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Are El Niño-La Niña weather patterns changing?

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Are El Niño-La Niña weather patterns changing?

  • A new study projects that climate change will significantly impact El Niño-La Niña weather patterns approximately by 2030 — a decade before what was earlier predicted.
  • This is bound to result in further global climate disruptions.

El Niño

  • Warming of sea water in central-east Equatorial Pacific occurring every few years.
  • During it:
  • surface temperatures in the equatorial Pacific rise
  • trade winds (east-west winds) blowing near the Equator weaken.
  • Faltering in easterly trade winds that blow from the Americas towards Asia.
  • Change direction to turn into westerlies, bringing warm water from the western Pacific towards the Americas.
  • Upwelling (where nutrient-rich waters rise towards the surface) is reduced under El Niño.
  • Reduces phytoplankton
  • Disrupting multiple ecosystems
  • Monsoonal Impacts:
  • Causes dry, warm winter in Northern U.S. and Canada
  • Increases flooding risks in U.S. gulf coast and southeastern U.S.
  • Also brings drought to Indonesia and Australia

La Niña

  • Opposite of El Niño
  • Sees cooler than average sea surface temperature (SST) in equatorial Pacific.
  • Trade winds are stronger than usual, pushing warmer water towards Asia.
  • American west coast - upwelling increases, bringing nutrient-rich water to the surface.
  • Pacific cold waters near Americas push jet streams northwards.
  • Leads to drier conditions in Southern U.S., and heavy rainfall in Canada.
  • Associated with heavy rains in Australia and India

El Niño–Southern Oscillation (ENSO)

  • El Niño + La Niña
  • Neutral state between the two opposite effects
  • Southern oscillations
  • Large-scale changes in sea level pressure in tropical Pacific.

Study’s findings

  • Increased SST variability from ENSO in the eastern Equatorial Pacific (EP) will emerge around 2030 ( error margin of +/- 6 years).
  • If Central Pacific (CP) and EP are not separated
  • SST variability will occur four decades earlier than expected.
  • Changes in the equatorial Pacific will be visible
  • Due to a stronger increase in the EP-ENSO rainfall response
  • Leads to increased SST variability.

Impact on India’s monsoons

  • El Niño causes weak rainfall and more heat
  • La Niña intensifies rainfall in India’s northwest
  • India is currently witnessing an extended ‘triple dip’ La Niña.

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