A record El Niño points to an even warmer 2027.
The sea in the equatorial part of the Pacific Ocean is warmer than at any time since satellite measurements began. According to an analysis by the British website Carbon Brief, on 21 September the anomaly in the key measurement zone near the equator reached 3.11 degrees Celsius. This broke the previous record, set in November 2015, during one of the strongest El Niños ever recorded. The measurements are carried out by the American agency NOAA, and weather services around the world also follow them. As early as July and early August the water below the surface in some places was as much as 8 degrees warmer than average.
El Niño is a natural phenomenon that occurs every two to seven years. When the trade winds over the equator weaken, warm water from the western part of the Pacific Ocean flows towards the coasts of South America. The change in the temperature of the ocean reshapes atmospheric circulation and shifts rain belts across the globe. The name, which means boy in Spanish, was given to it by Peruvian fishermen, because the warming usually began around Christmas. The opposite phenomenon, in which the water in the same part of the ocean cools, is called La Niña, meaning girl.
Forecasts suggest that the peak still lies ahead. Models project that the anomaly could reach about 4 degrees in November or December, which would be a level without precedent. Most models expect that El Niño will remain very strong throughout the winter. For the first time the World Meteorological Organization issued a forecast with almost 100 per cent certainty: El Niño will last at least until February 2027. The Secretary-General of the UN, António Guterres, said that El Niño is turning into a giant before our eyes. The head of the organization, Celeste Saulo, stressed that an exceptional phenomenon demands exceptional preparation.
The consequences are already visible on several continents. In Indonesia, where El Niño brings dry weather, vast areas of forest are burning. In the Atlantic Ocean, by contrast, the hurricane season is considerably calmer than usual, because El Niño strengthens the winds at high altitude, which tear apart the storms while still in their infancy. The forecasts give higher chances of a wetter winter for California and for the southern United States. Experts also warn of a risk to harvests in some of the most important farming regions, where droughts and floods can reduce yields.
El Niño also temporarily raises the global temperature, but with a delay of several months. For the period from September to November the World Meteorological Organization forecasts above-average temperatures almost across the entire land surface. That is why climatologists expect that 2026 will be the warmest or second warmest year since records began. Yet the real blow will come in 2027, which could be even warmer.
The key difference compared with 1997 and 2015 lies in the fact that this time El Niño is developing in an already warmer world. The natural fluctuation now comes on top of the warming that is caused by greenhouse gases from fossil fuels. So every new strong El Niño starts from a higher level and sets new records more easily.