BLACK CARBON AEROSOLS

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Context: The South Asia region adjacent to the Tibetan Plateau has among the highest levels of black carbon emission in the world.

Details:

• Black carbon aerosols have indirectly affected the mass gain of the Tibetan Plateau glaciers by changing long-range water vapour transport from the South Asian monsoon region, a study has found.
• Black carbon aerosols are produced by the incomplete combustion of fossil fuels and biomass, and are characterised by strong light absorption.
• Many studies have emphasised black carbon aerosols from South Asia can be transported across the Himalayas to the inland region of the Tibetan Plateau.
• Researchers noted that black carbon deposition in snow reduces the albedo of surfaces -- a measure of how much of Sun's radiations are reflected -- which may accelerate the melting of glaciers and snow cover, thus changing the hydrological process and water resources in the region.
• Black carbon aerosols in South Asia heat up the middle and upper atmosphere, thus increasing the North­–South temperature gradient.
• Accordingly, the convective activity in South Asia is enhanced, which causes convergence of water vapour in South Asia.
• Meanwhile, black carbon also increases the number of cloud condensation nuclei in the atmosphere.
• These changes in meteorological conditions caused by black carbon aerosols make more water vapour form precipitation in South Asia, and the northward transport to the Tibetan Plateau was weakened.
• As a result, precipitation in the central and the southern Tibetan Plateau decreases during the monsoon, especially in the southern Tibetan Plateau
• The decrease in precipitation further leads to a decrease of mass gain of glaciers.
• From 2007 to 2016, the reduced mass gain by precipitation decrease accounted for 11% of the average glacier mass loss on the Tibetan Plateau and 22.1% in the Himalayas.

Aerosol

• An aerosol is a suspension of fine solid particles or liquid droplets in air or another gas.
• Aerosols can be natural or anthropogenic.
• Examples of natural aerosols are fog or mist, dust, forest exudates and geyser steam.
• Examples of anthropogenic aerosols are particulate air pollutants and smoke.

Black Carbon

• Chemically, black carbon (BC) is a component of fine particulate matter (PM ≤ 2.5 µm).
• It is formed through the incomplete combustion of fossil fuels, biofuel, and biomass.
• Black carbon is a climate forcing agent contributing to global warming.
• It warms the Earth by absorbing sunlight and heating the atmosphere and by reducing albedowhen deposited on snow and ice (direct effects) and indirectly by interaction with clouds.
• Black carbon stays in the atmosphere for only several days to weeks
• The IPCC have posited that reducing black carbon is one of the easiest ways to slow down short term global warming.

https://www.thehindu.com/sci-tech/energy-and-environment/south-asian-black-carbon-aerosols-increase-glacial-mass-loss-over-tibetan-plateau/article66329434.ece