What is El Nino and how it affects global weather
What's the story
There is an increasing likelihood of a weather pattern called El Nino in the coming months and it could set new heat records, United Nation's World Meteorological Organization (WMO) has warned.
El Nino affects climate patterns in several parts of the world and is typically associated with higher global temperatures.
Let's take a deeper look at what is El Nino and its effects.
Detail
What is the El Nino weather pattern?
El Nino refers to the warming of the ocean surface in the central and eastern tropical Pacific Ocean, according to the United States Geological Survey.
The low-level surface winds, which usually blow from east to west along the equator—called the easterly winds—become weak and sometimes start blowing in the other direction. These currents blowing from west to east are called the westerly winds.
Warming
The winds undergo a change in fall and winter seasons
Strong winds traveling along the equator shove the surface water, which is warm, near South America westward toward Indonesia.
When this occurs, cooler water from underneath moves up toward the surface of the ocean near South America.
But, in some fall and winter seasons, these winds become weaker than usual. They blow the opposite way i.e. toward South America instead of Indonesia.
Explanation
The change in current direction affects marine life
So when the flow reverses, the warm surface water found along the equator accumulates along the coast of South America and then travels north towards California and south toward Chile.
Due to this, fish that normally thrive in the cooler waters off the coast of South America either move away or die.
South American fishermen first discovered this phenomenon in the 1600s.
Information
When does El Nino occur?
The El Nino weather event takes place every two to seven years, and the events typically last nine to 12 months. Interestingly, no two El Nino episodes are exactly similar and their effects partly depend on the time of year.
Effect
What are the effects of El Nino?
Broadly speaking, El Nino events affect the temperatures of oceans, the speed and intensity of ocean currents, coastal fisheries, and local weather conditions from Australia to South America and beyond.
Stronger El Nino events disturb the global atmospheric circulation, which refers to the large-scale movement of air that helps distribute and maintain heat across the surface of the Earth.
Information
It can cause increased rainfall in regions of central Asia
Usually, El Nino causes increased rainfall in some regions of southern South America, central Asia, and the Horn of Africa, among others. Conversely, it can also lead to seasons of severe droughts in Australia, Indonesia, and some portions of southern Asia.
Warning
60% chance for onset of El Nino during May-July: WMO
Coming to the upcoming El Nino, the WMO has stated that there is roughly a 60% chance for the onset of El Nino during May-July and the likelihood increases to 70-80% during July-September.
"The development of an El Niño will most likely lead to a new spike in global heating and increase the chance of breaking temperature records," said Petteri Taalas, WMO's chief.