Will the "Super El Niño" arrive? Experts interpret whether this summer will be "difficult"

(Source: China Environment Network)

Reprinted from: China Environment Network

Recently, topics such as “This year and next may become the hottest years in history” and “The Earth may迎超级厄尔尼诺现象” have frequently trended on the internet, sparking widespread public attention. On March 23, the World Meteorological Organization (WMO) released the “2025 Global Climate Status Report,” which shows that the years 2015 to 2025 are the hottest 11 years on record, and 2025 is one of the three hottest years on record.

The alarm bell of global warming rings again. When exactly will the El Niño arrive this time? Will it reach “super” strength? Will China experience more intense heatwaves or more severe floods this summer? In response to these questions, “China Science Daily” interviewed several experts.

Zheng Fei, a researcher at the Institute of Atmospheric Physics, Chinese Academy of Sciences (hereinafter referred to as the Institute), pointed out that the Institute’s forecast results indicate that the likelihood of a moderate-strength El Niño occurring in 2026 is the highest, with a probability exceeding 70%, while the chance of developing into a super El Niño is only about 10%.

“Under the background of global warming, extreme climate impacts caused by ENSO (El Niño-Southern Oscillation) or related to it, such as high temperatures and heavy rainfall, are more likely to be amplified, becoming stronger and more frequent. While it is premature to assert that this year will be the ‘hottest year,’ the related risks are indeed significantly increasing,” Zheng Fei said.

“Spring Forecasting Obstacles”

Leading to Model Prediction Biases

El Niño refers to the phenomenon of sustained abnormally high sea surface temperatures in the tropical central-eastern Pacific Ocean, while the opposite abnormal cooling is called La Niña. This cyclic oscillation is the most intense interannual variation signal in the climate system.

Monitoring by the National Climate Center shows that the La Niña state lasting for two years has come to an end, and the sea surface temperature in the equatorial central-eastern Pacific is warming up. Liu Yunyun, director of the Climate Prediction Office at the National Climate Center, explained that, based on historical statistics, the probability of entering an El Niño state in the year following the end of La Niña is about one-third.

However, predictions from various global agencies about when El Niño will arrive are inconsistent. The European Centre for Medium-Range Weather Forecasts predicts as early as April, the Australian Bureau of Meteorology expects May, Japan’s Meteorological Agency points to June, while U.S. experts focus predictions on July to September.

Why do different agencies have such large discrepancies in predicting “when El Niño will arrive”? Does this indicate that the prediction models are not accurate enough?

Zheng Fei explained that this cannot be simply attributed to model deficiencies. Behind it is a scientifically recognized challenge— the “spring predictability barrier.” In simple terms, during spring each year, the “communication” between the tropical Pacific Ocean and atmosphere is at its weakest, making the physical connection between sea surface and subsurface temperature changes, and wind fields, the least clear.

Meanwhile, the prediction modes of different agencies are based on different modeling approaches to complex natural phenomena. They each emphasize different aspects of the physical processes of atmosphere-ocean coupling and have varying sensitivities to initial conditions.

Zheng Fei further explained that over longer forecast periods, initial errors and random disturbances in the atmosphere tend to amplify, leading some models to predict rapid warming, others to predict slower warming, or even to evolve in different directions toward cooling or warming. Therefore, it is premature to conclude that a “super El Niño” will occur this year.

Additionally, there is no unified standard internationally for classifying the intensity of “strong” and “super” El Niño. Zheng Fei told “China Science Daily” that China’s operational standards typically define a peak sea surface temperature anomaly of 2.0°C or above as “strong,” and above 2.5°C as “super.”

Based on this, conditions for forming a strong or super El Niño are extremely stringent: not only must the warm pool in the western Pacific be sufficiently “stocked” with warm water “ammunition,” but also the trade winds in the tropical Pacific must significantly weaken, westerlies frequently erupt, and a series of atmospheric responses must occur. Through extremely strong “positive feedback” between the ocean and atmosphere, warm water is continuously accumulated eastward and kept warming. Historically, strong to super El Niños occurred in 1997 and 2015.

