Scientists unpack the influence of black carbon aerosols on rainfall in northeast India

Scientists unpack the influence of black carbon aerosols on rainfall in northeast India

Subject :Environment

Section :Pollution

Context: Understanding the ground realities in the energy transition is key to teasing apart the role of aerosols (mainly black carbon) in tinkering with atmospheric processes including those that drive rain in northeast India.

What is Black Carbon?

• It is formed by the incomplete burning of fossil fuels, biofuels, biomass (caused by human actions) and by natural sources such as wildfires
• It is the dominant form of light-absorbing particulate matter in the atmosphere
• It warms the atmosphere because it absorbs light (solar energy)
• It remains in the atmosphere for just a few days or weeks, compared to a century or more for carbon dioxide
• It is a major short-term contributor to global warming
• It has a heat-trapping power a million times more than carbon dioxide
• It can travel long distances on air currents
• The warming effects of black carbon aerosols are second only to carbon dioxide

What are the sources of Black Carbon?

• Agricultural biomass burning, especially in shifting cultivation practices in hilly regions in northeast India accounts for high black carbon levels
• Other prominent source is travel of black carbon from Indo Gangetic Plain
• Vehicles are the primary sources of black carbon in urban areas
• Residential fuel consumption (in the form of biomass burning and kerosene lamps for lighting) turned out to be the primary source of black carbon in suburban and rural areas

Black carbon influences in northeast India

• Studies shows that rising black carbon emissions lead to a decrease in low-intensity rainfall while pushing up severe rain in the pre-monsoon season in northeast India.
• Presence of higher aerosol amounts suppresses rain formation, which in turn subdues lower-intensity rainfall
• But an increase in black carbon concentration pushed up the moisture levels
• Increased black carbon also helps transfer more moisture to the upper atmosphere.
• It moves the cloud water to the upper atmosphere, where it converts to ice/hail. Melting of ice/hail produces severe rainfall.

Way forward measures to reduce Black Carbon:

• To electrify transportation in urban areas
• Replace coal with renewable
• Upgrade vehicles to the latest auto emission norms (Bharat Stage VI)
• Switch to clean cooking fuels and cleaner brick production technologies
• Enacting new policies later on and incorporating them through regional cooperation among states and neighboring countries (i.e., Nepal, Bhutan, Bangladesh, and Pakistan) can achieve enhanced benefits