Sometimes El Niño and La Niña do not follow expected patterns.
It is not a new phenomenon, but in recent years we have heard more and more about El Niño and its “climatological sister”, La Niña.
The name was given to it by some fishermen who noticed that, sometimes, the oceanic waters reached the coast of Peru warmer at Christmas time, at the beginning of summer in Peru.
They called it El Niño in reference to the baby Jesus, but their explanation has nothing to do with religion.
“The first written references are from a letter from 1891 in which a Peruvian explains that his country is in a year of plenty because deserts became greener and found types of fish never seen before ”, tells BBC Mundo Luis Alfredo Icochea Salas, Professor of Fisheries at the National Agrarian University La Molina (Peru) and specialist in oceanography.
But abundance became calamity, largely due to lack of infrastructure when, some 100 years later, in 1982-83, “a Child came who took us by surprise and who it was the disaster of the century”, Explains Icochea, who has spent his entire life studying the phenomenon.
Icochea says that now, more than an El Niño phenomenon, it is an event, since it occurs on a recurring basis. Usually every two to seven years on average, but dates can vary.
“You really started studying in the 1970s; The scientists saw that it was not local, but that it encompassed a large part of the Pacific, and they began to record the years in which the temperature and rainfall were somewhat extreme due to El Niño ”, Juan José Nieto, director of the International Center for Research on the El Niño Phenomenon (CIIFEN), based in Guayaquil, Ecuador.
But what do we know about El Niño and La Niña?
Next, we will tell you how these events develop, what their effects are and why it is important to study them.
What is El Niño and how is it different from La Niña?
“El Niño is part of a phenomenon that has to do with variations in both the ocean and the atmosphere,” explains Nieto.
If we summarize it a lot, we could say that El Niño is the warm phase of a weather event and La Niña, its cold phase. But it is much more complicated than that.
They are opposite phases of a complex meteorological pattern so powerful that can alter the global temperaturel and cause very extreme atmospheric effects on the entire planet.
El Niño tends to occur more frequently than La Niña and both can last most of the year, or even longer.
The changes in atmospheric circulation that they generate can affect the climate in various parts of the world in a more or less extreme way, depending on their intensity. It’s what scientists and meteorologists call teleconnections.
“In the sea itself, when one area heats up, the other gets cold; there is a balance and the changes include in several continents causing, for example, drought in Africa and rains in America. It alters the whole climate, ”says Icochea.
El Niño can bring rain or a drier winter in the southern United States and warmer conditions in South America, while La Niña can bring hurricanes in the North Atlantic and a wetter climate in Australia, to name a few examples.
Or they may not cause either. Or that they become a “mega event”.
Originating in the Pacific Ocean near the Equator, El Niño and La Niña are formed by a pattern called El Niño-Southern Oscillation, or ENSO, and can never occur at the same time.
What is ENSO?
“The ENSO helps us to group these two ocean-atmospheric events (El Niño and La Niña) into the same mechanism,” explains Nieto.
This pattern describes the fluctuation of certain atmospheric variables in the Pacific Ocean: mainly, the Sea Surface Temperature (TSM) and air pressure on ocean water.
These parameters are closely related to each other and the right conditions must exist in both for El Niño, La Niña or neither to form.
For example, when the sea surface temperature rises above normal, El Niño could develop. When it is below average, La Niña could form. And when it does not rise or fall outside of the average, chances are that neither will develop.
Therefore, the warm phase of ENSO corresponds to El Niño (oceanic warming), while the cold phase of ENSO corresponds to La Niña (oceanic cooling).
In terms of air pressure, specialists measure the difference between the western and eastern parts of the equatorial Pacific, using measurements of Darwin, in Australia, and Tahiti, in French Polynesia.
If the pressure is lower than normal in Tahiti and higher in Darwin, the conditions favor the development of El Niño. If the opposite occurs, La Niña could develop.
But It is not an exact science.
In fact, it is not even clear why these phenomena occur, although there are some clues.
Why are El Niño and La Niña formed?
Scientists are not sure what exactly starts the process. But, from time to time, air pressure conditions change over the equatorial Pacific, affecting the trade winds from the southeast – from the intertropical regions – that normally blow from east to west.
Icochea says that the Earth’s rotation affects the movement of those winds, which act on the surface of ocean water.
“We know that the wind is the trigger, but there are different theories about why that wind is altered. I am inclined to think that it has to do with variations in solar activity, which cause different warming on the planet and, in turn, different pressures ”, says Nieto.
Be that as it may, during El Niño the trade winds weaken, so less water moves westward, causing the central and eastern Pacific to heat up more than usual.
