KATHMANDU: Scientists warn that the El Nino weather phenomenon may reappear later in 2026, potentially contributing to record-breaking global temperatures.
According to the US National Oceanic and Atmospheric Administration (NOAA), there is a 50–60 percent chance of El Nino forming during the July–September period and extending beyond. The World Meteorological Organization is set to issue an update on the situation on Tuesday.
Understanding El Nino and La Nina
El Nino and its cooler counterpart, La Nina, are phases of the natural climate pattern known as the El Nino-Southern Oscillation (ENSO), which affects the tropical Pacific.
The term “El Nino,” meaning “the boy” or “the Christ Child,” was first used by Peruvian and Ecuadoran fishermen in the 19th century to describe unusually warm ocean currents that reduced fish catches before Christmas. La Nina, meaning “the girl,” was later adopted as its opposite. Between the two events is a neutral phase.
El Nino occurs every two to seven years and weakens trade winds across the tropical Pacific. This allows the usually cooler central and eastern Pacific waters to warm, altering rainfall patterns and global winds. The extra heat released into the atmosphere can temporarily raise global temperatures by 0.1°C–0.2°C, according to Nat Johnson, a NOAA meteorologist.
Typical El Nino effects include drier conditions in Southeast Asia, Australia, southern Africa, and northern Brazil, while the Horn of Africa, southern US, Peru, and Ecuador experience wetter conditions.
La Nina, on the other hand, cools the eastern Pacific for one to three years, producing opposite effects. The latest La Nina began in December 2024 but is expected to transition to a neutral phase between February and April.
Global temperature implications
The last El Nino, in 2023–2024, contributed to 2023 being the second hottest year on record and 2024 reaching an all-time high. Carlo Buontempo, director of the European Union’s Copernicus Climate Change Service, warned in January that 2026 could also be “another record-breaking year” if El Nino develops.
Tido Semmler, a climate scientist at Ireland’s National Meteorological Service, noted that the full impact may be felt in 2027, even if El Nino forms in the second half of 2026. “There is a risk that 2026 could be the warmest year on record even without El Nino due to the ongoing global warming trend,” he said.
New tracking method
NOAA has adopted a new approach to monitor El Nino and La Nina events. The previous Oceanic Nino Index (ONI) compared three-month sea surface temperature averages in one region with a 30-year baseline.
With oceans warming rapidly, the old baseline may no longer reflect current conditions. The new Relative Oceanic Nino Index (RONI) compares the east-central Pacific’s temperature relative to the rest of the tropics, providing a “clearer, more reliable way” to track these phenomena in real time.
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