After a triple La Niña, the return of the El Niño climatic phenomenon seems to be more and more confirmed for the end of this spring. This will have significant consequences on the weather of a large part of the world. Here are the five main ones.
These two climatic phenomena occur in cycles of one to three years and always have a significant impact on the weather phenomena of several continents. Thus, La Niña, which is characterized by a cooling of part of the waters of the Pacific, has resulted in torrential rains in Australia, an aggravation of the drought in California and probably a more intense monsoon in Asia in recent years. This natural oscillation between La Niña and El Niño, called ENSO (El Niño Southern Oscillation), is often interspersed with a neutral phase: this is exactly what NOAA predicts with near certainty between March and May 2023. Even if it is not completely confirmed at present, the return of El Niño is most likely after May, for late spring or summer. This phenomenon known to have a “warm” impact on the global climate should then continue during the fall and winter. In this case, it will have five major consequences on the Planet:
The risk of reaching +1.5°C of global warming
The year 2022 was the fifth warmest year despite the cooling effect of La Niña: the impact of global warming has therefore been mitigated by this cold anomaly of the Pacific waters. The global temperature of 2022 is 1.11°C above pre-industrial levels, which does not reach the record high of 2016 (marked by a strong El Niño) and 2020 with +1.23°C to +1 .25°C compared to pre-industrial levels. During a strong El Niño episode, the global temperature can rise by +0.2°C over a year, an effect that adds to that of global warming. According to The Conversationthe most pessimistic forecasts suggest the possibility of seeing this global temperature rise to the symbolic bar of +1.5°C in 2024, after the peak of El Niño intensity.
A drying up of the Amazon rainforest
South America is one of the areas most affected by the effects of the ENSO oscillation, because its coasts are located on the Pacific Ocean. However, its consequences are not the same in each of the countries in this region of the world: El Niño causes flooding in certain countries (Peru, Ecuador) and drought in others (Colombia). In this context, the Amazonian forest suffers from the lack of water: its vegetation dries up and grows less quickly, with, here too, the effects of global warming which add to this natural process. CO2, one of the main greenhouse gases, is then less absorbed by plants and therefore less sequestered in the soil. It remains more present in the atmosphere, further contributing to global warming. The Australian forest, as well as part of the African forests, are in the same situation in the El Niño phase.
Heat and fires in Australia
After three years marked by record rainfall and dramatic flooding in Australia, El Niño is expected to reverse the trend drastically. This phenomenon is well known to be responsible for increased heat and dryness during winter and spring in this part of the world. The rise in temperatures in Australia already reached +1.4°C in 2022 despite the cooling effect of La Niña.
An improvement in drought conditions in western North America
As far as the United States is concerned, El Niño will have variable consequences on the extent of the territory. Its return should be accompanied by new saving rains in the south-west of the country which has suffered from a mega-drought for more than 20 years. However, when they arrive, these rains are often violent in these desert regions and then cause floods and landslides, even if this is not systematic. The weather is often warmer in the US Rockies and much of Canada, and drier over the entire eastern half. The number of tornadoes is generally lower in an El Niño year.
Colder winters in northern Europe?
In Europe, the impact of the ENSO oscillation is not known: it is possible that there is none, or that scientists have just not yet determined its effect. Some studies hypothesize that during El Niño years, the weather would be drier and colder in northern Europe, and wetter in southern Europe. But to date, nothing has yet been proven about the effects of the ENSO oscillation in Europe, unlike other regions of the world.
Some scientists believe that El Niño leads to colder winters in northern Europe, but nothing has been proven. © Declan Hillman, Adobe Stock