“Generally, El Niño begins to form over Australia at the beginning of the year, and the hot pool begins to advance and arrives in South America towards the end of the year”, Says Icochea.
What happens then is that this huge body of warm water – what scientists call the “Hot water pool” – transfers a lot of heat to the atmosphere because warm, humid air rises from the surface of the sea.
“Sometimes, a very abrupt cooling comes afterwards and it becomes a La Niña, although there can also be Girls when there is no Boy,” adds the teacher.
During La Niña, the winds strengthen, so the sun-warmed body of water is pushed west. Meanwhile, in the eastern Pacific, cold, deep water rises to replace it.
“Those cold waters control the climate and air temperature,” says Icochea. “It is as if under the floor of your house you have hot springs (El Niño) that generate heat, or vice versa, blocks of ice (La Niña) that make you feel cold.”
What consequences can El Niño and La Niña have?
To a large extent, the effects generated by El Niño and La Niña have to do with the position of the jet stream, a core of strong winds of 8 to 12 km on the earth’s surface that blow the planet from west to east.
When El Niño occurs, those winds tend to drift south, which can result in precipitation across much of the southern United States, and warmer conditions in the north. At the same time, hot and dry conditions develop in Asia and Australia, and sometimes in parts of Africa and South America.
The direct hit it happens in both Oceania and America, says Nieto. In South America, it mainly affects northern Peru, Ecuador and southern Colombia.
“In Peru, the sea level can rise as 50 centimeters and the water sometimes heats up to 12 degrees more than normal on the surface, but in the north,” says Icochea. “December is the warmest season for us and if a strong Niño comes, the heat becomes unbearable, and there are also some abundant rains that we don’t normally have ”.
When La Niña occurs, these winds move northward and can cause the situation against El Niño– Hot, drier conditions in the southern United States and cooler, wetter weather in the north, with parts of Australia and Asia more humid than normal. It can also cause more hurricanes in the North Atlantic.
They are the “typical” effects. But sometimes El Niño and La Niña they do not follow the expected patterns.
It may happen that they are given with more force and have greater effects. Or that they are weak and have minor consequences.
“There are different intensities of El Niño,” explains Icochea. “Between two and seven years a weak or moderate Child always occurs, but sometimes in a few years – it can be 15 or even 60 – an extraordinary Child occurs”.
“Sea level rises a lot, so the waves hit further inland, destroying port areas, homes and roads near the coast,” says Nieto.
It is what is also called a “Super El Niño” or “Meganiño”, a more dangerous and increasingly frequent version of the phenomenon that is causing rains, droughts, floods and storms all over the planet.
What has been the most devastating so far? Icochea points out that before “the statistics and measurements that we have now did not exist, but it could be said that those of 1982-83 Y 1997-98 they were the most intense ”.
More recently, it should be noted that of 2015-16, adds Icochea, “which was very strong, but more worldwide than in South America.”
It may also happen that there is a “Double dip girl”; that is, two “Girls” that are formed consecutively.
How does climate change affect?
“El Niño and La Niña will continue to occur for many more years. Climate change is not the generator, but it creates a different scenario”Explains Nieto.
“If the temperature of the air and the oceans is higher or if the composition of the chemistry of the waters is altered, the impacts are going to be greater. Not because humans have generated it, but because it altered the scenario on which it is developed ”, he adds.
“On the other hand, we are more people, we live in risk areas, the agricultural area expanded … So, humans have a lot to do with the impact itself.”
What can we do about it?
“El Niño and La Niña don’t have to be negative,” says Icochea. The oceanographer believes that “they should be something usable”.
Juan José Nieto agrees. He believes that “we must learn to live with El Niño, just as ancient cultures did when building walls to collect water.”
Nieto recalls that similar systems were also used in Ecuador some 50 years ago when a strong Niño arrived and the rains intensified. And he says it’s important that we don’t lose that vision.
“We don’t have water all year. We should build more dams to take advantage of the rains that El Niño brings. It is necessary to take advantage of the years of abundance to face of scarcity. That is why El Niño of 1891-92 went down in history as a year of abundance: because they knew how to take advantage of it ”, adds Icochea.
“Peru is a country blessed by nature, with all kinds of microclimates. We must create a pilot oceanographic center in Peru that will serve as a base to train people from other developing countries in South America and Africa to take advantage of what El Niño brings. “
Paul is a talented author and journalist with a passion for entertainment and general news. He currently works as a writer at the 247 News Agency, where he has established herself as a respected voice in the industry.
