From UPSC perspective, the following things are important :
Prelims level : El-Nino, La-Nina
Mains level : ENSO impact on Indian Monsson
In what may be termed as an uncommon ocean phenomenon, the prevailing La Nina conditions over the equatorial Pacific Ocean have entered the third consecutive year.
What is the news?
- The current La Nina phase has been prevailing since September 2020.
- Since the 1950s, La Nina lasting for more than two years has been recorded only on six instances (see graph below), data by the India Meteorological Department (IMD) stated.
- It confirmed that India’s La Nina conditions are here to stay till the end of 2022.
What is El Nino and La Nina?
- While El Nino (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 Nina (Spanish for ‘little girl’) is an abnormal cooling of these surface waters.
- Together, the El Nino (Warm Phase) and La Nina (Cool Phase) phenomena are termed as El Nino Southern Oscillation (ENSO).
- These are large-scale ocean phenomena that 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 Nino regions, along this equatorial belt.
- Depending on the temperatures, they forecast either as an El Nino, an ENSO neutral phase, or a La Nina.
Why has La Nina conditions continued for 3 years?
- It is surprising that it has continued for the last three years. It may be good for India but not for some other countries.
- Under climate change conditions, one must expect more such instances. Climate change could be a factor driving such anomalous conditions.
Issues with La Nina
- La Nina years are infamous for frequent and intense hurricanes and cyclones in the Atlantic Ocean and the Bay of Bengal.
- Chances of more cyclones are likely due to multiple aiding factors, including high relative moisture and relative low wind shear over the Bay of Bengal.
Try this PYQ:
Q. 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.
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