Indian scientists advise against panic, say weather system won’t impact monsoon.
Representational image.
New Delhi: El Niño conditions have developed in the tropical Pacific for the first time in seven years, and there is a 90% probability of the El Niño event continuing during the second half of 2023, according to the latest update from the World Meteorological Organization (WMO) on Tuesday.
However, the India Meteorological Department (IMD) is treading with caution and said it would be issuing a fresh update later this week based on the latest data and fulfilment of threshold conditions.
Earlier, on June 6, the Bureau of Meteorology, Australia, moved from El Niño ‘watch’ to El Niño ‘alert’, indicating a 70% chance of El Niño developing this year. The US’ National Oceanic and Atmospheric Administration (NOAA) had declared the arrival of El Niño on June 8.
While the WMO described the El Niño phenomenon as “expected to be at least of moderate strength,” setting the stage for a likely surge in global temperatures and disruptive weather and climate patterns, experts in India have assured that there is no need to panic. They explained that it is likely to not have any negative impact on Indian monsoon rainfall due to a positive Indian Ocean Dipole (IOD), which is an ocean-atmosphere phenomenon occurring in the Indian Ocean.
“The onset of El Niño will greatly increase the likelihood of breaking temperature records and triggering more extreme heat in many parts of the world and in the ocean,” said WMO Secretary-General Prof Petteri Taalas.
What is El Niño, and what is the current situation?
El Niño occurs when sea surface temperatures (SSTs) are higher than average in the eastern tropical Pacific, and there is a simultaneous weakening of trade winds. This is the opposite of the phenomenon known as La Niña, characterised by below-average SSTs in the central and eastern tropical Pacific, along with strong trade winds.
El Niño typically has a warming influence on global temperatures, while La Niña has the opposite effect. A crucial factor in El Niño occurrence is the SST anomaly in an area known as NINO 3.4, referring to the tropical area in the eastern Pacific Ocean.
According to the WMO, since February 2023, monthly average sea surface temperature anomalies in the central-eastern equatorial Pacific have significantly warmed, rising from nearly half a degree Celsius below average (-0.44 in February 2023) to around half a degree Celsius above average (+0.47 in May 2023).
“On June 14, 2023, the warm sea surface temperature anomalies have continued to increase, reaching a value of +0.9 degrees Celsius,” the WMO said, adding, “The collective evidence from both oceanic and atmospheric observations strongly points towards the presence of El Niño conditions in the Pacific.”
“As of July 4, 2023, the NINO 3.4 index is 1.2 degrees Celsius. El Niño is peaking up much faster than the model predictions,” said Madhavan Rajeevan, former Secretary, Ministry of Earth Sciences, Government of India.
However, the WMO also pointed out that there remains “some uncertainty” due to “only weak ocean-atmosphere coupling, which is crucial for the amplification and sustenance of El Niño.”
The WMO update stated that it is anticipated that it will take approximately another month or so to witness a fully established coupling in the tropical Pacific.
No El Niño announcement from IMD yet
Perhaps the reason for the IMD not declaring El Niño as yet is the weak ocean-atmosphere coupling.
The IOD is a phenomenon occurring between the western tropical Indian Ocean and the eastern tropical Indian Ocean, where one side gets warmer than the other. The IOD is said to be positive when the western side of the Indian Ocean near the equator is warmer, and it is said to be negative when it is cooler.
During the month-end press conference on June 30, IMD Director General Dr. Mrutyunjay Mohapatra had stated that there are high probabilities for the development of El Niño conditions over the equatorial Pacific Ocean and positive Indian Ocean Dipole (IOD) conditions over the Indian Ocean during July to September 2023. He also mentioned that “currently (i.e., at the end of June), neutral Indian Ocean Dipole (IOD) conditions are prevailing over the Indian Ocean.”
According to the IMD, El Niño is declared only when the threshold of a 0.5-degree or above anomaly in the NINO 3.4 SST is observed for three continuous months. Mohapatra had stated that the anomaly in the central eastern Pacific SST based on June 17 data was 0.47.
On Tuesday, Mohapatra told News9 Plus, “IMD would be issuing its El Niño update this week based on fresh data.”
Indian monsoon and El Niño
“El Niño is a major climate variability driver. It will impact several countries differently. Generally known for its negative impact as it changes rainfall patterns potentially,” said K J Ramesh, former IMD DG, explaining the fear or widespread perception that the El Niño phenomenon brings drought or, at least, deficient rainfall.
“Monsoon is a planetary-scale, large-scale phenomenon with a footprint across most parts of South Asia, right from Pakistan to Vietnam. It has its own variability characteristic, such as El Niño, IOD, or North Atlantic Oscillation. And within this, there is a Madden Julian Oscillation phenomenon that also impacts within-season variability. All these factors will play on monsoon rainfall concurrently,” he said.
IMD records show that there is no 1:1 correlation between El Niño and Southwest Monsoon rainfall. For instance, on the one hand, 13 of the 18 drought years since 1901 were El Niño years. But on the other hand, nine of the 15 El Niño years between 1951 and 2022 had below-normal rainfall, and six had normal or above-normal rainfall.
The IMD has already predicted a normal monsoon for this year.
Termed as the real Finance Minister, the southwest monsoon is the driver of India’s economy as it impacts not just agriculture but subsequent trade as well.
The latest data from NITI Aayog shows that in 2022-23, 73 million hectares out of 141 million hectares (i.e., a little more than 50%) of gross sown area across India had access to irrigation in some form or the other. This was up from 41% in 2016.
Farmers tilling this almost 50% land are entirely dependent on southwest monsoon rainfall spanning four months from June to September. This monsoon rainfall brings 70% of the total annual rainfall and also helps in groundwater recharge and refilling surface water bodies.
The multiple weather models have established that the positive IOD is simultaneously developing as strongly as El Niño. Between April to August, the way El Niño developed, the IOD has developed positively, Ramesh said, adding, “Nino 3.4 value predicted by multi models shows that whatever negative effect El Niño can have, it will be strongly offset by positive IOD.”
Apart from the WMO’s confirmation about El Niño, there are supportive pieces of evidence as well. “The Copernicus season forecast (site) shows that there are multi-model ensemble monthly predictions over South Asia based on June conditions. It does not show any significant negative anomaly prediction for July, August, or September rainfall.
“There is no need at all to panic. There is no evidence for any negative anomaly for monsoon rainfall vis-a-vis El Niño,” Ramesh asserted.
El Niño and global impact
El Niño occurs on average every two to seven years, and episodes typically last nine to 12 months. It is a naturally occurring climate pattern associated with the warming of the ocean surface temperatures in the central and eastern tropical Pacific Ocean.
El Niño events are typically associated with increased rainfall in parts of southern South America, the southern United States, the Horn of Africa, and central Asia. In contrast, El Niño can also cause severe droughts over Australia, Indonesia, parts of southern Asia, Central America, and northern South America. El Niño’s warm water can also fuel hurricanes in the central/eastern Pacific Ocean, while it could hinder hurricane formation in the Atlantic Basin.
In anticipation of the El Niño event, a WMO report released in May predicted that there is a 98% likelihood that at least one of the next five years, and the five-year period as a whole, will be the warmest on record, surpassing the record set in 2016 when there was an exceptionally strong El Niño.
(This story first appeared on news9live.com on Jul 04, 2023 and can be read here.)
