Oceans Are Already Boiling: Climatologists Detect Record-Breaking El Niño Before It Even Peaks

Climatologists around the world are sounding the alarm: El Niño, still forming in the Pacific, risks becoming the strongest event ever recorded, according to several forecasting models. That's the assessment of prominent climatologist Zeke Hausfather, commenting on the July batch of forecasts for the so-called Southern Oscillation.

"I'm usually pretty measured when it comes to climate data. In recent years, I've said I was truly shocked only once — when the global average temperature in September 2023 blew past all previous records by 0.5°C. Now I'm shocked for the second time," Hausfather wrote.

The reason behind his strong words is straightforward: most models projecting the future strength of El Niño show that this autumn the phenomenon will significantly surpass anything ever recorded in the known observational history.

What El Niño Is and Why It Matters

El Niño refers to the warming of ocean waters in the eastern tropical Pacific by several degrees, triggered by weakening trade winds. Its counterpart, La Niña, cools the same region instead. Both terms come from Spanish and have been known since the days of Peruvian fishermen, who noticed the phenomenon hundreds of years ago.

The strength of El Niño is typically measured in two ways: the RONI index (comparing water temperatures to the rest of the tropics) and the older ONI index (comparing them to the region's 30-year average).

Forecasts Point to a Historic Record

According to the European Centre for Medium-Range Weather Forecasts (ECMWF), most model scenarios show a RONI anomaly exceeding 3°C by year's end. For comparison, the strongest El Niño on record (1982–1983) reached an anomaly of just 2.69°C.

The US National Oceanic and Atmospheric Administration (NOAA) puts the probability of reaching the highest category — a RONI anomaly above 2°C — at 80%. The current anomaly is already approaching that threshold, with months of intensification still ahead, since El Niño traditionally peaks toward the end of the year.

Hausfather analyzed 14 models (667 model runs in total) and arrived at a weighted median RONI anomaly of 3.1°C — meaning the previous record could be broken by several tenths of a degree, an enormous margin on a climatic scale.

The picture looks even more dramatic under the older ONI index: the median across the 14 models is 3.6°C. Previous record seasons — 2015/2016 and 1877/1878 — reached only around 2.7°C. The gap with the expected new record stands at a staggering 0.8°C.

"El Niño is very likely to become not just the strongest on reliable record — it could shatter the record by a stunning margin," Hausfather noted, pointing out that the difference between the strongest and the fifth-strongest El Niño over the past 150 years is only 0.5°C.

What This Means for People

El Niño raises both the likelihood and intensity of natural disasters around the world — above all, torrential rains and floods, as well as severe droughts, mostly in the Southern Hemisphere and Asia. Europe generally sees little noticeable impact.

A historical example: the super-strong El Niño of 1877–1878 contributed to catastrophic droughts and famine that claimed an estimated up to 50 million lives. In modern times, the death toll from such events is usually counted in the thousands, or at most tens of thousands, though the long-term economic damage can reach several trillion dollars — a significant share of global GDP.

The Planet Is Warming Faster Than Forecast

El Niño's peak effect on global average air temperature usually shows up with a delay of several months, which is why 2027 has the best odds of breaking 2024's temperature record. However, a new all-time high could actually be set this year — El Niño is developing rapidly and arriving on top of an already heavily warmed climate system.

Since June, the world's oceans have remained record-warm for this time of year, and lately the planet's average daily air temperature has followed suit.

Renowned American climatologist Michael Mann notes: "Because of this rapidly developing and powerful El Niño, global air and sea-surface temperatures are setting new records. Usually, the record year comes the year after El Niño, but this time it could happen in the current year itself."

According to Hausfather's calculations, 2027 is most likely to become the warmest year by a wide margin, though there is a 26% chance that 2024's record will already be broken this year. Another leading climatologist, James Hansen, is convinced the record will fall right now, attributing this not only to El Niño but also to accelerated warming caused by declining cloud reflectivity as human aerosol emissions decrease — though this hypothesis is still considered secondary by most scientists.

Experts agree on one thing: the rest of 2026, and especially 2027, will be exceptionally warm, and it's during this period that a new annual temperature record should be expected. Meanwhile, the past 11 years have already become the 11 warmest years on record.

Around Prague, based on reporting by seznamzpravy.cz