The climatic phenomenon La Nina directly influences the weather in some part of the world. This is a cooling of the waters of part of the Pacific Ocean which has an impact on temperatures and precipitation from the United States, South America, Australia, or even part of Asia.
The phenomenon has persisted since 2021, with particularly strong intensity, and its consequences have been dramatic for several regions of the world in 2022: accentuation of the already historic drought over the American West and the Horn of Africa, heat wave in the middle of winter in the southeastern United States, very active hurricane season in the Atlantic, torrential rainfall and catastrophic floods in eastern Australia, lasting heat wave over India and Pakistan last spring…
Coupled with global warming, the effects of La Niña are multiplied. In Europe, on the other hand, the effect of La Niña has never been demonstrated to date and it is, until proven otherwise, non-existent. Phenomenons El Nino and La Niña are determinants of the Earth’s climate system, although they are not the only ones. Climate forecasts of the World Meteorological Organization (WMO) aim to help governments, the United Nations, decision-makers and climate-sensitive sectors to prepare (agriculture and infrastructure), as well as to protect the lives of citizens.
A “triple La Niña” more and more likely
La Niña appears in phases of one to two years, alternating with its warm counterpart El Niño (which has other consequences). Whereas La Nina suffered several drops in intensity since September 2020, before rising sharply (especially last spring), the meteorologists and climatologists expected to see it fade away gradually, either over the summer or over thefall.
However, in a press release dated June 10the World Meteorological Organization (WMO) announces that there is now a 70% chance that La Niña continues after August. Moreover, the long-term forecasts even indicate that the episode could persist until 2023, and even strengthen during thewinter. If true, this would be the third “triple La Niña” (three consecutive winters ofnorthern hemisphere under the La Niña regime) since 1950, according to the WMO. These forecasts for 2023 will need to be confirmed at the end of next summer, but the spectrum of a “triple La Niña” seems more and more probable.
After La Niña, a “super El Niño”?
Remember that La Niña tends to cause a slight cooling of the global climate: we can therefore think that the rise in temperatures, although already worrying, could have been limited by the phenomenon. Some climatologists believe that after a powerful and lasting episode of La Niña, we risk witnessing a “super El Niño” during 2023/2024, a warming of the waters of the Pacific which, in turn, would have the capacity to significantly worsen ongoing global warming. If this were confirmed, because it is only a hypothesis, the global rise in temperatures could be increased tenfold with particularly serious effects for several regions of the world.
Climate: La Niña turns into an unwanted guest
Article of Karine Durandwritten on 1er June 2022
The persistence of the La Niña climate phenomenon for two years is a matter of concern in the United States, Australia and part of Asia. Responsible for endless droughts and torrential rains, La Niña doesn’t seem to want to stop.
The La Niña phenomenon has persisted for 2 years and is influencing weather conditions in part of the world: the mega-drought of the American West, historic rains on Australia, the record number of hurricanes in the Atlantic in 2020, or the historic heat wave in India. La Niña is a natural phenomenon that occurs in phases of one or two years, and which is characterized by a cooling of part of the waters of the Pacific.
La Niña doesn’t seem to want to leave anymore
While scientists from theatmosphere considered a few months ago the return of its hot El Niño counterpart during 2022, nothing is less certain at the present time. La Niña will persist throughout the summer and the NOAA then estimate at a one in two chance the probability that La Niña remains during the fall, or even after. If La Niña persists for the third consecutive year, the event would then become remarkable in terms of climate: this has already happened in the past, but remains very rare. La Niña occurred 28% of the time between 1950 and 1999, the other 72% of the time was occupied by El Niño.
All climate prediction models estimated that El Niño would become more frequent due to climate change
However, the La Niña phenomenon seems to be becoming more and more frequent: since 2000, it has occurred almost half the time. A surprising finding because all climate forecasting models estimated that El Niño, a warming of the waters of the Pacific, would become more and more frequent due to climate change.
According to NOAA, however, the period of the last 20 to 25 years is not long enough to draw conclusions about a trend: the recurrence of La Niña could be due to chance, or else be linked to global warming in some way. that scientists don’t yet understand. The recurrence of the phenomenon could also be linked to the Pacific Decadal Oscillation (PDO): this is a variation in sea surface temperature in the Pacific that occurs in cycles of several decades ( 20 to 30 years). This variation influences major weather systems.
Disastrous consequences for some countries
La Niña is more costly than El Niño for the USA and Australia: droughts and forest fires in the American West, for example, cost twice as much with La Niña as during an El Niño year. In general, when the phenomenon persists for two years in a row, the second year is weaker because the system is weakening. But La Niña suddenly strengthened in the fall of 2021 after a dip in the spring. It then experienced record intensity (linked to the temperatures recorded in the ocean) between winter and the beginning of spring: when American water reservoirs should have been replenished by the rains, the drought has intensified. The recurrent episodes of drought in the western United States also correspond to the last 22 years marked by the incessant return of La Niña.
A powerful La Niña likely helped by climate change
According to Park Williams, hydrologist for the University of California, La Niña is the first phenomenon that influences the American climate: The persistence of La Niña is surely the main factor of the historic drought in the USA [mais] while La Niña could easily be responsible for the worst drought in 300 years, for the worst drought in 1,200 years that we are currently experiencing, La Niña has clearly been helped by climate change “. As often in the climate, it is the concomitance of several factors which makes it possible to explain a phenomenon. But, at present, the La Niña phenomenon seems set to resist for at least the next six months.
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