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.