Are we seeing signs of a 'super El Niño'?

A moderate to strong El Niño event is expected to emerge in May and last at least until the end of the year, China's National Climate Center said on Saturday, suggesting increased risks of record-breaking heatwaves in the next two years.

The National Climate Center expected the sea surface temperature (SST) to continue the rising trend observed in recent months in the central-to-eastern equatorial Pacific, also known as the Niño 3.4 region. Meteorologists measure the monthly average SST in this strip of ocean, spanning from 170°W to 120°W longitude between 5° North and 5° South latitude, to monitor temperature anomalies that would classify El Niño-Southern Oscillation (ENSO).

El Niño is a recurring natural phenomenon characterized by fluctuating ocean temperatures in the equatorial Pacific that causes major influence on global climate patterns, according to the World Meteorological Organization. 

If the 3-month moving average SST of the monitored area shows an anomaly that exceeds 0.5 degrees Celsius, and the anomaly persists for at least 5 months, it would account for an El Niño event, Chen Lijuan, chief meteorologist at China's National Climate Center, said on Saturday.

A temperature anomaly peaking between 1.3 and 2 degrees Celsius would account for a moderate El Niño event, Chen explained. A peak anomaly over 2 degrees Celsius classifies a strong event, and a "super event" if the anomaly peaks at over 2.5 degrees Celsius.

An El Niño event involves widespread warming across specific regions of the ocean, which releases massive amounts of heat into the atmosphere, Chen explained. With the existing effects of global warming, global average temperatures could spike significantly. 

Heatwaves, because of an El Niño event, aren't just more likely to occur – they are prone to be stronger, last longer and arrive earlier than expected, Chen warned.

Global consensus on a worrisome trend 

Reports from meteorological institutions across the globe concur with the trend forecasted by China's National Climate Center, although there's yet to be a precise consensus on the intensity and time frame of the potential El Niño event. 

The US National Oceanic and Atmospheric Administration (NOAA) issued an El Niño Watch in March, suggesting an over 60% chance of El Niño emerging during May and July. The European Center for Medium-range Weather Forecasts (ECMWF) also predicted moderate or strong El Niño conditions by mid-June. 

Notably, around half of the 20-plus prediction models used by ECMWF projected the October sea surface temperature in the Niño 3.4 region to exceed 2.5 degrees Celsius above the baseline temperature, suggesting a "super El Niño" event.

Ways a 'super El Niño' could affect the weather

Since 1950, the only El Niño cycle extreme enough to break the 2.5 degrees Celsius threshold occurred in 2015, which caused severe droughts in Indonesia and Ethiopia and three Category 4 hurricanes at the same time over the Pacific in August, a first in the modern record.

The warming effects of El Niño often lag by one year. The 2015 super El Niño preceded the record-breaking heat of 2016, Chen pointed out, just as the 2023 event led to the surface temperature breaking records in 2024.

"While it is too early to conclude that Earth will hit record temperatures this year," Chen said, "the associated risks are rising significantly." 

Chances of witnessing a 'super El Niño' in 2026

In April, a trio of tropical cyclones formed simultaneously on both sides of the equator in the Western Pacific. This rare incident is believed to be a major signal of an abnormally volatile ocean-atmosphere system, Zhu Dingzhen, former chief expert at the China Meteorological Administration, told a CMG reporter.

Meteorologists have acknowledged the challenge of predicting El Niño events in spring, calling this limitation "the spring predictability barrier." Several US federal scientists working for NOAA have noted false alarms in past decades, with El Niño events failing to form after spring-time predictions suggested otherwise. 

However, some scientists believe that there are enough indicators suggesting a strong or super El Niño is forming this year. Dr. Paul Roundy, a professor of atmospheric sciences at the State University of New York, wrote that there is a "real potential for the strongest El Niño event in 140 years," while reposting the latest forecasts from ECMWF on social media. He pointed out that the surface west-to-east wind anomalies, a main ingredient in El Niño, over the western tropical Pacific are currently exerting even greater force than during spring 1997, the year that saw one of the strongest El Niño events on record.