Are odds stacking up in favour of southwest monsoon?

As El Niño starts to weaken, the question for meteorological agencies is whether 2016 will be the year of La Niña

Photo: Priyanka Parashar/Mint
Photo: Priyanka Parashar/Mint

New Delhi: The year 2015 saw one of the strongest El Niño on record, roiling global weather conditions and giving India its second consecutive deficient monsoon season. But as El Niño starts to weaken, the question for meteorological agencies is whether 2016 will be the year of La Niña and whether India would finally see a good southwest monsoon.

While El Niño is an abnormal warming of the Pacific waters near Ecuador and Peru, La Niña is a weather phenomenon resulting from an unusually cold east-central Equatorial Pacific. La Niña is associated with average to above average rainfall in India.

The 2015 El Niño has been the strongest since 1997, and was attributed by India Meteorological Department (IMD) as one of the primary reasons for the deficient southwest monsoon which was 14% below normal.

This year’s Economic Survey observed that the average agricultural growth in El Niño years since between 1981-82 and 2015-16 has been -2.1 % compared with a period average of 3%. But in La Niña years, the average growth was 8.4%, much higher than the period average.

The Australian Bureau of Meteorology (BOM) in its latest update said, “The 2015-16 El Niño is now at moderate levels, and is likely to end in the second quarter of 2016. History and model outlooks indicate that neutral conditions are slightly favoured ahead of La Niña for the second half of 2016.”

Taking into account 26 El Niño events since 1900, around 50% have been followed by a neutral year, and 40% have been followed by La Niña, according to an analysis by BOM. “There is no prediction as yet, but we know that La Niña tends to follow El Niño. Right now we should be looking at the pace with which the El Niño condition decays. Chances are that by northern summer, a La Niña condition would be formed,” said Wenju Cai, a climate expert at Australia’s Commonwealth Scientific and Industrial Research Organisation.

But IMD remains cautious on whether La Niña could have an impact on the southwest monsoon. “El Niño may turn neutral by summer, La Niña may not be here before the southwest monsoon,” said a senior IMD scientist. The US National Oceanic and Atmospheric Administration in its latest forecast said that the probability of La Niña developing goes up to 50% only for September-October-November.

But weather scientists say it is unlikely that the 2015-16 El Niño is on the decline and another El Niño will emerge this year. So does this mean that the 2016 Southwest monsoon would be good?

“That would be consistent with what occurred in the past,” said Cai.

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