Scientists were already describing the current El Niño as the strongest on record months before it was expected to peak, according to a New Scientist analysis. The piece says two main factors helped turn it into such an unusually intense event.
The first started before the El Niño itself. As New Scientist explains, La Niña conditions push sun-warmed surface water west across the equatorial Pacific, where it piles up near Australia and Indonesia into what scientists call the “warm pool.” In this case, the article says that reservoir had been primed by a preceding multiyear La Niña, including the “triple dip” period before the 2023-24 El Niño, which Michael McPhaden of NOAA said helped stack unusually warm water in the western Pacific. The analysis also notes that long-term global warming has raised ocean temperatures over the past decades, even though McPhaden said the western Pacific heat content in late 2025 was not the highest ever recorded. New Scientist
The second factor was a series of strong eastward wind bursts that pushed that warm pool back toward South America, New Scientist reports. McPhaden said those bursts created Kelvin waves, which are downward bulges in the warm layer of ocean water that then travel across the Pacific over several weeks. In the analysis, he says the cumulative effect was an exceptional deepening of the thermocline in the eastern Pacific, making it harder for colder water to rise and cool the surface.
That matters because a deeper warm layer gives El Niño more room to keep feeding heat into the atmosphere. New Scientist says some parts of the thermocline were more than 80 meters deeper than normal, helping spread an enormous amount of extra warmth across the Pacific and, in turn, affecting weather far beyond it. New Scientist
One of those wind bursts may have gotten help from a rare bit of tropical timing. The article says a strong April burst was driven by three tropical cyclones forming in the western Pacific around the same time. Meteorologist and author Bob Henson told New Scientist that stronger westerly wind nudges make it easier for El Niño to develop and intensify. He also said global warming could, in principle, have increased the odds of three cyclones forming at once, though the article presents that as a possibility rather than a settled finding. New Scientist
What researchers say about climate change and El Niño strength
On the bigger question, the analysis says scientists still do not have a clear answer on whether global warming is making El Niño events themselves stronger. New Scientist quotes Michael Mann of the University of Pennsylvania calling it “an open question,” citing the limited modern record, gaps in longer coral-based reconstructions and climate models that are split on whether El Niño amplitude should increase or decrease with human-caused warming. New Scientist
What appears less disputed in the article is the damage side of the equation. Mann told New Scientist that warming amplifies the harms associated with El Niño, with hotter oceans and air loading the dice for heavier flooding, worse drought and more destructive wildfires when these events hit. Even if the strength question is still unsettled, the consequence is not especially comforting: a powerful El Niño now plays out on a warmer planet.
Comments