesia likely to be worst affected.
The implication is that the effects of a 2026 super El Niño may not simply reverse when Pacific temperatures cool again – some changes could lock in.
Roundy urged caution about overstating that conclusion, however. With only three super El Niños on record, the foundations of any predictions about what follows are shaky at best.
“Scientists who are basing their conclusions on what is likely to happen this time, based on a small sample of past events, should not have as much confidence in whether we are going to have supercharged global warming for the next 10 years, or whether it is just enhanced for the next year or so,” Roundy said.
In short, the scale and trajectory of what’s developing in the Pacific is unusual, and we’re heading into it with a climate system running hotter than at any point in our post-industrial era.
“Ecosystems have evolved with El Niño for millions of years, and they need some of these extreme events in order to renew those ecosystems,” Roundy said.
“But it has a big human impact, a social impact, and an impact on life.”
Exactly how dramatic, damaging and long-lasting its impacts are, though, remains deeply uncertain.
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