If you have come across the word “El Niño” several times in the past and have wondered what’s the fuss around it, then you have come to the right place. Through this article, we’ll try to explain the phenomenon in a simple language and also tell you why it actually matters.
El Niño is one of the most high-impact weather patterns existing in the world. It shows how interconnected the world is and how something occurring in one ocean can change the weather across countries.
What are we focusing on?
Three things: the Pacific Ocean – which covers one-third of our planet – along the equatorial region, trade winds and water current.
Tell me what happens usually
Ok. So, normally we have friendly easterly winds (winds that start from the east) blowing from the east and central part of the Pacific region, towards the west. Or you can in simple terms say that the winds blow from the Americas towards Asia. The West is typically warmer. These trade winds push the water current from The Americas to Asia.
The warm water slowly rises in height, evaporates, precipitates and causes normal rainfall over Asia. On the other hand, cold water accumulates in the East, rising slowly (called upwelling), thus keeping the easterly winds in motion. All good till now.
What happens during El Niño?
Nothing less than a mystery. The Easterly winds sometimes weaken and can no longer push the warm water towards the West. Sometimes, they might even change their direction and transform into Westerly winds. Warm water current starts flowing in the opposite direction now…towards the Americas. This shift in the pattern also shifts the region of rainfall over the Pacific equatorial belt.
This is El Niño. Asia remains hot; the warm water current starts moving in the reverse direction towards the Americas,. So the Pacific equatorial region towards the Americas is warmer than it should be and Asia receives no rainfall when it should be receiving normal rainfall.
Why does El Niño matter?
For the very reason that it dries up countries like Indonesia and India in Asia and floods countries in South and Central America. Since the moisture has now moved away from Asia towards the Americas, El Niño can stall rainfall in Asia, increase temperatures and produce drought-like conditions. In America, there could be heavy snowfall/rainfall, flash floods, cyclones and tornadoes wreaking havoc.
Not just that, as the warm water moves towards the East, it replaces cold ocean water. Cold ocean water is full of nutrients and low cold water levels mean fishes can no longer survive. This impacts the fishing industry along the coast.
So yes, El Niño impacts not just the weather but also the macroeconomy of a country.
How frequently does it occur?
El Niño is part of El Niño-Southern Oscillation (ENSO). It has a sister – La Niña. The weather pattern keeps oscillating between the two irregularly. The hotter phase is El Niño while La Niña is the cooling pattern of the cycle. Typically, it takes 2-7 years for a complete cycle. El Niño on its own remains for a few months to two years.
El Niño in the years 1972-73, 1982-83, 1997-98 and 2015-16 are known to be one of the most severe episodes triggering one of the biggest floods, droughts, coral bleaching and forest fires in the previous half century that passed.
When is El Niño declared?
Climatologists examine the sea surface temperature in the east-central tropical Pacific (referred to as the Niño 3.4 region). El Niño is declared when the water temperature stays 0.5 degrees above its natural temperature for 5 months straight.
Is there a connection between global warming and the frequency of El Niño?
For now, the research is still on to understand if the rising global temperatures affect the ENSO pattern in any way. However, if it does prove that these are connected, it gives us all the more reasons to fight climate change.
Human and the Climate 