El Nino & La Nina (Syllabus: GS Paper 1 – Geography)

News-CRUX-10     25th September 2023        

Context: Recently, the World Meteorological Organization declared the development of El Niño conditions in the tropical Pacific for the first time in seven years, potentially leading to a rise in global temperatures and the onset of disruptive weather and climate patterns. El Nino is likely to fuel further global temperature increase. It is one facet of the El Nino Southern Oscillation (ENSO).

El Nino Southern Oscillation (ENSO)

  • ENSO refers to the oscillation between the El Nino and the La Nina. ENSO shifts irregularly back and forth between El Nino and La Niña every two to seven years.
  • IPCC AR6 indicates that “it is very likely that ENSO rainfall variability, used for defining extreme El Ninos and La Ninas, will increase significantly.

El Nino

  • It was formerly referred to as "El Niño de Navidad" as it reaches its peak around December.
  • El Niño involves the warming of sea waters in the Central-east Equatorial Pacific, occurring irregularly every few years.
  • This warm phase is observed off the coast of Peru.
  • During El Niño events, there is an increase in surface temperatures within the equatorial Pacific region.
  • This phenomenon leads to a weakening of the trade winds, which are the east-west winds that typically blow near the Equator.
  • Consequently, warm water from the western Pacific Ocean is transported towards the American continent.

La Nino

  • La Niña involves below-average sea surface temperatures (SST) in the equatorial Pacific area.
  • Stronger trade winds than usual push warmer water towards the Asian region.
  • It is the opposite of El Niño, characterized by colder conditions.
  • La Niña occurs when ocean temperatures in the equatorial Pacific become lower than normal
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