How global warming and air pollution converge

According to NASA, the earth’s average surface temperature in 2018 was the fourth-highest in nearly 140 years of record keeping. It was also the continuation of an unmistakable warming trend. That is because 18 of the 19 warmest years have occurred since 2001.

NASA scientists opined that the results of this warming could be seen in heat waves in Australia, extended droughts and coastal flooding in the United States (US) and in the disappearing Arctic ice.

Scientists have stated that the global record-breaking heat in 2016, including the extreme heat in Asia, happened because of global warming, due to human activities like burning of fossil fuels. Until now, human-driven climate change has been understood to raise the odds of certain floods, droughts, storms and heat waves, but not serve as the sole cause. The 2016 heat marks a fundamental change, according to Jeff Rosenfeld, editor-in-chief of the US scientific journal Bulletin of American Meteorological Society (BAMS).

Wallace Smith Broecker, who brought the term ‘global warming’ into common use, predicted in a 1975 article that rising CO2 levels in the atmosphere would lead to pronounced warming.

Researchers from the University of California suggest that rising temperature increases the concentration of aerosols in the atmosphere that cause air pollution.

Aerosols are tiny solid particles or liquid droplets suspended in the atmosphere. They can come from natural sources like dust or wild fires or human-made sources such as vehicle and industrial emissions. Aerosols affect the climate, including disturbances to the water cycle as well as human health. They also cause smog and other kinds of air pollution that can lead to health problems.

Humans burn fossil fuels, increase carbon dioxide, which in turn, increases temperature. But the carbon dioxide harms human health too, including that of the most vulnerable.

Quoting multiple studies, the UNICEF points out that polycyclic aromatic hydrocarbons, commonly found in areas of high automobile traffic, contribute to a loss of or damage to white matter in the brain. Not only do pollutants harm babies developing lungs; they can permanently damage their developing brains.

Children are highly vulnerable to air pollution because their physical defences and immune systems are not fully developed. According to a recent study by the Department of Pulmonary Medicine, Vallabhbhai Chest Institute, New Delhi, children in the national capital have a far lower lung capacity and lung growth rate than kids of the same age in the US. While much of this could be attributed to genetics and nutrition, environmental factors like air pollution were also to blame.

The study observed that by the time the children reach 18 years of age, the lung capacity of both boys and girls is about 10 per cent lower than American children. The lungs were also found to be growing at a slower rate; so the maximum size they were reaching was smaller.

There are many other studies, especially those conducted on Chinese children which link retarded growth and lower lung capacity due to air pollution. A study in the British journal The Lancet has found that the dose of air pollution older people received when taking a two-hour walk in a congested city street stiffens the arteries and impairs lung function. The study suggests that short term exposure to traffic pollution prevents the cardio-respiratory benefits of physical activity during that time.

The convergence

A recent study from the Massachusetts Institute of Technology suggests for the first time that air pollution is lingering longer over cities and summer storms are becoming powerful. The new study also reveals how the more mundane aspects of weather are being affected by anthropogenic activity.

The problem has to do with how the atmosphere’s changing heat structures, which are directly related to global warming, drive massive weather systems in regions where most people live.

High in the atmosphere, these ‘extratropical cyclones’ are powered by the mix of warm and cool air, and are the force behind blizzards, nor’esters and everyday thunderstorms. While climate change has intensified hurricanes, and increased sea levels, the circulation of these huge weather systems has been weakening. The result is cities swathed for days in pollution and whole regions more vulnerable to sudden torrential storms.

Needless to say, the air pollution level in the Delhi-NCR region remains very high around the year, worsening during the winter. Delhi has witnessed sudden spikes in air pollution levels, leading to a "Very Severe" category in early November. The city has been blanketed with smog, leading to poor visibility and people are advised to stay indoors.

According to the World Health Organization (WHO) Study Report, 2014, Delhi is the most polluted city in the world when it comes to air quality. Vehicular pollution has become a health hazard besides polluting air. It is reported that the number of vehicles in Delhi alone is more than that of Mumbai, Kolkata and Bangalore put together.

According to the WHO Study Report, 2016, there are 32 highly polluting cities in India. Curbing high pollution levels of these cities deserves urgent action from the competent authorities.

The link between global warming and air pollution is becoming clearer with each passing year. It is time we in India also recognise and give it the attention it deserves.

Samar Lahiry is former Advisor to the Planning Commission

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