In 2022, this rare weather system brings better air quality in the north and autumn in southern India!

In 2022, this rare weather system brings better air quality in the north and autumn in southern India!

The air turns foggy in Delhi, the national capital (Rajesh Mehta/BCCL)

Representative image

(Rajesh Mehta/BCCL)

Delhi and many landlocked parts of northern India have continued to build a reputation for smog-like conditions, especially in the winter months. While many southern cities also suffer from polluted air, they do not have as much of a bad reputation. However, despite popular discrimination, things took a surprising turn in 2022.

A study found that air quality actually improved in northern India during the 2022-2023 winter season, while the Indian peninsula saw an increase in air pollution. This sudden reversal trend contradicts what has been observed in recent decades, and a rare climate phenomenon may be the reason.

The El Niño-Southern Oscillation (ENSO) is a climate phenomenon that has caught on in recent times due to its persistent heating and drying effects on India since its onset in June 2023. Before we moved into the warming phase of El Niño, the world was under the brunt of El Niño. La Niña cooling effects – this may have been a special effect at that time, it seems.

La Niña conditions occur when tropical trade winds cause cold water to rise to the surface over the Pacific Ocean, cooling it. While this phase typically lasts 9-12 months, the final phase began in 2020 and has continued for an amazing three years! Although such “triple dips” are not new, they usually follow strong El Niño events, such as the La Niña that lasted from 1998 to 2001. However, the 2020 El Niño was not particularly severe, leaving climate scientists with Extreme confusion.

The other shock was its impact on air quality in India. The study found that in 2022, cities in northern India saw significant improvements in air quality, with Ghaziabad recording the largest decline at 33%, followed by Rohtak (30%) and Noida (28%). Delhi, a city notorious for pollution, also saw a 10% improvement.

In contrast, cities in the Indian peninsula have seen their air quality deteriorate dramatically. Mumbai recorded the largest increase in PM2.5 levels at 30%, followed by Coimbatore (28%), Bengaluru (20%), and Chennai (12%).

In fact, the researchers found that many northern Indian cities nearly reached the five-year goals set by the National Clean Air Program relatively quickly during this time as well. But once El Niño began during the winter of 2023-2024, air quality returned to normal levels.

The researchers explained that strong northerly winds at high altitudes – thanks to the persistence of La Niña – helped push pollutants away from cities in northern India. This, coupled with weak western disturbances, faster ventilation and absence of rain and clouds in the north, has improved the air quality in north India. In contrast, calmer conditions in peninsular India allowed pollutants to accumulate.

The study authors stress that these findings highlight the significant impact of global weather patterns as well as climate change on air quality. They urge a long-term strategy to reduce anthropogenic emissions as a way to simultaneously combat air pollution and mitigate climate change. Understanding these links is essential for developing effective strategies to protect our environment and human health.

The results of this study were published in Elsevier.

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