The World Meteorological Organization (WMO) is studying the official declaration, in the coming weeks, of the end of the 2023-2024 episode of the El Niño-Southern Oscillation (ENSO) phenomenon. Awaiting the verdict of the WMO, the United States Oceanic and Atmospheric Administration (NOAA) and the Australian Bureau of Meteorology have issued reports in recent days in which they consider that this climate episode can be called to an end .
The WMO’s provisional balance sheet of March 3 indicated that El Niño conditions (temperatures above normal in the eastern equatorial Pacific, with an impact on a large part of the planet) had weakened. However, he warned that its effects could last for months (droughts and floods in several parts of America and Asia, mainly).
Therefore, the change of cycle can be seen and the proof is that we are starting to notice decreases in the anomalies of warm temperatures in the Pacific, and what is expected is that they will continue in the coming months.
El Niño – Southern Oscillation episodes are part of a climate pattern that consists of variations in the surface temperatures of the equatorial eastern Pacific with large-scale consequences on the planet. The weakening of the trade winds causes the deep ocean waters to stop surfacing and this causes a warming of a vast ocean surface, with an impact on a large part of the planet. In the opposite direction, in episodes of trade winds, the bottom waters emerge on the surface and this gives rise to La Niña and a cooling.
NOAA forecasts a transition to ENSO-neutral conditions between April and June (85% probability), with La Niña likely to develop between June and August this year ( with a 60% probability).
In March, sea surface temperature anomalies continued to weaken over most of the equatorial Pacific Ocean, while surface temperature anomalies were cooler in the far eastern Pacific Ocean.
“As a whole, the coupled ocean-atmosphere system reflected the continued weakening of Niño,” summarizes NOAA. “Neutral conditions are expected this spring in the northern hemisphere, between April and June, and in the summer, between July and August, there is a 60% probability that we will have a Niña,” says Rubén del Campo, spokesperson for the State Meteorological Agency (Aemet).
El Niño and La Niña have different effects depending on the geographical areas. El Niño is generally associated with increased temperatures, is associated with more frequent rain events in the southern and southwestern United States, and is capable of causing significant droughts, for example, in the Amazons. The opposite phenomenon, La Niña, is associated with droughts in areas of the Horn of Africa and also in the southwestern United States.
To what degree can El Niño be held responsible for record temperatures? “ El Niño pushes temperatures up. We have recorded monthly temperature records on a global scale for ten consecutive months. These records would not have been possible without anthropogenic climate change, which is the main factor, but this is another added factor that contributes to a greater rise in temperatures”, says Rubén del Campo.
Therefore, it could be expected that, with the probable arrival of La Niña, there will be a decrease in temperatures or that at least the increases will not be as spectacular and consecutive as in recent months. However, some experts fear that even with La Niña global temperatures will continue to set record highs, as a result of climate change alone.
Del Campo indicates that “it is not very clear” how ElNiño affects Spain. Some research indicates a “certain correlation with rainier autumns and drier late winters. But it is not a direct factor, and in the climate of the autumns and winters in Spain, many other factors are involved”.
