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.