Extreme High Temperatures

May Be Longer, Earlier, and More “Unbearable”

If this El Niño forms, combined with the ongoing trend of global warming, will it make extreme heatwaves more intense?

Li Kexin, a doctoral student at the Institute, described this risk as an “additive effect.” She explained that El Niño itself releases a huge amount of heat from the ocean to the atmosphere, naturally causing interannual warming. When this “natural warming” overlays the long-term “anthropogenic warming,” the baseline of global average temperatures is raised. This means that heat events are not only more likely but may also be stronger, longer-lasting, and arrive earlier.

Historical records support this. The super El Niño in 2015 was followed by a record-breaking global average temperature in 2016; the 2023 El Niño pushed 2024 to become the first year when the global average surface temperature exceeded the 1.5°C threshold above pre-industrial levels. The warming effect of El Niño often has a lag, typically peaking in the following year.

Therefore, while it is premature to assert that this year will be the “hottest year,” the associated risks are indeed significantly rising.

Focusing on China, Li Kexin stated that current research is quite certain that El Niño will significantly promote extreme high temperatures and heatwaves, with obvious regional and seasonal characteristics. Especially in the summer following El Niño, the world is more prone to stronger and longer heatwaves. Under the background of global warming, this “amplification” effect will become even more prominent.

“This means that if El Niño forms as expected in the second half of this year, then in the summer of 2027, especially in northern China, we should be psychologically prepared and have material reserves for ‘super long standby’ heatwaves,” Li Kexin said.

El Niño

Cannot Be “Customized” for Droughts and Floods with a Single Click

China has a typical monsoon climate zone. Besides high temperatures, the impact of El Niño on China’s flood and drought patterns during the flood season is more complex. Sometimes, El Niño is associated with “super heavy rain” or “major droughts nationwide,” but this understanding is actually quite biased.

Zheng Fei pointed out that this first ignores the “chaotic” nature of the climate system, often called the “butterfly effect.” Although El Niño is a powerful external forcing signal, it is not a “decisive switch” for droughts or floods in any specific part of China.

More importantly, El Niño never acts alone. China is located in the typical East Asian monsoon zone, where summer precipitation is the result of multiple factors including the western Pacific subtropical high, East Asian summer monsoon, mid- to high-latitude atmospheric circulation, local topography, and typhoon activity. Even during El Niño years, the distribution of rainfall bands can vary greatly.

Gao Gongbei, senior engineer at the Institute, said that based on historical patterns, the impact of El Niño on China’s precipitation shows significant phase characteristics. The most typical and strongest effects usually occur from the peak of El Niño in winter to the following summer.

“Taking the strong El Niño of 2015–2016 as an example, the public’s impression of the huge flood control pressure in the Yangtze River basin mainly corresponds to the summer of 2016, not the formation of El Niño in 2015,” Gao said.

Gao analyzed that, with the transition from La Niña to El Niño, and influenced by decadal climate background, the rainfall band in China during this year’s flood season is more likely to be in northern China, but the real test may come later.

“If an El Niño event forms in the second half of the year, its more significant impacts on China will appear from this winter to next summer. At that time, the risk of excessive southern China rainfall in winter and spring, and prolonged floods in the Yangtze River basin in summer, should be closely monitored,” Gao said.

In the face of the “new normal” of more unstable climate, how should we respond? Zheng Fei said that the key lies in initiating a series of “invisible” preparations, including strengthening the rolling monitoring and refined prediction of key factors such as sea surface temperature and monsoon; coordinating water resources management to ensure reservoirs’ “flood and drought mutual aid”; proactively inspecting urban flood-prone areas and mountain flood channels; improving power peak shaving plans to handle electricity demand surges. More importantly, enhancing departmental coordination and public communication to minimize the potential hazards of extreme weather.