El Niño could become strongest since 1950: What it means for India

The ENSO phase and the intensity of the El Niño and La Niña events are decided by the sea surface temperatures measured in a specific region of the Pacific Ocean, called the Niño 3.4 region. An El Niño is declared when the average sea surface temperature anomaly in this region surpasses 0.50°C.

In its latest bulletin, the NOAA said the Niño 3.4 index had crossed 1.2°C. This is still in the moderate range. An El Niño is usually considered strong when the Niño 3.4 index goes beyond 1.5°C, and very strong when it crosses 2°C. The strength of an El Niño phase is also dependent on how long it persists.

The 2015-2016 El Niño is the strongest one in recent memory. Termed Godzilla, this persisted for almost two years, 2014 to 2016, and broke several climate records. The Niño 3.4 index had remained above 2°C Celsius for well over four months. In India, both 2014 and 2015 figure in the top four driest years this century, with the monsoon rains in both those years remaining well below 90 per cent of the normal.

Other very strong El Niño phases occurred in 1991-92, 1997-98, and 1982-83.

Even though El Niño events usually mature toward winter, this year it has been rapidly intensifying since April-May, remarked Roxy Mathew Koll, climate scientist at Pune-based Indian Institute of Tropical Meteorology.

“The rapid strengthening of the current El Nino event appears to be linked to a combination of oceanic and atmospheric conditions. Ocean dynamics increased subsurface temperatures in the eastern Pacific, which under background global ocean warming, provides the heat reservoir that can sustain and amplify surface warming. At the same time, weakened trade winds help push warm water eastward, further reinforcing the El Niño state through ocean-atmosphere feedbacks,” he said.

In July, the El Nino is expected to remain in the ‘moderate’ category but a strong El Nino is impending.

What it means for India

With El Niño conditions rapidly strengthening, India could soon start to feel its negative effects.

According to Mrutyunjay Mohapatra, director general, India Meteorological Department (IMD), strong El Nino can have a more adverse impact on rainfall.

“In the past, 60 per cent of the El Nino years have reported either below normal or deficient seasonal rainfall. The other 40 per cent El Nino years have received normal rainfall during the monsoon season over India,” he said.

In its weekly update issued on July 9, the IMD forecast slightly below-normal rainfall to occur over the country till July 22.

“With the monsoon trough shifting towards Himalayan foothills, the rainfall over western India will reduce significantly,” said IMD chief.

During the fortnight till July 22, normal rainfall is forecast limited to Rajasthan, Telangana, Andhra Pradesh, Maharashtra, and north interior Karnataka.

Earlier this month, IMD had forecast country-wide rainfall to be below 94 per cent of the long period average and this comes after a 40 per cent deficient rain in June.

Current El Niño phase likely to continue till next spring

The current El Niño event began in June and is predicted to intensify and continue into 2027.

“A strong El Niño developing over a warmer climate background can push global temperatures higher, and 2027 could well be among the hottest years on record. This will also increase the risk of extreme weather across many regions. While extreme rains still happen, as the warm oceans keep supplying additional moisture, which the monsoon winds carry and dump over the land in a few hours to a couple of days’ time,” remarked Koll.

In its latest bulletin, the NOAA said the Niño 3.4 index had crossed 1.2°C. This is still in the moderate range. An El Niño is usually considered strong when the Niño 3.4 index goes beyond 1.5°C, and very strong when it crosses 2°C. The strength of an El Niño phase is also dependent on how long it persists.

The NOAA bulletin said the current El Niño phase was almost certain to continue through the early part of next year. “El Niño continues and will strengthen through the end of the year, with a 97 per cent chance it will last through early spring 2027,” it said.

The 2015-2016 El Niño is the strongest one in recent memory. Termed Godzilla, this persisted for almost two years, 2014 to 2016, and broke several climate records. The Niño 3.4 index had remained above 2°C Celsius for well over four months. In India, both 2014 and 2015 figure in the top four driest years this century, with the monsoon rains in both those years remaining well below 90 per cent of the normal.

Other very strong El Niño phases occurred in 1991-92, 1997-98, and 1982-83.