The Ocean and the Climate 2mn

What is El Niño?

A new El Niño event, described as “very strong”, is set to occur from this spring onwards.

Indeed, meteorological experts at the National Oceanic and Atmospheric Administration (NOAA) announced in a press release on 11 June 2026 that ‘a prolonged period of above-average temperatures in the equatorial Pacific is expected to peak this winter’. 

C’est quoi El niño ? 

El Niño, the warm phase of the Southern Oscillation (ENSO), is a natural climatic phenomenon that usually occurs every two to seven years in the central and eastern equatorial Pacific Ocean and lasts for around nine to twelve months.  

El Niño is characterised by a rise in surface temperature and a change in global atmospheric circulation, resulting in exceptional droughts or rainfall in certain regions of the world.  

An El Niño event is declared when these temperatures exceed the average by 0.5 °C for several consecutive months.  

It usually begins in spring and reaches its peak between November and February, although its impact on global temperatures is felt the year after it begins. 

The most recent episode took place in the summer of 2023 and lasted until spring 2024, with record-breaking temperatures, described by the WMO Secretary-General, Ms Celeste Saulo, as “one of the five most intense episodes ever recorded”.  

On 2 June, the World Meteorological Organisation issued a bulletin stating that “the probability of an El Niño event occurring between June and August 2026 stands at 80 per cent. The probability of this event persisting at least until November is around or above 90 per cent.” 

This latest El Niño event is taking place against a backdrop of climate change and “will add fuel to the fire of a warming planet,” said UN Secretary-General António Guterres in a video address. 

How does it work?

Normally:

  • The winds (known as trade winds) push the warm waters of the Pacific westwards (towards Asia).
  • The coasts of South America receive colder, nutrient-rich waters.

During an El Niño event:

  • The trade winds weaken or reverse direction.
  • The warm waters flow back eastwards.
  • Less cold water rises to the surface: fewer nutrients at the surface and therefore fewer fish.