The World Meteorological Organization (WMO) has warned that this year could see the third consecutive occurrence of a La Nia climate event.
The Meteorological Agency of the United Nations Organization (UN) has warned that 70% chance That La Nia will continue during September and November this year.
If this happens, it will be the first time in this century that a “Triple Episode” of La Nias,
The current weather event started in September 2020.
If it lasts until the end of the year, it will reach three consecutive boreal winters, which is why it is considered a “triple episode”.
The WMO has also estimated that there is a 55% chance of La Nia continuing till February 2023.
What is Nina?
girl and IEl Nio are two opposite phases of the same weather patternThis is known as the El Nio-Southern Oscillation (ENSO).
ENSO is a natural phenomenon of surface temperature anomaly in the equatorial Pacific Ocean, which has important consequences for the climate around the planet.
Boy the hot phaseand usually appears first.
It occurs when air pressure conditions change, weakening the trade winds in the Southern Pacific Hemisphere.
Thus winds in that ocean generally move from east to west from subtropical areas of high pressure to equatorial regions of low pressure.
The trade winds carry warm surface waters from the equatorial region along the coast of South America to the other side of the ocean towards Asia.
Due to this the water of the depths, which is cold, starts rising in its place.
But when these winds weaken, or even move in the opposite direction, they carry warm water from Southeast Asia to South America.
La Nia occurs when the opposite event occurs, When the trade winds are very strong, the rise of deep cold water prevails in the equatorial region and the sea temperature drops below normal.
that’s why La Nia is considered a cold phase. of incident.
Typically, there is a period called the “neutral zone” between the two phases, in which neither event is particularly active and the temperature is average.
Climatologist Alfredo “Alpio” Costa, an expert on climate change at Argentina’s Antarctic Institute, explained to BBC Mundo that ENSO is fairly erratic: from when a boy starts until a girl ends, and the cycle starts all over again. is usually between two and seven years.
but These two events do not always alternate, Sometimes, as is happening now, only one step is repeated several times, without the opposite appearing.
“It’s been decades since we’ve visited three Nina’s in a row,” says the expert.
In this BBC Mundo video you can see how El Nio and La Nia interact, and how they differ:
Costa explains that ENSO produces impacts over a large part of the world because “the equatorial Pacific Ocean is so vast that it affects climate patterns on a global scale.”
Regarding La Nia, he confirms that it causes changes in the Americas, Asia, Africa and Oceania, “but not so much in Europe”, where the climate is more influenced by other meteorological factors.
“The effects of La Nia around the world, called teleconnections, they are very diverse: in the east of Argentina and in the south of Brazil and Uruguay it causes drought”, he details.
“But in northeastern Brazil and northern Australia and Southeast Asia it is the complete opposite, with increased rainfall. And there are parts of China, India and Japan as well as western Canada and southern Alaska (USA) that are affected by lower temperatures.” are affected. Normal,” he says.
“East Africa is also affected by drought,” he warned.
In his report on “the first triple episode of La Nia in this century”, WMO Secretary-General, Petri Talas highlighted the impact it would have on the continent.
“Unfortunately, the most recent data on La Nia confirms regional climate projections that indicate Horn of Africa’s devastating drought continues to worsenThe consequences of which will affect millions of people,” lamented Talas.
guess that some 18 million people The region experienced severe famine as a result of the worst drought in 40 years.
The United Nations clarifies that ENSO not because of climate change,
“This is a recurring natural phenomenon that has been going on for thousands of years,” the agency says.
However, it highlights that “some scientists believe that[El Nio and La Nia]may be more intense and/or more frequent as a result of climate change, although this is not 100 percent clear. that’s how they interact.”
“Climate change is likely to influence El Nio and La Nia-related effects, in terms of extreme weather events. Further research will help to separate natural climate variability from any trends due to human activities.”
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