A TRIPLE DIP LA NINA

The Pacific forms the largest division of the World Ocean with 165.25 million square km in area. It means it covers  about 46 per cent of the earth’s water surface and about one-third of its total surface area, making it larger than all of the Earth’s land area combined. 

Because of the sheer size of the Pacific waters, its influence on weather and climate extends from the Americas & Asia to West Asia and Europe.

This is best seen in alternating El Nino means abnormal warming & La Nina means abnormal cooling of the Equatorial Eastern Pacific that lies closer to the Americas. Corresponding to this, the west of the Pacific, lying closer to Asia turns cooler during an El Nino and warmer during a La Nina. 

The warming of the ocean due to  summer heat, sets up lower atmospheric pressure and triggers convection (the process of cloud-building) and precipitation (rainfall). Cooling is associated with higher atmospheric pressure that suppresses cloud-building and rainfall, and produces dry conditions.

El Nino and La Nina events occur every three to five years and generally reach peak strength between October and March when sea surface temperatures across the equatorial Pacific are the warmest.

 El Niño begins as a giant pool of warm water swelling in the eastern tropical Pacific that sets off a chain reaction of weather events around the world. While the La Nina situation is exactly opposite of it , in which it brings a giant pool of cold waters in the  eastern & central  Pacific. 

According to, a recent observations of World Meteorological Organization (WMO), the La Nina weather pattern will last until at least the end of the year, This will be for the first time this century that La Nina have spanned three consecutive years.

 According to WMO, the condition has intensified between mid-July & mid-August and may result in intense floods, droughts & tropical cyclones around the world. La Niña is the cooler than the normal phase of the El Niño Southern Oscillation (ENSO) phenomenon in the central and eastern equatorial Pacific Ocean.

According to WMO, there is 70% possibility that, the La Nina will persist from September to November and there is 55% possibility that it will persist between December and February. 

According to National Oceanic & Atmospheric Administration (NOAA),the longest La Nina was recorded in 1973, which retained itself for 37 month.

During a La Niña event, the high atmospheric pressure  mounted on the sea surface of central and eastern Pacific oceans as it becomes cooler than normal. This makes the trade winds & storms to blow from this region to southeast Asia, especially Indonesia & many parts of Australia.

So the South Asian , South East Asian & North East Australia & surrounding region will receive unusual rainfall , while the regions like Horn of Africa and western United States experiences draughts. The impacts of global warming are exacerbating ENSO and the phenomenon itself may be affected by a warming atmosphere and oceans.

According to , Petteri Taalas, secretary general of WMO, “It is exceptional to have three consecutive years with a la Niña event. Its cooling influence is temporarily slowing the rise in global temperatures, but it will not halt or reverse the long-term warming trend,” 

Despite La Niña, when a large pool of cold waters is added into eastern & central Pacific,  there have been destructive heat waves and resultant droughts and wildfires  across five continents this summer. The droughts in the Horn of Africa, Europe & China are particularly intense, showing the impact of human-induced warming of the atmosphere.

The La Niña started in September, 2020 & is expected to continue till  February 2023.This implies an intensification of the devastating droughts in the Horn of Africa, the southern part of South America, especially Chile and the United States.

The extended La Niña, the first triple dip of the 21st century and only the third since 1950, may also lead to an overactive Atlantic Hurricane season in 2022. 

NOAA has already issued  storm warnings at the beginning of August. Its National Hurricane Centre is currently monitoring storm development in three regions of the Atlantic Ocean. 

The continuation of the La Niña also means a possible extension of southwest monsoon season for India & the rest of south Asia with heavy precipitations and possible floods.

 In 2021, La Niña was one of the factors that caused extraordinary rainfall during the post-monsoon season in the southern part of India. 

In 2022, an active monsoon caused floods in many Indian states, such as Assam, Meghalaya and other northeastern states in June. It has also affected neighboring Bangladesh.

The flash floods in Gujarat in the early July & subsequent floods in north & peninsular India  experienced the effect of the La Niña. Amidst the La Nina situations, warming of sea surfaces leading to the continuous formation of low-pressure areas and depressions. 

More such floods can be expected in the next few months due to the extended  La Niña. 

The torrential downpours  in Pakistan, which has submerged a third of the country and displaced 33 million people, may also have been affected by an active La Niña. 

Global warming causing the devastating floods & droughts that occur during La Nia but may also impact the ENSO.

The strength of ENSO and the frequency of significant ENSO events have increased since 1950 as compared to ENSO events between 1400 and 1950, according to Tom Di Liberto, a climate scientist at NOAA.

The Intergovernmental Panel on Climate Change’s Sixth Assessment Report also noted that a higher number of El Niño events in the last 20-30 years have been associated with temperature changes that are stronger in the central Pacific rather than the east,” Liberto wrote in the ENSO blog published by NOAA.

A research paper published in the journal Nature Reviews Earth and Environment in August 2021 predicted a change in the variability of ENSO-associated rainfall and sea surface temperatures in future warming scenarios.

It has also predicted an eastward shift of the phenomenon, most probably intensifying its impact in North America and South America. The study also cautioned against putting too much trust in the models because of the internal variability of the ENSO.