American scientists said El Niño — the pure Pacific weather phenomenon that raises global temperatures — has officially begun.
The US National Oceanic and Atmospheric Administration (NOAA) said El Niño conditions are already occurring in the equatorial Pacific as sea surface temperatures have risen dramatically in recent months.
Many forecasts suggest that this phenomenon could become a so-called “tall El Niño” and that it could even be among the most intense that have been recorded so far.
If we add to this the decades of warming caused by human activity, there could be a year of record temperatures – most likely in 2027 –, presenting alterations in the climate, food supply and economies that could last throughout that year.
Successor of “The Girl”
But the NOAA announcement is not surprising, because meteorologists anticipated this warming phase after the end of the weather pattern considered “sister” to El Niño and that tends to cause colder weather: La Niña, earlier this year.
Sea surface temperatures in the central and tropical Pacific have now surpassed the threshold of 0.5°C above average that American scientists use to define an El Niño event.
“Over the past month, El Niño conditions have developed, as indicated by above-average sea surface temperatures in the belt spanning the central to eastern equatorial Pacific,” the agency said.
NOAA also saw a change in winds over the equatorial Pacific, a sign that the atmosphere is responding to ocean warming, and it’s not just isolated ocean warming.
What has surprised researchers is the high degree of certainty that computer models show regarding the intensity of the phenomenon.
The parameter that is American. To measure the intensity of El Niño is the average sea surface temperature in a key area of the Pacific.
A strong episode occurs as one in which the temperature exceeds the average by more than 1.5°C; a very strong one, when it exceeds it by more than 2°C.
According to NOAA’s June forecast, “there is a 63% chance of a very strong El Niño event between November and January, which would place it among the strongest recorded since 1950,” the agency said.
Attention, with caution
The three most intense episodes since 1950 were those of 1982-1983, 1997-1998 and 2015-2016.
Some of the most recent models from the United States and Europe (ECMWF) go further and show that temperatures in the tropical Pacific could reach above average by more than 3°C by the end of the year.
However, the US agency recommended some caution when interpreting what its intensity predictions imply.
“Even very strong El Niño events do not always cause the expected effects everywhere, although more intense phenomena can tip the balance more clearly in favor of the expected results.”
The biggest concern is that all of this is happening on a planet that is already much warmer.
“We need to worry about the impacts,” said Professor Adam Scaife, head of month-to-decade forecasts at the Met Office.
“The current El Niño phenomenon… adds up to basically global warming.”
“This means that actual temperatures in the affected regions could reach unprecedented levels, as the warming caused by El Niño is enhanced by climate change.”
A very strong El Niño usually raises global air temperatures by about 0.2°C by releasing heat stored in the ocean into the atmosphere.
That additional thermal boost now affects a world that is already breaking records.
The year 2024—the warmest on record—was driven by an El Niño that wasn’t even particularly strong.
And, despite the cooling effect of a La Niña episode, 2025 was the third warmest year on record, even surpassing 2016, marked by a “super El Niño.”
The approaching heat
“It is doubtless that at the end of this year and until 2027 we will see very high temperatures on a global scale,” said Professor Scaife.
“In 2027, it is doubtless that we will see excess heat adding to already existing global warming; this could easily lead to another year with a temperature increase of more than 1.5ºC [respecto a los niveles de finales del siglo XIX]”.
No two El Niño events are the same, but its effects are felt more intensely in tropical regions.
Floods are frequent in northern Peru and southern Ecuador, and can also affect areas of East Africa, Central Asia and the southern United States.
At the same time, the risk of drought and wildfires increases in much of Australia, Indonesia and northern South America, harming agriculture and global food reserves.
El Niño also tends to inhibit the formation of hurricanes in the Atlantic, and meteorologists are already predicting a season with less activity than usual.
“While this may seem positive, for Central America it means a significant reduction in rainfall and the potential for drought,” said Liz Stephens, professor of climate risk and resilience at the University of Reading.
Even the United Kingdom perceives its effects, although mildly: El Niño can tip the balance towards a winter that begins with mild temperatures but ends with cold, although the relationship is not entirely direct.
For many people, this forecast is far from abstract.
“The declaration of an El Niño event is not just another weather forecast; for millions of people, it represents a terrifying alarm signal,” said Mohamed Adow, director of the climate advocacy organization Vitality Shift Africa.
“It means insufficient rain, failed crops, a rise in food prices and families once again pushed to the limit. In East Africa in particular, this will affect communities already hit by droughts and floods in recent years.”
The Japan Meteorological Agency agrees with NOAA in considering that El Niño conditions already exist. In addition, he points out that it is practically certain that the phenomenon will last until autumn.
However, not all organizations have yet commented on the matter. The Australian Bureau of Meteorology applies stricter criteria, requiring sea surface temperatures to be more than 0.8°C above average.
This week, the agency indicated that the tropical Pacific was “approaching El Niño conditions”—with temperatures in the central Pacific already exceeding its reference thresholds—but stopped short of formally declaring the onset of the phenomenon.
They expect El Niño to develop later this year and warn that it could be intense.
El Niño occurs at intervals of two to seven years and tends to last about a year.
There is still no conclusive evidence that climate change is intensifying these phenomena or increasing their frequency, but global warming may exacerbate their effects.
Additional reporting by Erwan Rivault.
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