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.
What is ENSO(El Nino Southern Oscillation)? The combination of El Nino, La Nina and the neutral state between the two opposite effects is called as ENSO. Southern Oscillations are large-scale changes in sea level pressure in the tropical Pacific region. Syllabus : prelims and mains, GS-1 geography.