BLACK CARBON AEROSOLS

Description

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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.