El Niño could cause extreme heat, water shortages in Vietnam later this year El Niño could cause extreme heat, water shortages in Vietnam later this year
El Niño could return this year, intensifying heatwaves, water shortages and extreme weather patterns in Vietnam, particularly in the latter half of the year, an expert warns.
Dr. Truong Ba Kien, deputy executive director of the Vietnam Institute of Meteorology, Hydrology and Climate Change’s Center for Meteorology and Climatology, speaks to VnExpress about the likelihood of El Niño and its potential impacts on Vietnam.
International meteorological agencies have warned of a possible “super El Niño” this year. What is your take on this?
First, in climatology there is no term such as “super El Niño” or “super La Niña.” These are media-driven labels used to describe exceptionally strong El Niño events.
El Niño’s intensity is measured using the Oceanic Niño Index (ONI), defined as the three-month running mean of sea surface temperature anomalies in the Niño 3.4 region of the central equatorial Pacific. Based on this index, El Niño events are classified as weak (0.5-0.9 C), moderate (1.0-1.4 C), strong (1.5-1.9 C), and very strong (2.0 C or higher).
In that sense, a “super El Niño” effectively refers to a very strong event with ONI exceeding 2.0 C.
Updates from major forecasting centers such as the U.S. National Oceanic and Atmospheric Administration (NOAA) and the European Centre for Medium-Range Weather Forecasts indicate a greater than 60% probability of a transition to El Niño in summer 2026, potentially lasting through the end of the year. The likelihood of reaching very strong intensity by year-end is estimated at around 25%. However, model projections still diverge on peak intensity and require further monitoring.
Overall, confidence in the formation of El Niño is relatively high, given clear oceanic signals and favorable atmospheric conditions for warming. However, uncertainty remains significant regarding peak intensity due to the ENSO “spring predictability barrier,” a period when forecast skill declines and model spread widens.
If there is indeed a very strong El Niño event, how would you assess its likely impact compared to those in 1997-1998 and 2015-2016?
Such comparisons should be treated with caution.
Similar ONI values or classification levels do not imply identical climate impacts. ENSO effects depend not only on temperature anomalies in the Niño 3.4 region but also on the spatial structure of sea surface temperature anomalies across the tropical Pacific, the timing of peak intensity, the coupling between oceanic and atmospheric systems, and the concurrent state of other climate oscillations.
A temperature anomaly is the difference between the current temperature and the long-term average.
Moreover, under climate change, the relationship between ENSO intensity and extreme weather is not linear. Extremes result from the interaction of natural variability, risk management capacity based on seasonal forecasts and a warming climate with higher humidity and altered thermodynamic conditions. Therefore, even with the same ONI level, impacts on heatwaves, drought, heavy rainfall, or storms can vary significantly across regions and periods.
In short, while intensity may approach historical extremes, impacts cannot be assumed to replicate past scenarios.
