La Niña is back for the second year in a row.
The United States’ National Oceanic and Atmospheric Administration (NOAA) announced Thursday that the climate phenomenon responsible for Harsh winters and major droughts around the world have arrived again and will be felt for several months.
According to NOAA, after a period of relative atmospheric equilibrium since the beginning of the year, La Niña will intensify over the next several weeks and will not begin to weaken until the spring of 2022, which may have an impact on rainfall, the end of the hurricane season and the intensity of the upcoming boreal winter.
“La Niña conditions have developed and are expected to continue with a 87% probability between December 2021 and February 2022 “, indicated the agency.
According to the statement, experts began to notice that the climatic event was approaching in the last month, when they detected several factors that pointed to its development among them:
- temperatures of below-average sea surface in the equatorial Pacific
- thermal anomalies in most of the central and eastern Pacific Ocean
- anomalies in easterly winds at low levels and in westerly winds in the upper levels of the atmosphere.
Although generally the signs of its activation begin to be detected in the boreal summer, now, as happened in 2017, La Niña began to manifest itself in the fall.
“Our scientists have been tracking the potential development of La Niña since this summer. or, and it was a factor in the forecast for the above-normal hurricane season that we have seen unfold, ”said Mike Halpert, deputy director of NOAA’s Climate Prediction Center.
But What is La Niña and how does it affect the climate of our planet and Latin America?
La Niña
To understand what La Niña is, it is necessary to explain the more general phenomenon in which it is encompassed: the so-called ENSO event or El Niño-Southern Oscillation .
El Niño is a weather pattern that causes a weakening of the trade winds in the southern Pacific hemisphere.
Those winds, when they are normal, carry surface waters from the coasts towards the ocean and this causes the cold waters of the depths to arise there.
That cold water is normal in the equatorial zone of the coast of South America.
When these trade winds weaken that process ceases, hot water accumulates and there is an increase in the sea surface on the coast of Peru and Ecuador, mainly .
Now, when the trade winds are very strong and the rise of that cold water in the equatorial zone is reinforced and the temperature of the sea is below normal, the phenomenon of La Niña , which is a climatic pattern opposite to El Niño conditions.
Generally, between the two phases , there is a period called “ neutral zone ” (in which we were until recently) in which neither of the two events are remarkably active and temperatures are above average.
What are their effects?
The effects of La Niña and El Niño, which go from e droughts to floods, from heavy rains to hurricanes, always depend on the area of the oscillation: it can produce either droughts in Latin America, heavy snowfalls in the northern United States or droughts in Australia or the Pacific islands.
And although they follow patterns, this does not imply that each time the conditions are activated they manifest in the same way: no La Niña event is like another.
Although the forecasts more certain for the current season will be known at the end of this month, NOAA and other meteorological organizations in Latin America foresee “ a La Niña of moderate intensity “.
This, however, does not by itself predict the conditions in which it will manifest itself since historical data reveal that there have been cases of droughts more severe in weak or moderate La Niña events than in strong to intense events.
In previous years, the phenomenon has manifested itself very weak, although since 2020 began to experience symptoms of a potential strengthening, such as the long Atlantic hurricane season, conditions drought in South America and heavy rains in Central America and northern South America.
How it will affect Latin America
Generally, La Niña manifests itself in two totally different forms in Latin America: intense and abundant rains, increased river flow and subsequent floods in Colombia, Ecuador and northern Brazil; and in drought conditions in Peru, Bolivia, southern Brazil, Argentina and Chile.
Several of the latter countries have lived in the past year an intense drought, which has affected crops, dried up rivers and impacted hydroelectric generation.
Now there are fears that La Niña will further delay the rainy season in the Southern Cone and make 2022 an even drier year.
Meanwhile, in the northeast of South America landslides have occurred in several countries and in others, such as Colombia, the dams are located in a 86% capacity, almost double the levels of a year, which is considered historically high.
NOAA has noted that L a Niña may influence the last months of the current hurricane season in the Atlantic, which has been particularly active.
In Mexico, the meteorological authorities indicated that a new activation of the event could translate into an extension of the rainy period until the end of November, as well as intense rainfall in some parts of the country where they are not frequent and then a drier winter.
In Central America, for its part, the Regional Committee for Hydraulic Resources had predicted since the summer that La Niña could bring “rainier conditions than normal” to the region, mainly on the border of Mexico with Guatemala, the south of El Salvador; the central part of Honduras and in the Pacific of Costa Rica and Panama.
The previous La Niña occurred during the winter of 2020 – 2020 and previously, enter 2017 and 2018.
The last El Niño event took place between 2018 and 2019.
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