Context: Recently, the National Oceanic and Atmospheric Administration revealed that the El Nino, associated with a warming of the ocean surface in the central and eastern tropical Pacific Ocean has arrived.

• El Nino could lead to more warming with the hottest year on record (2016) coinciding with a strong El Nino.

Predictions about the El Nino in 2023

• According to the National Weather Service Climate Change Predictor, El Nino conditions are present and expected to strengthen in the Northern Hemisphere’s winter in 2023-24.

• According to the National Oceanic and Atmospheric Administration (NOAA), there is an 84% chance of an El Nino of greater than moderate strength and a 56% chance of a strong El Nino by the winter.

• According to a climate scientist at the Climate Prediction Center, El Nino can lead to impacts such as the increased risk of heavy rainfall and droughts in certain locations around the world, depending on its strength.

• Climate change can exacerbate or mitigate impacts related to El Nino such as new records in temperatures, particularly in areas that were subject to above-average temperatures during El Nino.

• In May 2023, the World Meteorological Organization (WMO) predicted a 60% chance of an El Nino between May and July 2023 with the likelihood of it rising to around 70% between June and August and 80% between July and September.

• According to the statistics, May 2023 is tied for the second-hottest May globally. Experts have stated that an El Nino-like signature is continuing to emerge in the equatorial Pacific and could lead to more warming.

• El Nino adds extra heat to the atmosphere, therefore Earth’s rising temperature could exceed the 1.5°C threshold prescribed by the Paris Agreement sometime after the peak of El Nino in 2024.

• However, experts have claimed that it is too early to predict how strong the next event will be.

• In comparison, La Nina, a climate pattern associated with the cooling of surface-ocean water along the tropical west coast of South America, ended in 2023 after a three-year period.

What is El Nino?

• The El Nino, meaning little boy in Spanish, is a climatic pattern associated with an unusual warming of the eastern tropical Pacific Ocean.

• It forms the warm phase of the El Nino Southern Oscillation and is considered to be more frequent than the La Nina.

• The El Nino, whose impacts can be felt far and wide, takes place every two to seven years.

• El Nino was first recognized by Peruvian fishermen as the warming of the Peruvian coast.

How does El Niño happen?

• When the El Niño Southern Oscillation (ENSO) is in its neutral phase, the trade winds blow west along the equator and take the warm water from South America towards Asia.

• However, during an event of El Niño, these trade winds weaken (or may even reverse) — and instead of blowing from the east (South America) to the west (Indonesia), they could turn into westerlies.

• As the winds blow from the west to east, they cause masses of warm water to move into the central and eastern equatorial Pacific Ocean, and reach the coast of western America.

What is the impact of the El Nino?

• It has been known to cause droughts of a severe nature over Australia, Indonesia, and parts of South Asia, and heavy rainfall in parts of South America, the southern U.S.A., the Horn of Africa, and Central Asia.

• Impact on Oceans: El Nino impacts ocean temperatures, the speed and strength of ocean currents, the health of coastal fisheries, and local weather.

• Increased Rainfall: Convection above warmer surface waters results in increased precipitation. A drastic increase in rainfall in South America contributes to coastal flooding and erosion.

• Impact on Public Health: Flooding caused by El Nino is associated with an increase in the incidence of cholera, dengue, and malaria while wildfires that create respiratory problems are common under the drought conditions caused in other places.

• El Nino can also have a positive impact as it is known to reduce the occurrence of hurricanes in the Atlantic.

• The droughts caused by El Nino in Indonesia and Australia are a threat to the water supplies in the country, as reservoirs dry up and the water carried by rivers is much lower than usual. This is also an indirect threat to agriculture in the region.

• In Western Pacific, the winds push warm surface water towards the western Pacific bordering Asia and Australia. This results in the upwelling of water near the western coast of South America bringing cold nutrient-rich water to the surface.

Does El Nino have any impact on India?

• There is an inverse relationship between the El Nino and the Indian monsoon.

• Six of the most notable droughts in India, including 2002 and 2009, have been associated with the El Nino. However, not all droughts in India are associated with the El Nino and vice versa.

• El Nino directly influences India's agricultural sector by reducing the output of summer crops such as rice, sugarcane, cotton, and oilseeds.

• Indirectly El Nino results in high inflation and low GDP growth on account of its effect on the agriculture sector of the Indian economy.

Measurement of El Nino

• The Oceanic Nino Index (ONI) is a tool used for the calculation of variations from normal sea surface temperatures.

• The primary method for determining and forecasting each instance of El Nino is a measure of the deviation from normal sea surface temperature in the east-central Pacific Ocean.

• The El Nino ranges in severity from mild temperature rises with minor local impacts on weather to extremely severe increases connected with global climatic shifts.

• Buoys located in the ocean measure temperature, currents, winds, and humidity. The data is then used by scientists to predict El Nino patterns across the globe.