The violent climate phenomenon El Niño, which contributed to the extremely high global temperatures of the past few months, is coming to an end. However, the weather is likely to continue to shape this year. Loud an update from the World Weather Organization (WMO) published on Tuesday El Niño, which has been active since June 2023, reached its peak in December and was one of the five strongest ever recorded. The phenomenon is now weakening. El Niño conditions are likely to continue in the coming weeks. The WMO expects April to June like experts from the US Climate Prediction Center before them but already with the end – at least with 80 percent probability. It is still unclear whether the counterpart to El Niño, a La Niña, will subsequently develop. However, according to the Climate Prediction Center’s latest report, there is a “historical trend” for strong Niños to be followed by a La Niña.
El Niño typically occurs every two to seven years and lasts nine to twelve months. The phenomenon causes the water on the surface of the central and eastern tropical Pacific, i.e. the sea west of Peru, to warm up. The trade winds that normally blow from east to west weaken or reverse. This phenomenon influences weather patterns worldwide: it tends to rain less over Indonesia, and it can also become drier in parts of the Sahel. In Central America and the Horn of Africa, however, there may be unusually heavy rainfall.
The sea surface off Peru was two degrees Celsius warmer than normal
Overall, an El Niño also acts like a kind of pump that shovels heat upwards from deeper layers of the ocean. As a result, global mean temperatures are usually higher than usual in El Niño years. La Niña has almost exactly the opposite effect: lower temperatures off Peru, stronger trade winds and cooler conditions worldwide.
It became apparent that the current El Niño would be one of the stronger ones. According to the WMO, however, it remains behind the historically strong Niños of 1997/98 and 2015/2016. This is measured by the surface temperature of the ocean off Peru, which in this case was around two degrees Celsius above the long-term average. According to the WMO, an El Niño typically has the strongest effects in the second year, in this case that would be 2024. For this reason and due to the still high surface temperatures in large parts of the oceans, the WMO expects increased temperatures over almost all of them in the coming months land areas.
Since the current El Niño began in June 2023, every single month has set a new monthly temperature record. The year 2023 was by far warmer globally than any other year measured so far. The WMO experts emphasize that El Niño contributed to these records. But the main reason is climate change. “Ocean surface temperatures in the equatorial Pacific clearly reflect El Niño,” said WMO Secretary-General Celeste Saulo, according to a statement from the agency. But ocean temperatures have also been far too high in other parts of the world over the past ten months; the sea surface temperature in January was by far the highest ever recorded this month. “This is worrying and cannot be explained by El Niño alone.”