From UPSC perspective, the following things are important :
Prelims level : El-Nino, La-Nina
Mains level : ENSO impact on Indian Monsson
This year the La Nina is being blamed for worsening the longest spell of heatwaves from March to April in north, west and Central India.
In most years, meteorologists considered the La Nina to be a friend of India.
What is El Nino and La Nina?
- While El Niño (Spanish for ‘little boy’), the more common expression, is the abnormal surface warming observed along the eastern and central regions of the Pacific Ocean (the region between Peru and Papua New Guinea).
- The La Niña (Spanish for ‘little girl’) is an abnormal cooling of these surface waters.
- Together, the El Niño (Warm Phase) and La Niña (Cool Phase) phenomena are termed as El Niño Southern Oscillation (ENSO).
- These are large-scale ocean phenomena which influence the global weather — winds, temperature and rainfall. They have the ability to trigger extreme weather events like droughts, floods, hot and cold conditions, globally.
- Each cycle can last anywhere between 9 to 12 months, at times extendable to 18 months — and re-occur after every three to five years.
- Meteorologists record the sea surface temperatures for four different regions, known as Niño regions, along this equatorial belt.
- Depending on the temperatures, they forecast either as an El Niño, an ENSO neutral phase, or a La Niña.
Impact on India
- El Nino during winter causes warm conditions over the Indian subcontinent and during summer, it leads to dry conditions and deficient monsoon.
- Whereas La Nina results in better than normal monsoon in India.
- It has been established that Indian summer monsoon is a fully coupled land-atmosphere-ocean system and that it is linked to ocean temperature variability.
- In an agricultural country like India, the extreme departure from normal seasonal rainfall seriously affects the agricultural output and thus the economy of the country.
Try this PYQ:
La Nina is suspected to have caused recent floods in Australia. How is La Nina different from El Nino?
- La Nina is characterized by unusually cold ocean temperature in equatorial Indian Ocean whereas El Nino is characterized by unusually warm ocean temperature in the equatorial Pacific Ocean.
- El Nino has an adverse effect on south-west monsoon of India, but La Nina has no effect on monsoon climate.
Which of the statements given above is/are correct?
(a) Only 1
(b) Only 2
(c) Both 1 and 2
(d) Neither 1 nor 2
Post your answers here.