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Source: The post is based on the article “The ‘triple dip’ La Niña, and its likely impact in India” published in Indian Express on 21st September 2022.
What is the News?
The World Meteorological Organization(WMO) is predicting that the current La Niña phase will likely continue for the next six months, making it a Triple dip La Nina.
What is El Nino and La Nina?
El Nino and La Nina, which mean ‘the boy’ and ‘the girl’ in Spanish, are mutually opposite phenomena.
La Niña refers to the phase in which sea-surface temperatures are cooler than normal. The warmer phase is known as El Niño.
Together they constitute what is known as the El Niño-Southern Oscillation system, or ENSO for short.
Normally, El Nino and La Nina occur every four to five years. El Nino episodes occur more frequently and are usually associated with more impactful weather events. La Niña, on the other hand, has a longer run.
How do La Nina and El Nino impact the Indian monsoon?
El Niño years in India have witnessed extreme heat and below-normal rainfall levels during monsoon, even though El Niño might not be the only factor or even have direct links to them. In 2014, an El Niño year, India received 12% deficient rainfall from June to September.
On the other hand, La Nina years are known to favour the Indian summer monsoon. This year, India has received 740.3 mm of rainfall, quantitatively 7% higher than the seasonal average till August 30.
What is Triple Dip La Nina?
‘Triple Dip’ La Niña is a period where the La Niña period extends for up to three consecutive winters.
For instance, La Niña phenomenon started building up in September 2020 and will continue for another six months. There is a 70% chance of this phenomenon to continue from September to November 2022 and a 55% chance of it continuing through December 2022 – February 2023.
What will be its impact?
The continuance of La Niña further into 2023 is not bad news from the Indian standpoint. But it is not the same for many other regions where La Niña has very different impacts.
In most parts of the United States, for example, La Niña is associated with very dry winters. In Australia and Indonesia, and generally in the tropical region, La Niña is expected to bring more rainfall.
The excessive rainfall in Pakistan, which is experiencing its worst flooding disaster, can also be blamed in part on La Niña.
