TOKYO - The El Niño phenomenon developing in the Pacific Ocean has reached its strongest level since records began in 1949, with sea surface temperatures off Peru rising 4 degrees Celsius above normal in September, the Japan Meteorological Agency announced on October 9, raising concerns about extreme weather worldwide and the prospect of an unusually warm winter in Japan.
The latest measurements have exceeded the previous record of 3.6 degrees recorded in December 1997, placing the current event well beyond the threshold for what meteorologists call a "super El Niño." Some Western media have described its extraordinary intensity as a "Godzilla El Niño," reflecting fears that the phenomenon could produce weather conditions beyond those observed in previous decades.
The agency has warned that the unprecedented scale of the warming could lead to weather patterns not adequately captured by historical statistics. An official said that conditions were developing in ways not previously observed and that events beyond the understanding provided by past records could occur.
El Niño is a recurring climate phenomenon involving unusually warm sea surface temperatures in the central and eastern equatorial Pacific Ocean, particularly off the coast of Peru. Under normal conditions, easterly trade winds push warm surface water toward the western Pacific, allowing colder water from deeper layers to rise near South America.
When these trade winds weaken, warm water spreads eastward across the Pacific, suppressing the upwelling of cold water and causing sea surface temperatures to rise. The resulting changes in ocean temperatures influence atmospheric circulation, rainfall patterns and tropical storm activity across large parts of the world.
Japan's Meteorological Agency defines an El Niño event as a period when sea surface temperatures in its designated monitoring region remain at least 0.5 degrees above the reference level for six consecutive months. The reference is calculated using average temperatures over a 30-year period.
The current event is believed to have begun around April, marking the first El Niño since the event that lasted from spring 2023 to spring 2024.
Meteorologists generally use the term "super El Niño" when temperatures rise at least 2 degrees above normal. September's departure of 4 degrees was twice that threshold, highlighting the exceptional strength of the latest event.
El Niño typically occurs every two to seven years. The phenomenon had been recorded 19 times since 1949 before the current event, but only five of those episodes reached the 2-degree threshold associated with a super El Niño.
The latest forecasts indicate that the warming is likely to continue, with the Meteorological Agency projecting that the phenomenon will intensify further toward a winter peak. Its outlook indicates an effectively 100% probability that El Niño conditions will persist in the near term.
The agency's forecast charts also show a range within which future sea surface temperatures are expected to fall with a probability of 70%, illustrating the possibility of further warming over the coming months.
The World Meteorological Organization has warned that a strong El Niño could increase the risk of droughts, floods and other extreme weather events across extensive parts of the globe.
In Japan, attention has focused on whether the unusually powerful El Niño contributed to the large number of typhoons and episodes of heavy rainfall during the summer.
Between June and August, 17 typhoons formed in the western North Pacific, substantially exceeding the seasonal average of 11. The succession of storms brought prolonged periods of rain and repeated disruptions across Japan.
El Niño can influence the formation of tropical cyclones by strengthening atmospheric disturbances known as easterly waves, which develop within eastward-originating trade wind flows and generally move westward across tropical waters.
These disturbances can develop into tropical storms when atmospheric and ocean conditions are favorable. Warmer ocean surfaces can also provide additional energy to developing typhoons, potentially allowing them to intensify and remain active for longer periods.
The combination of these conditions is believed to have contributed to the unusually frequent formation of typhoons during the summer, although the relationship between individual storms and El Niño involves several interacting atmospheric factors.
The summer also brought unusually high temperatures to Japan, despite El Niño generally being associated with cooler summer conditions in the country.
Japan experienced its fifth-hottest summer on record, partly because the prevailing westerly winds flowed farther north than usual, allowing warm air to cover extensive areas of the country.
The simultaneous occurrence of record Pacific Ocean warming, repeated typhoons and unusually high summer temperatures has raised questions about the possible influence of global climate change.
Scientists say several factors contribute to fluctuations in sea surface temperatures, but some researchers believe human-induced global warming may be amplifying the current El Niño.
One expert expressed concern that the increase in ocean temperatures appeared to be extending beyond the range of natural variability, suggesting that warming associated with climate change could be contributing to the exceptional conditions.
However, the precise extent of that contribution remains uncertain, and researchers continue to examine how long-term warming interacts with naturally occurring climate cycles.
Looking ahead, the Meteorological Agency expects El Niño to influence atmospheric temperatures across the tropics during the coming winter, increasing the likelihood of warmer-than-normal weather in Japan.
For the December-to-February period, temperatures in northern Japan are forecast to be near or above the seasonal average, while eastern Japan, western Japan and the Okinawa and Amami regions are expected to experience higher-than-normal temperatures.
The prospect of a mild winter has implications for agriculture, retail businesses and winter tourism, prompting preparations in several sectors.
Farmers growing crops that require prolonged exposure to winter cold are particularly concerned that higher temperatures could disrupt normal growth and production cycles. Agricultural businesses are already considering measures to reduce potential damage.
Department stores are adjusting their merchandise selections to reflect expectations of a warmer winter, while ski resorts are increasing artificial snowmaking capacity in anticipation of possible shortages of natural snowfall.
Such preparations illustrate how a major climate phenomenon originating thousands of kilometers from Japan can affect domestic business activity, agricultural production and consumer demand.
The Meteorological Agency has said it will continue monitoring the development of El Niño closely and provide updated forecasts, urging the public and businesses to pay attention to the latest weather information as winter approaches.
The consequences are already being felt in other parts of the world.
In Central America, Honduras has experienced drought conditions affecting agricultural production, while El Salvador has issued warnings in response to water shortages.
The World Meteorological Organization has highlighted the potential for similarly severe conditions elsewhere, with some regions facing prolonged drought and others experiencing unusually heavy rainfall and flooding.
The effects may also continue after the present El Niño reaches its peak.
Global temperatures often respond most strongly in the year following the development of an El Niño event, meaning the influence of the current warming could extend into 2027 and beyond.
The phenomenon transfers heat from the ocean to the atmosphere and can temporarily increase global average temperatures, adding to the underlying warming trend associated with greenhouse gas emissions.
Scientists warn that exceptionally strong El Niño events could therefore compound the risks associated with climate change, particularly in regions already vulnerable to drought, flooding and agricultural disruption.
Experts have emphasized the importance of reducing carbon dioxide emissions and adopting practices that limit further global warming, arguing that long-term changes in human activity are necessary to address the growing risks of extreme weather.
With Pacific Ocean temperatures already surpassing all previous measurements and further intensification expected during winter, meteorologists face considerable uncertainty about how the current event will develop.
For Japan, the immediate concerns include a warmer winter, potential disruption to agriculture and reduced snowfall in mountain regions. Globally, the possibility of more widespread weather extremes means the consequences of the record-strength El Niño could continue well beyond its anticipated winter peak.
Source: Kyodo
