The World Meteorological Organization anticipates new heat records in the next five years and the return of El Niño.
The World Meteorological Organization confirmed on Wednesday May 17 that El Niño is 80% likely to reappear by the end of September, as it regularly does every two to seven years. This climatic anomaly is cyclical: it allows a rebalancing of the system and the release of certain heat reserves in the Pacific Ocean.
Why is this meteorological phenomenon so feared? Because it can change the weather conditions around the world and cause a lot of damage. It is generally accompanied by a risk of flooding in Latin America and the southern United States, above-normal rainfall in Central Africa and, conversely, drought phenomena with the risk of fire in Indonesia and Australia.
How can these changes on a planetary scale be explained?
In normal conditions, the prevailing winds along the Equator are the trade winds: they blow from east to west and cause the warm waters of the Pacific to move from South America to Asia, explains Eric Guilyardi, climatologist and oceanographer at the CNRS.
And when the warm water moves, there is cold water that comes up from the bottom along the American coasts to replace it. But, when El Niño sets in, the trade winds weaken, the warm water is pushed eastward, which regionally modifies the temperature of the ocean and its evaporation. The rains no longer fall in the same place.
In France, we are too far from this Pacific zone, and if there are high temperatures or drought this summer, it will not be related to El Niño. But the World Meteorological Organization is adamant: by 2027, the planet will experience its five hottest years since the start of the industrial era, under the cumulative effect of El Niño and greenhouse gas emissions. tight. And, there is more than a 60% chance that we will temporarily cross the threshold of 1.5 degrees of annual warming globally within the next five years.