Unusual triple dip La Nina triggers, a sign of changing climate, impacted the large-scale wind pattern
Photo: iStock A rare triple dip La Nina episode, said to be a mark of climate change, set off a peculiar air quality trend in the 2022-23 winter season, showed a new study. This period was characterised by improved air quality in north India and increased pollution levels in Peninsular India, the report published in the journal Elsevier February 18 stated.
“The 2022-23 winters did coincide with the last phase of a rare triple-dip La Nina event, the first in the 21st century. This phenomenon, which was an influence of climate change, did impact the large-scale wind pattern playing a decisive role in prevention of stagnation conditions in cities of North India, thus improving air quality,” RH Kripalani, the report co-author told the news agency Press Trust of India. Kriplani is a climate scientist at the Indian Institute of Tropical Meteorology.
“In North India, Ghaziabad recorded the most significant improvement with a reduction of 33 per cent, which was closely followed by Rohtak and Noida with a reduction of 30 per cent and 28 per cent, respectively,” the authors wrote in the report.
Landlocked Delhi in the northern plains of India, notorious for its unhealthy air, also recorded an improvement with a reduction of about 10 per cent in the winter months of 2022-23.
In contrast, the atmospheric pattern led to calmer conditions in peninsular Indian cities, accelerating transboundary pollution and significantly deteriorating air quality, Kriplani added.
As per the report, Mumbai became the city to record the highest deterioration with a 30 per cent rise in Particulate Matter (PM) 2.5 levels. This, it elaborated, was followed by the cities of Coimbatore recording an increase in PM 2.5 levels by 28 per cent and Bengaluru, and Chennai recording a rise in the same by 20 per cent and 12 per cent respectively.
In order to validate this hypothesis, a newly developed advanced NIAS-SAFAR air quality forecasting model was used. This model is said to combine a chemical-transport model with an indigenously developed modern artificial intelligent algorithm.
“Our findings are vindicated as the air quality in the winter of 2023-24, at the end of La Nina, did return to normal levels. The current paper’s findings suggest we need to wake up to the fact that extreme and unusual happenings in the phenomenon of air pollution either directly or indirectly are the manifestations of climate change,” Gufran Beig, another study author as quoted by PTI said.
“Such disclosures, most probably, are set to increase by leaps and bounds. This, unless our focus is on a long-term strategy to decrease the menace of anthropogenic emissions direct at the source. It would be a win-win for both air quality and climate change,” further said Beig, as per the news agency.
To understand the association of La Nina-induced changes in large-scale wind pattern and variability in particulate pollutants in 2022 across various regions in the country, the study authors utilised the chemical transport model as a primary methodology. They also carried out sensitivity simulations to validate their findings.
While extreme weather and changing climate patterns take a heavier toll on the planet, new trends in the frequency of severe pollution events are taking a toll on a regional scale, hence threatening health and food security, the study concluded.
“Current research advocated that the sudden flip-flop of the current Indian pollution cycle forms a part of a larger meteorological phenomenon linked to the last phase of triple dip La Nina,” also stated the conclusion.
We are a voice to you; you have been a support to us. Together we build journalism that is independent, credible and fearless. You can further help us by making a donation. This will mean a lot for our ability to bring you news, perspectives and analysis from the ground so that we can make change together.
.png)
Comments are moderated and will be published only after the site moderator’s approval. Please use a genuine email ID and provide your name. Selected comments may also be used in the ‘Letters’ section of the Down To Earth print edition.