Air Pollution and Climate Change
Air pollution and climate change are closely interlinked. The main sources of global warming—the extraction and burning of fossil fuels—are not only key drivers of climate change, but are also major sources of air pollutants. Many air pollutants that are harmful to human health and ecosystems also contribute to climate change by affecting the amount of incoming sunlight that is reflected or absorbed by the atmosphere. Climate change mitigation actions can help to reduce air pollution, and clean air measures can help to reduce greenhouse gas emissions, leading to reductions in global warming.
Air pollutants include more than just greenhouse gases, principally carbon dioxide but also methane, nitrous oxide and others. These often interact with each other and are often referred to as climate forcers. Ozone in the atmosphere warms the climate, while different components of particulate matter can have either warming or cooling effects on the climate. Black carbon, a particulate pollutant from combustion, contributes to the warming of the Earth, while particulate sulphates cool the earth's atmosphere.
To illustrate the cause and effect of air pollution and climate change, let us take the example of particulate matter (PM) from diesel engines. This particulate matter is circulated around the globe, ending up in the most remote places, including the polar regions. When it lands on ice and snow it darkens them slightly, leading to less sunlight being reflected back into space, thus contributing to global warming. The slightly warmer temperatures encourage plants in the sub-Artic region to grow a bit bigger, and as they grow through the snow they cast a shadow, which, when multiplied over millions of small plants, also has the effect of darkening the Earth’s surface, leading to further warming.
As per a recent study by researchers from Indian Institute of Tropical Meteorology in Pune, India, air pollution and a rise in west Pacific tropical cyclones have weakened the Indian monsoon in the past few decades. The researchers stated that the greenhouse gas emissions and other human activities can significantly alter the pattern of monsoon flow over the tropical Indo-Pacific Oceans and lead to an increase in tropical cyclones over the west Pacific. Higher frequency of tropical Pacific cyclones can cause a weakening of the monsoon, as it is associated with moisture depletion over India. As per Dr.T.P.Sabin, a senior scientist, the monsoons in India depend upon low level moisture movement from the Indian Ocean towards the Indian sub-continent land. This flow gets weak due to human-induced climate drivers such as greenhouse gases and aerosols. These impact rainfall patterns. Increase in greenhouse gases can intensify rainfall. Aerosol emissions, on the other hand, decrease rainfall. High levels of aerosol in the atmosphere deflect the sun’s heat back into space instead of warming the earth’s surface. This leads to a decrease in the earth’s surface temperature resulting in reduced rainfall. The study concluded that aerosol emissions in the northern hemisphere have contributed to a decline in the monsoon rain over India.
A study done by the World Bank states that PM2.5 from the burning of fossil fuels such as coal combustion or diesel-fueled vehicle emissions is among the most toxic types of PM2.5. Particles from these sources are more damaging to health than particles from most other air pollution sources. Addressing these sources of PM2.5 ,like coal combustion and traffic, would address the most toxic air pollution. Given that these sources are also key contributors to climate warming, tackling air pollution from these sources also mitigates climate change. As per Yewande Awe, a Senior Environmental Engineer at the World Bank, “ Air pollution and climate change are two sides of the same coin, but they are typically addressed separately. They should be tackled jointly, with a focus on protecting peoples’ health – particularly in low- and middle-income countries – to strengthen human capital and reduce poverty.”
Air pollutants include more than just greenhouse gases, principally carbon dioxide but also methane, nitrous oxide and others. These often interact with each other and are often referred to as climate forcers. Ozone in the atmosphere warms the climate, while different components of particulate matter can have either warming or cooling effects on the climate. Black carbon, a particulate pollutant from combustion, contributes to the warming of the Earth, while particulate sulphates cool the earth's atmosphere.
To illustrate the cause and effect of air pollution and climate change, let us take the example of particulate matter (PM) from diesel engines. This particulate matter is circulated around the globe, ending up in the most remote places, including the polar regions. When it lands on ice and snow it darkens them slightly, leading to less sunlight being reflected back into space, thus contributing to global warming. The slightly warmer temperatures encourage plants in the sub-Artic region to grow a bit bigger, and as they grow through the snow they cast a shadow, which, when multiplied over millions of small plants, also has the effect of darkening the Earth’s surface, leading to further warming.
As per a recent study by researchers from Indian Institute of Tropical Meteorology in Pune, India, air pollution and a rise in west Pacific tropical cyclones have weakened the Indian monsoon in the past few decades. The researchers stated that the greenhouse gas emissions and other human activities can significantly alter the pattern of monsoon flow over the tropical Indo-Pacific Oceans and lead to an increase in tropical cyclones over the west Pacific. Higher frequency of tropical Pacific cyclones can cause a weakening of the monsoon, as it is associated with moisture depletion over India. As per Dr.T.P.Sabin, a senior scientist, the monsoons in India depend upon low level moisture movement from the Indian Ocean towards the Indian sub-continent land. This flow gets weak due to human-induced climate drivers such as greenhouse gases and aerosols. These impact rainfall patterns. Increase in greenhouse gases can intensify rainfall. Aerosol emissions, on the other hand, decrease rainfall. High levels of aerosol in the atmosphere deflect the sun’s heat back into space instead of warming the earth’s surface. This leads to a decrease in the earth’s surface temperature resulting in reduced rainfall. The study concluded that aerosol emissions in the northern hemisphere have contributed to a decline in the monsoon rain over India.
A study done by the World Bank states that PM2.5 from the burning of fossil fuels such as coal combustion or diesel-fueled vehicle emissions is among the most toxic types of PM2.5. Particles from these sources are more damaging to health than particles from most other air pollution sources. Addressing these sources of PM2.5 ,like coal combustion and traffic, would address the most toxic air pollution. Given that these sources are also key contributors to climate warming, tackling air pollution from these sources also mitigates climate change. As per Yewande Awe, a Senior Environmental Engineer at the World Bank, “ Air pollution and climate change are two sides of the same coin, but they are typically addressed separately. They should be tackled jointly, with a focus on protecting peoples’ health – particularly in low- and middle-income countries – to strengthen human capital and reduce poverty.”
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