EI Nino- La Nina

EI Nino- La Nina

Why in news : According to the study, published in the Nature Communications journal, increased sea surface temperature variability from ENSO in the eastern Equatorial pacific  will emerge around 2030, more than a decade earlier than that of the central pacific ENSO.

What is El Nino ?

  • El Nino is the warming of sea water in the central-east Equatorial Pacific that occurs every few years.
  • Normally, easterly trade winds blow from the Americas towards Asia.
  • Due to El Nino, they falter and change direction to turn into westerlies, bringing warm water from the western pacific towards the Americas.
  • During El Nino, surface temperatures in the equatorial pacific rise, and trade winds that blow near the Equator weaken.


  • El Nino impacts on marine life :
    • The phenomena of upwelling (nutrient-rich waters rise towards the surface) is reduced under El Nino.
    • Due to reduced upwelling, phytoplankton are reduced. This will automatically reduce the fishes that are dependent on the phytoplankton.
    • Warm water from tropical areas carry tropical species towards colder areas, disrupting multiple ecosystems.
  • Impact on climate :
    • El Nino causes dry warm winter in Northern U.S. and Canada.
    • It increases the risk of flooding in the U.S. gulf coast and southeastern U.S.
    • It also brings drought to Indonesia and Australia.
  • Impact on India :
    • El Nino causes weak rainfall and more heat.
    • It may cause severe drought conditions in some parts of India.

What is La Nina :

    • La Nina is the opposite of El Nino.
    • In La Nina the sea surface temperature(SST) in the equatorial Pacific region is cooler than the normal conditions.
    • Trade winds are stronger than usual, pushing warmer water towards Asia.


      La Nina conditions and its impacts on weather patterns

  • Effects on marine life :
    • On the American west coast, upwelling increses, bringing nutrient rich water to the surface.
  • Effects on climate and weather patterns :
    • Pacific cold waters close to the Americas push jet streams northwards.
    • It will lead to drier conditions in Southern U.S., and heavy rainfall in Canada.
    • It will bring heavy floods in Australia, resulting in significant damage.
  • Effect on India :
    • La Nina has positive impact on Indian rainfall.
    • La Nina intensifies rainfall across South Asia, especially in India’s NorthWest and Bangladesh during the monsoon.








Syllabus : prelims and mains, GS-1 geography.